Does instrumented movement analysis alter, objectively confirm, or not affect clinical decision-making in musicians with focal dystonia?

Focal dystonia (FD) is a movement disorder that frequently affects instrumental musicians. Distinguishing between primary dystonic movement and secondary compensatory abnormal movement is crucial for the correct treatment of planning in FD. Such distinction is complex in musicians because of the complexity, speed, and small-ness of involved movement. The goal of the current study was to assess the influence of instrumented movement analysis (MA) in treatment decision making in musician's FD. A group of 18 musicians with FD was instrumentally analyzed in an MA laboratory equipped with optoelectronic and electromyographic (EMG) acquisition systems. The muscle(S) primarily responsible for the dystonic movement or posture (trigger muscle) was identified on the basis of clinical assessment alone and, in a second phase, with the additional information provided by instrumented assessment. Comparison between clinical and instrumented assessment outcomes and the subjective rating of found differences were then analyzed. In 67% of patients, instrumental assessment changed the decision made by clinical assessment, indicating identification of a different trigger muscle or allowing for a more specific identification. In 28% of patients, instrumental assessment confirmed the outcome of the clinical assessment, with an increase in the confident level of the clinical decision. The most frequent change was an improved specification of which finger flexor muscle (superficialis or profundus) was triggering the dystonic movement. Although caution is needed due to the non blinded design of the present study, our results suggest that instrumented movement analysis is a useful complementary tool to clinical assessment in treatment planning for musician's focal dystonia-its use might change the identification of the muscles primarily responsible for dystonic movements as well as increase the confidence level of the clinician in treatment decision-making. Med Probl Perform Art 2008;23:99-106.