How to perform the skull vibration-induced nystagmus test (SVINT)

Abstract

The skull vibration-induced nystagmus test is a robust, nonintrusive and easy to perform test. This test acts as a vestibular Weber test and is performed as a bedside examination. It usually instantaneously reveals vibration-induced nystagmus (VIN) even in long standing or chronic compensated unilateral vestibular lesions. The test requires stimulation at 30, 60 or more efficiently at 100Hz. The vibrator is applied perpendicularly to the skin on a subject sitting up straight on the right and then the left mastoid (level with external acoustic meatus) and vertex. The VIN can be observed under videonystagmoscopy or Frenzel goggles. Either the direct tracing or the VIN slow phase velocity can be recorded on a 2D or 3D videonystagmograph. The patients should be relaxed and not treated by strong sedative medications. This rapid first-line test is not influenced by vestibular compensation and usefully complements other tests in the multifrequency evaluation of the vestibule. It acts as a global vestibular test by stimulating both canal and otolithic structures at 100Hz. It is useful in case of external acoustic meatus or middle ear disease as a substitute for the water caloric test and is preferable in elderly patients with vascular disease or arthritis of the neck to the head-shaking-test or head-impulse-test.