Sensorimotor overactivity as a pathophysiologic trait of embouchure dystonia.
BACKGROUND
Embouchure dystonia is a focal task-specific dystonia affecting the complex interplay of lower facial, jaw, and tongue muscles in musicians playing brass or woodwind instruments. Although it is highly disabling for affected patients, little is known about the pathophysiologic basis of this rare movement disorder.


METHODS
We therefore studied sensorimotor activation patterns during 2 orofacial motor tasks in brass players with embouchure dystonia by using fMRI. A "dystonia-specific" task involved buzzing at an instrument-specific, fully functional mouthpiece. A "neutral" task involved simply blowing into a tube.


RESULTS
Compared with healthy brass players, patients with embouchure dystonia showed significantly increased activation of somatotopic face representations within the bilateral primary sensorimotor cortex and of the bilateral premotor cortex during buzzing at the mouthpiece. Interestingly, a similar activation pattern was present during the neutral task when patients were clinically asymptomatic.


CONCLUSIONS
Sensorimotor overactivity could reflect deficient subcortical and intracortical inhibition as well as abnormal sensorimotor integration and reorganization in musicians with embouchure dystonia. Because this overactivity was also found during the neutral task, it could be a crucial pathophysiologic factor predisposing for the development of orofacial dystonia rather than a mere correlate of dystonic motor output.
Neurologische Klinik, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, D-81675 München, Germany. haslinger@lrz.tum.de
B
B
Haslinger
E
E
Altenmüller
F
F
Castrop
C
C
Zimmer
C
C
Dresel
D000328:Adult; D004421:Dystonia / Q000473:pathology* / Q000503:physiopathology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005152:Facial Muscles / Q000098:blood supply / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009146:Music; D009460:Neurologic Examination / Q000379:methods; D010100:Oxygen / Q000097:blood; D013003:Somatosensory Cortex / Q000098:blood supply / Q000503:physiopathology*
D010100:Oxygen