Electrophysiological predictors of hyperfunctional dysphonia

Abstract

Background The relation between the autonomic nervous system (ANS) and muscles of the vocal tract is of particular importance when considering the pathomechanism of a functional voice disorder. Aims The aim of this study was to record electrophysiological indicators from the ANS as well as the tone of the external laryngeal muscle and test whether together they could point to an enhanced risk of primary functional voice disorder. Materials and methods The study material consisted of 81 people, 27 of whom were professional opera singers. None reported any voice complaints. The research comprised ENT and phoniatric examination, superficial electromyography (SEMG), and recording of physiological indicators (pulse rate, skin resistance). Results All subjects had a clear voice with no sign of vocal disability. Endoscopy revealed laryngeal hyperfunction in 26 people. SEMG revealed that the 26 had increased external laryngeal muscle tone during phonation, and this finding correlated with a change in certain electrophysiological indicators HRV, BVP, EDA. Conclusions We conclude that anomalies in electrophysiological parameters in individuals with subclinical symptoms of functional voice disorder may be at risk of developing fully symptomatic hyperfunctional dysphonia in the future. Vocal training, which differentiates singers and non-singers, is known to have an effect on subclinical hyperfunctional dysphonia. Significance By measuring indicators of hyperfunctional dysphonia, it may be possible to take remedial action before symptomatic dysphonia develops.