Electroglottographic tracking of phonatory response to Botox (TM)

Botox injection into the thyroarytenoid muscle is thought to alter the glot tal competence and laryngeal adduction of patients with adductor spasmodic dysphonia (ADSD). Hypofunctional responses to treatment have been rated sub jectively and inferred from postinjection breathy voice, aphonia, midline g lottal gap, ol subclinical aspiration. Clinical experience suggests that te mporary hypofunction varies in duration and severity among patients. This s tudy used electroglottographic measures to examine changes over time in glo ttal competence during the relatively stable phonation produced by 5 patien ts with ADSD. Hierarchical linear modeling was used to test 3 hypotheses: ( a) that reduced laryngeal adduction would occur during the first 3 weeks po stinjection, followed by a reversal; (b) that patients' hypofunctional resp onse curves would differ one from another; and (c) that changes in adductio n, if present, would be related to changes in severity ratings of ADSD symp toms. For 3 participants, significant hypoadduction occurred after injectio n and reversed toward preinjection level over an 8-week period. Two partici pants demonstrated a flat or increasing vocal fold contact response curve d uring the early postinjection period. Observations were consistent with the previously reported differences and possibly complex relation between the resolution of breathy hypofunction and ultimate return of ADSD symptoms.