Quantification of static and dynamic supraglottic activity.

For estimating supraglottic compression in disordered voice production, categorical rating scales of true vocal fold coverage by supraglottic structures are the current standard. Quantification of change in the position of supraglottic structures compared to no supraglottic activity would be a better method for distinguishing between and within voice-disordered groups. This study developed a method for quantifying static supraglottic activity and extent of false vocal fold (FVF) motion during dynamic supraglottic activity. Twelve control participants and 12 individuals with voice disorders (6 with complaints of vocal fatigue and 6 with vocal fold nodules) were enrolled in the study. These individuals participated in a transnasal fiberoptic laryngeal examination in which various speech tasks were recorded. Single-frame images were selected to represent the positions of minimum and maximum supraglottic compression for each speech task. Two individuals rated these single-frame images using a categorical rating scale. Two other individuals measured the anterior-to-posterior (A-P) distance, vocal fold length, and vocal fold area. A-P and FVF compression were derived from these three measures. Reliability was demonstrated between judges for the ratings and between and within judges for the measures. Significant differences in normalized static supraglottic compression measures corresponded to the rating scale categories. Significant differences in normalized dynamic supraglottic compression measures corresponded to the differences in category ratings between minimum and maximum compression. Using the normalized measures, the voice-disordered groups demonstrated significantly greater static A-P compression (t test, p < .03) than did the control participants. These results suggest that static supraglottic activity may be diagnostic of voice disorder. Normalized dynamic FVF compression ratios were not significantly different between groups. This supports a previous hypothesis that dynamic supraglottic activity serves as an articulatory function at the level of the larynx and is part of the linguistic/phonemic system, rather than evidence of disordered laryngeal function.

Supraglottic activity: evidence of vocal hyperfunction or laryngeal articulation?

False vocal fold (FVF) adduction and compression of the arytenoid cartilages to the petiole of the epiglottis in an anterior to posterior (A-P) direction have been thought to characterize voice disorders with abnormally increased muscle tension or effort, often termed hyperfunctional voice disorders. To further evaluate the association between hyperfunctional voice disorders and supraglottic activity, we compared the incidence of static and dynamic supraglottic activity in individuals with normal laryngeal mucosa, normal voice quality, and no voice complaints to two populations: subjects with vocal fold nodules and subjects with complaints of dysphonia without visible vocal fold lesions, glottal incompetence, or impairment of arytenoid cartilage motion ("hyperfunctional" group). Thirty-two subjects were assigned to one of these three groups (10 control, 12 nodule, and 10 hyperfunctional). Laryngeal movements were recorded using flexible videoendoscopy while a subject was performing speech tasks such as sustained phonation, syllable repetitions, sentence imitations, and conversation. Samples were randomized by subject and task and rated for presence or absence of A-P and FVF compression. Statistically significant group differences were found for FVF compression across speech tasks (chi-square, p<0.001). The control group had the smallest incidence (45%), nodule patients the next larger incidence (68%), and hyperfunctional patients the largest incidence (80%). Statistically significant group differences were found for A-P compression across speech tasks (chi-square, p<.05). The control group had the smallest incidence (74%), nodule patients the next larger incidence (78%), and hyperfunctional patients the largest incidence (92%). Statistically significant task differences were found for the presence of FVF compression in control subjects (chi-square, p<.005), hyperfunctional patients (chi-square, p<.025), and nodule patients (chi-square, p<.001), but not for A-P compression for any of the groups. A higher incidence of FVF compression was present for the speech tasks that included glottal stops. This context-specific variation in supraglottic activity suggested a dynamic component to FVF compression and also explained the high proportion of FVF compression in the control group. Each video sample was also rated for consistency of FVF or A-P compression to explore the static and dynamic nature of supraglottic activity. For samples on which raters agreed, A-P compression was typically present consistently, suggesting a static component, and FVF compression inconsistently, suggesting a dynamic component, for all three groups (chi-square, p<.001). These findings do not support previous suggestions that supraglottic activity may be a precursor to developing vocal fold nodules, as the nodule patients did not exhibit a higher incidence or consistency of A-P or FVF compression than patients with hyperfunctional voicing patterns in this study. Subjects in the hyperfunctional voice group were found to have static components of FVF and A-P compression. The presence of FVF compression in speech tasks that included glottal stops in the control group suggests an articulatory function at the laryngeal level.