Treatment of Focal Hand Dystonia

Focal hand dystonia (FHD) in musicians is a painless task-specific motor disorder characterized by an involuntary loss of control of individual finger movements. The aim of this study was to investigate the effects of an innovative behavioural therapy intervention, aimed at normalising movement patterns, in musicians affected by FHD. Eight musicians volunteered to take part in this retraining protocol. Intensive constraint-induced therapy and motor control retraining at slow speed were the interventions. Video recordings of the subjects playing two pieces were used for data analysis. The Frequency of Abnormal Movements scale (FAM), the change in metronome speed achieved during motor control retraining, and two ordinal dystonia evaluation scales were chosen as outcome measures. It was hypothesised that there would be significant differences in the FAM scores and metronome speeds over a 12-month period. For the main outcome measure, the FAM scale scores, the two-factor repeated measures ANOVA revealed a very significant decrease in the number of abnormal movements per second of instrumental playing over the 12-month period (F = 6.32, df = 7, p < 0.001). Tukey's post-hoc tests carried out for the FAM scores revealed that significant changes occurred after 8 months of therapy. These results suggest that a combination of constraint-induced therapy and specific motor control retraining may be a successful strategy for the treatment of musicians' FHD. Furthermore, the results suggest that retraining strategies may need to be carried out for at least 8 months before statistically significant changes are noted.

Botulinum toxin is now the first-line therapy for writer's cramp and other occupational dystonias, with well-established efficacy and safety. Future studies will allow us to understand better the physiological effects of injection and to refine and enhance our treatment of focal hand dystonia.

Dystonia is a set of disorders characterized by abnormal postures and unwanted muscle spasms that interfere with motor performance. Focal dystonias, the most common, affect just 1 body part. A 25-year-old woman had a focal hand dystonia with pain and muscle spasms in the right hand after surgical treatment for thumb duplication. According to Wassel's classification, she was type II, with duplication of the distal phalanx. She had undergone Bilhaut-Cloquet surgery to remove a radial supernumerary thumb. During repetitive movements, she reported pain and muscle cramping in the right thumb and wrist. Force was rated, according to the Medical Research Council scale, from grades 0 to 5, and the patient had a score of 4. No sign of joint instability was found in her hand, and normal active and passive range of motion were found for interphalangeal or metacarpophalangeal joints of right thumb. However, right thenar muscle hypoplasia was found. Repetitive activity acted as an environmental trigger for the reconstructed thumb on thenar muscle hypoplasia as residual anatomical modification. Surface electromyography showed movements suggestive of dystonia. After 5 days of treatment with botulinum toxin type A, with both the flexor pollicis longus and the abductor pollicis brevis of right hand injected with a dose of 20 microM each, the patient reported a regression of most signs and symptoms. Two-month follow-up revealed that clinical effects of botulinum toxin type A were still present.

Focal hand dystonia (FHD) is usually adult-onset focal dystonia that can be associated with marked occupational and functional disability leading to reduced quality of life. Relevant studies on treatment options for FHD, their limitations, and current recommendations were reviewed using the PubMed search until March 31, 2021. Besides, the reference lists of the retrieved publications were manually searched to explore other relevant studies. and conclusion Currently, botulinum toxin has the best evidence for treatment of FHD, and 20-90% of patients experience symptomatic improvement. However, its benefit is often limited by the reduction of muscle tonus acting on the muscle spindle. Different surgical modalities that have been used to treat focal hand dystonia include lesional surgery, deep brain stimulation, and magnetic resonance-guided focused ultrasound thalamotomy. Recent studies exploring the role of behavioral techniques, sensorimotor training, and neuromodulation for the treatment of focal hand dystonia have reported good outcomes, but larger studies are required before implementing these interventions in practice.

Background: Posttraumatic focal hand dystonia after cervical whiplash injury is rare. Moreover, the treatment of peripheral posttraumatic dystonia is usually ineffective. Herein, we report a case of successful thalamotomy for a patient with focal hand dystonia after cervical whiplash injury.Case Description: A 39-year-old woman was hit from behind by a car; subsequently, she felt strange in the right hand and was diagnosed with whiplash injury. A month later, she developed a persistent abnormal posture of the right hand. Brain imaging showed no lesions, and cervical magnetic resonance imaging showed stenosis but no spinal cord signal changes. Posttraumatic dystonia was diagnosed, for which the patient underwent left ventro-oral (Vo) thalamotomy. One year after the first surgery, the patient underwent left Vo and ventral intermediate nucleus (Vim) thalamotomy due to recurrence of dystonia. Nine years after the second surgery, the patient continues to be able to maintain her normal physical routine.Conclusion: Vo-Vim thalamotomy may be a feasible and effective treatment for focal hand dystonia after cervical whiplash injury.

Focal hand dystonia in musicians, which is characterized by involuntary flexion and/or extension of fingers while playing musical instruments, is a disabling neurological disorder that can even threaten their careers. The present study investigated whether or how a non-invasive intervention for focal hand dystonia called “slow-down exercise” affects motor performance, muscular activity, and somatosensation in a dystonic pianist. The patient was asked to performa simple five-finger exercise at three different tempi on a digital piano, just prior to, 1, 2, 3, 6, and 12 months after the onset of the slow-down exercise training. As the rehabilitation proceeded, the patient improved the regularity of piano keystrokes, as objectively quantified using musical instrument digital interface signals. Measurements of surface electromyographic activity from the forearm muscles demonstrated that the patient gradually regained the inherent bilateral difference in the co-contraction level of the extensor digitorum communis and flexor digitorum superficialis muscles. Furthermore, the practice of slow-down exercise lowered the two-point discrimination thresholds of affected fingers, indicating the restoration of tactile spatial resolution. These findings not only confirm the effectiveness of slow-down exercise for the treatment of focal hand dystonia but also provide objective evidence that a simple behavioral intervention can reverse the reorganization of sensorimotor neural networks in dystonic patients.

Sensory motor retuning: A behavioral treatment for focal hand dystonia of pianists and guitarists

New perspectives in neurorehabilitation suggest that behavioral treatments of movement disorders may modify the functional organization of central somatosensory neural networks. On the basis of the assumption that use-dependent reorganization in these networks contributes to the fundamental abnormalities seen in focal dystonia, we treated 10 affected musicians and measured the concomitant somatosensory changes by using whole-head magnetoencephalography. We found that effective treatment, using the method of sensory motor retuning, leads to alterations in the functional organization of the somatosensory cortex. Specifically, before treatment, somatosensory relationships of the individual fingers differ between the affected and unaffected hands, whereas after treatment, finger representations contralateral to the dystonic side become more similar to the less-affected side. Further, somatosensory finger representations are ordered more according to homuncular principles after treatment. In addition, the observed physiologic changes correlated with behavioral data. These results confirm that plastic changes in parallel with emergent neurological dysfunction may be reversed by context-specific, intensive training-based remediation.

Ten patients with focal dystonia of the hand, all of whom had benefited in an open-label study of botulinum toxin, were treated with botulinum toxin-A in a double-blind study. Response was assessed by three measures: (a) subjective rating, provided by patients' reports of the effect of the injections on the dystonia; (b) objective testing, consisting of manual muscle testing (MRC scale) to measure muscle strength in all patients, timing of a writing sample and counting the number of errors of writing off-the-line in six patients with writer's cramp, counting the number of errors on a standard test of transcription in two patients with stenographer's cramp, and rating by professional musicians of the performances of two patients with musician's cramp; and (c) physicians' rating, provided by a review of the patients' videotaped performance by neurologists who were unaware of which treatment was administered. Eight of the 10 patients had greater subjective improvement with botulinum toxin than with placebo, and this impression was verified by at least one objective test in six patients. Two patients failed to have a better response to botulinum toxin than to placebo, and their reports were verified by the objective tests. This study confirms the efficacy of botulinum toxin in many patients with focal hand dystonia.

Focal hand dystonia (FHD) is characterized by excessive and unwanted muscle activation in both the hand and arm resulting in impaired performance in particular tasks. Understanding the pathophysiology of FHD has progressed significantly for several decades and this has led to consideration of other potential therapies such as non-invasive brain stimulation (NIBS). A number of studies have been conducted to develop new therapy for FHD using transcranial magnetic stimulation and transcranial direct current stimulation. In this paper, we review previous studies and describe the potential therapeutic use of NIBS for FHD. We also discuss the future direction of NIBS to treat FHD.

Focal hand dystonia (FHD) in musicians is a painless, task-specific motor disorder characterized by involuntary loss of control of individual finger movements. The aim of this study was to investigate the long-term effects of a combined behavioral therapy intervention aimed at normalizing finger movement patterns. Eight musicians with FHD had taken part in the 1-year study involving intensive constraint-induced therapy and motor control retraining at slow speed as the interventions. Four of these subjects volunteered to take part in this 4-year follow-up. A quasi-experimental, repeated measures design was used, with 9 testing sessions over 4 years. Video recordings of the subjects playing two pieces were used for data analysis. The Frequency of Abnormal Movements scale (FAM) was the main outcome measure. It was hypothesized that there would be significant differences in FAM scores achieved over the 4-year period. The results from the ANOVA revealed a significant decrease, by approximately 80%, in the number of abnormal movements for both pieces over the 4-year period (F=7.85, df=8, p<0.001). Tukey's post-hoc test revealed that significant improvements occurred after 6 months of therapy (p-values between p<0.001 and p=0.044). Although the results were not significant between month 12 and follow-up at year 4, the trend revealed that the progress achieved during the first year of intensive retraining was maintained at year 4. A 1-year period of intensive task-specific retraining may be a successful strategy with long-term, lasting effects for the treatment of musician's FHD. Results suggest that retraining strategies may need to be carried out for at least 6 months before statistically significant changes are noted.

ABSTRACTBackgroundThe efficacy of magnetic resonance‐guided focused ultrasound (MRgFUS) thalamotomy for the treatment of focal hand dystonia (FHD) is not well known.ObjectiveWe aimed to prospectively investigate the efficacy of MRgFUS thalamotomy for the treatment of FHD.MethodsWe performed MRgFUS thalamotomy of the ventro‐oral (Vo) nucleus in 10 patients with FHD. We evaluated the scores of the Writer's Cramp Rating Scale (WCRS, 0–30; higher scores indicating greater severity), Tubiana Musician's Dystonia Scale (TMDS, 0–5; lower scores indicating greater severity), and Arm Dystonia Disability Scale (ADDS, 0%–100%; lower scores indicating greater disability) at baseline and 3 and 12 months post‐treatment.ResultsWCRS, TMDS, and ADDS scores significantly improved from 6.3 ± 2.7, 1.4 ± 0.5, and 58.7% ± 14.3% at baseline to 1.6 ± 3.1 (P = 0.011), 5.0 ± 0 (P = 0.0001), and 81.6% ± 22.9% (P = 0.0229) at 12 months, respectively. There was one prolonged case of dysarthria at 12 months.ConclusionWe show that MRgFUS Vo‐thalamotomy significantly improved FHD. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

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.

Though the pathophysiology of dystonia remains uncertain, two primary factors implicated in the development of dystonic symptoms are excessive cortical excitability and impaired sensorimotor processing. The aim of this study was to determine the functional efficacy of an intervention combining repetitive transcranial magnetic stimulation (rTMS) and sensorimotor retraining. A randomized, single-subject, multiple baseline design with crossover was used to examine participants with focal hand dystonia (FHD) (n = 9). Intervention: 5 days rTMS + sensorimotor retraining (SMR) vs. Five days rTMS + control therapy (CTL) (which included stretching and massage). The rTMS was applied to the premotor cortex at 1 Hz at 80% resting motor threshold for 1200 pulses. For sensorimotor retraining, a subset of the Learning-based Sensorimotor Training program was followed. Each session in both groups consisted of rTMS followed immediately by 30 min of the therapy intervention (SMR or CTL). Contrary to our hypothesis, group analyses revealed no additional benefit from the SMR training vs. CTL. When analyzed across group however, there was significant improvement from the first baseline assessment in several measures, including tests of sensory ability and self-rated changes. The patient rated improvements were accompanied by a moderate effect size suggesting clinical meaningfulness. These results provide encouragement for further investigation of rTMS in FHD with a need to optimize a secondary intervention and determine likely responders vs. non-responders.

The treatment of writer's cramp, a task-specific focal hand dystonia, needs new approaches. A deficiency of inhibition in the motor cortex might cause writer's cramp. Transcranial direct current stimulation modulates cortical excitability and may provide a therapeutic alternative. In this randomized, double-blind, sham-controlled study, we investigated the efficacy of cathodal stimulation of the contralateral motor cortex in 3 sessions in 1 week. Assessment over a 2-week period included clinical scales, subjective ratings, kinematic handwriting analysis, and neurophysiological evaluation. Twelve patients with unilateral dystonic writer's cramp were investigated; 6 received transcranial direct current and 6 sham stimulation. Cathodal transcranial direct current stimulation had no favorable effects on clinical scales and failed to restore normal handwriting kinematics and cortical inhibition. Subjective worsening remained unexplained, leading to premature study termination. Repeated sessions of cathodal transcranial direct current stimulation of the motor cortex yielded no favorable results supporting a therapeutic potential in writer's cramp.