Kymographic characterization of vibration in human vocal folds with nodules and polyps

Authors

  • Ann M. Chodara BS,

    1. Department of Surgery, Division of Otolaryngology–Head and Neck Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, U.S.A
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  • Christopher R. Krausert BS,

    1. Department of Surgery, Division of Otolaryngology–Head and Neck Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, U.S.A
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  • Jack J. Jiang MD, PhD

    Corresponding author
    1. Department of Surgery, Division of Otolaryngology–Head and Neck Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, U.S.A
    • 1300 University Avenue, 2745 Medical Sciences Center, Madison, WI 53706
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  • This research was supported by National Institutes of Health grant number R01 DC008850 from the National Institute on Deafness and Other Communication Disorders. The authors have no other funding, financial relationships, or conflicts of interest to disclose.

Abstract

Objectives/Hypothesis:

Digital kymography (DKG) can provide objective quantitative data about vocal fold vibration, which may help distinguish normal from pathological vocal folds as well as nodules from polyps.

Study Design:

Case-control study.

Methods:

There were 87 subjects who were separated into three groups: control, nodules, and unilateral polyps, and examined using a high-speed camera attached to an endoscope. Videos were analyzed using a custom MATLAB program, and three DKG line-scan positions (25%, 50%, and 75% of vocal fold length) were used in statistical analyses to compare vocal fold vibrational frequency, amplitude symmetry index (ASI), amplitude order, and vertical and lateral phase difference (VPD and LPD, respectively).

Results:

Significant differences among groups were found in all vibrational parameters except frequency. Polyps and nodules groups exhibited greater ASI values (less amplitude symmetry) than the control group. Although the control group consistently showed its largest amplitudes at the midline, the polyps group showed larger amplitudes toward the posterior end of the vocal folds. A significant anterior-posterior pattern in amplitude was not found in the nodules group. LPD values were usually largest (most symmetrical) in the control group, followed by nodules and polyps. LPD at the 25% position allowed for differentiation between polyp and nodule groups. The largest VPD (more pronounced mucosal wave) values were usually found in the control group.

Conclusions:

Vibratory characteristics of normal and pathological vocal folds were quantitatively examined and compared using multiline DKG. These findings may allow for better characterization of pathologies and eventually assist in improving the clinical utility of DKG.

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