Vocal Fold Opening Position Impacts Bowing Measures in Age-Related Vocal Atrophy

Age-related vocal atrophy (ARVA) impacts voice and quality of life. In ARVA, vocal folds appear thin and bowed. Bowing Index (BI) is used to quantify vocal fold bowing. However, it remains unclear how abduction and adduction of the vocal folds influence BI. The purpose of this study was to assess the relationship of BI to vocal fold task and angle.

Patients with ARVA were included (n = 22). Flexible video laryngostroboscopy was collected during an alternating voice-sniff task, during which vocal folds transition from adducted (closed) to fully abducted (open) positions. BI was measured at each non-phonatory frame. Two clinical raters then rated each subject by severity, and their ratings were compared to BI.

Mean BI was higher during vocal fold abduction than adduction (8.15 ± 3.29, 6.34 ± 2.21, respectively, mean difference 1.81, 95% CI: 1.25-2.38, p < 0.0001). Mean BI was higher when vocal folds were between 40% and 60% of maximal abduction compared to 80%-100% (mean difference 2.61, 95% CI: 1.26-3.96, p < 0.0001). Mean BI increased with clinical severity (7.30 ± 1.85 mild; 8.90 ± 2.52 moderate), with a BI of 14.62 in the single severe case.

Vocal fold bowing is influenced by the degree of opening and the adduction versus abduction tasks in patients with ARVA. Bowing was greater during the abducting task than during the adducting task, with the most pronounced bowing observed at a semi-abducted position. Future studies are warranted to further characterize these findings and to support standardization of BI measurement.

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