Spontaneous Activity in Laryngeal Electromyography for Prognosis Prediction for Unilateral Vocal Fold Paralysis

This study aims to examine the prognostic significance of spontaneous activity (SA) detected by laryngeal electromyography (LEMG) in patients with unilateral vocal fold paralysis (UVFP).

A prospective observational cohort study.

A tertiary medical center.

We enrolled 124 patients with UVFP who underwent initial LEMG within 6 months of symptom onset and a second LEMG evaluation at follow-up. SA in the thyroarytenoid-lateral cricoarytenoid (TA-LCA) muscle complex was categorized as present (SA+; n = 87) or absent (SA-; n = 37). Outcome measures included LEMG parameters (peak turn frequency and turn ratio), glottal gap, acoustic voice analysis, and quality of life.

At baseline, SA+ patients exhibited significantly more decreased recruitment and lower peak turn frequency in the TA-LCA muscle complex compared to SA- patients. By follow-up, only the difference in decreased recruitment remained significant. SA+ was also associated with lower maximum phonation time at baseline; however, no significant group differences were observed in glottal gap, acoustic voice measures, or quality of life at follow-up. SA independently predicted decreased recruitment over the long term, aligning with prior observations that SA is often accompanied by recruitment deficits during the subacute to chronic phases post-denervation.

Although SA independently predicted the presence of decreased recruitment at long-term follow-up, it lacked predictive value for quantitative LEMG peak turn frequency. Therefore, SA should be evaluated alongside recruitment patterns to provide a more comprehensive prognosis for UVFP. This study offers a more nuanced view of the prognostic role of SA, thereby enhancing the predictive accuracy of LEMG in patients with UVFP.