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KMID : 1130620060020010058
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Journal of Clinical Neurology
2006 Volume.2 No. 1 p.58 ~ p.65
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Upbeat Nystagmus: Clinicoanatomical Correlations in 15 Patients
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Kim Ji-Soo
Yoon Bo-Ra
Choi Kwang-Dong
Oh Sun-Young
Park Seong-Ho
Kim Byung-Kun
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Abstract
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Background and Purpose: The mechanism of upbeat nystagmus is unknown and clinicoanatomical correlative studies in series of patients with upbeat nystagmus are limited.
Methods: Fifteen patients with upbeat nystagmus received full neuro-ophthalmological evaluation by the senior author. Nystagmus was observed using video Frenzel goggles and recorded with video-oculography. Brain lesions were documented with MRI.
Results: Lesions responsible for nystagmus were found throughout the brainstem, mainly in the paramedian area: in the medulla (n=8), pons (n=3), pons and midbrain with or without cerebellar lesions (n=3), and midbrain and thalamus (n=1). Underlying diseases comprised cerebral infarction (n=10), multiple sclerosis (n=2), cerebral hemorrhage (n=1), Wernicke encephalopathy (n=1), and hydrocephalus (n=1). Upbeat nystagmus was mostly transient and showed occasional evolution during the acute phase. In one patient with a bilateral medial medullary infarction, the upbeat nystagmus changed into a hemiseesaw pattern with near complete resolution of the unilateral lesion. Gaze and positional changes usually affected both the intensity and direction of the nystagmus. A patient with a cervicomedullary lesion showed a reversal of upbeat into downbeat nystagmus by straight-head hanging and leftward head turning while in the supine position. Gaze-evoked nystagmus (n=7), ocular tilt reaction (n=7), and internuclear ophthalmoplegia (n=4) were also commonly associated with upbeat nystagmus.
Conclusions: In view of the responsible lesions and associated neuro-ophthalmological findings, upbeat nystagmus may be ascribed to damage to the pathways mediating the upward vestibulo-ocular reflex or the neural integrators involved in vertical gaze holding.
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KEYWORD
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Upbeat Nystagmus, Vestibulo-ocular reflex, Neural integrator
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