Lidocaine block of the recurrent laryngeal nerve in adductor spasmodic dysphonia: a multidimensional assessment.

Abstract

Lidocaine block of the recurrent laryngeal nerve (RLN) has been reported as a procedure for surgical selection of patients with adductor spasmodic dysphonia (ADSD). However, its effects on phonation have not been rigorously assessed in a prospective fashion using strict entry criteria and multiple measures of phonatory function. This investigation assessed the phonatory effects of RLN lidocaine block in ADSD to explore its potential as a diagnostic tool. Single group, pre/postexperimental trial. Twenty-one consecutive patients with suspected ADSD underwent unilateral RLN block, causing temporary ipsilateral vocal fold paralysis. Voices were recorded before and during the block. Patients completed self-ratings of overall level of dysphonia severity, vocal effort, and laryngeal tightness. Blinded listeners completed auditory-perceptual ratings, and the frequency of phonatory breaks was acoustically analyzed. During the block, patients reported significant reductions on overall severity (P = .045), vocal effort (P < .001), and laryngeal tightness (P = .002). Listeners rated the voices during the block as significantly more breathy (P < .001), less strained (P < .001), and less severe (P = .059). Acoustic analysis confirmed significantly fewer phonatory breaks during the block (P < .001). Patient-based ratings of improvement were more consistent than listener ratings, and reduction in overall severity correlated with perceived breathiness. Although individuals varied in their outcomes, group results suggest that response to RLN lidocaine block warrants further study as a possible diagnostic tool in ADSD.