FOCAL DYSTONIA IN MUSICIANS

E.Altenmueller, H.C.Jabush, Institute of' Music Physiology and Musicians Medicine Hannover University of Music anf Drama

Sensory-motor skills of musicians have some specific qualities: learning begins at an early age in a playful atmosphere. Routines for stereotyped movements are rehearsed for extended periods of time with gradually increasing degrees of complexity. Via auditory feedback, the motor performance is extremely controllable by both, performer and audience. And all movements are strongly linked to emotions, (pleasure or anxiety), processed by the limbic system. These specific circumstances seem to play an important role in the development of focal limb dystonia, also referred to in the medical literature as occupational cramps (?violinist's cramp?, ?pianist's cramp?). Characteristically, focal dystonia presents as painless muscular incoordination or loss of voluntary motor control of highly trained movements while playing the instrument. The incidence of focal dystonia is increased in musicians when compared to other professions demanding skilled hand-movements.

According to new research data, focal dystonia may be caused by training induced cortical dysplasticity with pathological fusion of single digit representations in sensory or motor cortical regions. Besides brain imaging data, additional arguments support this theory: 1) there is a higher incidence of dystonia in instrumentalists practising over average, suggesting a relation to training and overuse of repetitive movements; 2) the disorder may occur subsequently to sensory disturbances, which have been shown to lead to a similar fatal reorganisation of cortical representations of the hand.

Since the majority of highly trained musicians and of musicians having suffered from nerve compression or pain syndromes are able to maintain the accuracy of their movements, additional risk factors or a certain susceptibility for developing focal dystonia must exist. The existence of "focal-dystonia-families" hints on a genetically fixed predisposition, but also psychological predispositions may contribute to the development of the disorders.

Besides anticholinergic drugs and local injections of Botulinum-Toxin in the cramping muscles, new training programs developed in co-operation with physiotherapists and instrumental teachers may improve the condition - although these methods still remain to be evaluated with respect to long-term outcome. Further research is urgently needed to establish evidence based prophylactic interventions.

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