Clinical implications of head-shaking nystagmus in central and peripheral vestibular disorders: is perverted head-shaking nystagmus specific for central vestibular pathology?

Background and purpose: The patterns of head-shaking nystagmus (HSN) aid in differentiation between central and peripheral vestibular disorders, and perverted HSN (pHSN) has been considered a central sign. The aim was to determine the characteristics of HSN in a large number of patients with either peripheral or central vestibular disorders in a dizziness clinic of a university hospital. Methods: The medical records of 7544 dizzy patients were reviewed during a year and 822 patients with a clinical diagnosis of vestibular disorders were recruited. The findings of spontaneous nystagmus (SN) and HSN in these patients were compared with those of healthy controls (n = 48). Results: A total of 217 of the 822 patients (26.4%) were classified as having a central vestibular disorder, whilst 397 (48.3%) had a peripheral vestibular disorder. In the peripheral vestibular disorder group, SN was observed in 14.1% and HSN in 40.8%, amongst whom 24.1% were the pHSN form. In the central group, SN was observed in 17.5% and HSN in 24.0% of whom 57.7% was pHSN. HSN was more frequently observed in the peripheral vestibular disorder group than in the central group (40.8% vs. 24.0%, P < 0.01). However, the proportion of pHSN was significantly increased in the central group compared to the peripheral vestibular patient group (57.7% vs. 24.1%, P < 0.01). Conclusions: Since pHSN is not specific for central vestibular disorders, other clinical features should be considered in pursuing a central lesion in patients with pHSN.