Head-shaking nystagmus: a sensitive indicator of vestibular dysfunction.

This study investigated 258 consecutive patients with the complaint of vertigo undergoing vestibular function tests between August 1992 and July 1994. The head-shaking nystagmus test was performed in a passive fashion with the patient placed in a sitting position with the head anteflexed at 30 degrees and oscillated +/- 45 degrees horizontally for 30 cycles in 15 s; the post head-shaking nystagmus was recorded by electronystagmography. Conventional bithermal caloric tests were conducted with the normal limit of canal paresis set at 20%. The results show significant correlation between head-shaking nystagmus and canal paresis. Head-shaking nystagmus is more sensitive than canal paresis in predicting vestibular dysfunction. The sensitivity of head-shaking nystagmus in detecting a canal paresis was 90%. Although the direction of head-shaking nystagmus does not always accord with the side of peripheral vestibular dysfunction, it is an indicator of vestibular dysfunction and this test could be performed easily as a screening test in every otoneurological investigation.