Six patients with adductor spasmodic dysphonia were evaluated for evidence of brainstem dysfunction using the auditory brainstem response (ABR). In four, abnormally large increments in wave V latencies were found at high stimulus repetition rates. Latency increments exceeded three standard deviations above the mean in a normative adult population. A fifth patient had the prolonged interpeak latencies described previously by other investigators. In five of six patients the capacity of the auditory brainstem to conduct impulses was compromised. These results suggest a central nervous system abnormality in adductor spasmodic dysphonia.

Adult↗

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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.

Adult↗