Brainstem conduction abnormalities in spasmodic dysphonia.

Twelve spasmodic dysphonia patients were evaluated by three different auditory brainstem response parameters; 75% were abnormal. Three of the 12 had prolonged wave I-V interpeak latency. Seven had pathologic wave V latency shifts at a high stimulus rate. Amplitude ratios were normal for all subjects. The authors hypothesize that spasmodic dysphonia is a disorder of variable cranial nerve symptom presentations, and offer several possible models to account for its sporadic representation in the nervous system.