Focal dystonia in musicians: phenomenology, pathophysiology and triggering factors.

BACKGROUND Musician's dystonia is a task-specific movement disorder that 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. The pathophysiology of the disorder is still unclear. Findings include: (i) reduced inhibition in different levels of the central nervous system, (ii) maladaptive plasticity, e.g. in the somatosensory cortex and in the basal ganglia and (iii) alterations in sensorimotor processing. METHODS Review of the literature. RESULTS 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 behavioural factors may be involved in the etiology of musician's dystonia. Hereditary factors may play a greater role than previously assumed. CONCLUSIONS We propose a heuristic model that may explain the relatively high incidence of focal dystonia in musicians. This model assumes the coactions between a predominantly genetically determined predisposition and intrinsic and extrinsic triggering factors.