Muscle misuse voice disorders: description and classification.

It is apparent that voice disorders frequently labelled "functional" are associated with laryngeal muscle misuse. This use of the word "functional" is, however, intrinsically ambiguous, and so we propose an alternative term based on descriptive features of dysfunction: "muscle misuse voice disorders". Persistent phonation with an abnormal laryngeal posture can lead to organic changes such as nodules or polyps, particularly in females with posterior glottic chink. We hypothesized that the chink was related to an overall increase in laryngeal muscle tension, and more directly due to inadequate relaxation of the posterior crico-arytenoid muscle during phonation. We employed the term "muscular tension dysphonia" (MTD) to note this condition, but it may be that the term "laryngeal isometric" is superior since there are other misuses of the larynx that obviously are manifestations of abnormalities of muscular tension. With this in mind we have evolved a new classification based on the laryngeal isometric, glottic and supraglottic lateral contraction states, antero-posterior contraction states, conversion aphonia, psychogenic bowing, and adolescent transitional dysphonia.