Vertical components of head-shaking nystagmus in vestibular neuritis, Meniere's disease and migrainous vertigo.

OBJECTIVES: To describe vertical and horizontal components of head-shaking nystagmus (HSN) in various vestibular disorders.

DESIGN: Retrospective case review.

SETTING: Tertiary care academic referral centre.

PARTICIPANTS: Head-shaking nystagmus was assessed in 66 vestibular neuritis (VN) patients at acute (<7 days) and follow-up (2 months), and 65 Meniere's disease (MD) and 76 migrainous vertigo (MV) in interictal period.

MAIN OUTCOME MEASURES: Head-shaking nystagmus was categorised as pure horizontal, pure vertical or mixed. Horizontal HSN was classified as monophasic or biphasic and paretic or recovery. Vertical HSN was classified as upbeat or downbeat.

RESULTS: Abnormal HSN (pathologic monophasic, biphasic or delayed-peak HSN) showed different positive rates depending on the vestibular disorders and compensation (94% in acute VN; 89% in FU VN; 78% in MD; 50% in MV). Paretic HSN with the nystagmus towards the lesioned side was the most common type in VN and MD; however, recovery HSN with the nystagmus towards the intact side could be rarely observed especially in patients with MD or compensated VN. Vertical nystagmus could be combined with horizontal HSN, and upbeat HSN was observed in most (83%) of the patients with acute VN, but downbeat HSN was common in follow-up VN (83%), MD (97%) and MV (85%). Weak perverted HSN, which is assumed to be a central nystagmus, was rarely observed in MD and MV (6-9%), but not in VN.

CONCLUSIONS: Head-shaking nystagmus (HSN) in horizontal plane is a valuable tool in the assessment of vestibular imbalance. Common observation of upbeat HSN in acute VN and downbeat HSN in follow-up VN, MD and MV suggests that vertical components are possibly related to the involvement of vestibular apparatus and compensation. Weak perverted HSN and delayed-peak HSN were rarely observed in MD and MV, and never observed in VN, suggesting that it is possibly related to either asymmetrically impaired vertical canals or misorientation of the velocity-storage system.