Focal dystonia in musicians: From phenomenology to therapy

Abstract

Background: Musician’s dystonia is a task-specific movement disorder which manifests itself as a loss of voluntary motor control in extensively trained movements. In many cases, the disorder terminates the careers of affected musicians. Approximately 1% of all professional musicians are affected. Etiology and Pathophysiology: The pathophysiology of the disorder is still unclear. Findings include (a) reduced inhibition in different levels of the central nervous system, (b) maladaptive plasticity, e.g. in the somatosensory cortex and in the basal ganglia, and (c) alterations in sensorimotor processing. Epidemiological data demonstrated a higher risk for those musicians who play instruments requiring maximal fine-motor skills. For instruments where workload differs across hands, focal dystonia appears more often in the more intensely used hand. In psychological studies, musicians with dystonia had more perfectionist tendencies than healthy musicians. These findings strengthen the assumption that behavioral factors may be involved in the etiology of musician’s dystonia. Hereditary factors may play a greater role than previously assumed. Preliminary findings suggest a genetic contribution to focal task-specific dystonia with phenotypic variations including musician’s dystonia. Treatment: Treatment options for musician’s dystonia include pharmacological interventions such as administration of Trihexyphenidyl or Botulinum Toxin-A as well as retraining programs and ergonomic changes in the instrument. A long-term follow-up study was performed in 144 patients with musician’s dystonia. The outcome was revealed on average 8.4 years after onset of symptoms. Outcome was assessed by patients’ subjective rating of cumulative treatment response and response to individual therapies. Seventy-seven patients (54%) reported an alleviation of symptoms: 33% of the patients with Trihexyphenidyl, 49% with Botulinum Toxin, 50% with pedagogical retraining, 56% with unmonitored technical exercises, and 63% with ergonomic changes. In embouchure dystonia, only 15% of patients reported improvement. The results demonstrate that the situation of musicians with focal hand dystonia may be significantly improved. Positive results after retraining and unmonitored technical exercises underline the benefit of an active involvement of patients in the treatment process. Only exceptionally, however, can musicians with focal dystonia return to normal motor control using the currently available therapies.