Treatment of writer’s cramp based on current pathophysiological concepts

Abstract

Task specific dystonia belongs to the group of focal dystonias. They are debilitating movement disorders that present with co-contraction of antagonist muscles during a specific task. The most common one is writer’s cramp. Botulinum toxin is the symptomatic standard treatment. Its response rate is 50% after 1 year, and the overall efficacy limited due to unwanted weakness in not injected muscles. The pathophysiology of writer’s cramp remains unclear, but genetic and additional environmental causes have been proposed. A possible underlying mechanism may be maladaptive reorganization in the sensorimotor cortex. Based on this background alternative treatment strategies were developed such as several different sensory and motor training programs that have been applied to reverse these brain abnormalities. In some studies, sensory and motor training were combined and adjunct with fitness exercises. They were conducted either as an outpatient setting or were established home based. Clinical outcome was measured with different clinical scales such as the writer’s cramp rating scale, the arm dystonia rating scale or the Burke, Fahn Marsden Scale. For objective assessment, kinematic handwriting parameters were analyzed. Functional or structural changes of the sensorimotor cortex were estimated using functional magnetic tomography, magnetencephalography and voxel-based morphometry. The results of these training programs were promising; however, one drawback is that the number of patients studied were small and the programs were not controlled since it is difficult to establish a control training to conduct a randomized controlled study.