Objectivation of laryngeal electromyography (LEMG) data: turn number vs. qualitative analysis

This paper describes a first attempt to quantify LEMG data based on turn number calculation. The results obtained for both healthy and ailing thyroarytenoid (TA) muscles of patients with unilateral vocal fold immobility (UVFI) were compared with the respective qualitative evaluation concerning volitional activity to determine whether the two types of analyses deliver similar results.

LEMG data obtained from 44 adults with UVFI were considered for the study. Semiquantitative evaluation of TA volitional activity and turn number were assessed for the ailing and the healthy TA and the difference in percentage was calculated. Paired data were compared with the Wilcoxon signed-rank test. The volitional activity assessment and the turn number evaluation were compared with the Kruskal-Wallis test, and their relationship was tested with the Kendall rank correlation.

Datasets of 27 patients were considered compatible with turns/s calculation. The results showed that complete paralysis correlated with no turns; single fiber volitional activity with 62-208 turns/s, strongly decreased volitional activity with 198-501 turns/s; and dense volitional activity with 441-1234 turns/s. On the ailing VF only, the Kruskal-Wallis test showed a statistically significant difference (p = 0.0001), and the Kendall rank correlation a positive relationship (r = 0.853,p ≤ 0.0001) between the volitional activity rating and the turn number assessment.

Our preliminary results showed that turn number evaluation is an effective tool to confirm LEMG qualitative analysis, and that, in combination with laryngostroboscopy and voice assessment, can help improving the accuracy of the diagnosis and prognosis and the effectiveness of the chosen therapy.