The Distribution and Severity of Tremor in Speech Structures of Persons with Vocal Tremor

Vocal tremor may be associated with cyclic oscillations in the pulmonary, laryngeal, velopharyngeal, or oral regions.

This study aimed to correlate the overall severity of vocal tremor with the distribution and severity of tremor in structures involved.

Endoscopic and clinical examinations were completed on 20 adults with vocal tremor and two age-matched controls during sustained phonation. Two judges rated the severity of vocal tremor and the severity of tremor affecting each of 13 structures.

Participants with mild vocal tremor typically presented with tremor in three laryngeal structures, moderate vocal tremor in five structures (laryngeal and another region), and severe vocal tremor in eight structures affecting all regions. The severity of tremor was lowest (mean = 1.2 out of 3) in persons with mild vocal tremor and greater in persons with moderate (mean = 1.5) and severe vocal tremor (mean = 1.4). Laryngeal structures were most frequently (95%) and severely (1.7 out of 3) affected, followed by velopharynx (40% occurrence, 1.3 severity), pulmonary (40% occurrence, 1.1 severity), and oral (40% occurrence, 1.0 severity) regions. Regression analyses indicated tremor severity of the supraglottic structures, and vertical laryngeal movement contributed most to vocal tremor severity during sustained phonation (r = 0.77, F = 16.17, P < 0.0001). A strong positive correlation (r = 0.72) was found between the Tremor Index and the severity of the vocal tremor during sustained phonation.

It is useful to obtain a wide endoscopic view of the larynx to visualize tremor, which is rarely isolated to the true vocal folds alone.