The Poor Validity of Asymmetric Laryngoscopic Findings in Predicting Laterality in Vocal Fold Paresis

Abstract

Objective: To determine the laryngoscopic findings most predictive of laterality in vocal fold paresis in patients with known RLN and/or SLN paresis by laryngeal electromyography (LEMG).

Study design: Blinded, prospective video perceptual analysis study.

Methods: Patients with vocal fold paresis diagnosed by LEMG at a tertiary care hospital from 2017 to 2019 were identified. Two fellowship-trained laryngologists blinded to clinical history and LEMG results reviewed laryngostroboscopic examinations and assessed for evidence of paresis using defined criteria. Inclusion criteria were adults with laryngeal asymmetry and evidence of decreased recruitment on LEMG. Exclusion criteria were children, presence of laryngeal lesions, myasthenia gravis, vocal fold paralysis, and normal laryngeal symmetry.

Results: We identified 95 patients who were diagnosed with vocal fold paresis with LEMG who met inclusion and exclusion criteria (mean age 43.8 ± 20.4 years (18-88), 38.9% male). When comparing the laterality of the observed laryngoscopic finding with LEMG, we found that in patients who had severe true vocal fold (TVF) range of motion disturbance, the laterality of the finding matched the LEMG distribution of paresis in 12 out of 13 (92.3%) patients (P = 0.002). No other laryngoscopic findings reliably predicted laterality including corniculate and cuneiform cartilage asymmetry, pyriform sinus dilation, abnormal TVF show, petiole deviation, abnormal ventricular show, increased supraglottic area, and FVF hyperfunction of the opposite side.

Conclusion: With the exception of severe TVF range of motion disturbance, there seems to be poor validity of laryngoscopic findings in predicting the affected side in vocal fold paresis. We recommend neurophysiologic testing to confirm the clinical diagnosis of vocal fold paresis.

Keywords: Electromyography; Laryngoscopy; Vocal fold paresis.