Focal, task-specific dystonia in professional musicians represents a special type of focal, adult-onset dystonia, manifesting itself exclusively while playing music. Disease onset is usually sudden, characterized by painless incoordination while playing certain notes of music; it does not occur in non-professional musicians. Musicians` dystonia barely responds to treatment, which usually terminates musicians` careers (Altenmüller, 2012).
The aim of this review is to examine whether extensive music-practice contributes essentially to the pathogenesis of focal, task-specific dystonia in professional musicians. If proved true, the formal criteria for an occupational disorder would be fulfilled.
Before conducting a systematic research of the current literature, we defined the PICOS-criteria required for a systematic review (Stroup et al., 2000; Liberati et al., 2009). The population to be examined (p = population) was set to professional musicians, the exposition (i = intervention) was defined as extensive music-practice, the control group (c = controls) as non-professional musicians, the outcome (o =outcome) as the manifestation of dystonic symptoms and the study design (s = study design) was set up. A literature research was conducted using the search string "musician`s dystonia" within 23 databases from 1950-2013. Initially, 866 hits were retrieved, among which 16 articles qualified for uptake into this systematic review, containing clinical information on 1144 diseased musicians. Quality appraisal was conducted by two independent authors according to the Liverpool adaptation of the Newcastle Ottawa Scale (Voss, Rehfuess, 2013).
For each patient, clinical manifestation of dystonia, age at first manifestation, sex and corresponding factors were extracted in reference to the instrumental group. We identified an instrument-specific manifestation of focal dystonia with a predilection of the limb most exposed to fine-motor demands during extensive music-practice. Orofacial dystonia was exclusively noted for brass and woodwind instrumentalists; in keyboard and plucked string instrumentalists, predominant affection of the right hand was noted, whereas, in percussionists, the lower limbs were exclusively affected.
To assess the relationship between extensive music-practice and the manifestation of focal dystonia in musicians as causal or associative, the viewpoints according to Bradford-Hill were applied (Lucas, McMichael, 2005). They account for the strength of association, consistency of results, specifity, temporal relation, biological gradient, plausibility, coherence, experiment and analogy. We were able to apply all of the nine viewpoints on the data retrieved in this systematic review, prompting us to assume a causal relationship between extensive music-practice and the manifestation of focal dystonia in professional musicians.
-cross sectoral-Type of hazard:
health impairments and disorders, physical strain/stressDescription, key words:
Focal dystonia, professional musicians