Organic Voice Tremor Health Article

Definition

Organic voice tremor is a neurogenic voice disorder of adulthood that most often occurs as a component of essential or hereditofamilial tremor; it may occur by itself, however. Organic voice tremor must be distinguished from other conditions, which also present with voice disturbances in the early stages. These include Parkinsonism, cerebellar disease, thyrotoxicosis, and anxiety.

Description

Organic voice tremor is a disorder of voice production characterized by unsteadiness of pitch and loudness and quavering intonation. In some patients, it may result in rhythmic arrests of voicing that occur at a rate of four to six per second. Voice quality is characterized by harshness, vocal strain, abnormally low pitch, and voice stoppages. Laryngeal examination typically reveals vocal folds of normal appearance, with no evidence of aberrant innervation. The abnormal oscillations of the larynx occur as a result of vigorous up-and-down vertical movements that occurred synchronously with the oscillation of the tremor. The quavering speech quality that characterizes organic voice tremor has been thought to include extralaryngeal influences arising from tremors in the diaphragm, lips, and tongue (Critchley, 1949; Tomoda, et al., 1985).

The origin of organic voice tremors has not been conclusively determined, though aging and occlusive arterial disease are thought to contribute significantly to the effects. Critchley (1949) showed that essential tremor occurred in persons with confirmed lesions in the brain stem, basal ganglia (e.g., putamen and lentiform nuclei) and within neural connections joining the red nucleus, dentate nucleus, and inferior olive. Vocal tremors usually coexist with tremors in the head and limbs, but may be localized entirely within the larynx. Disturbed central innervation to the larynx is thought to disturb coordination between abductor and adductor groups of laryngeal muscles, which may affect the symmetry of vibration of the vocal folds, and result in excess force of approximation or abruptness of vocal fold separation during conversational speech. Symptoms may be difficult to fully appreciate in conversational speech but become quite evident in sustained vowel production (Brown and Simonson, 1963). This finding is significant for differential diagnosis of essential tremor from spasmodic dysphonia, a focal dystonia affecting voicing.

Demographics

Organic voice tremor is a condition that usually occurs in persons over age 50. Males and females appear to be affected equally. Specific incidence data are not available.