Benign paroxysmal positional vertigo, or BPPV, is a mechanical issue in the inner ear. It occurs when some of the calcium carbonate crystals (otoconia) that are normally embedded in gel at the utricle become dislodged and migrate to at least one of those 3 fluid-filled semicircular canals, where they are not supposed to be. When enough of these particles accumulate in one of the canals they interfere with the normal fluid motion that these canals utilize to sense head motion, causing the inner ear to send false signals to the mind.
Fluid in the semi-circular canals doesn’t normally react to gravity. However, the crystals do proceed with gravity, thereby shifting the fluid when it normally would be still. When the fluid moves, nerve endings in the canal are eager and send a message to the brain the mind is moving, even though it is not. This false information doesn’t match what another ear is sensing, together with what the eyes are seeing, or with what the joints and muscles are doing, and also this mismatched information is perceived by the brain as a turning sensation, or vertigo, which generally lasts less than one minute. Between vertigo spells some people today feel symptom-free, while some feel a mild sense of imbalance or disequilibrium.
A healthcare professional will execute a collection of tests and evaluations in order to properly diagnose the individual’s BPPV. Regular medical imaging (e.g. an MRI) is not helpful in diagnosing BPPV, because it doesn’t show the crystals which have moved to the semi-circular canals. But when someone with BPPV has their own head moved into a position that produces the dislodged crystals move within a tube, the error signals cause the eyes to move in a very specific pattern, called”nystagmus”.
The nystagmus will possess distinct characteristics that let a trained practitioner to identify which ear the crystals that are displaced are in, and then canal(s) they have moved into. Tests such as the Dix-Hallpike or Roll Tests involve moving the head into specific orientations, allowing gravity to move the dislodged crystals and activate the vertigo while the professional watches for the tell-tale eye movements, or nystagmus.�To execute the Dix-Hallpike test, a healthcare professional will ask the patient to sit on the test table with their legs stretched out. They will then turn the head 45 degrees to one side, which contrasts the right posterior semicircular canal with the sagittal plane of the body, then they are going to allow the patient to lie back quickly, while the eyes are open, so that their head hangs slightly over the edge of the desk.
When the health care provider has finished the diagnosis, then they can perform the appropriate treatment maneuver. The maneuvers make use of gravity to guide the crystals back to the room where they are supposed to be via a very specific series of head movements, commonly referred to as Repositioning Maneuvers. Repositioning maneuvers are highly effective in treating BPPV, inexpensive, and easy to apply.
Dr. Alex Jimenez’s Insights
While the use of surgical interventions as well as that of drugs and/or medications are occasionally recommended to relieve the symptoms associated with benign paroxysmal positional vertigo, or BPPV, they do not treat the underlying health issue. Repositioning maneuvers, like the ones demonstrated below, are considered to be safe yet effective treatment options for BPPV. There is good evidence to support the treatment of BPPV with the Epley maneuver. Although less amounts of research studies have been conducted on other repositioning maneuvers, outcome measures of a variety of patients with BPPV have benefitted from the other treatment options for benign paroxysmal positional vertigo.
Considering that the therapeutic efficacy among maneuvers for every canal is comparable, the option of treatment is generally predicated on clinician preference, complexity of their maneuvers themselves, therapy response to certain maneuvers, as well as musculoskeletal considerations, such as arthritic changes and range of motion of the cervical spine. Below, many repositioning maneuvers are demonstrated, for instance, deep mind hanging maneuver, the Lempert (BBQ) maneuver and the Epley maneuver.
The deep head hanging maneuver is a repositioning maneuver which is used for one of the least common places where BPPV occurs, the superior semi-circular canal, amounting to only about 2 percent of most benign paroxysmal positional vertigo instances. However, the advantage of deep head hanging maneuvers is that they may be effectively performed without knowledge of the side involved. It consists of three steps with four position changes at intervals of approximately 30 seconds.
The deep head hanging maneuver is performed with the patient at the long-sitting position, while the head is brought to a minimum of 30� below the horizontal with the head straight up. When the nystagmus induced by this measure is finished, the head is brought up rapidly to touch the chest while the patient remains supine, and after 30 seconds, the individual has been brought back to a seated position with head flexion maintained. Finally, the patient will be brought back to a neutral head position.
The Lempert maneuver, also referred to as the Barbeque maneuver or the Roll maneuver, is a repositioning maneuver commonly utilized to help treat canilithiasis of the horizontal and lateral canal. It might occur as a complication of posterior canal BPPV treatment repositioning maneuvers. The side with the most notable horizontal nystagmus is assumed to be the affected side.
To perform the Lempert maneuver, the patient should lie supine on the exam table, using the affected ear facing down. Afterward, the healthcare professional will quickly turn the head 90� towards the unaffected side, facing up, waiting 15-20 minutes between each head turn. The medical professional will subsequently turn the head 90� so the affected ear is currently facing up. The next step includes having the individual tuck their arms to their torso, in order to allow the doctor to roll the patient to a more moderate position with their head down. The individual must be turned on their side since the physician rolls their head 90� (returning them to their original position, with the affected ear facing down ). At length, the medical professional should place the patient so that they are face up and bring them into a sitting posture.
Treatment with the Lempert maneuver is efficient approximately 75% of the moment, however, the effectiveness can vary from individual to individual. It is important to keep in mind that longer periods of time between head turns may provoke nausea. This sort of repositioning maneuver shouldn’t be done on patients in which it isn’t safe to move their mind, including in the case of cervical spine injuries.
Epley Maneuver for BPPV
The most common repositioning maneuver for the treatment of benign paroxysmal positional vertigo, or BPPV, is known as the Epley maneuver. The Epley maneuver, occasionally referred to as the canalith repositioning maneuver, is a process which involves a series of head movements, normally performed by a healthcare professional who’s experienced and qualified in the treatment of vestibular disorders, so as to relieve the symptoms associated with BPPV, including dizziness.
The Epley maneuver is performed by placing the patient’s mind at an angle in where gravity can help alleviate the symptoms. Tilting the mind can move the crystals out of the semicircular canals of the inner ear. This means that they will quit displacing the fluid, relieving the dizziness and nausea they may have been causing. In this manner, the Epley maneuver alleviates the symptoms of BPPV. But, it may have to be repeated more than once, as occasionally, some head movements can once again displace the small crystals of the internal ear, once they had been repositions after the first treatment.
Research studies have shown that the Epley maneuver is a safe and effective treatment for the specific vertigo disorder, offering both long-term and immediate relief. The Epley maneuver, named after Dr. John Epley, has been named the canalith repositioning maneuver because it helps to reposition the small crystals at a person’s inner ear, which might be causing the sensation of dizziness.
Repositioning these tiny crystals called otoconia helps to ease BPPV symptoms.�There are two types of BPPV: one where the loose crystals can move freely in the fluid of the canal (canalithiasis), and, more rarely, one where the crystals are thought to be �hung up� on the bundle of nerves that sense the fluid movement (cupulolithiasis).�It is important to make this distinction, as each repositioning maneuver may affect each variant differently. The scope of our information is limited to chiropractic as well as to spinal injuries and conditions. To discuss the subject matter, please feel free to ask Dr. Jimenez or contact us at 915-850-0900 .
Curated by Dr. Alex Jimenez
Additional Topics: Sciatica
Sciatica is medically referred to as a collection of symptoms, rather than a single injury and/or condition. Symptoms of sciatic nerve pain, or sciatica, can vary in frequency and intensity, however, it is most commonly described as a sudden, sharp (knife-like) or electrical pain that radiates from the low back down the buttocks, hips, thighs and legs into the foot. Other symptoms of sciatica may include, tingling or burning sensations, numbness and weakness along the length of the sciatic nerve. Sciatica most frequently affects individuals between the ages of 30 and 50 years. It may often develop as a result of the degeneration of the spine due to age, however, the compression and irritation of the sciatic nerve caused by a bulging or herniated disc, among other spinal health issues, may also cause sciatic nerve pain.
Ankle pain and injury are not issues reserved solely for athletes. In the United States, more than 25,000 people deal with ankle sprains or pain every day. Studies show that somewhere around 40 percent of ankle sprains are not treated correctly or are misdiagnosed, which leads to disability or chronic ankle pain.
When the ankle does not function properly, it can affect the entire body. The muscles on either side of the leg or even under the foot can become sore or painful. This can lead to loss of mobility, an uneven gait, and hip and back pain.
Contents
Anatomy Of The Ankle
Three bones connect to the joint that is the ankle. The lower ends of the tibia (shinbone) and the fibula (lower leg small bone) meet to form a socket that the talus (ankle bone) sits in.
The bottom of the talus rests on the calcaneus (heel bone). There is about an inch-thick lining of somewhat soft cartilage in the joint, which provides shock absorption for carrying body weight, but it is tough and durable so that, provided there is no injury, it will last for a lifetime.
The bones are held together by ligaments and the muscles are attached to the bones by tendons. When there is an injury, it can impact the bone, muscles, tendons and ligaments.
Treatment For Ankle Injury & Pain
The typical treatment for pain, such as with a sprain, is R.I.C.E., which is rest, ice, compression and elevation. A somewhat newer treatment approach replaces the R with an M, meaning that instead of rest, movement is required instead.
However, it is important that the movement is done safely and carefully. Certain types of ankle injuries can be exacerbated by movement so it should be approached with care.
Other types of traditional treatment include varying methods of pain control from ibuprofen to opioids. Severe injuries, such as a torn ligament, may require surgery. When a patient experiences pain, an x-ray is often used to see if there is an injury and to determine the extent of that injury. Sometimes, though an x-ray is not able to see the injury. In such cases, an MRI may be used.
Chiropractic For Ankle Pain
Chiropractic is very effective for treating foot and ankle pain. The chiropractor will begin by assessing the patient�s source of pain and determine what is causing it. They may use x-rays, MRI, CT scan, and other types of diagnostic tools to help them select the best course or treatment.
When an injury is new and the area is inflamed and tender, the course of treatment may include ultrasound, iontophoresis and whirlpool baths. This is in addition to rest, ice, compression and elevation. As it heals, the inflammation subsides and it becomes more stable, chiropractic adjustments to the foot may be introduced.
Chiropractic can help reduce pain without prescription medication and the associated side effects. This alone is often a great draw for many patients. However, there are other benefits that chiropractic can provide for ankle pain.
Regular chiropractic treatment can help strengthen the ankle and increase its stability while increasing mobility and flexibility. Often nerves and soft tissue can become damaged. Chiropractic treatments done on a consistent basis facilitates blood flow, which speeds healing and reduces the chance of injury. It also uses a whole body approach so that the patient can get recommendation on diet and lifestyle changes, such as losing weight or exercising.
Chiropractic care is a very effective therapy for treating ankle pain and injury. It is non-invasive and a natural approach to healing that allows the body to heal itself.
Injury Medical Chiropractic Clinic: Migraine Treatment & Recovery
Auto Accident Injuries: Alfonso J. Ramirez, retired, has been pursuing a life full of health and wellness. Before he began following this type of lifestyle, however, Mr. Ramirez was hit by a car and suffered many injuries. He was treated accordingly at the time but was then referred to Dr. Alex Jimenez for chiropractic care. Once he received his first spinal adjustment, Alfonso Ramirez experienced tremendous relief from his symptoms. Grateful for all the medical services he’s been provided with, Mr. Ramirez expresses how Dr. Jimenez has helped restore his quality of life. Alfonso J. Ramirez recommends Dr. Alex Jimenez as the non-surgical choice for a variety of injuries and conditions.
Auto Accident Injuries Chiropractor
Millions of people are injured in automobile accidents every year, and many of these incidents can unfortunately result in long-term injuries and disability. Even if you are not in immediate pain following a car crash, seeking prompt chiropractic care may help prevent years of chronic pain. Chiropractic care is among one of the most popular ways for treating auto accident injuries. Chiropractic adjustments correct misalignments in the spine and help restore normal function to the nervous system so that the body can heal naturally. A chiropractor can help cure auto accident injuries without drug use. Also, chiropractic care can help with recovery without surgery.
We are blessed to present to you�El Paso�s Premier Wellness & Injury Care Clinic.
As El Paso�s Chiropractic Rehabilitation Clinic & Integrated Medicine Center,�we passionately are focused treating patients after frustrating injuries and chronic pain syndromes. We focus on improving your ability through flexibility, mobility and agility programs tailored for all age groups and disabilities.
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Following upper limb peripheral nerve transection and surgical repair, some patients regain good sensorimotor function while others do not. Understanding peripheral and central mechanisms that contribute to recovery may facilitate the development of new therapeutic interventions. Plasticity following peripheral nerve transection has been demonstrated throughout the neuroaxis in animal models of nerve injury. However, the brain changes that occur following peripheral nerve transection and surgical repair in humans have not been examined. Furthermore, the extent to which peripheral nerve regeneration influences functional and structural brain changes has not been characterized. Therefore, we asked whether functional changes are accompanied by grey and/or white matter structural changes and whether these changes relate to sensory recovery? To address these key issues we (i) assessed peripheral nerve regeneration; (ii) measured functional magnetic resonance imaging brain activation (blood oxygen level dependent signal; BOLD) in response to a vibrotactile stimulus; (iii) examined grey and white matter structural brain plasticity; and (iv) correlated sensory recovery measures with grey matter changes in peripheral nerve transection and surgical repair patients. Compared to each patient�s healthy contralesional nerve, transected nerves have impaired nerve conduction 1.5 years after transection and repair, conducting with decreased amplitude and increased latency. Compared to healthy controls, peripheral nerve transection and surgical repair patients had altered blood oxygen level dependent signal activity in the contralesional primary and secondary somatosensory cortices, and in a set of brain areas known as the �task positive network�. In addition, grey matter reductions were identified in several brain areas, including the contralesional primary and secondary somatosensory cortices, in the same areas where blood oxygen level dependent signal reductions were identified. Furthermore, grey matter thinning in the post-central gyrus was negatively correlated with measures of sensory recovery (mechanical and vibration detection) demonstrating a clear link between function and structure. Finally, we identified reduced white matter fractional anisotropy in the right insula in a region that also demonstrated reduced grey matter. These results provide insight into brain plasticity and structure-function-behavioural relationships following nerve injury and have important therapeutic implications.
Following upper limb peripheral nerve transection and surgical repair (PNIr), ?25% of patients have not returned to work 1.5 years after surgery (Jaquet et al., 2001). In addition, ?57% of patients with nerve injuries are between 16�35 years of age (McAllister et al., 1996); thus, a long life of disability and economic difficulties may accompany upper limb nerve transection. Understanding the central and peripheral ramifications of peripheral nerve injury may facilitate the development of new therapeutic strategies and intervention programs.
It is not known how the brain responds to PNIr in humans. However, animal studies have established that plasticity within the somatosensory cortex begins immediately following peripheral nerve transection, and that 1 year after complete nerve transection and surgical repair, cortical maps contain patchy, non- continuous representations of the transected and adjacent nerves (Wall et al., 1986). The mechanisms that facilitate functional plasticity are thought to include the immediate unmasking of pre-existing projections from adjacent cortical and subcortical levels, and long term sprouting of axons at multiple levels of the neuroaxis, including the primary somatosensory cortex (S1) (Florence and Kaas, 1995; Hickmott and Steen, 2005).
Human brain imaging studies have corroborated the findings from animal models with the identification of altered functional MRI activation maps due to spinal cord injury, amputation, toe- to-thumb transfer, and in patients with carpel tunnel syndrome (Lotze et al., 2001; Manduch et al., 2002; Jurkiewicz et al., 2006; Napadow et al., 2006). Furthermore, structural MRI studies have recently visualized grey and white matter changes following traumatic injuries and in diverse pathological conditions, including limb amputation and chronic pain (Apkarian et al., 2004; Draganski et al., 2006; Davis et al., 2008; Geha et al., 2008; May, 2008). Grey matter changes are thought to be related to changes in cell size, atrophy and/or loss of neurons or glia, whereas white matter changes are impacted by axonal degenera- tion and loss of myelin (Beaulieu, 2002; May, 2008).
A powerful approach to delineate mechanisms of pathology and plasticity is to combine functional and structural grey and white matter imaging techniques. We previously reported that patients with complete upper limb PNIr retained profound somatosensory deficits that persist 41.5 years following surgery (Taylor et al., 2008a). Based on these findings, we reasoned these patients would exhibit functional and structural brain changes in key somatosensory brain areas. Therefore, in this study, we hypothesized that PNIr patients would have: (i) reduced blood oxygen level dependent (BOLD) responses to vibratory stimulation of the transected nerve territory, in the region of S1 that represents the injured upper limb and in the secondary somatosensory cortex (S2); (ii) a corresponding reduction in cortical thickness in these regions of the contralesional S1 and S2; (iii) a correlation between changes in cortical thickness and psychophysical measures of somatosensory function (vibration and touch detection thresh- olds); and (iv) reduced fractional anisotropy (a measure of white matter integrity) in white matter feeding into/out of these somatosensory cortical areas.
Methods
Subjects
We recruited 27 patients with complete transection of the median and/or ulnar nerve followed by surgical repair from plastic surgeons affiliated with the University of Toronto Hand Program between June 2006 and May 2008. From this larger cohort, 14 pain-free patients (three females, 11 males; 34 ? 10 years) with complete transection of the right median and/or ulnar nerve were included in the study [to avoid confounds related to the presence of pain and laterality patients with pain (n=6) and left sided lesions (n=7) were excluded from this analysis]. All patients underwent microsurgical nerve repair at least 1.5 years prior to study enrolment (recovery time varied from 1.5 to 8 years). In addition, we recruited 14 age- and sex-matched healthy controls (3 females, 11 males; 34 ? 10 years). All subjects gave informed written consent to procedures approved by the University Health Network Research Ethics Board. All subjects were right handed (determined using the Edinburgh handedness inventory: Oldfield, 1971) and had no history of neurological injury or chronic pain (either before or after nerve transection). See Table 1 for demographic details.
Study Design
All subjects participated in an imaging session that included: (i) functional magnetic resonance imaging (fMRI) in response to vibrotactile stimuli applied to the right index finger (within the median nerve territory); (ii) a high-resolution anatomical scan of the whole brain, acquired for image registration and for the analysis of cortical grey matter; and (iii) two diffusion tensor imaging scans for the assessment of white matter integrity. Prior to imaging, subjects were instructed in the basic design of the experiment and reminded to remain as still as possible throughout the duration of the scan.
Subjects were free to withdraw from the study at any time. In addition, a sensory and motor assessment was performed for all subjects (Taylor et al., 2008a). As touch and vibration detection thresholds were correlated with cortical thickness a description of these methods is included below (other psychophysical measures will be reported elsewhere).
Vibration Threshold
Vibration detection thresholds were determined using a hand held Bio-Thesiometer (Bio-Medical Instrument Company, USA). The device has a 12-mm probe that was placed on the distal phalanx of the right index finger (D2). Thresholds were determined using the method of limits: the amplitude (voltage) was gradually increased until the subject indicated that they perceived the stimulus. Vibration thresholds were acquired three times and an average value was calculated. During vibration threshold testing, subjects were instructed to close their eyes and rest the back of their hand on a supportive cushion.
Mechanical Detection Threshold
Mechanical detection thresholds were determined using a standardized set of von Frey filaments (OptiHair2 Marstock Nervtest, Germany) containing 12 logarithmically spaced calibrated filaments that delivered forces from 0.25�512 mN. The contact surface diameter of all 12 filaments was ~0.4mm. Trials were conducted with the subject�s eyes closed and hands resting on a soft cushion. Probes were applied in an ascending series and subjects were required to make a response every time they felt a probe touch the right D2 fingertip. This process was repeated three times. The force for the filament that was detected in at least two of three trials was reported as that subject�s mechanical detection threshold.
Nerve Conduction Testing
Patients participated in bilateral sensory and motor nerve conduction studies at the Toronto Western Hospital electromyography (EMG) clinic. For motor nerve conduction, the stimulating electrode was placed at the wrist and elbow (separately) and the recording electrode was placed over the abductor pollicis brevis, for median nerve assessment, or the abductor digiti minimi for ulnar nerve assessment. For sensory nerve testing the recording electrode was placed at the wrist and the stimulating electrode was placed at digits D2, D3 and D5. A senior, experienced neurologist from the Toronto Western Hospital EMG Clinic (Dr Peter Ashby) reviewed all clinical assessments to deter- mine which nerves demonstrated normal/abnormal responses. As amplitude and latency measures are known to vary substantially between subjects (due to factors such as the density of innervation, the depth of the nerve and the thickness of an individual subject�s skin) (Kimura, 2001) each patient�s untransected nerve served as their own control for comparison with values from the transected side. In those patients with detectable nerve conduction responses, paired t-tests were performed to assess the difference in latency or amplitude measures between each patient�s transected and contralesional untransected nerves.
Imaging Parameters
Brain imaging data were acquired using a 3T GE MRI system fitted with an eight-channel phased array head coil. Subjects were placed supine on the MRI table and each subjects� head was padded to reduce movement. Whole-brain fMRI data was acquired using echo planar imaging (28 axial slices, field of view (FOV) = 20 x 20 cm, 64 x 64 matrix, 3.125 x 3.125 x 4mm voxels, echo time (TE) = 30 ms, repetition time (TR) = 2000 ms). The scan time was 5 min and 8 s (154 frames). During scanning, a non-painful, 12 Hz vibrotactile stimulus was applied to the distal phalanx of the right D2 using balloon diaphragms driven by compressed air (Device man- ufactured by Dr Christo Pantev; www.biomag.uni-muenster.de). Stimuli were delivered in blocks of 10s interleaved with 20s of rest, for a total of 10 blocks of stimulation and 10 blocks of rest. The first 8 s (4 TRs) of data acquired from each run were discarded to allow for fMRI signal equilibration. Subjects were instructed to keep their eyes closed throughout scanning and focus on the stimuli. A whole brain three dimensional (3D) high-resolution anatomical scan (124 sagittal slices, 24 x 24 cm FOV, 256 x� 256 matrix, 1.5 x 0.94 x 0.94 mm voxels) was acquired with a T1-weighted 3D spoiled gradient echo sequence (one signal average, flip angle = 20? , TE ?5 ms). In addition, two diffusion tensor imaging scans (38 axial slices, FOV 24 x 24 cm, 128 x 128 matrix, 1.875 x 1.875 x 3 mm voxels) were acquired along 23 directions with a b-value of 1000smm�2. Each run also contained two volumes with no diffusion weighting.
fMRI Analysis
Data were analysed using Brainvoyager QX v1.8 (Brain Innovaton, Maastricht, Netherlands). Pre-processing included: 3D motion correction, slice scan-time correction, linear trend removal, high-pass filtering (five cycles per run), and spatial smoothing with a 6mm full width at half maximum (FWHM) Gaussian kernel. fMRI data sets were interpolated to 3 x 3 x 3 mm voxels, registered to the high-resolution ana- tomical image, and normalized to standard Talairach space (Talairach and Tournoux, 1988). Voxels are reported as 1 x 1 x 1 mm. Data were analysed using the general linear model; the model was obtained by convolving the boxcar function of the time course of tactile stimulation with the standard haemodynamic response function. To identify between group differences in activation patterns a fixed effects analysis was performed with the contrasts: (i) healthy controls: stimulation 4 rest; (ii) PNIr: stimulation 4 rest; and (iii) healthy controls 4 PNIr. Activation maps were thresholded at a corrected value of P50.05 (derived from an uncorrected P50.0001 and 120mm3 contiguous voxels as previously reported: Taylor and Davis, 2009); this was also validated by running a Monte Carlo Simulation with AlphaSim application implemented in the Analysis of Functional Neuroimage (AFNI) software. This analysis included only the 11 patients that sustained transection of the right median nerve (n=9) or the right median and ulnar nerve (n = 2) (i.e. the three patients with a pure right ulnar nerve transection were not included in this analysis).
Cortical Thickness Analysis
Cortical thickness analysis was performed using Freesurfer (http:// surfer.nmr.mgh.harvard.edu); methods have been outlined in detail elsewhere (Dale et al., 1999; Fischl et al., 1999a, b; Fischl and Dale 2000). Briefly, high-resolution T1-weighted anatomical data sets were registered to the Talairach atlas (Talairach and Tournoux, 1988). This was followed by intensity normalization, skull stripping and separation of the hemispheres. Subsequently, the white/grey matter (called the white surface) and grey/CSF (called the pial surface) boundaries were identified and segmented. The distance between the white and pial surfaces was then calculated at every point in each hemisphere of the brain. To identify group differences between the 14 patients and 14 age/sex-matched controls, a general linear model analysis was performed at every point on the brain. As individual�s cortical topography is inherently heterogeneous, a 5mm FWHM spatial smoothing kernel was applied prior to statistical analysis. Data are displayed at a corrected P50.05 (derived from an uncorrected P50.0075 and 102 contiguous vertices); this was calculated by running a Monte Carlo simulation with AlphaSim. A vertex represents a point on a two dimensional sheet, and, in this study, the distance between two vertices is 0.80mm2.
As patients exhibited significant deficits in somatosensory function within the transected nerve territory, we hypothesized that measures of somatosensory function (vibration and touch detection) would correlate with cortical thickness in the contralesional post-central gyrus (primary and secondary somatosensory cortices). Therefore, we performed correlation analyses in the patient group between: (i) cortical thickness and vibration detection threshold; and (ii) cortical thickness and touch detection thresholds. One patient did not complete psychophysical assessment; therefore, this analysis included 13 PNIr patients. In addition, to determine if there was a relationship between cortical thickness and recovery time a correlation analysis was also performed between these two measures. These correlation analyses were restricted to the contralesional post-central gyrus by including a mask (taken from Freesurfer�s built in atlas) in the general linear model. A Monte Carlo simulation was performed that was restricted to the number of vertices within contralesional post-central gyrus; images are displayed with a corrected P50.05 (derived from an uncorrected P50.0075 and 68 contiguous vertices).
Diffusion Tensor Imaging Analysis
Diffusion tensor image processing was performed with DTiStudio (www.MriStudio.org) and FSLv.4.0 (www.fmrib.ox.ac.uk/fsl/). Images were first realigned with the Automatic Image Registration tool implemented in DTiStudio, using the first B0 image in the first series acquired as the template. This process corrects for subject motion and eddy-current distortion. All images were then inspected visually to assess image quality and the alignment of the separate diffusion tensor imaging runs. If an artefact was detected, the slice was removed prior to calculating the average of the two separate diffusion tensor imaging runs. Individual FA maps were calculated using the DTIFIT tool implemented in FSL. Voxel-wise statistical analysis was performed to identify group differences in the mean fractional anisotropy using Tract Based Spatial Statistics; for a full description of these methods see Smith et al. (2006). Briefly, images were non-linearly registered to a target image (MNI152), the mean image was then created from all datasets and this image was subsequently thinned to represent all tracts that were common to all subjects. Each subject�s highest fractional anisotropy values were then projected onto the skeleton by searching in white matter perpendicular to each point on the white matter skeleton. A whole-brain voxel-wise statistical analysis was then performed between groups (14PNIr and 14 healthy controls) and images were whole brain corrected at P50.05. In addition, a region of interest analysis was performed in white matter tracts adjacent to the contralateral S1, thalamus and bilateral anterior and posterior insula. These regions were chosen as they have previously been implicated in aspects of somatosensation and because they correspond with regions that were identified in the fMRI and cortical thickness analysis (CTA) group analyses. Regions of interest were drawn on the white matter skeleton as follows: (i) The contralateral S1 region of interest originated medially at the junction between the white matter skeleton of the corona-radiata and the skeleton section feeding into the post- central gyrus; terminating at the end of the tract within a given slice.
In the z direction the region of interest extended from z=49 to 57; white matter tracts supplying the hand region. (ii) The contralateral thalamus region of interest was restricted to white matter tracks surrounding the posterior and medial thalamic nuclei (nuclei involved in somatosensory function), extending from z = �1 to 4. (iii) Insular regions of interest were drawn bilaterally within white matter adjacent to the anterior and posterior insula based on criteria previously published by our lab (Taylor et al., 2008b). The region of interest extended from z = 2 to 8. Fractional anisotropy values were extracted from each of these regions of interest and a multivariate analysis of variance (MANOVA) was performed using the Statistical Package for the Social Sciences v13.0 (SPSS Inc, Chicago), which included fractional anisotropy values for all six regions of interest.
Results
Table 1 provides demographic details for study participants. All 14 patients sustained a complete transection of the right median and/or ulnar nerve followed by microsurgical repair at least 1.5 years prior to study enrolment. The time from surgery to testing ranged from 1.5 to 8 years with a mean (?SD) of 4.8 ? 3 years. Patients and controls did not (34 ? 10 years both groups; t = 0.04; P = 0.97).
Psychophysics
Vibration thresholds were calculated from all three measurements since one-way repeated measures analysis of variance (ANOVA) indicated no significant differences between the three trials [F (25, 1)=0.227, P=0.64]. Vibration and mechanical detection thresh- olds were significantly impaired in PNIr patients compared to healthy controls (vibration: t = 4.77, P50.001, Fig. 3A; mechanical: t=3.10, P=0.005, Fig. 3D).
Nerve Conduction Testing
Amplitude and latency measures obtained from each patient�s contralesional nerves were classified as normal by an experienced neurologist at the Toronto Western Hospital EMG Clinic. Nine of the 14 patients completed nerve conduction testing. Table 2 displays the average increase/decrease latency and amplitude data for sensory nerve conduction from the wrist to the abductor pollicis brevis (median) or abductor digiti minimi (ulnar) muscles and for sensory conduction from the wrist to D2 (median) and D5 (ulnar) compared to each patients uninjured contralesional nerve. Out of nine, seven patients had transections that included the median nerve. Of these seven, one patient had no detectable response during motor testing and another patient had no detectable response during sensory testing.
In the six patients with detectable responses, motor conduction latencies were increased by 43% (t=6.2; P=0.002) and amplitudes were decreased by 38% (t=�2.6; P=0.045) when each patient�s transected nerve was compared to their non-injured side. Sensory conduction in median nerves also revealed a 26% increase in latency (t=3.9; P=0.011) and a 73% decrease in amplitude (t=�8.0; P=0.000) compared to normal contralesional nerves. In the four patients with ulnar nerve transections one patient had no detectable response during sensory nerve testing. In those patients with responses, ulnar nerve motor latencies were not significantly elevated (t = 2.8; P = 0.070); however, amplitudes were significantly
decreased by 41% (t = �5.9; P = 0.010). Sensory testing of the ulnar nerve demonstrated a 27% increase in latency (t = 4.3; P = 0.049) but no significant increase in amplitude (t = 3.5; P = 0.072).
Functional Plasticity In The Primary Somatosensory Cortex
Functional MRI maps were calculated from the 11 PNIr patients with right median nerve transections (patients with ulnar nerve transections were excluded from this analysis) and 11 age- and sex-matched healthy controls. From Fig. 1A, it is clear that PNIr patients have significantly less activation, compared to healthy controls, in a region of S1 corresponding to Brodmann area 2 (BA2) (Talairach and Tournoux, 1988) and S2 (see Table 3 for details). The average event-related responses from these regions of interest highlight the attenuated BOLD response within the patients� left BA2 and left S2 (Fig. 1B and C, respec- tively). Curiously, vibrotactile stimulation in the patients activated a more superior part of the post-central gyrus (probably BA1/3) (Talairach and Tournoux, 1988) (Fig. 1A and Table 3). An event- related average (Fig. 1D) demonstrates that healthy controls had minimal activation in this region. Furthermore, patients had significantly more activation in brain regions collectively known as the task positive network (asterisks in Fig. 1). See Table 3 for the full list of task positive brain areas activated. This network includes lateral prefrontal, lateral parietal, premotor and inferior temporal cortices (Table 3): brain areas that are activated during the performance of an attention demanding task and suppressed or inactive during rest or tasks that are not cognitively or attentionally challenging (Fox et al., 2005; DeLuca et al., 2006; Seminowicz and Davis 2007).
Reduced Grey Matter In The Primary Somatosensory Cortex Correlates With Sensory Recovery
Cortical thickness analysis in all 14 patients and 14 age/ sex-matched healthy controls revealed several loci of significant cortical thinning in the PNIr group (Fig. 2 and Table 4). Specifically, patients had a 13%�22% reduction in cortical thick- ness in the left (contralesional) S1, S2, pregenual anterior cingulate gyrus, ventrolateral prefrontal cortex and right anterior insula, anterior/posterior mid cingulate gyrus and paracentral lobule. Interestingly, the locations of grey matter thinning within the post-central gyrus coincide with the regions of reduced BOLD following vibrotactile stimulation (Table 4). Since we had prior knowledge of the patients� sensory deficits and recovery time (i.e. time since microsurgical repair), we next asked whether the patients� cortical thickness in the post-central gyrus correlated with their sensory mechanical and vibration detection thresholds, or with their recovery time. These analyses revealed a negative correlation between cortical thickness and vibration detection thresholds in a region encompassing BA1/2 and S2 (P50.001, r=?0.80 and ?0.91, for BA1/2 and S2, respectively; Fig. 3 and Table 5). In addition, mechanical detection thresholds were also negatively correlated with cortical thickness in a slightly more superior BA2 region and the same S2 region (P50.001, r = ?0.83 and ?0.85, for BA2 and S2, respectively; Fig. 3 and Table 5). However, we did not identify a significant relationship between recovery time and cortical thickness. Therefore, in the post-central gyrus cortical thinning was associated with more severe sensory deficits. However, we did not identify a significant relationship between recovery time and cortical thickness. Again, there was a correspondence between the cortical thinning in areas negatively correlated with vibratory stimuli and the regions showing group fMRI and CTA abnormalities.
White Matter Abnormalities Following Nerve Transection
To assess white matter integrity we utilized a region of interest approach to examine white matter group differences based on a priori hypotheses. Regions of interest were restricted to white matter tracts surrounding and feeding into the contralesional S1 and thalamus. In addition, we also drew regions of interest in white matter adjacent to left and right, anterior and posterior insula. The insula was chosen as it is implicated in somatosensory processing and because we identified reduced grey matter in the right anterior insular with CTA. This region of interest approach revealed that patients had significantly reduced white matter fractional anisotropy values (MANOVA including all six regions of interest) adjacent to the right anterior [F (1, 26) = 4.39, P = 0.046; Fig. 4A] and posterior insula [F (1, 26) = 5.55, P = 0.026; Fig. 4B], but there were no group differences in the white matter adjacent to the left insula (left anterior insula: P = 0.51; left posterior insula: P=0.26), thalamus (P=0.46) or S1 (P=0.46).
Discussion
Here, we have demonstrated for the first time that there is functional plasticity and both grey and white matter structural abnormalities in several cortical areas following upper limb peripheral nerve transection and surgical repair. This plasticity may arise from incomplete peripheral nerve regeneration (peripheral cell death and/or incomplete re-myelination), as nerve conduction measures in these patients demonstrated severe abnormalities. In addition, our data demonstrate that decreased vibrotactile-evoked fMRI responses in the post-central gyrus correspond with grey matter thinning in the patient group. These results suggest that reduced BOLD responses may be facilitated by a reduction in cortical grey matter and/or a decrease in the afferent input to the post-central gyrus. In addition, cortical thickness within these same parts of the post-central gyrus negatively correlated with behavioral measures of somatosensory function. That is, increased somatosensory deficits were correlated with thinner cortex; both of which may be related to afferent input. Taken together, our data suggest that incomplete peripheral nerve regeneration contributes to somatosensory impairments, cortical grey matter atrophy and reduced fMRI activation (see Fig. 5 for a summary of these findings).
It is well known that cortical plasticity following peripheral nerve transection and surgical repair can occur throughout the CNS in non-human primates (Kaas, 1991). This plasticity is thought to be due to the unmasking of previously silent synapses or axonal sprouting into deafferented territory (Wall et al., 1986; Florence and Kaas, 1995). In the primate model, 1 year following nerve transection and surgical repair, the denervated cortex is characterized by incomplete and disorderly representations of the regenerated and adjacent (intact) nerves. This patchy representation is attributed to incomplete peripheral regeneration resulting in a partial recovery of the denervated cortical space (Kaas, 1991). To assess the extent of peripheral regeneration in our patient population we performed sensory and motor nerve conduction studies across the transected area. Our nerve conduction results demonstrate that PNIr patients have significantly decreased amplitude and increased latency in both sensory and motor nerves compared to their own untransected side. Decreased amplitude combined with increased latency is indicative of peripheral fibre loss (i.e. cell death) and/or abnormal or incomplete re-myelination following transection (Kimura, 1984). In addition, it is well established that between 20% and 50% of dorsal root ganglion neurons die following nerve transection (Liss et al., 1996). Thus, afferent cell death and incomplete regeneration can result in decreased afferent input to the cortex, which may account for ongoing sensory deficits and decreased BOLD response in BA2 and S2. Furthermore, this diminished afferent input could also account for the cortical thinning we observed in the same regions of the cortex. Sensory deprivation has been shown to cause trans- neuronal degeneration in several regions of the CNS, including the dorsal horn following sciatic nerve section (Knyihar-Csillik et al., 1989), and may involve second- and third-order neurons (Powell and Erulkar, 1962). Transneuronal degeneration is characterized by cell shrinkage and is thought to be related to decreased, or non-existent, afferent input (Knyihar-Csillik et al., 1989). Thus, cortical grey matter loss (or atrophy) could also be directly related to decreased afferent input.
We also demonstrated increased activation in the post-central gyrus in a region corresponding to BA1/3 (Talairach and Tournoux, 1988). Electrophysiological, anatomical tracing and neuroimaging studies have established that for the majority of cutaneous mechanoreceptive afferents the first cortical destina- tions are BA1 and BA3b. These cytoarchitectonic brain areas each possess a somatotopic body map with small receptive fields. In addition, these areas respond to many features of tactile information, such as texture and roughness, velocity and curvature of stimuli (Bodegard et al., 2001). fMRI studies have demon- strated that activity within the somatosensory cortex is influenced by attention such that fMRI responses to tactile stimuli in S1 are increased when subjects attend to a tactile stimulus, but are atte- nuated when subjects are distracted (Arthurs et al., 2004; Porro et al., 2004). Furthermore, our patients activated a network of brain areas known as the task positive network (DeLuca et al., 2006) more than healthy controls. These brain areas are activated during attention demanding processes (Fox et al., 2005; Seminowicz and Davis, 2007). Together, these findings imply that patients must attend to the stimulus more than controls because of their impaired sensory input. This increased attention may also account for the increased activation in BA1/3b. Of course, the increased activation in BA1/3b may also reflect plasticity that is unrelated to attentional load.
BA2 and S2 both receive projections from BA1/3b and also from distinct parts of the ventroposterior thalamic complex (Pons et al., 1985; Friedman and Murray, 1986). Both of these brain areas have large, often multi-digit (BA2) or bilateral (S2) receptive fields (Pons et al., 1985; Iwamura et al., 2002). Based on ana- tomical projections and neuronal response properties, hierarchical processing of tactile information has been demonstrated from BA1/3b to BA 2 (Kaas et al., 2002). In addition, electrophysiolo- gical studies in macaques (Pons et al., 1987) and magnetoence- phalography data acquired in humans, suggest that serial processing of tactile inputs occurs from S1 to S2 in higher primates (Frot and Mauguiere 1999; Disbrow et al., 2001). Several studies have demonstrated that BA2 is preferentially activated by shape and curvature (Bodegard et al., 2001), while S2 may be involved in tactile learning (Ridley and Ettlinger 1976; Murray and Mishkin, 1984), supporting the notion that these brain areas are involved in higher-order somatosensory processing. Our psychophysical assessment demonstrated that patients were significantly impaired at the detection of simple tactile stimuli, and in the Shape Texture Identification test 1.5 years after surgery (Taylor et al., 2008a). This latter test assesses a patient�s ability to recognize character- istics of an object while actively exploring a shape or texture, requiring the integration of sensory information across regions of the body (Rosen and Lundborg, 1998). Taken together, one inter- pretation of our data is that PNIr patients attend more to the vibrotactile stimulus, leading to increased activation of the task positive network and BA1/3. However, in these patients, our data imply that higher-order processing areas, such as BA2 and S2, did not receive tactile information, which, in turn, may result in cortical thinning and reduced BOLD responses.
The insula is thought to play a role in integrating multimodal information important for sensorimotor, emotional, allostatic/ homeostatic and cognitive functions (Devinsky et al., 1995; Critchley, 2004; Craig, 2008) and has been designated a limbic sensory cortex (Craig, 2008). Several studies have reported insular activation in response to tactile stimulation (Gelnar et al., 1998;
Downar et al., 2002) and anatomical tracing studies in primates have demonstrated that the insula is reciprocally connected to frontal, parietal and temporal lobes (Augustine, 1996). In our patients, the right anterior insula was the only cortical area that demonstrated significant cortical thinning in conjunction with reduced fractional anisotropy values in the adjacent white matter, suggesting that the cortical thinning within this region is associated with a loss of fibres projecting to or from this structure. The right anterior insula has been implicated in interoception as it is situated to integrate homeostatic input from the body with motivational, emotional and social conditions (Craig, 2008). Furthermore, Critchley et al. (2004) reported a correlation between interoceptive abilities and the grey matter volume of the right anterior insula. Given our finding that the patients have decreased grey matter in the right anterior insula, it would be of interest to assess interoceptive capabilities following peripheral nerve injury in a future study.
Taken together, we have demonstrated for the first time that functional and structural alterations are present in the human cerebral cortex 1.5 years after a complete transection of an upper limb peripheral nerve that was microsurgically repaired. In addition, nerve conduction measures indicate incomplete peripheral regeneration in these patients. Furthermore, we show that cortical thickness is related to psychophysical measures of recovery, in that thinner cortex within BA2 and S2 was associated with poorer somatosensory function. These data suggest that the reestablishment of normal functional activation maps is directly associated with the successful regeneration of peripheral afferents.
Keri S. Taylor,1,2 Dimitri J. Anastakis2,3,4 and Karen D. Davis1,2,3
1 Division of Brain, Imaging and Behaviour � Systems Neuroscience, Toronto Western Research Institute, University Health Network, Toronto, Canada M5T258
2 Institute of Medical Science, University of Toronto, Canada
3 Department of Surgery, University of Toronto, Canada
4 Clinical Studies Resource Centre, Toronto Western Research Institute, University Health Network, Toronto, Canada M5T2S8
Correspondence to: Karen D. Davis, Ph.D.,
Division of Brain, Imaging and Behaviour � Systems Neuroscience, Toronto Western Research Institute,
Toronto Western Hospital,
University Health Network,
Room MP14-306, 399 Bathurst Street,
Toronto, Ontario,
Canada M5T 2S8
E-mail: kdavis@uhnres.utoronto.ca
Acknowledgements
The authors thank Mr. Geoff Pope, Dr. Adrian Crawley, Mr. Eugene Hlasny and Mr. Keith Ta for expert technical assistance. The authors would like to thank Dr. Peter Ashby and Mr. Freddy Paiz from the Toronto Western Hospital EMG Clinic for conduct- ing the nerve conduction tests and for providing expert assess- ment of the findings. The authors also thank Drs Dvali, Binhammer, Fialkov and Antonyshyn for collaborating with this project. Dr. Davis is a Canada Research Chair in Brain and Behaviour (CIHR MOP 53304).
Funding
The Physicians� Services Incorporated and a joint seed grant from the University of Toronto Centre for the Study of Pain/ AstraZeneca.
Supplementary material
Supplementary material is available at Brain online.
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Epigenetic: A fine interplay exists between sensory experience and innate genetic programs leading to the sculpting of neuronal circuits during early brain development. Recent evidence suggests that the dynamic regulation of gene expression through epigenetic mechanisms is at the interface between environmental stimuli and long lasting molecular, cellular and complex behavioral phenotypes acquired during periods of developmental plasticity. Understanding these mechanisms may give insight into the formation of critical periods and provide new strategies for increasing plasticity and adaptive change in adulthood.
Contents
Introduction
During early development, neuronal circuits are created and connections between neurons undergo remodeling as they develop their adult functional properties in response to the surrounding environment. The adult brain loses this extraordinary plasticity. Recent findings support a key role of epigenetic factors in mediating the effects of sensory experience on site-specific gene expression, synaptic transmission, and behavioral phenotypes. Here we review recent evidence implicating multiple epigenetic mechanisms in experience-dependent changes during development and discuss their role in critical period expression in the developing and adult brain.
Epigenetics: Molecular Mechanisms Of Gene Regulation
The term �epigenetic� refers to chromatin modifications which alter gene expression without affecting DNA sequence. The factors that contribute to the epigenetic regulation of transcriptional activity are numerous and include microRNA [1], DNA methylation [2,3] and post- translational modifications of nucleosomal histones [2,4]. DNA methylation refers to a chemical modification to DNA whereby cytosine is converted to 5-methylcytosine with the consequence of reduced accessibility of the DNA to transcription factors (Figure 1a�d). These modi- fications can be stable and heritable and provide a critical mechanism in cellular differentiation [3]. The process of methylation is dependent on the presence of methyl donors (provided by nutrients such as folic acid, meth- ionine and choline) and methyltransferases which med- iate either maintenance (i.e. DNMT1) or de novo DNA methylation (i.e. DNMT3). Transcriptional repression associated with DNA methylation is further sustained through methyl-binding proteins such as MeCP2 [5]. Epigenetic control of gene expression is also mediated through multiple post-translational modifications of histone proteins, including methylation, acetylation and ubiquination, which can alter the accessibility of DNA and the density of chromatin structure (Figure 1e,f). In particular, histone acetylation is associated with increased transcriptional activity whereas histone deacetylation is associated with transcriptional repression. The acetylation state of these nucleosomal proteins is controlled by the presence of histone acetyltransferases (HATs), histone deacetylases (HDACs), which are recruited by methyl-binding proteins, and by HDAC inhibitors, which effectively increase gene expression through shifting histones to an acetylated state [2,6]. The timing and degree of gene expression are controlled through these complex mechanisms, thus providing a link between single genotypes and multiple phenotypes.
Epigenetic Factors & The Influence Of Early Life Experiences
In mammalian development, the prenatal and postnatal periods are characterized by rapid changes in neuronal organization, thus providing a critical window of opportunity during which environmental experiences can lead to long-term influences on brain and behavior. There is increasing evidence for the role of epigenetic factors in mediating the relationship between these experiences and long-term outcomes. Mueller and Bale [7] have recently demonstrated decreased DNA methylation of the corticotrophin-releasing-factor (CRF) gene promotor and increased methylation of the glucocorticoid receptor (GR) exon 17 promotor region in hypothalamic tissue of adult male mice born to gestationally stressed females. These epigenetic modifications are associated with exposure to stress during the early stages of prenatal development and may involve dysregulation of placental gene expression. The nutritional environment during fetal development has likewise been demonstrated to influence growth, metabolism and brain development and there is increasing evidence that dietary levels of methyl-donors can epigenetically alter gene expression in offspring [8,9]. In rats, Lillycrop et al. [10] illustrate that GR 110 and PPARa (peroxisome proliferator-activated receptor alpha) gene promotor methylation is reduced in the hepatic tissue of offspring born to protein restricted dams whereas methylation is increased in offspring of dams whose diet is supplemented with methyl donors [10,11]. These effects may be related to DNMT1 expression, which is likewise decreased with dietary protein restriction [11]. Prenatal nutritional regulation of DNA methylation has similarly been observed in brain tissue associated with levels of DNMT1 expression [12], suggesting that in the rapid period of cell division ocurring during fetal development, the level of methyl donors can have a significant impact on transcriptional activity that is maintained into adulthood.
The role of epigenetic modification in sustaining the effects of environmental experience has also been demonstrated in the context of postnatal mother�infant interactions. Individual variations in maternal care during the immediate postpartum period in rats are associated with changes in offspring hypothalamic-pituitary-adrenal (HPA) activity, neuroendocrine systems involved in reproduction and hippocampal plasticity [13]. Analyses of levels of promotor methylation within the hippocampal GR 17 and hypothalamic ERa genes in offspring of rat dams that provide high vs. low levels of maternal care indicate that high levels of care are associated with decreased promotor methylation and thus increased gene expression [14,15]. Though the route through which these epigenetic changes are mediated is not yet clear, there is evidence for increased binding of nerve growth factor-inducible protein A (NGFI-A) to the GR exon 17 promoter amongst offspring who receive high levels of care in infancy [15] and in vitro models suggest that NGFI-A up-regulation is associated with histone acetylation, DNA demethylation, and activation of the exon 17 GR promoter [16]. The relevance of these effects in humans has recently been demonstrated by Oberlander et al. [17] in the analysis of methylation status of the GR promotor at NGFI-A binding sites in cord blood mononuclear cells of infants exposed to third trimester maternal depressed or anxious mood. Maternal depression was found to be associated with increased GR 1F promotor methylation in fetal blood samples and these methylation patterns predicted HPA reactivity in infants at 3 months of age [17]. Analysis of hippocampal tissue from suicide victims with a history of childhood abuse similarly indicates lower GR expression and higher GR 1F promotor methylation associated with disruptions of the early environment and confirms the findings from rodent studies that differential NGFI-A binding is a functional consequence of these epigenetic effects [18]. However, the impact of perinatal mother� infant interactions is not limited to GR regulation as illustrated by Roth et al. [19] examining the effects of postnatal abuse on offspring brain derived neurotrophic factor (BDNF) methylation [19]. In rats, an increase in methylation of exon IV of the BDNF promotor and consequent decrease in BDNF mRNA in the prefrontal cortex was found in association with exposure to periods of abusive maternal care (dragging, rough handling, etc.). As was the case with the effects of individual differences in maternal care, these effects emerged in infancy and were sustained into adulthood. Moreover, these effects on BDNF exon IV methylation are perpetuated to the F1 generation suggesting a role for epigenetic mechanisms in transgenerational effects [20].
Development Across The Lifespan: Epigenetics & Experience Dependent Plasticity
The previous section highlights the stable effects of early life experiences and how these events become encoded at a molecular level. Another approach to the study of epigenetics and development comes from studies of synaptic plasticity during the expression of long-term potentiation (LTP) and memory consolidation. High levels of maternal care and exposure to juvenile environ- mental enrichment (EE) have been demonstrated to improve capacity for learning and memory associated with LTP enhancement [21,22]. Moreover, recent evidence suggests that EE modulates NMDAr/p38/LTP signaling pathways in the hippocampus and improves contextual fear memory formation across generations such that offspring of enriched mothers likewise show enhanced LTP even when cross-fostered at birth to non- enriched mothers [23]. Environmental enrichment has been associated with increased histone acetylation in the hippocampus and improved spatial memory [24,25]. Pharmacological targeting of the epigenome has been used to demonstrate the role of histone acetylation and DNA methylation in the consolidation of long-term memory [26]. Treatment with zebularine (an inhibitor or DNA methyltransferases) has been shown to block memory formation and reduce histone acetylation following con- textual fear conditioning in adult rats [27] whereas treatment with the HDAC inhibitor sodium butyrate lead to enhanced formation of contextual fear memories [28]. The particular HDAC target of these inhibitors may be HDAC2 as recent evidence has emerged illustrating decreased synaptic plasticity and memory formation in mice over-expressing HDAC2 but not HDAC1; with the converse effect in HDAC2-deficient mice [29]. These studies illustrate a possible relationship between synaptic activity and histone acetylation/DNA methylation in mature neurons, suggesting that there is continued plasticity in these epigenetic systems beyond the prenatal and postnatal periods of development.
Epigenetic Mechanism & The Regulation Of Synaptic Transmission
Activity-dependent changes in gene expression within neuronal pathways during development may serve as a critical pathway linking experience of the external environment and epigenetic modifications within the cell nucleus. In a recent study, Monteggia and colleagues elegantly demonstrated that spontaneous synaptic trans- mission in hippocampal neurons is regulated by alterations in DNA methylation that occur in response to synaptic activity [30]. Treatment with a DNMT inhibitor lead to a significant decrease in frequency of miniature excitatory post-synaptic currents (mEPSCs) and rate of spontaneous synaptic vesicle fusion correlated with a decrease in BDNF promoter I methylation and increased BDNF expression. This effect was blocked with inhibition of synaptic activity and reductions in mEPSCs were prevented in the absence of MeCP2. These results strongly suggest a role for DNA methylation/MeCP2 pathways in the control of synaptic function. Activity- dependent phosphorylation of MeCP2 via Ca2+-calmodulindependent kinase II has been shown to cause MeCP2 dissociation from target genes and relieve transcriptional repression [31]. Consequently, genes such as BDNF are increased in expression leading to normal dendritic patterning and dendritic spine development [32]. These findings suggest an epigenetic mechanism through which neurons can monitor alterations in activity level and adjust neurotransmitter output via altered gene expression with consequences for network excitability and circuit refinement. Impairments in these MeCP2 pathways may lead to several neurodevelopmental abnormalities including Rett syndrome, infantile autism, mental retardation, and schizophrenia [33] and targeted deletion of MeCP2 in the amygdala has recently been demonstrated to impair learning and memory and lead to increased anxiety-like behavior in mice [34].
Epigenetic Control Of Critical Period Plasticity
Though epigenetic mechanisms have certainly been implicated in mediating the high levels of plasticity in early development, it is also possible to view the decreased plasticity and sensitivity that occurs later in development from an epigenetic perspective. Neocortical circuits are extremely sensitive to manipulations of the sensory environment during restricted temporal windows of postnatal development called �critical periods�. For example, an imbalance in binocular vision during child- hood affects perception leading to amblyopia or �lazy eye�. Monocular deprivation (MD) reproduces this classical paradigm of experience-dependent plasticity [35]. The striking physiological effect of MD is a shift in visual cortical neuron response in favor of the non-deprived eye; an example of ocular dominance (OD) plasticity. The critical period during which this OD plasticity occurs is defined by the activation and subsequent inhibition of specific molecular pathways involving signaling molecules such as aCaMKII, calcineurin, PKA, ERK, and CREB [36]. Recently, Pizzorusso and colleagues identified rapid increases in ERK-dependent phosphorylation of histones associated with activation of the juvenile visual cortex and a developmental downregulation of this effect in older mice [37]. In adult mice, the reduced OD plasticity can be reinstated through treatment with the HDAC inhibitor trichostatin A (TSA). Multiple cellular mechanisms might contribute to experience-dependent plasticity expression [38]. Further work is necessary to understand if epigenetic mechanisms are generally acting in all cellular substrates or only within a specific subset.
Myelin maturation has also been proposed as one of the major factors contributing to decreased neuronal plasticity. During the onset of critical period plasticity, oligodendrocytes start to express specific myelin structural proteins, including myelin basic protein (MBP), myelin-associated glycoprotein (MAG), myelin oligodendrocyte glycoprotein (OMgp) and myelin-associated oligodendrocyte basic protein (MOBP) [39]. As myelination reaches adult levels, OD plasticity is strongly reduced or absent. MAG and OMgp may contribute to critical period closure through activation of Nogo receptors. Indeed, mice lacking Nogo receptors exhibit OD plasticity even in adulthood [40]. Manipulation of epigenetic status of oligodendrocytes may also be an effective strategy for modulating plasticity. Casaccia-Bonnefil and colleagues have shown that histone modifications are involved in oligodendrocyte precursor cell (OPC) differentiation during development and in recovery from injury [41� 43]. Administration of the HDAC inhibitor valproic acid during the critical period of myelination onset was found to prevent the OPC maturation into myelinating cells. These results suggest that HDAC activity during a specific temporal window of postnatal development is required for OPC differentiation and myelination. At later developmental stages, histone deacetylation subsides and is replaced by repressive histone methylation and the establishment of a compact chromatin structure, characteristic of the differentiated oligodendrocyte phenotype [43]. Shen et al. [44] found that in response to damage of oligodendrocytes, robust remyelination occurred in juvenile but not in older animals with the new myelin synthesis preceded by down regulation of oligodendrocyte differentiation inhibitors and neural stem cell markers and the recruitment of HDACs to promoter regions. This HDAC recruitment is inefficient in older brains, allowing for the accumulation of transcriptional inhibitors and prevention of myelin gene expression. This age-depend- ent effect can be induced in young mice treated with HDAC inhibitors during the period when damage to oligodentrocytes is occurring. Thus, there are epigenetic changes that are characteristic of periods of developmental plasticity that could provide a target for therapeutic intervention in the event of CNS damage. The use of HDAC inhibitors to increase plasticity in the brain may be a promising therapeutic approach as there is conver- ging evidence from rodent models that treatment with these compounds (1) can lead to dramatic shifts in gene expression and behavior in adult offspring who have received low levels of maternal care [15] and (2) mimic the effects of EE on reversal of neurodevelopmental abnormalities [24]. Rather than producing a generalized increase in transcription, these compounds lead to acti- vation of a specific subset of genes [45�47], suggesting possible targeted intervention to reinstate plasticity in adult brain.
Conclusions
There is converging evidence for the role of epigenetic modifications such as histone acetylation and DNA meth- ylation in both the stability and plasticity of developing neuronal circuits. The persistent effects on gene expression that can be achieved through these mechanisms provide a biological route through which environmental experiences can become embedded, leading to long-term changes in neurobiology and behavior. Enhancing plasticity in the adult brain is an exciting prospect and there is certainly evidence emerging that suggest the possible use of epigenetic factors to induce a �younger� brain. The challenge of future studies is to establish the pathways through which site-specific and gene-specific transcriptional modifications can be achieved and to better understand the route through which experiences across the lifespan induce this molecular plasticity.
Michela Fagiolini 1, Catherine L Jensen 2 and Frances A Champagne 2
Current Opinion in Neurobiology 2009, 19:1�6
This review comes from a themed issue on Development
Edited by Takao Hensch and Andrea Brand
0959-4388/$ � see front matter Published by Elsevier Ltd.
DOI 10.1016/j.conb.2009.05.009
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Epigenetic: A fine interplay exists between sensory experience and innate genetic programs leading to the sculpting of neuronal circuits during early brain development. Recent evidence suggests that the dynamic regulation of gene expression through epigenetic mechanisms is at the interface between environmental stimuli and long lasting molecular, cellular and complex behavioral phenotypes acquired during periods of developmental plasticity. Understanding these mechanisms may give insight into the formation of critical periods and provide new strategies for increasing plasticity and adaptive change in adulthood.
Contents
Introduction
During early development, neuronal circuits are created and connections between neurons undergo remodeling as they develop their adult functional properties in response to the surrounding environment. The adult brain loses this extraordinary plasticity. Recent findings support a key role of epigenetic factors in mediating the effects of sensory experience on site-specific gene expression, synaptic transmission, and behavioral phenotypes. Here we review recent evidence implicating multiple epigenetic mechanisms in experience-dependent changes during development and discuss their role in critical period expression in the developing and adult brain.
Epigenetics: Molecular Mechanisms Of Gene Regulation
The term �epigenetic� refers to chromatin modifications which alter gene expression without affecting DNA sequence. The factors that contribute to the epigenetic regulation of transcriptional activity are numerous and include microRNA [1], DNA methylation [2,3] and post- translational modifications of nucleosomal histones [2,4]. DNA methylation refers to a chemical modification to DNA whereby cytosine is converted to 5-methylcytosine with the consequence of reduced accessibility of the DNA to transcription factors (Figure 1a�d). These modi- fications can be stable and heritable and provide a critical mechanism in cellular differentiation [3]. The process of methylation is dependent on the presence of methyl donors (provided by nutrients such as folic acid, meth- ionine and choline) and methyltransferases which med- iate either maintenance (i.e. DNMT1) or de novo DNA methylation (i.e. DNMT3). Transcriptional repression associated with DNA methylation is further sustained through methyl-binding proteins such as MeCP2 [5]. Epigenetic control of gene expression is also mediated through multiple post-translational modifications of histone proteins, including methylation, acetylation and ubiquination, which can alter the accessibility of DNA and the density of chromatin structure (Figure 1e,f). In particular, histone acetylation is associated with increased transcriptional activity whereas histone deacetylation is associated with transcriptional repression. The acetylation state of these nucleosomal proteins is controlled by the presence of histone acetyltransferases (HATs), histone deacetylases (HDACs), which are recruited by methyl-binding proteins, and by HDAC inhibitors, which effectively increase gene expression through shifting histones to an acetylated state [2,6]. The timing and degree of gene expression are controlled through these complex mechanisms, thus providing a link between single genotypes and multiple phenotypes.
Epigenetic Factors & The Influence Of Early Life Experiences
In mammalian development, the prenatal and postnatal periods are characterized by rapid changes in neuronal organization, thus providing a critical window of opportunity during which environmental experiences can lead to long-term influences on brain and behavior. There is increasing evidence for the role of epigenetic factors in mediating the relationship between these experiences and long-term outcomes. Mueller and Bale [7] have recently demonstrated decreased DNA methylation of the corticotrophin-releasing-factor (CRF) gene promotor and increased methylation of the glucocorticoid receptor (GR) exon 17 promotor region in hypothalamic tissue of adult male mice born to gestationally stressed females. These epigenetic modifications are associated with exposure to stress during the early stages of prenatal development and may involve dysregulation of placental gene expression. The nutritional environment during fetal development has likewise been demonstrated to influence growth, metabolism and brain development and there is increasing evidence that dietary levels of methyl-donors can epigenetically alter gene expression in offspring [8,9]. In rats, Lillycrop et al. [10] illustrate that GR 110 and PPARa (peroxisome proliferator-activated receptor alpha) gene promotor methylation is reduced in the hepatic tissue of offspring born to protein restricted dams whereas methylation is increased in offspring of dams whose diet is supplemented with methyl donors [10,11]. These effects may be related to DNMT1 expression, which is likewise decreased with dietary protein restriction [11]. Prenatal nutritional regulation of DNA methylation has similarly been observed in brain tissue associated with levels of DNMT1 expression [12], suggesting that in the rapid period of cell division ocurring during fetal development, the level of methyl donors can have a significant impact on transcriptional activity that is maintained into adulthood.
The role of epigenetic modification in sustaining the effects of environmental experience has also been demonstrated in the context of postnatal mother�infant interactions. Individual variations in maternal care during the immediate postpartum period in rats are associated with changes in offspring hypothalamic-pituitary-adrenal (HPA) activity, neuroendocrine systems involved in reproduction and hippocampal plasticity [13]. Analyses of levels of promotor methylation within the hippocampal GR 17 and hypothalamic ERa genes in offspring of rat dams that provide high vs. low levels of maternal care indicate that high levels of care are associated with decreased promotor methylation and thus increased gene expression [14,15]. Though the route through which these epigenetic changes are mediated is not yet clear, there is evidence for increased binding of nerve growth factor-inducible protein A (NGFI-A) to the GR exon 17 promoter amongst offspring who receive high levels of care in infancy [15] and in vitro models suggest that NGFI-A up-regulation is associated with histone acetylation, DNA demethylation, and activation of the exon 17 GR promoter [16]. The relevance of these effects in humans has recently been demonstrated by Oberlander et al. [17] in the analysis of methylation status of the GR promotor at NGFI-A binding sites in cord blood mononuclear cells of infants exposed to third trimester maternal depressed or anxious mood. Maternal depression was found to be associated with increased GR 1F promotor methylation in fetal blood samples and these methylation patterns predicted HPA reactivity in infants at 3 months of age [17]. Analysis of hippocampal tissue from suicide victims with a history of childhood abuse similarly indicates lower GR expression and higher GR 1F promotor methylation associated with disruptions of the early environment and confirms the findings from rodent studies that differential NGFI-A binding is a functional consequence of these epigenetic effects [18]. However, the impact of perinatal mother� infant interactions is not limited to GR regulation as illustrated by Roth et al. [19] examining the effects of postnatal abuse on offspring brain derived neurotrophic factor (BDNF) methylation [19]. In rats, an increase in methylation of exon IV of the BDNF promotor and consequent decrease in BDNF mRNA in the prefrontal cortex was found in association with exposure to periods of abusive maternal care (dragging, rough handling, etc.). As was the case with the effects of individual differences in maternal care, these effects emerged in infancy and were sustained into adulthood. Moreover, these effects on BDNF exon IV methylation are perpetuated to the F1 generation suggesting a role for epigenetic mechanisms in transgenerational effects [20].
Development Across The Lifespan: Epigenetics & Experience Dependent Plasticity
The previous section highlights the stable effects of early life experiences and how these events become encoded at a molecular level. Another approach to the study of epigenetics and development comes from studies of synaptic plasticity during the expression of long-term potentiation (LTP) and memory consolidation. High levels of maternal care and exposure to juvenile environ- mental enrichment (EE) have been demonstrated to improve capacity for learning and memory associated with LTP enhancement [21,22]. Moreover, recent evidence suggests that EE modulates NMDAr/p38/LTP signaling pathways in the hippocampus and improves contextual fear memory formation across generations such that offspring of enriched mothers likewise show enhanced LTP even when cross-fostered at birth to non- enriched mothers [23]. Environmental enrichment has been associated with increased histone acetylation in the hippocampus and improved spatial memory [24,25]. Pharmacological targeting of the epigenome has been used to demonstrate the role of histone acetylation and DNA methylation in the consolidation of long-term memory [26]. Treatment with zebularine (an inhibitor or DNA methyltransferases) has been shown to block memory formation and reduce histone acetylation following con- textual fear conditioning in adult rats [27] whereas treatment with the HDAC inhibitor sodium butyrate lead to enhanced formation of contextual fear memories [28]. The particular HDAC target of these inhibitors may be HDAC2 as recent evidence has emerged illustrating decreased synaptic plasticity and memory formation in mice over-expressing HDAC2 but not HDAC1; with the converse effect in HDAC2-deficient mice [29]. These studies illustrate a possible relationship between synaptic activity and histone acetylation/DNA methylation in mature neurons, suggesting that there is continued plasticity in these epigenetic systems beyond the prenatal and postnatal periods of development.
Epigenetic Mechanism & The Regulation Of Synaptic Transmission
Activity-dependent changes in gene expression within neuronal pathways during development may serve as a critical pathway linking experience of the external environment and epigenetic modifications within the cell nucleus. In a recent study, Monteggia and colleagues elegantly demonstrated that spontaneous synaptic trans- mission in hippocampal neurons is regulated by alterations in DNA methylation that occur in response to synaptic activity [30]. Treatment with a DNMT inhibitor lead to a significant decrease in frequency of miniature excitatory post-synaptic currents (mEPSCs) and rate of spontaneous synaptic vesicle fusion correlated with a decrease in BDNF promoter I methylation and increased BDNF expression. This effect was blocked with inhibition of synaptic activity and reductions in mEPSCs were prevented in the absence of MeCP2. These results strongly suggest a role for DNA methylation/MeCP2 pathways in the control of synaptic function. Activity- dependent phosphorylation of MeCP2 via Ca2+-calmodulindependent kinase II has been shown to cause MeCP2 dissociation from target genes and relieve transcriptional repression [31]. Consequently, genes such as BDNF are increased in expression leading to normal dendritic patterning and dendritic spine development [32]. These findings suggest an epigenetic mechanism through which neurons can monitor alterations in activity level and adjust neurotransmitter output via altered gene expression with consequences for network excitability and circuit refinement. Impairments in these MeCP2 pathways may lead to several neurodevelopmental abnormalities including Rett syndrome, infantile autism, mental retardation, and schizophrenia [33] and targeted deletion of MeCP2 in the amygdala has recently been demonstrated to impair learning and memory and lead to increased anxiety-like behavior in mice [34].
Epigenetic Control Of Critical Period Plasticity
Though epigenetic mechanisms have certainly been implicated in mediating the high levels of plasticity in early development, it is also possible to view the decreased plasticity and sensitivity that occurs later in development from an epigenetic perspective. Neocortical circuits are extremely sensitive to manipulations of the sensory environment during restricted temporal windows of postnatal development called �critical periods�. For example, an imbalance in binocular vision during child- hood affects perception leading to amblyopia or �lazy eye�. Monocular deprivation (MD) reproduces this classical paradigm of experience-dependent plasticity [35]. The striking physiological effect of MD is a shift in visual cortical neuron response in favor of the non-deprived eye; an example of ocular dominance (OD) plasticity. The critical period during which this OD plasticity occurs is defined by the activation and subsequent inhibition of specific molecular pathways involving signaling molecules such as aCaMKII, calcineurin, PKA, ERK, and CREB [36]. Recently, Pizzorusso and colleagues identified rapid increases in ERK-dependent phosphorylation of histones associated with activation of the juvenile visual cortex and a developmental downregulation of this effect in older mice [37]. In adult mice, the reduced OD plasticity can be reinstated through treatment with the HDAC inhibitor trichostatin A (TSA). Multiple cellular mechanisms might contribute to experience-dependent plasticity expression [38]. Further work is necessary to understand if epigenetic mechanisms are generally acting in all cellular substrates or only within a specific subset.
Myelin maturation has also been proposed as one of the major factors contributing to decreased neuronal plasticity. During the onset of critical period plasticity, oligodendrocytes start to express specific myelin structural proteins, including myelin basic protein (MBP), myelin-associated glycoprotein (MAG), myelin oligodendrocyte glycoprotein (OMgp) and myelin-associated oligodendrocyte basic protein (MOBP) [39]. As myelination reaches adult levels, OD plasticity is strongly reduced or absent. MAG and OMgp may contribute to critical period closure through activation of Nogo receptors. Indeed, mice lacking Nogo receptors exhibit OD plasticity even in adulthood [40]. Manipulation of epigenetic status of oligodendrocytes may also be an effective strategy for modulating plasticity. Casaccia-Bonnefil and colleagues have shown that histone modifications are involved in oligodendrocyte precursor cell (OPC) differentiation during development and in recovery from injury [41� 43]. Administration of the HDAC inhibitor valproic acid during the critical period of myelination onset was found to prevent the OPC maturation into myelinating cells. These results suggest that HDAC activity during a specific temporal window of postnatal development is required for OPC differentiation and myelination. At later developmental stages, histone deacetylation subsides and is replaced by repressive histone methylation and the establishment of a compact chromatin structure, characteristic of the differentiated oligodendrocyte phenotype [43]. Shen et al. [44] found that in response to damage of oligodendrocytes, robust remyelination occurred in juvenile but not in older animals with the new myelin synthesis preceded by down regulation of oligodendrocyte differentiation inhibitors and neural stem cell markers and the recruitment of HDACs to promoter regions. This HDAC recruitment is inefficient in older brains, allowing for the accumulation of transcriptional inhibitors and prevention of myelin gene expression. This age-depend- ent effect can be induced in young mice treated with HDAC inhibitors during the period when damage to oligodentrocytes is occurring. Thus, there are epigenetic changes that are characteristic of periods of developmental plasticity that could provide a target for therapeutic intervention in the event of CNS damage. The use of HDAC inhibitors to increase plasticity in the brain may be a promising therapeutic approach as there is conver- ging evidence from rodent models that treatment with these compounds (1) can lead to dramatic shifts in gene expression and behavior in adult offspring who have received low levels of maternal care [15] and (2) mimic the effects of EE on reversal of neurodevelopmental abnormalities [24]. Rather than producing a generalized increase in transcription, these compounds lead to acti- vation of a specific subset of genes [45�47], suggesting possible targeted intervention to reinstate plasticity in adult brain.
Conclusions
There is converging evidence for the role of epigenetic modifications such as histone acetylation and DNA meth- ylation in both the stability and plasticity of developing neuronal circuits. The persistent effects on gene expression that can be achieved through these mechanisms provide a biological route through which environmental experiences can become embedded, leading to long-term changes in neurobiology and behavior. Enhancing plasticity in the adult brain is an exciting prospect and there is certainly evidence emerging that suggest the possible use of epigenetic factors to induce a �younger� brain. The challenge of future studies is to establish the pathways through which site-specific and gene-specific transcriptional modifications can be achieved and to better understand the route through which experiences across the lifespan induce this molecular plasticity.
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El Paso, TX. Chiropractor, Dr. Alexander Jimenez continues with the cerebellum overview. The cerebellum is one of the most identifiable parts of the brain based on its unique shape and location. It is an extremely important part of the brain. It is responsible for being able to perform everyday voluntary tasks likes walking and writing. And it’s essential for being able to keep balance and remain upright. People who have suffered from a damaged cerebellum struggle with balance and maintaining proper muscle coordination.
Contents
EVERYTHING PERIPHERAL HAS A CENTRAL CONSEQUENCE!
CASE STUDY
Cerebellar Ataxia
54-YEAR-OLD FEMALE PRESENTED TO OUR CLINIC FOR FEELINGS OF �UNSTEADINESS�
Patient woke up one morning over one year ago with vertigo.
Patient has difficulty with balance and walking. She sometimes resorts to using a cane. Extreme difficulty walking downstairs
Patient has been proactive in her weight loss, however, this has served as a speed bump in her plan of getting back to health.
She has not been able to exercise like she had in the past.
Patient has been to several vestibular rehabilitation clinics to no avail.
PHYSICAL EXAMINATION HIGHLIGHTS
Cranial nerves I-XII WNL
Wide-based gait
Right cerebellar findings
Provocative Romberg testing produced significant sway in the right posterior and left anterior canal position.
Comfortable walking and standing with more narrow- based gait.
Ability to walk down stairs without holding handrail.
CASE STUDY
Meet Aaron & McKayla
**Permission given to use names, images and whatever else needed to spread the word
A 39-year-old retired Explosives Ordinance Disposal Technician who in 2011…
And in 2015…
WHAT CAN FUNCTIONAL NEUROLOGY DO FOR AARON?
HOW CAN WE HELP HIS BALANCE?
IF YOU DON�T USE IT….
WHAT DO YOU SEE?
WHAT DO YOU SEE?
WHAT DO YOU SEE?
WHAT DO YOU SEE?
WHAT DOES IT MEAN?
AFFERENTATION WITH METABOLIC CONSIDERATIONS
A-BETA – MECHANORECEPTORS
Merkel�s disc � slow adapting to pressure and texture. Sharpest resolution for spatial patterning. �steady light pressure�
Meissner�s Corupuscle � superfiicial motion detection. Two point discretion.
Ruffini�s Corpuscle � located in dermis. Steady skin stretch and joint pressure.
Pacinian Corpuscle � rapid adapter, Associated with vibration.
GOLGI TENDON ORGAN IB FIBERS
Responds to muscle tension changes.
1A IIA SOMATOSENSORY
Muscle spindle fiber is the largest fiber in the human body.
Respond to the rate of change in muscle length, as well to change in velocity, rapidly adapting.
This will require the most demands on metabolic capacity.
BACK TO THE CASE
In 2011, Aaron had lost both of his eyes in an IED explosion.
Due to the blast, Aaron also lost his sense of smell and taste.
After several months of rehab, Aaron learned how to �be really good at being blind.�
Although he could not see, balance was no major issue. �I was climbing mountains, running marathons, kayaking…you name it.�
In 2015, a few months after running the Boston Marathon, Aaron was on the phone with Mckayla.
�He said he was not feeling well and was going to go lie down. I was concerned but did not think much of it.�
After a day and a half of waiting for his call, McKayla found out Aaron contracted meningitis and was intubated in the ICU.
Finding out Aaron is completely deaf after meningitis…
The meningitis obliterated his hearing and left him completely deaf for 5 months.
Not only that, the meningitis wreaked havoc on Aaron�s balance centers (his vestibulocerebellum) and he suffered from severe vertigo and difficulty standing and walking.
After recovering from meningitis:
�You can see how he’s walking on the treadmill in the very beginning. It took so much out of him to be able to do that.� � Mckayla
Remember �metabolic capacity?�
Aaron was actually able to get himself back into running shape and ran one of his best times in Ohio, but not without struggle.
�Every little change in pace and every little movement was a huge calibration for me and it took a lot out of me.�
�I still have a lot of work to do…�
CHALLENGE ACCEPTED
Sooooo….back to the basics!
We utilized different surfaces to challenge his balance system (foam pads, wobble boards, etc….
We also had him do most of his therapies barefoot to increase afferentation to the somatosensory cortex
Updates from McKayla:
�Pace is a 7:30 and he’s doing 6 miles. Completed core work too.�
Typically in the OVARD we would spin Aaron in specific directions and he would tell us which direction he was spinning in.
At first this was very difficult and he could not perceive the movement, however it was not long until he was sensing each direction of his spin.
We let him have a little fun in this particular video….
I asked Aaron and McKayla how they felt therapy was going.
They responded �great, but we won�t really know until he goes for a run outside…�
So we went on a seven mile run at an 8 minute pace.
Here we are working on turns.
Cured!
Aaron is back home in Florida continuing his training for Boston in two weeks.
He is continuing at-home exercises and vestibular rehab with specialists
He and I are running a half marathon together in the not-so-distant future
SOME SIMPLE CEREBELLAR THERAPIES
GENERAL CEREBELLAR EXERCISES
Spinning in desk chair will stimulate ipsilateral cerebellum
Passive muscle stretch will stimulate ipsilateral cerebellum
Squeezing tennis ball will stimulate ipsilateral cerebellum
Passive or active non-linear complex movements will stimulate ipsilateral cerebellum
Finger to nose pointing will stimulate ipsilateral cerebellum
Vermal & Paravermal Exercises
Passive and active gaze stabilization exercises with central fixation
Wobble board/unsteady surface exercises
Balance beam exercises and tandem walking
Bouncing a ball against the ground or throwing it against the wall
Core exercises such as planks, sit-ups and yoga
Learning how to balance on a bicycle
Supine cross crawl activity
Lateral Cerebellum Exercises
Cognitive processes
Learning a musical instrument
Tracing a maze
Playing �catch�
Tapping fingers/hand or toes/feet to the beat of a metronome
Although the cerebellum has many responsibilities, its central function is to coordinate and handle motor activities. Balance, coordination, posture, equilibrium and eye motion are controlled in part by the cerebellum. Additionally, it works to calibrate motor actions in order for our movements to have a smooth, flowing nature to them. The cerebellum receives data from various other structures, like the inner ear and the vestibular system, and fine-tunes incoming sensorimotor information to achieve naturally smooth movements.
Contents
Cerebellum Exercises
Many cerebellum exercises are available which help the cerebellum enhance the operation of its neurons. Essentially, neurons want stimulation to be able to function accordingly. When neurons do not get enough stimulation, they become unstable, which can lead to a lot of behavioral difficulties, such as the ones connected with ADHD, among others. But, exercising the cerebellum can increase operation as well as decrease negative symptoms.
Exercises that require focused attention are demonstrated to help cerebellar development. Deliberate and purposeful physical movements, such as balancing on a balance board or working with a rehabilitation ball, will help neurons get the stimulation they need to maximize their functioning. Because there’s a substantial connection between physical activity and mental functioning, pairing physical tasks with psychological exercises is also very beneficial towards enhancing cerebellar functioning. By way of instance, a child diagnosed with ADHD may be requested to keep their balance on a balance board whilst simultaneously reciting the alphabet.
If a child or individual demonstrates weak cerebellar development in one quadrant, doing physical exercises between the legs and arms on the exact same side of the body is able to help that portion of the cerebellum “catch up” to the level of development of it’s other half. These exercises might involve arm or leg stretches or complex motions that include the hands, wrists, elbows and shoulders. Vestibular-based actions, such as catching and throwing a ball or performing balance exercises such as standing on one leg, are also great cerebellum exercises that ease the stabilization, growth and development of neurons.
Cerebellar rehabilitation programs incorporate each of these exercises into an extensive regimen for tapping into the brain’s neuroplasticity. The exercises involved require patients to perform tasks that involve balance, spatial judgments, and motor actions, all which enhance cerebellar functioning and operation. Basically, since the brain’s neural networks arrange the incoming sensory information, they improve their functioning and become more effective.
Dr. Alex Jimenez’s Insight
Cerebellar ataxia is a disorder which affects the normal functioning of the brain and the nervous system by decreasing balance and coordination, most commonly in the back, arms and legs. Cerebellar rehabilitation exercises are often utilized to help alleviate the symptoms associated with cerebellar ataxia. Cerebellar exercises can also be recommended by a chiropractor or physical therapist for children and individuals in order to stimulate the brain and help with cerebellar development. Participating in cerebellar exercises has been demonstrated to improve balance, coordination and posture as well as promote more natural and smooth motor activities.
Many cerebellar exercises can be utilized in order to help stimulate specific regions of the brain, particularly the cerebellum. Each zone of the cerebellum is in charge of performing essential functions, therefore, enhancing these different regions is fundamental towards ultimate function and operation. Below, a series of exercises have been divided to enhance specific zones of the cerebellum.
General Cerebellar Exercises
Spinning in a desk seat can stimulate the ipsilateral cerebellum
Vertical muscle stretch can stimulate the ipsilateral cerebellum
Squeezing a tennis ball can stimulate the ipsilateral cerebellum
Passive or active non-linear complex movements can stimulate the ipsilateral cerebellum
Finger to nose extending can stimulate the ipsilateral cerebellum
Vermal and Paravermal Exercises
Passive and active gaze stabilization exercises using central fixation
Wobble board/unsteady surface exercises
Balance beam exercises and tandem walking
Bouncing a ball against the floor or throwing it against the wall
Core exercises, such as planks, sit-ups and yoga
Learning how to balance on a bicycle
Supine cross crawl action
Lateral Cerebellum Exercises
Cognitive procedures
Learning a musical instrument
Tracing a maze
Playing “catch”
Tapping fingers/hand or toes/feet to the beat of a metronome
Seeking to compose with eyes shut
Strategic board games
Cerebellar Rehabilitation Exercises for Cerebellum Dysfunction
When the cerebellum is damaged or not fully developed, individuals can display erratic or slow movements, demonstrate an inability to judge distance, have difficulty performing rapid moves, and walk with an unnatural gait. Dysfunction from the cerebellum have also been linked to symptoms of ADHD and other behavioral disorders. Cerebellar rehabilitation exercises can be helpful towards enhancing the indications of cerebellum dysfunction, most commonly, cerebellar ataxia.
Cerebellar ataxia is a disease which originates from the cerebellum. Cerebellar ataxia can happen as a result of several ailments and presents with symptoms of an inability to coordinate balance, gait, upper/lower extremity and eye motions. Healthcare professionals frequently use visual monitoring of people performing motor tasks so as to look for signs of ataxia. Research studies have shown that cerebellar rehabilitation exercises can be helpful towards improving symptoms related to cerebellum dysfunction.
Treatment of cerebellar ataxia generally involves treating the underlying illness in addition to the symptoms. Cerebellar rehabilitation exercises are used to improve balance and increase the independence of the patient using methods focusing on balance, posture and coordination control. Stabilizing the back and proximal muscles ought to begin with mat activities, like moving onto the forearms out of a lying face down position and crawling/moving onto the knees into a sitting posture. Gait training should also be performed, since it’s an excellent indicator of balance and insertion.
Cerebellar rehabilitation exercises for cerebellum dysfunction can also improve proprioception. Proprioception is controlled by the cerebellum and involves knowing which body parts are situated in space and in connection with each other. Treatment entails plyometric exercises, balance board and mini trampoline exercises. Vibration and match treatment can also be utilized to enhance proprioception, posture and movement. Yoga and other body-awareness exercises might also be included in the treatment plan to increase proprioception.
Rehabilitation goals include enhancing balance and posture against external stimuli, increasing joint stabilization as well as creating independent, practical gait to promote independence. Training principles include progressing from simple to complicated exercises and providing support with home exercise and sports activities. Cerebellar rehabilitation exercises should be prescribed by a healthcare professional who specializes in cerebellum dysfunction, such as a chiropractor or physical therapists. The language of the brain is repetition, and rehabilitation can enhance brain function. The scope of our information is limited to chiropractic as well as to spinal injuries and conditions. To discuss the subject matter, please feel free to ask Dr. Jimenez or contact us at 915-850-0900 .
Curated by Dr. Alex Jimenez
Additional Topics: Sciatica
Sciatica is medically referred to as a collection of symptoms, rather than a single injury and/or condition. Symptoms of sciatic nerve pain, or sciatica, can vary in frequency and intensity, however, it is most commonly described as a sudden, sharp (knife-like) or electrical pain that radiates from the low back down the buttocks, hips, thighs and legs into the foot. Other symptoms of sciatica may include, tingling or burning sensations, numbness and weakness along the length of the sciatic nerve. Sciatica most frequently affects individuals between the ages of 30 and 50 years. It may often develop as a result of the degeneration of the spine due to age, however, the compression and irritation of the sciatic nerve caused by a bulging or herniated disc, among other spinal health issues, may also cause sciatic nerve pain.
Knee Injuries: Alex Jimenez was a wrestler for 15 years when he suffered an ACL tear. Once diagnosis confirmed his knee injury, Alex Jimenez began an extensive care regimen, consisting of chiropractic care with Dr. Alex Jimenez and crossfit rehabilitation, in order to help him recover. Now that Alex Jimenez dedicates himself to health and fitness, he’s always mindful of engaging in the proper exercises to avoid suffering another sports injury. With a positive mentality, Alex Jimenez was able to find his life plan when his ACL tear healed completely.
Chiropractic Care For Knee Injuries
The anterior cruciate ligament (ACL) is one of the most commonly injured ligaments of the knee. The prevalence of ACL injury is higher in athletes who take part in sports, such as basketball, soccer, skiing, and football. Roughly half of ACL injuries occur together with injury to the meniscus, articular cartilage, or other ligaments. Furthermore, patients may have lumps of the bone beneath the cartilage surface. These might be seen on a magnetic resonance imaging (MRI) scan and might indicate injury to the overlying articular cartilage.
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El Paso, TX. Chiropractor Dr. Alexander Jimenez presents an introduction to the cerebellum. The brain is a complex structure that has billions of nerve cells. The basic anatomy is easily understandable. But there is one part of the brain, the cerebellum, which is involved in virtually all movement. This is the part of the brain that helps a person drive, throw a ball, or walk across the street.
Problems with the cerebellum are uncommon and mostly involve movement and coordination difficulties. This article will give an overview of the anatomy, purpose, and disorders of the cerebellum, as well as, how to keep the brain healthy.
Contents
FAGIOLINI ET AL. EPIGENETIC INFLUENCES ON BRAIN DEVELOPMENT AND PLASTICITY CURR OPIN NEUROBIOL, 2009
�Enhancing plasticity in the adult brain is an exciting prospect and there is certainly evidence emerging that suggest the possible use of epigenetic factors to induce a �younger� brain.�
�Recent findings support a key role of epigenetic factors in mediating the effects of sensory experience on site-specific gene expression, synaptic transmission, and behavioral phenotypes.�
TAYLOR ET AL. CUTTING YOUR NERVE CHANGES YOUR BRAIN BRAIN, 2009
�Animal studies have established that plasticity within the somatosensory cortex begins immediately following peripheral nerve transection, and that 1 year after complete nerve transection and surgical repair, cortical maps contain patchy, noncontinuous representations of the transected and adjacent nerves.�
�Here, we have demonstrated for the first time that there is functional plasticity and both grey and white matter structural abnormalities in several cortical areas following upper limb peripheral nerve transection and surgical repair.�
THE CEREBELLUM
IMPORTANT FUNCTIONAL AREAS OF THE CEREBELLUM
Spinocerebellum
Vestibulocerebellum
Cerebrocerebellum
SPINOCEREBELLUM
Responsibilities:
Regulation of muscle tone for posture and locomotion
Example: piano playing, finger taping, finger to nose, etc.
TAYLOR ET AL. CUTTING YOUR NERVE CHANGES YOUR BRAIN BRAIN, 2009
�Animal studies have established that plasticity within the somatosensory cortex begins immediately following peripheral nerve transection, and that 1 year after complete nerve transection and surgical repair, cortical maps contain patchy, noncontinuous representations of the transected and adjacent nerves.�
�Here, we have demonstrated for the first time that there is functional plasticity and both grey and white matter structural abnormalities in several cortical areas following upper limb peripheral nerve transection and surgical repair.�
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