The Clinical Features of Functional Dysphonia

TLDR

The study investigates the prevalence of laryngeal muscle tension features in patients with functional dysphonia compared to nondysphonic controls. A prospective, control‑blinded, cross‑sectional study rated video laryngoscopies of 51 FD patients and 52 controls for 12 laryngoscopic features of hyperfunction and overall vocal technique. More than 60% of controls exhibited at least one hyperfunction feature, and the prevalence of all assessed features and abnormal vocal technique did not differ significantly between FD patients and controls, indicating that these laryngoscopic features cannot reliably distinguish functional dysphonia.

Abstract

Abstract Objective This report aims to study the prevalence of features of laryngeal muscle tension in a population of patients with functional dysphonia (FD) and nondysphonic control subjects. Study Design Prospective control‐blinded, cross‐sectional study. Methods We reported on a prospective control‐blinded, cross‐sectional study of the prevalence of the six features described by Van Lawrence and the six features incorporated in the Morrison‐Rammage classification. A senior laryngologist and senior speech pathologist independently rated sound‐free, random‐sequence video laryngoscopies of 51 patients with FD and 52 nondysphonic control subjects. Assessments were made of the presence or absence of the 12 laryngoscopic features of laryngeal dysfunction, and an overall rating made of the vocal technique as “normal” or “abnormal.” Results More than 60% of the control population demonstrated 1 or more of the 12 features of hyperfunction. There was no significant difference in the prevalence of the six Van Lawrence features, the six Morrison‐Rammage features, or the total number of abnormal features between patients with FD and control subjects. On overall assessment, both assessors noted a high prevalence (50% and 36%, respectively) of abnormal vocal technique in the control population. There was no statistical difference in the total number of abnormal features observed between patients with FD and control subjects. Positive predictive value calculations showed that the presence of a clinical feature, at best, presented a 75% chance of correctly identifying a patient with FD and, at worst, a 50% chance. Conclusion The laryngoscopy features commonly associated with FD are frequently prevalent in the nondysphonic population and fail to distinguish patients with FD from normal subjects.