Positional Nystagmus after Acute Vertiginous Attack in Meniere's Disease.

There have been no reports regarding nystagmus observed immediately after the end of an acute vertiginous attack in patients with Meniere's disease. The aim of this study was to demonstrate positional direction-changing nystagmus in patients with Meniere's disease, and to discuss the mechanism that underlies this nystagmus. Video-nystagmography was recorded in two patients with definite Meniere's disease, who showed positional direction-changing nystagmus during the period immediately after a vertigo attack. In one patient, video-nystagmographic recording was conducted 5 h after an episode of vertigo attack, and it showed very weak, persistent positional geotropic direction-changing nystagmus. In the other patient, video-nystagmographic recording was conducted 23 h after an episode of vertigo attack, and it showed very weak, persistent positional apogeotropic direction-changing nystagmus. Our patients exhibited very weak, persistent positional direction-changing nystagmus, which was geotropic in one and apogeotropic in the other. This type of positional nystagmus has been reported in other inner ear disorders and it cannot be clearly explained by typical benign paroxysmal positional vertigo. The change in chemical composition and/or electrolyte concentration of the inner ear fluid, although still unclear, may underlie the production of this characteristic nystagmus in these patients.