Laryngeal Electromyography as a Predictive Factor in the Evolution of Unilateral Recurrent Paralysis Post-Thyroidectomy.

Background

Dysphonia, a common symptom after thyroid surgery, is most often caused by damage to the recurrent laryngeal nerve. Laryngeal electromyography (LEMG) is used as a qualitative diagnostic tool to distinguish neurological etiology from other causes of dysphonia. The purpose of this study is to establish the value of LEMG as a predictor factor in the recovery of unilateral recurrent paralysis post-thyroidectomy.

Methods

This study included 11 patients with unilateral vocal fold palsy (UVFP) evidenced on the videostrobolaryngoscopy (VSL) after thyroidectomy. Electrical activity of thyroarytenoid (TA) muscles of the patients included in the study was recorded through LEMG and the prognosis of the lesions was classified as excellent, fair, or poor based on the presence of spontaneous activity and motor unit recruitment.

Results

LEMG at the first clinic visit showed an excellent prognosis in three of the cases, a fair prognosis in three of the cases, and five of them indicated a poor prognosis. At 6 months after the first LEMG, patients with a poor prognosis were unchanged and showed no LEMG improvement. Those with an excellent prognosis showed an increased recruitment response, and LEMG was normal. In one patient with a fair prognosis and minimal spontaneous activity, LEMG recruitment decreased during reevaluation. The other two fair-prognosis patients had a normal LEMG.

Conclusions

A correlation was found between LEMG findings and functional recovery of the vocal cords, demonstrating that the presence of spontaneous activity represents a negative prognostic factor. However, due to limited patient cohorts, the sensitivity of the LEMG as a prognostic tool in the functional recovery of the larynx is not yet established and requires further research.