The evaluation of the causes of subjective voice disturbances after thyroid surgery

Voice changes following thyroidectomy is a rare form of morbidity not infrequently encountered. Injury to the recurrent laryngeal nerve or external branch of the superior laryngeal nerve is the most well-known cause of post-thyroidectomy voice disturbances. However, voice dysfunction is a more complex entity. The aim of the current study was to assess the possible factors that influence voice changes after thyroidectomy.

Forty-eight consecutive patients who had undergone thyroidectomy were studied. The acoustic voice analysis (mean vocal fundamental frequency [Fo], mean percentage vocal jitter and shimmer, and noise-to-harmonic ratio) and videolaryngostroboscopic examination of these patients were performed preoperatively, on the second postoperative day, and 3 months after the operation. The presence of subjective voice changes was recorded prospectively based on a symptom scale.

No major complications occurred perioperatively or in the postoperative period. Videolaryngostroboscopic examinations were normal in all patients before and after thyroidectomy. Eighteen (37.5%) patients complained of subjective voice changes in the early postoperative period and 7 (14.6%) of these were still uncomfortable after 3 months. Although the difference was significant by means of all acoustic voice parameters measured in the early postoperative period, Fo is the only parameter that continues to be significant after 3 months.

Irrespective from recurrent laryngeal nerve and/or injuries to the external branch of the superior laryngeal nerve, voice may temporarily be affected by thyroidectomy. Most of the subjective complaints and acoustic voice parameters return to normal in a few months after surgery.