Anterior-posterior and medial compression of the supraglottis: signs of nonorganic dysphonia or normal postures?

Abstract

Two vocal tract postures commonly identified as hallmarks of nonorganic dysphonia are anterior-posterior and medial compression of the supraglottis. However, insufficient data exist to support their diagnostic utility. The purpose of this study was to compare these two postures in patients with nonorganic dysphonia and normal controls using interval data derived from quantitative measures of videostroboscopic images obtained with an oral endoscope. Retrospectively, 40 patients with nonorganic dysphonia and 40 normal controls were selected. Relative anterior-posterior compression (LO(AP)) was calculated as the laryngeal outlet (LO) (the view of the true vocal folds during phonation) normalized to the anterior-posterior dimension in pixels. Relative ventricular fold medial compression (LO(w)) was calculated as the laryngeal outlet normalized to the medial dimension in pixels. Results were as follows: (1) LO(AP) was significantly greater for the dysphonic group, (2) the range of LO(AP) values between the two groups overlapped considerably, (3) no significant difference was found between groups for LO(w), (4) the correlation between LO(AP) and LO(w) within each subject yielded r values of 0.71 and 0.67 for the nonorganic dysphonia and normal control groups, respectively. It is concluded that medial compression of the ventricular folds can be a normal laryngeal posture, and that although anterior-posterior compression is present in greater degree in dysphonics, it is sufficiently common in normals to question its utility as a diagnostic sign of phonatory dysfunction.