Hand Dystonia Research Articles

Long-Term Muscular Atrophy and Weakness Following Cessation of Botulinum Toxin Type A Injections in the Flexor Digitorum Muscle of Musicians with Focal Hand Dystonia

The present study assessed muscular atrophy and weakness of the flexor digitorum superficialis (FDS) and profundus (FDP) muscle as possible long-term side effects of botulinum toxin (BoNT) injections in hand dystonia patients after the termination of their treatment. For the assessment of both parameters, a group of 12 musicians diagnosed with focal hand dystonia was compared with a group of 12 healthy matched musicians. The minimum and maximum times since the last injection across patients were 0.5 to 3.5 years, respectively. The thickness and strength of the FDS and FDP were assessed via ultrasonography and a strength measurement device. Group differences were estimated through the calculation of the symmetry index between the dominant and non-dominant hand. The results revealed that compared to the control group, thickness and flexion strength of the injected FDS and FDP were decreased by 10.6% ± 5.3% (95% CI) and 12.5% ± 6.4% (95% CI), respectively, in the patient group. The amount of weakness and atrophy was predicted significantly by the total amount of BoNT injected throughout the entire treatment period. In contrast, the time after the last injection did not predict the amount of strength and muscle mass recovery after the cessation of the treatment. The current study revealed that even up to 3.5 years after the termination of BoNT injections, long-term side effects such as weakness and atrophy can still be observed. We suggest that the total BoNT dose should remain as small as possible to reduce long-lasting side effects to the minimum. Although side effects differ significantly among patients, a potential full recovery of atrophy and weakness after the cessation of BoNT treatment might be observed after periods longer than 3.5 years.

Laminar VASO fMRI in focal hand dystonia patients.

Focal Hand Dystonia (FHD) is a disabling movement disorder characterized by involuntary movements, cramps and spasms. It is associated with pathological neural microcircuits in the cortical somatosensory system. While invasive preclinical modalities allow researchers to probe specific neural microcircuits of cortical layers and columns, conventional functional magnetic resonance imaging (fMRI) cannot resolve such small neural computational units. In this study, we take advantage of recent developments in ultra-high-field MRI hardware and MR-sequences to capture altered digit representations and laminar processing in FHD patients. We aim to characterize the capability and challenges of layer-specific imaging and analysis tools in resolving laminar and columnar structures in clinical research setups. We scanned N = 4 affected and N = 5 unaffected hemispheres at 7T and found consistent results of altered neural microcircuitry in FHD patients: 1) In affected hemispheres of FHD patients, we found a breakdown of ordered finger representation in the primary somatosensory cortex, as suggested from previous low-resolution fMRI. 2) In affected primary motor cortices of FHD patients, we furthermore found increased fMRI activity in superficial cortico-cortical neural input layers (II/III), compared to relatively weaker activity in the cortico-spinal output layers (Vb/VI). Overall, we show that layer-fMRI acquisition and analysis tools have the potential to address clinically-driven neuroscience research questions about altered computational mechanisms at the spatial scales that were previously only accessible in animal models. We believe that this study paves the way for easier translation of preclinical work into clinical research in focal hand dystonia and beyond.

Clinical Features of Common Types of Dystonia and Practical Approach for Occupational Dystonia

Dystonia is a movement disorder characterized by sustained muscle contractions that result in abnormal "patterned" movements and/or postural abnormalities. Based on the accompanying symptoms, dystonia can be classified as isolated (i.e., with dystonia only), combined (i.e., with other movement disorders such as myoclonus), or complex (i.e., with symptoms other than movement disorders such as mental retardation). Moreover, dystonia may affect single or multiple parts of the body and accordingly be classified as focal, segmental, multifocal, hemi, or generalized. The most common type of dystonia is isolated focal dystonia, often accompanied with a specific action (task-specific action). The "task-specificity" uniquely illustrates the nature of dystonia, and this phenomenon is most clearly observed in occupation-related dystonias that include musician's and athlete's dystonia. In this article, we first elucidate the general issues of common focal dystonia (cervical dystonia, blepharospasm, and focal hand dystonia) and then present several educational cases of occupational (task-specific) dystonia with some clinical pearls for practical management.

Metaplasticity and non-invasive brain stimulation: the search for new biomarkers and directions for therapeutic neuromodulation

Metaplasticity (plasticity of synaptic plasticity) is defined as a change in the direction or degree of synaptic plasticity in response to preceding neuronal activity. Recent advances in brain stimulation methods have enabled us to non-invasively examine cortical metaplasticity, including research in a clinical setting. According to current knowledge, non-invasive neuromodulation affects synaptic plasticity by inducing cortical processes that are similar to long-term potentiation and depression. Two stimulation blocks are usually used to assess metaplasticity priming and testing blocks. The technology of studying metaplasticity involves assessing the influence of priming on the testing protocol effect.
 Several dozen studies have examined the effects of different stimulation protocols in healthy persons. They found that priming can both enhance and weaken, or even change the direction of the testing protocol effect. The interaction between priming and testing stimulation depends on many factors: the direction of their effect, duration of the stimulation blocks, and the interval between them.
 Non-invasive brain stimulation can be used to assess aberrant metaplasticity in nervous system diseases, in order to develop new biomarkers. Metaplasticity disorders are found in focal hand dystonia, migraine with aura, multiple sclerosis, chronic disorders of consciousness, and age-related cognitive changes.
 The development of new, metaplasticity-based, optimized, combined stimulation protocols appears to be highly promising for use in therapeutic neuromodulation in clinical practice.

Alterations in dexterity and manual function in patients with focal hand dystonia

IntroductionFocal hand dystonia is a movement disorder whose symptoms cause alterations in the performance of tasks requiring a high level of dexterity. Currently, there is no model for interpreting the disease and few studies have identified the difficulties of patients with dystonia in carrying out activities of daily living (ADL). This study aims to describe manipulative dexterity and its influence on ADLs in patients with focal hand dystonia. Materials and methodsWe performed an observational, cross-sectional, case-control study including 24 participants (12 patients with focal hand dystonia and 12 controls). The patients were referred by the neurology department of Hospital Ramón y Cajal. We gathered sociodemographic data, as well as retrospective clinical data for patients. We subsequently administered evaluation tests, in the following order: Nine-Hole Peg Test (NHPT), Box and Blocks Test (BBT), Purdue Pegboard Test (PPT), and Jebsen-Taylor Test of Hand Function (JTTHF). ResultsThe study sample included a total of 24 participants, 7 women and 17 men, with a mean age (standard deviation) of 50.79 (14.40) years. In the patient group, neuromuscular involvement or psycho-emotional problems were not detected in half of cases; smaller numbers of patients presented difficulties associated with the right shoulder (25%) and anxious state (33.3%). ConclusionsOur results indicate that focal hand dystonia affects manipulative dexterity in these patients, who showed poorer performance and required more time to complete the tasks.

Comparison of Ultrasound and Electrical Stimulation Guidance for Onabotulinum Toxin-A Injections: A Randomized Crossover Study.

Botulinum neurotoxin (BoNT) injection is an established therapy for limb spasticity and focal limb dystonia. Comparative benefits of injection guidance procedures have not been rigorously studied. We compared 2 targeting techniques for onabotulinumtoxin-A (onabotA) injection for the treatment of focal hand dystonia and upper limb spasticity: electrophysiologic guidance using electrical stimulation (E-stim) and ultrasound (US). This was a 2-center, randomized, crossover, assessor-blinded trial. Participants with focal hand dystonia or upper limb spasticity, on stable onabotA therapy for at least 2 previous injection cycles, were randomly assigned to either E-stim or US with crossover at 3 months. The primary outcome was improvement in dystonia or spasticity severity on a visual analog scale (VAS; 0-100) measured 1 month after each injection. The secondary outcome was participant discomfort assessed on a VAS. Repeated-measures analysis of covariance was used with linear mixed-model covariate selection. A total of 19 participants (13 men) completed the study, 10 with upper limb spasticity and 9 with dystonia. Benefit was equivalent between the 2 techniques (VAS least-square mean [LSmean] 51.5 mm with US and 53.1 with E-stim). E-stim was perceived as more uncomfortable by participants (VAS LSmean 34.5 vs. 19.9 for E-stim and US, respectively). Procedure duration was similar with the 2 procedures. There were no serious adverse events related to either approach. US and E-Stim localization guidance techniques provide equivalent efficacy in onabotA injections for spasticity and dystonia. US guidance injections are more comfortable for participants. Both techniques are effective guidance methods, with US potentially preferable based on participant comfort.

Characterizing the temporal discrimination threshold in musician’s dystonia

The temporal discrimination threshold (TDT) has been established as a biomarker of impaired temporal processing and endophenotype in various forms of focal dystonia patients, such as cervical dystonia, writer’s cramp or blepharospasm. The role of TDT in musician’s dystonia (MD) in contrast is less clear with preceding studies reporting inconclusive results. We therefore compared TDT between MD patients, healthy musicians and non-musician controls using a previously described visual, tactile, and visual-tactile paradigm. Additionally, we compared TDT of the dystonic and non-dystonic hand and fingers in MD patients and further characterized the biomarker regarding its potential influencing factors, i.e. musical activity, disease variables, and personality profiles. Repeated measures ANOVA and additional Bayesian analyses revealed lower TDT in healthy musicians compared to non-musicians. However, TDTs in MD patients did not differ from both healthy musicians and non-musicians, although pairwise Bayesian t-tests indicated weak evidence for group differences in both comparisons. Analyses of dystonic and non-dystonic hands and fingers revealed no differences. While in healthy musicians, age of first instrumental practice negatively correlated with visual-tactile TDTs, TDTs in MD patients did not correlate with measures of musical activity, disease variables or personality profiles. In conclusion, TDTs in MD patients cannot reliably be distinguished from healthy musicians and non-musicians and are neither influenced by dystonic manifestation, musical activity, disease variables nor personality profiles. Unlike other isolated focal dystonias, TDT seems not to be a reliable biomarker in MD.

TU-156. Increased susceptibility to long-term depression and impaired metaplasticity in the primary motor cortex of focal hand dystonia patients

TU-156. Increased susceptibility to long-term depression and impaired metaplasticity in the primary motor cortex of focal hand dystonia patients

Efficacy and Safety of Zolpidem for Focal Dystonia After Neurosurgical Treatments: A Retrospective Cohort Study.

Although there are several reports of the significant efficacy of zolpidem for treating dystonia, zolpidem is still considered an anecdotal treatment. Here, we evaluated the efficacy and safety of zolpidem for treating residual dystonia in patients who previously received various neurosurgical treatments majorly including deep brain stimulation and radiofrequency ablation. We retrospectively reviewed medical records from January 2021 to September 2021 to identify patients with dystonia who had been prescribed zolpidem after undergoing neurosurgery. Twenty patients were enrolled in this study, including those with blepharospasm (two), tongue dystonia (four), mouth dystonia (one), spasmodic dysphonia (two), cervical dystonia (six), focal hand dystonia (three), hemidystonia (two), blepharospasm with cervical dystonia (one), and mouth dystonia with cervical dystonia (one). Single doses of zolpidem ranged between 2.5 and 10 mg, while daily dosages ranged from 10 to 30 mg. The zolpidem dose prescribed was 5–10 mg, with single and daily doses of 7 ± 2.9 and 14.5 ± 6.0 mg, respectively. With zolpidem administration, the participants' Burke-Fahn-Marsden Dystonia Rating Scale-Movement Scale score significantly improved from 8.1 ± 6.7 to 3.7 ± 2.5 (50.6% improvement, p < 0.0001). Improvements in arm dystonia, blepharospasm, and spasmodic dysphonia were observed using the Arm Dystonia Disability Scale, Jankovic Rating Scale, and Voice Handicap Index, respectively. No improvements were observed in cervical dystonia on the Toronto Western Spasmodic Torticollis Rating Scale. Drowsiness, including three cases each of mild and moderate drowsiness, was the most frequent adverse effect (30%), which persisted for 2–3 h. Transient amnesia and rapid eye movement sleep behavior disorder occurred in two patients and one patient, respectively. Although our findings suggest that zolpidem can be a valuable treatment option for patients with residual dystonia after neurosurgical treatments, the beneficial effects for cervical dystonia were limited.

Investigation of the posterior parietal cortex to ventral premotor connection in writer's cramp using transcranial magnetic stimulation.

The posterior parietal, premotor and motor cortices are brain regions relevant in the planning of movement. Previous transcranial magnetic stimulation (TMS) studies have shown ipsilateral premotor-to-motor inhibition in healthy subjects at rest. This premotor-to-motor inhibition has been found to be altered in patients with writer's cramp (WC), a common type of focal hand dystonia. We aimed to investigate the influence of the posterior parietal cortex on the ipsilateral ventral premotor cortex using a three single-pulse TMS paradigm. Nineteen right-handed subjects (eleven healthy volunteers and eight WC patients) completed the study. A three single-pulse TMS paradigm (preconditioning, conditioning, and test stimuli) was used to sequentially stimulate the left posterior parietal, ventral premotor, and primary motor cortices. We found that in both healthy subjects and patients, stimulating the ipsilateral posterior parietal cortex resulted in reversal of the resting premotor-to-motor inhibition. Resting premotor-to-motor inhibition was also found, with no statistically significant group difference. Furthermore, a facilitatory effect of the posterior parietal cortex on the primary motor cortex was found in both groups. Our results suggest that in the resting state, the inhibitory effect of the left posterior parietal cortex on the ipsilateral ventral premotor cortex found in healthy subjects is also intact in WC patients. While we are unable to identify any parietal-to-premotor connectivity abnormality in the resting state, an abnormality during a specific task cannot be excluded. Previously reported conductivity abnormalities in resting fMRIdo not appear to translate into a TMS physiological abnormality.

Teaching Video NeuroImage: Congenital Hemidystonia-Hemi-midbrain Atrophy Syndrome.

An 18-year-old man with normal birth and development and a negative family history complained of nonprogressive clumsiness and posturing of his left hand since early childhood. His left limbs were shorter than his right but showed no evidence of atrophy (eFigure 1, A-C, [links.lww.com/WNL/B902][1]). Examination revealed dystonic posturing with mirror dystonia of the left hand and subtle mirror movements in his feet (Video 1). MRI of the brain showed right hemiatrophy of the midbrain, bilateral cortical activation with unilateral finger taps on fMRI, and normal corticospinal tract decussation (Figure, A-F). Levodopa response was present, suggesting dopaminergic denervation due to a congenital hemi-midbrain insult.1 This case represents hemidystonia-hemiatrophy syndrome.2 Subtle limb shortening and mirror dystonia can aid in diagnosis. [1]: http://links.lww.com/WNL/B902

A Critical Investigation of Cerebellar Associative Learning in Isolated Dystonia

BackgroundImpaired eyeblink conditioning is often cited as evidence for cerebellar dysfunction in isolated dystonia yet the results from individual studies are conflicting and underpowered.ObjectiveTo systematically examine the influence of dystonia, dystonia subtype, and clinical features over eyeblink conditioning within a statistical model which controlled for the covariates age and sex.MethodsOriginal neurophysiological data from all published studies (until 2019) were shared and compared to an age‐ and sex‐matched control group. Two raters blinded to participant identity rescored all recordings (6732 trials). After higher inter‐rater agreement was confirmed, mean conditioning per block across raters was entered into a mixed repetitive measures model.ResultsIsolated dystonia (P = 0.517) and the subtypes of isolated dystonia (cervical dystonia, DYT‐TOR1A, DYT‐THAP1, and focal hand dystonia) had similar levels of eyeblink conditioning relative to controls. The presence of tremor did not significantly influence levels of eyeblink conditioning. A large range of eyeblink conditioning behavior was seen in both health and dystonia and sample size estimates are provided for future studies.ConclusionsThe similarity of eyeblink conditioning behavior in dystonia and controls is against a global cerebellar learning deficit in isolated dystonia. Precise mechanisms for how the cerebellum interplays mechanistically with other key neuroanatomical nodes within the dystonic network remains an open research question. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.

Impact of Alexander technique, mirror therapy versus conventional therapy on musician’s cramp in guitarists

Introduction and Aim: Musicians may perceive the early symptoms of dystonia because of faulty technique or lack of sufficient preparation. Hand dystonia affecting musicians is often called musician’s dystonia or musician’s cramp. Guitarists are typically affected in their left hand and the spasms may cause the fingers to contract and curl under when attempting to play. The condition called focal dystonia (musician’s cramp), can afflict typist or anyone else who makes repetitive, forceful, precise movements. The objective of the study is to observe the impact of alexander technique versus mirror therapy on musician’s cramp. Methodology: A total of 150 subjects were randomly selected based on the inclusion criteria. The selected subjects were divided in three groups namely group A, B and C respectively. The evaluation parameters were performed using the Likert scale and was framed based on pain, mobility, and grip. Results: Likert scale for pain, mobility and grip was used to analyse data. The results of this study show that the Alexander Technique is more effective than mirror therapy and conventional therapy to reduce pain and improve mobility and grip for guitarists. Conclusion: These results suggest that playing guitar by adapting Alexander technique is advantageous for building speed.

Exploring the connections between basal ganglia and cortex revealed by transcranial magnetic stimulation, evoked potential and deep brain stimulation in dystonia.

We review the findings for motor cortical excitability, plasticity and evoked potentials in dystonia. Plasticity can be induced and assessed in cortical areas by non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and the invasive technique of deep brain stimulation (DBS), which allows access to deep brain structures. Single-pulse TMS measures have been widely studied in dystonia and consistently showed reduced silent period duration. Paired pulse TMS measures showed reduced short and long interval intracortical inhibition, interhemispheric inhibition, long-latency afferent inhibition and increased intracortical facilitation in dystonia. Repetitive transcranial magnetic stimulation (rTMS) of the premotor cortex improved handwriting with prolongation of the silent period in focal hand dystonia patients. Continuous theta-burst stimulation (cTBS) of the cerebellum or cTBS of the dorsal premotor cortex improved dystonia in some studies. Plasticity induction protocols in dystonia demonstrated excessive motor cortical plasticity with the reduction in cortico-motor topographic specificity. Bilateral DBS of the globus pallidus internus (GPi) improves dystonia, associated pain and functional disability. Local field potentials recordings in dystonia patients suggested that there is increased power in the low-frequency band (4-12Hz) in the GPi. Cortical evoked potentials at peak latencies of 10 and 25ms can be recorded with GPi stimulation in dystonia. Plasticity induction protocols based on the principles of spike timing dependent plasticity that involved repeated pairing of GPi-DBS and motor cortical TMS at latencies of cortical evoked potentials induced motor cortical plasticity. These studies expanded our knowledge of the pathophysiology of dystonia and how cortical excitability and plasticity are altered with different treatments such as DBS.

Functional Neural Networks in Writer's Cramp as Determined by Graph-Theoretical Analysis.

Dystonia, a debilitating neurological movement disorder, is characterized by involuntary muscle contractions and develops from a complex pathophysiology. Graph theoretical analysis approaches have been employed to investigate functional network changes in patients with different forms of dystonia. In this study, we aimed to characterize the abnormal brain connectivity underlying writer's cramp, a focal hand dystonia. To this end, we examined functional magnetic resonance scans of 20 writer's cramp patients (11 females/nine males) and 26 healthy controls (10 females/16 males) performing a sequential finger tapping task with their non-dominant (and for patients non-dystonic) hand. Functional connectivity matrices were used to determine group averaged brain networks. Our data suggest that in their neuronal network writer's cramp patients recruited fewer regions that were functionally more segregated. However, this did not impair the network's efficiency for information transfer. A hub analysis revealed alterations in communication patterns of the primary motor cortex, the thalamus and the cerebellum. As we did not observe any differences in motor outcome between groups, we assume that these network changes constitute compensatory rerouting within the patient network. In a secondary analysis, we compared patients with simple writer's cramp (only affecting the hand while writing) and those with complex writer's cramp (affecting the hand also during other fine motor tasks). We found abnormal cerebellar connectivity in the simple writer's cramp group, which was less prominent in complex writer's cramp. Our preliminary findings suggest that longitudinal research concerning cerebellar connectivity during WC progression could provide insight on early compensatory mechanisms in WC.

Sensitivity and pain in focal dystonia of the hand

IntroductionA growing body of evidence highlights the importance of understanding both the sensory and the motor pathophysiology of focal dystonia in order to improve its treatment. This study aims to evaluate somatosensory afferences in patients with focal or segmental dystonia affecting the upper limbs, to analyse whether the dominant limb is more frequently affected, to analyse pain tolerance, and to examine the potential association with pain perception in patients with hand dystonia. MethodsWe recruited 24 participants: 12 patients with focal hand dystonia and 12 individuals without dystonia. All participants were evaluated with a digital algometer (Somedic SenseLab AB®, Farsta, Sweden), a Semmes-Weinstein monofilament test, and the visual analogue scale for pain. ResultsAccording to our data, patients showed greater impairment in surface sensitivity than controls, both in the dominant and the non-dominant hands, as well as greater presence of pain (P > .001). Furthermore, the dystonia group showed a negative correlation between perceived pain and pressure pain tolerance threshold (rho = −0.83; P < .001). ConclusionsPatients with focal hand dystonia presented alterations in sensitivity and more severe perceived pain than individuals without dystonia. Future studies with larger samples should aim to analyse the clinical implications and everyday impact of both objective and subjective pain.

Pathophysiology of dystonia

Pathophyiology of dystonia Alfredo Berardelli and Daniele Belvisi Dystonia is now considered a heterogeneous condition, characterized by motor and non-motor features. Several studies have clearly demonstrated that the pathophysiology of motor symptoms in dystonia is characterized by a combination of mechanisms including loss of inhibition, maladaptative cortical plasticity and deficits in sensorimotor integration, at various levels of the central nervous system. Recent evidence, however, casts doubts on the disease-specificity of these abnormalities. From an anatomical perspective, dystonia has been traditionally considered as a consequence of a cortico-basal ganglia-thalamo-cortical circuit dysfunction. Growing evidence suggests that also cerebellum may be involved in the pathophysiology of dystonia, either exerting a compensatory role or being involved in specific motor manifestations of dystonia, such as tremor. Dystonia has been recently modeled as a “network disorder” in which the clinical phenotype depends on an abnormal interaction among several neural pathways. In this complex scenario, idiopathic, inherited, and acquired forms of dystonia may have different pathophysiological mechanisms. In addition, different mechanisms and distinct neural structures seem to underlie the various forms of focal dystonia (cranial, cervical and focal hand dystonia). Patients with dystonia may also show non-motor symptoms, including cognitive, psychiatric, sleep and sensory disturbances. The pathophysiology of non-motor symptoms in patients with dystonia has been poorly investigated. The coexistence of motor and non-motor symptoms suggests that dystonia is characterized by the involvement of a wide and highly-interconnected network, that include several brain regions.

Personality Profile in Focal Hand Dystonia: A Cross-Sectional Study.

It has been suggested that focal hand dystonia (FHD) should be viewed as a neuropsychiatric disorder rather than as a pure movement disorder. We aimed to compare the personality factors that are common to people with FHD and evaluate how personality factors could affect the functionality of the upper limbs and community participation. We conducted a cross-sectional case–control study in which 12 people with FHD were matched with 12 age and gender matched healthy control participants. The Big Five Questionnaire; the Quick Disabilities, Arm, Shoulder, and Hand questionnaire; and the Jebsen–Taylor Test of Hand Function were used as assessment measures. Control of emotions was the only variable for which a significant difference was found, with participants with FHD displaying lesser control. Correlations were not observed between different personality profiles, the functionality of the upper limbs and the perceived participation of people with FHD in activities of daily living. People with FHD may present with low emotional stability, but this does not have a negative impact on the functionality of the upper limbs and activities of daily living. These findings have clinical implications to be considered for interventions, as they suggest that personality aspects, such as extraversion, may not predict for better functionality and perceived participation in activities of daily living.

P-MD018. Diagnostic approach for idiopathic simple writer’s cramp: A rare case of neurofunctional disorder

Introduction . Writer’s cramp is a part of focal hand dystonia that occurs task specifically during writing. It may happen in a person with the habit to write rapidly, continuously, and combined with individual vulnerability. This condition is highly disabling, accompanied by pain, and significantly decreases functional activity. Not only professionally disturbing, but this condition also leads to emotional and social problems for the patient. Results . We present here an unusual case of a 25-year-old right-handed woman with complaint of difficulty in writing since one year ago. She complained of involuntary muscle contraction in her upper right extremity, an extension of the finger, deviation of the wrist and elbow, followed by pain that happened only when she was writing. The symptoms progressed, and she was unable to write even a few words. Neurological examination revealed no abnormality. A series of laboratory tests, neurophysiology examinations, and brain MRI was performed. Diagnosis was suggestive of idiopathic simple writer’s cramp. Botulinum toxin was injected to the affected muscle. We also performed neuromuscular electrical stimulation as a neuro-rehabilitation therapy. The handwriting performance was examined and compared before and after treatment. The response to treatment was good, and the patient could write better with reduced tension in her right hand after treatment. Conclusion . Diagnosis writer’s cramp requires careful observation of the movements and motor control. Identifying patient properly can be of great first step to overcome this condition. Several diagnostic processes should perform to make an accurate diagnosis and appropriate treatment. Keywords: Writer’s Cramp, Focal Dystonia, Diagnostic Approach.

SY2.4. Sensori-motor organisation in focal hand dystonia

Focal Hand Dystonia is a task specific dystonia with co-contraction of agonists and antagonistic muscles. This disorder is attributed to a plausible dysfunction of the basal ganglia, but the exact role and sites are not yet well characterized. At our institution, we did experiments’ to explore the ontogeny of muscle contraction, sensory abnormalities and precision grip studies to explore dysfunction. The first study looked at the utility of 16 Channel surface EMG using customized software to objectively assess FHD during different phases of a writing task used to study timing, activation patterns and spread of muscle contractions in FHD when compared to normal controls. SEMG of FHD subjects showed ‘early onset’ during motor imagery, rapid proximal recruitment, co-contraction of agonist-antagonist proximal muscle groups, delayed offset after stopping to write, mirror activity in contralateral limb when compared to controls. The second experiment aimed to look at the degree of sensory dysfunction in subjects with Writer’s cramp using tasks for spatial discrimination and Aristotle illusory phenomenon and to look for Neural correlates using f MRI. There were abnormalities of sensory processing in patients with FHD in both spatial and illusory phenomenon. Spatial discriminatory abnormality was see in both hands indicating abnormalities in bilateral somatosensory cortex leading to abnormal sensory motor integration and resultant maladaptive plasticity and f MRI showed lack of good separation of activity for index and little finger stimulation with JVP dome. The third experiment looked at precision grip (both qualitative and quantitative measures) to discriminate FHD and PD from normal subjects. Healthy controls and patients (PD/FHD) gripped and lifted objects of 2 different weights;1.3 N &1.7 N with Dry Skin Condition and Very Wet Skin Condition. After practice trials, subjects were asked to reach, lift and hold stationary an object for 5 seconds and release the object on command. The force, rate and time parameters are measured and a ROC curve was measured and this study could qualitatively differentiate FHD and PD. These studies highlight that in FHD there is motor and sensory processing abnormalities demonstrating abnormal plasticity.