Inefficiencies in Motor Strategies of Horn Players with Embouchure Dystonia: Comparisons to Elite Performers.

Abstract

Motor control of the muscles of the face, lips, and tongue of horn players has traditionally been described from externally observed phenomena. Developments in real-time, high-speed magnetic resonance imaging (MRI) extend the scope of study to include descriptive and quantitative information from within the mouth. We employed these developments to compare oral movement strategies between 12 elite horn players and 5 horn players with embouchure dystonia (ED). Serial images with an acquisition time of 33.3 ms were obtained from each subject as they performed 6 exercises on an MRI-compatible horn: 1) a slurred ascending harmonic sequence, 2) a slurred descending harmonic sequence, 3-6) sustained high and low notes, each performed softly and loudly. Temporal changes in pixel luminescence along a series of lines positioned within the oral cavity were calculated using a customized MATLAB toolkit. This allowed the extraction of temporal line profiles for comparative analyses between elite and dystonic horn players. Differing motor strategies of controlling the tongue and jaw were observed during ascending and descending exercises. In ascending exercises, the elite players employed a strategy of elevation and anterior tongue displacement and elevation of the jaw, whereas dystonic players exhibited more variability in their responses. With descending exercises, both groups exhibited a lowering of the tongue and jaw, though this was more pronounced and consistent in the elite horn players. Sustained note exercises also elicited differences between groups. We suggest that elite strategies are more efficient and that the less-efficient patterns of dystonic players may exacerbate muscular tension with ED.