Baseline Features Influencing the Effectiveness of Retraining Therapy for Writer's Cramp

Evidence of rehabilitation therapy in task-specific focal dystonia: a systematic review

INTRODUCTION

Task-specific dystonias are primary focal dystonias characterized by excessive muscle contractions producing abnormal postures during selective motor activities that often involve highly skilled, repetitive movements. Based on the idea of excessive motor excitability and aberrant sensorimotor integration in the pathophysiology of task-specific dystonia, sensorimotor retraining may hold promise. The purpose of this systematic review was to investigate the available evidence about the role of rehabilitation therapy as a treatment for task-specific dystonia.

EVIDENCE ACQUISITION

A systematic review was performed of studies identified through Pubmed and Embase in a structured search strategy by independent author screening. The JBI (Joanna Briggs Institute) Critical Appraisal Checklist and RoB 2 were used to evaluate their methodological quality.

EVIDENCE SYNTHESIS

21 studies were included for qualitative synthesis. Most of the reports are small single group pre-/post-test study designs with a variability in the type of task-specific dystonia and the type of evaluated outcome measures. Rehabilitation interventions were grouped into six categories based upon the underlying theoretical basis of different approaches: 1) movement practice, 2) training with constraint, 3) sensory reorganization, 4) biofeedback training, 5) neuromodulation with training and 6) compensatory strategies.

CONCLUSIONS

Although it appears that a number of task-specific dystonia patients may improve with rehabilitation therapy, no definitive conclusions can be drawn. More research in this field is needed, using standardized approaches and clearly defined outcome measures in larger cohorts of task-specific dystonia patients that are clinically and diagnostically well characterized.

Dystonia

Dystonia is a neurological condition characterized by abnormal involuntary movements or postures owing to sustained or intermittent muscle contractions. Dystonia can be the manifesting neurological sign of many disorders, either in isolation (isolated dystonia) or with additional signs (combined dystonia). The main focus of this Primer is forms of isolated dystonia of idiopathic or genetic aetiology. These disorders differ in manifestations and severity but can affect all age groups and lead to substantial disability and impaired quality of life. The discovery of genes underlying the mendelian forms of isolated or combined dystonia has led to a better understanding of its pathophysiology. In some of the most common genetic dystonias, such as those caused by TOR1A, THAP1, GCH1 and KMT2B mutations, and idiopathic dystonia, these mechanisms include abnormalities in transcriptional regulation, striatal dopaminergic signalling and synaptic plasticity and a loss of inhibition at neuronal circuits. The diagnosis of dystonia is largely based on clinical signs, and the diagnosis and aetiological definition of this disorder remain a challenge. Effective symptomatic treatments with pharmacological therapy (anticholinergics), intramuscular botulinum toxin injection and deep brain stimulation are available; however, future research will hopefully lead to reliable biomarkers, better treatments and cure of this disorder.