(0834) Standardized Glottal Measurements for Quantitative Evaluation of Vocal Fold Mobility Disorders

Introduction: Flexible laryngoscopy is the gold standard for evaluation of vocal fold mobility disorders, but standardized quantitative measures of glottal anatomy have not been validated. We hypothesize unilateral vocal fold immobility (UVFI) and bilateral vocal fold immobility (BVFI) have characteristic measures that differ from normal controls and may be used to identify and quantify degree of pathology.

Methods: Recorded flexible laryngoscopy exams from patients with BVFI (n=5) and UVFI (n=5) were compared with normal controls (n=5). Representative images of maximal glottic opening were analyzed in ImageJ by two independent raters to calculate unilateral and combined bowing index (BI), maximal glottic surface area (MGSA), and maximal opening angle (MOA). Normality was confirmed with Shapiro-Wilk test and statistical comparisons were performed with one-way ANOVA or paired t-test, with threshold for significance of  = 0.05. Interrater reliability for objective glottal measures was compared with intraclass correlation coefficient (ICC).

Results: MGSA decreased from a mean (standard deviation) of 1.01 (0.41) sq. units in normal controls to 0.76 (0.08) in UVFI and 0.32 (0.11) in BFVI (p=0.002). MOA was 52.3 degrees (16.0 deg) in normal controls in contrast to 38.4 deg (5.54 deg) in UVFI and 12.4 deg (3.0 deg) in BVFI (p < 0.001). Combined BI was significantly higher for UVFI (0.11 [0.01]) and BVFI (0.12 [0.07]) compared to normal controls (0.05 [0.03], p=0.02), but was not different between UVFI and BVFI (p=0.93). However, when comparing unilateral BI, UVFI showed significantly higher BI on the affected side compared to both normal controls and BVFI patients (p=0.01). There was good to excellent ICCs for all comparisons (0.83 – 0.95).

Conclusions: Quantitative measures of glottal anatomy are described which have characteristic values across differing pathologies of glottic mobility. These may be used in the future to help quantify severity of disease and degree of improvement from therapeutic intervention.