Ictal downbeat nystagmus in Meniere disease

Ictal downbeat nystagmus in Meniere disease: A cross-sectional study.:

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Ictal downbeat nystagmus in Meniere disease: A cross-sectional study.
Neurology. 2020 Aug 14;:
Authors: Lee SU, Kim HJ, Choi JY, Kim JS
Abstract
OBJECTIVES: To determine the mechanism of ictal downbeat nystagmus in Meniere's disease (MD), we compared the head impulse gain of the vestibulo-ocular reflex (VOR) for each semicircular canal between the patients with (n=7) and without (n=70) downbeat nystagmus during the attacks of MD.
METHODS: We retrospectively analyzed the results of video-oculography, video head-impulse tests, and cervical vestibular-evoked myogenic potentials (VEMPs) in 77 patients with definite MD who were evaluated during an attack.
RESULTS: Pure or predominant downbeat nystagmus was observed in seven patients (7/77, 9%) with unilateral MD during the attacks. All seven patients showed spontaneous downbeat nystagmus without visual fixation with a slow phase velocity ranging from 1.5 to 11.2°/s [median = 5.4, interquartile range (IQR) = 3.7 - 8.5]. All showed a transient decrease of the head impulse VOR gains for the posterior canals (PCs) in both ears (n=4) or in the affected ear (n=3). Cervical VEMPs were decreased in the affected (n=2) or both ears (n=2) when evaluated during the attacks. Downbeat nystagmus disappeared along with normalization of the VOR gains for PCs after the attacks in all patients. During the attacks, the head impulse VOR gains for the PC on the affected side were lower in the patients with ictal downbeat nystagmus than in those without (Mann-Whitney U test, p<0.001) while the gains for other semicircular canals did not differ between the groups.
CONCLUSION: Downbeat nystagmus may be observed during the attacks of MD due to an asymmetry in the vertical VOR or saccular dysfunction. MD should be considered in recurrent audiovestibulopathy and ictal downbeat nystagmus.

PMID: 32817190 [PubMed - as supplied by publisher]