Adductor muscle activity abnormalities in abductor spasmodic dysphonia

OBJECTIVE: To determine laryngeal muscle activation abnormalities associate d with speech symptoms in abductor spasmodic dysphonia (ABSD). STUDY DESIGN: Bilateral laryngeal muscle recordings from the posterior cric oarytenoid, thyroarytenoid, and cricothyroid muscles were conducted in 12 A BSD patients, Patients' measures were compared during speech breaks and dur ing speech without breaks and with In normal controls. RESULTS: Significant group differences were found in the thyroarytenoid mus cle; the patients had significantly greater activity on the right side both during speech breaks and nonbreaks in comparison with the controls, Cricot hyroid muscle levels were also increased on the right in the patients. CONCLUSION: An asymmetry in adductor muscle tone between the 2 sides in ABS D may account for difficulties with maintaining phonation and voice onset a fter voiceless consonants, SIGNIFICANCE,. These abnormalities may indicate why PCA BOTOX injections have not been as effective in ABSD as thyroaryteno id injections have been in adductor spasmodic dysphonia.