Tongue Position Variability During Sustained Notes in Healthy vs Dystonic Horn Players Using Real-Time MRI

Embouchure dystonia (EmD) is a variant of focal task-specific dystonia in musicians characterized by the loss of control in facial and oral muscles while controlling airflow into the mouthpiece of a wind or brass instrument. We compared tongue position variability (TPV) during sustained notes between healthy, elite horn players and horn players affected by EmD.

Real-time MRI films at 33.3 ms resolution were obtained from 8 healthy elite and 5 EmD horn players as they performed on a non-ferromagnetic horn at each of three different dynamic levels: pianissimo, mezzo forte, and fortissimo. Nine profile lines (3 from anterior, 3 from middle, and 3 from posterior oral cavity regions) were overlaid on each image using a customized MATLAB toolkit, and the variability of the dorsal tongue edge position was examined at each dynamic from temporal intensity profiles produced by MATLAB.

Despite trends for more pronounced TPV (larger standard deviations) in the elite musicians (p=0.062), 2-way repeated measures ANOVA revealed no significant differences between groups. However, dynamic level significantly influenced TPV for all subjects, combined (p=0.048) and different regions of the oral cavity showed differing TPV (p<0.001). When only the most active region (anterior oral cavity) was included in the model, differences between groups reached statistical significance (elite > EmD, p<0.048), particularly at the fortissimo dynamic. We postulate that these differences may be due, in part, to a greater degree of generalized orofacial muscle tension in the EmD subjects that includes the tongue.