The Comparison of Thyroarytenoid Muscle Myectomy and Type II Thyroplasty for Spasmodic Dysphonia

Surgical treatments for adductor spasmodic dysphonia include bilateral thyroarytenoid muscle myectomy (TAM) and type II thyroplasty (TPII), both of which are commonly performed. The present study aimed to compare the effects of TAM and TPII.

Retrospective study.

Subjects were 30 and 35 patients who underwent TAM and TPII, between March 2008 and November 2012. Voice quality was evaluated based on "voice handicap index 10 (VHI10)" and auditory impressions before and 6 months after surgery using five parameters: "strangulation," "interruption," "tremor," "grade," and "breathiness."

Comparison of the two procedures revealed significant improvements in VHI10, strangulation, interruption, and tremor, and a significant decline in breathiness after surgery. In particular, VHI10 was improved by more than six points in 90% of patients with TAM, and 96% with TPII. No significant difference was observed between the severities of two procedures preoperatively. Comparison of each postoperative score between the two procedures revealed that TAM significantly improved strangulation, interruption, and tremor, and significantly worsened breathiness, with no significant difference in VHI10. Scatter plots (x: preoperative scores; y: postoperative scores) and regression lines of evaluation items demonstrated that TAM is more effective than TPII in severe cases.

Compared with TPII, TAM tends to improve strangulation, interruption, and tremor; however, it tends to worsen breathiness postoperatively. Postoperative VHI10 scores did not differ significantly between the two procedures. Given favorable improvement rates, both surgical procedures were considered effective.