How Can We Predict the Recovery from Pitch Lowering After Thyroidectomy

BACKGROUND Some of patients are suffered from pitch lowering of voice after thyroidectomy. We sought to identify factors predictive of a recovery from lowered pitch voice after thyroid surgery. METHODS We retrospectively reviewed the records of 133 patients who underwent total thyroidectomy to treat papillary carcinoma between January 2012 and February 2013. Of these, we enrolled 78 who exhibited a lower-pitched voice (SFF fall > 12 Hz) at 2 weeks post-operatively than pre-operatively and investigated pitch recovery after 3 months. We subclassified patients into recovery and non-recovery groups and compared videostroboscopic findings, acoustic voice data, and thyroidectomy-related voice questionnaire scores pre-operatively and 2, 8, and 12 weeks post-operatively. RESULTS Vocal cord asymmetry on videostroboscopic examination at 2 weeks post-operatively (odds ratio 19.056, p = 0.001*) was more frequent in the non-recovery group. In acoustic analysis, mean pre-operative SFF was higher in the non-recovery group than the recovery group (190.9 ±  27.5 and 180.9 ±  24.6 Hz, respectively; p = 0.030*). Also, a reduction in the SFF of > 19.6 Hz, at 2 weeks post-operatively versus pre-operatively, predicted non-recovery of pitch-lowering in patients with reduced SFF within post-operative 3 months, with 72.0% sensitivity and 71.2% specificity. After 6 months of follow-up, no patient who exhibited an SFF fall > 19.6 Hz recovered to within 10 Hz of the pre-operative value. CONCLUSION A reduction in the speaking fundamental frequency (SFF) > 19.6 Hz at 2 weeks post-operatively predicted persisting lowering of voice pitch after thyroidectomy among those with lower-pitched voices after surgery. Pre-operative high SFF and post-operative stroboscopic findings including vocal cord asymmetry at 2 weeks post-operatively also predicted persisting lowering of voice pitch for 3 months.