"Innocent" arytenoid adduction asymmetry: An etiological survey

To estimate the incidence of "innocent" arytenoid adduction asymmetry (AAA) among patients presenting at a laryngology clinic, identify its association with demographic characteristics, symptomatology and various clinical/pathological conditions and thereby determine its clinical significance.

A prospective comparative observational clinical study was conducted. Group 1 included patients presenting at the Department of Laryngology, identified with a primary diagnosis and coexisting "innocent" AAA i.e., an overriding arytenoid with normal vocal fold mobility on laryngoscopy. Group 2 included an equal number of randomly selected patients fulfilling the same criteria, without AAA. Demographic and clinical details were recorded and analyzed.

110 cases were included in each group. The incidence of innocent AAA was 12.7%. Males were predominant in both Groups, with the gender difference significant in Group 1. Patients in Group 1 were significantly younger than in Group 2. Professional voice users, namely singers, were significantly greater in Group 1. Symptoms associated with Group 1 (i.e. AAA) were high pitch strain while singing (p = 0.01) and unilateral throat pain (p = 0.01), and the associated diagnoses were Singing Voice Dysphonia (p = 0.005), Vocal Process Granuloma (p = 0.04) and Ventricular Band Dysphonia (p = 0.047). As a definitive diagnosis was made in all patients, the presenting complaints were not attributed to AAA. Right sided preponderance of AAA was significant. Among the diagnoses with a laterality (e.g. vocal process granuloma), AAA was observed contralateral to the pathology in 70.7% and ipsilaterally in 29.3% (p = 0.0058).

Innocent AAA is common among males in the 3rd-4th decades, in singers among professional voice users, and in those with the muscle tension dysphonia spectrum and vocal process granuloma, thereby suggesting that it is an acquired habit/response to greater vocal demand. The observation of AAA contralateral to laryngeal lesions, highlights its compensatory nature, attempting to optimize glottic closure.