Musician's dystonia is highly task specific: no strong evidence for everyday fine motor deficits in patients.

OBJECTIVES: 1) To examine the fine motor skills used everyday by patients suffering from musician's dystonia (MD) in the upper limb in order to verify whether MD is task-specific; and 2) to compare the affected and non-affected hands of MD musicians vs healthy musicians in performance of these tasks in order to clarify whether dystonic symptoms can be found in the non-affected side of MD patients. BACKGROUND: MD is typically considered to be focal and task specific, but patients often report impairment in everyday life activities. Furthermore, in the course of MD, about 15% of patients complain of dystonic symptoms in other parts of the body. METHODS: Twenty-seven musicians affected by MD and 27 healthy musicians were studied using 1) the Motor Performance Test Series, 2) a kinematic analysis of handwriting, and 3) an assessment of the grip force regulation while lifting and moving a manipulandum. RESULTS: Patients performed most fine motor tasks without any evidence of a deficit. Exclusively in the handwriting tasks (2), they exhibited fewer frequencies of the written trace and a prolonged overall writing time. CONCLUSION: MD is highly task specific and does not strongly affect other motor skills. The subtle deficits in handwriting may be explained as a consequence of a general psychological disposition rather than as compensatory mechanisms to avoid the appearance of dystonic symptoms. Furthermore, we did not find signs of multifocal motor deficits in the unaffected hands of MD patients.

Musician's cramp as manifestation of maladaptive brain plasticity: arguments from instrumental differences.

Musician's cramp is a task-specific movement disorder that presents itself as muscular incoordination or loss of voluntary motor control of extensively trained movements while a musician is playing the instrument. It is characterized by task specificity and gender bias, affecting significantly more males than females. The etiology is multifaceted: a combination of a genetic predisposition, termed endophenotype, and behavioral triggering factors being the leading features for the manifestation of the disorder. We present epidemiological data from 591 musician patients from our outpatient clinic demonstrating an influence of fine-motor requirements on the manifestation of dystonia. Brass, guitar, and woodwind players were at greater risk than other instrumentalists. High temporospatial precision of movement patterns, synchronous demands on tonic and phasic muscular activation, in combination with fine-motor burdens of using the dominant hand in daily life activities, constitute as triggering factors for the disorder and may explain why different body parts are affected.