Quantitative evaluation of video laryngostroboscopy: reliability of the basic parameters.

Objective: The purpose of this study was to evaluate quantitatively the basic parameters of the video laryngostroboscopy (VLS) and determine the sensitivity and specificity of these parameters discriminating healthy and pathological voice classes.

Methods: Digital VLS recordings were performed for 159 individuals: 26 healthy and 133 patients. VLS variables (glottal closure, regularity, mucosal wave on the affected/healthy side, symmetry of vibration, and symmetry of image) were rated two times with the time interval of 1 year by three laryngologists. To evaluate interrater and test-retest reliability, intraclass correlation coefficients (ICCs) were calculated. To evaluate sensitivity and specificity of the VLS parameters, discriminant analysis was used.

Results: Moderate to almost perfect levels (ICC 0.46-0.90) of interrater reliability were revealed for most of the basic VLS parameters. The ICC of the interrater reliability was highest for symmetry of glottal image; the most problematic VLS parameter for rating was mucosal wave on the healthy side. ICC of the test-retest reliability were 0.71-0.95, P<0.001. An optimum system of VLS parameters discriminating normal and pathological voice subgroups with sensitivity 96.3% and specificity 100% included glottal closure and mucosal wave on the affected side.

Conclusions: The quantitative evaluation of the VLS using basic parameters showed to be reliable in clinical settings and demonstrated high sensitivity and specificity distinguishing healthy and pathological voice patient groups.