The first attack of Ménière's disease: a study through SVV perception, clinical and pathogenetic implications.

This is a study of Subjective Visual Vertical (SVV) perception during acute attacks of Ménière's disease (MD) with comparative evaluation of concurrent nystagmus. We studied 21 patients with unilateral MD during the acute phase and 7 days later. Of the nine patients with an initial attack of MD, seven had an alteration of SVV perception and of these, three indicated a match with canal functional signs, while four patients showed an opposite trend of SVV perception relative to the spontaneous nystagmus. Nine of the 12 patients with definite MD had a pathological SVV perception always in correspondence with the same type of canal event. At 1-week control, no patient with an initial MD attack had alteration of SVV perception, whereas 5 patients with definite MD presented a pathological SVV perception toward the affected side. In the course of acute attacks of unilateral MD, clinical manifestations may include otolithic involvement and this may have an opposite trend compared to concomitant canal signs, especially during initial attacks. This behavior allows us to distinguish clinical signs of maculo-canal "correspondence" and "dissociation" with a significant prevalence of the second indication in those subjects with an initial MD attack.