Usefulness of galvanically induced nystagmus as a diagnostic test of peripheral vestibular hypofunction.

BACKGROUND: Galvanic Vestibular Stimulation (GVS) has long been used as a vestibular stimulus. A major issue observed in GVS research was the high variability of the responses, which has led some researchers to question its diagnostic utility.

OBJECTIVES: Determine the diagnostic accuracy of galvanically induced nystagmus for the diagnosis of subjects with unilateral peripheral vestibular hypofunction.

METHODS: A total of 195 dizzy patients were prospectively enrolled, forming a consecutive series as they were received. Individuals with spontaneous nystagmus or using vestibular sedatives were excluded. Nystagmus induced by a 4 mA galvanic stimulus was compared with the caloric test as a reference standard.

RESULTS: Of the 195 subjects tested with GVS, 115 were subjects with a unilateral peripheral vestibular hypofunction. The presence of nystagmus showed an AUC of only 0.529 (0.478 to 0.580, p = 0.125), and the maximum slow phase velocity of nystagmus showed an AUC of only 0.523 (0.472 to 0.573, p = 0.439).

CONCLUSIONS: Since neither AUC is better than random discrimination, this study concludes that GVS-induced nystagmus is not useful as a diagnostic tool for unilateral peripheral vestibular hypofunction. These findings discourage the use of GVS-induced nystagmus in the clinical setting.