Vibration-Induced Nystagmus in Patients with Vestibular Disorders

ABSTRACT

BACKGROUND AND OBJECTIVES: It has been reported that vibration applied either on the mastoid or the sternocleidomastoid (SCM) muscles induces nystagmus in patients after unilateral vestibular neuritis. The aims of the study were to characterize the vibration-induced nystagmus (VIN) in patients with various vestibular disorders and to compare the results of VIN to unilateral weakness in caloric test. MATERIALS AND METHODS:Fifthy-four patients with Meniere's disease, 58 patients with unilateral vestibular neuritis, 170 patients with migraine-associated dizziness, and 78 patients with chronic recurrent vestibulopathy were included. We recorded eye movements during unilateral 100-Hz vibration on the mastoids and SCM muscles. The bithermal caloric test was also performed. Abnormal criteria of VIN were slow-phase slow-phase velocity (SPV) at 4 all different conditions > or = 2degrees/s with the same directions or mean of SPV at vibration on both mastoids or both SCM muscles > or = 5degrees/s with the same directions. RESULTS: In Meniere's disease, 28 of 57 (49.1%) of patients show pathologic VIN, 21 of 57 (36.8%) show pathologic canal paresis. 14 of 57 (24.6%) show abnormalities in both tests, and 35 of 57 (61.4%) show any abnormalities in either test. In unilateral vestibular neuritis, 43 of 58 (77.6%) showed pathologic VIN, 58 of 58 (100%) show canal paresis. In migraine-associated dizziness, 48 of 170 (28.2%) showed pathologic VIN, 58 of 170 (18.8%) show canal paresis. 15 of 170 (8.8%) showed abnormalities in both tests, and 65 of 170 (38.2%) show any abnormalities in either test. In chronic recurrent vestibulopathy, 23 of 78 (29.5%) of patients show pathologic VIN and 17 of 78 (21.8%) show pathologic canal paresis. Seven of 78 (9.0%) showed abnormalities in both tests, and 33 of 78 (42.3%) show any abnormalities in either test. CONCLUSION: VIN test can increase the sensitivity in detecting vestibular imbalance in vestibular disorders when combined with caloric test.