Quantitative analysis of videokymography in normal and pathological vocal folds: a preliminari study.

Videokymography (VKG) captures high-speed
images of the vocal folds independently of the periodicity
of the acoustic signal. The aim of this study was to preliminarily
assess a software package that can objectively
measure specific parameters of vocal fold vibration. From
August 2009 until December 2010, we prospectively
evaluated 40 subjects (Group A, 18 normal subjects;
Group B, 14 patients with benign lesions of the middle
third of the vocal fold, such as polyps and cysts; Group C, 8
patients treated by endoscopic excision of vocal fold
benign lesions) by videoendoscopy, videolaryngostroboscopy,
and VKG. A VKG camera was coupled to a 70
telescope and video was recorded during phonation. Images
were objectively analyzed by a post-processing software
tool (VKG-Analyser) with a user-friendly interface
developed by our group. Different parameters were considered,
including the ratio between the amplitude of the
vibration of one vocal fold with respect to the contralateral
(Ramp), the ratio between the period of one vocal fold
vibration and the opposite one (Rper), and the ratio between
the duration of the open and closed phase within a glottal
cycle (Roc). Mean values for Ramp, Rper, and Roc in Group A
were 1.05, 1.04, and 1.35, respectively; in Group B were
1.63, 0.92, and 0.97, respectively; and in Group C were
1.13, 0.91, and 1.85, respectively. Quantitative analysis of
videokymograms by the herein presented tool, named VKG-Analyser, is useful for objective evaluation of the
vibratory pattern in normal and pathologic vocal folds.
Important future developments of this tool for the study of
both physiologic and pathologic patterns of vocal fold
vibration can be expected.