COMPARISON OF MUSCLE ACTIVATION PATTERNS IN ADDUCTOR AND ABDUCTOR SPASMODIC DYSPHONIA

Patients with adductor and abductor spasmodic dysphonia were compared with normal controls on speech items particularly difficult for the tw o patient groups. Intrinsic and extrinsic laryngeal muscles were measu red during adduction for voicing and for a glottal stop, and during ab duction after a vowel and after a glottal stop. Muscle activity was me asured while the patients attempted the speech items, with considerabl e difficulty, but not during periods of complete voice loss. Muscle ac tivity at rest, activity increases for speech, and percent changes for adduction and abduction did not differ from normal in either patient group. The results demonstrated normal muscle activation levels and ch anges for speech in the patients, and suggested that symptoms occur wh en spasmodic bursts intrude on an otherwise normal pattern.