Recent Findings Related to Vocalization and Laryngeal Sensation

Abstract

Vocalization is controlled by the neuronal networks from the cerebral cortex to the medulla oblongata. The neuronal circuitry of vocalization is closely related to the respiratory neuronal network that controls respiration during vocalization. Laryngeal sensory inputs are transmitted as visceral afferent inputs, primarily to the nucleus tractus solitarius in the medulla oblongata via the internal branch of the superior laryngeal nerve. This signal is then transmitted to the medulla oblongata and cerebral cortex and may be involved in the modulation of vocal motor control as well as that of breathing and swallowing. Animal studies have shown that increasing or decreasing laryngeal sensory input affects the vocal motor patterns and voice quality. However, interferential current stimulation of the neck is a non-invasive method of increasing sensory inputs and is expected to have clinical applications. We encountered a 31-year-old female with hypofunctional dysphonia and a glottal chink during phonation. Interferential current stimulation was performed, and the glottal chink was immediately reduced. Interferential current stimulation of the larynx is a new therapeutic strategy for managing functional dysphonia.