Downbeat nystagmus could be observed during attacks of unilateral Meniere’s disease (MD) due to an asymmetry in the vertical vestibulo-ocular reflex (VOR) or saccular dysfunction.
Why this matters ?
Lesions in the vestibulocerebellum may attribute to pure or predominant downbeat nystagmus in individuals. The exact mechanism of downbeat nystagmus is not currently known.
In a previous report, relative hypofunction of the posterior semicircular canals (PCs) was suggested to cause ictal downbeat nystagmus among individuals with MD.
The results of this study suggest that individuals with recurrent audio vestibulopathy and ictal downbeat nystagmus should be considered for an MD diagnosis.