Vertigo attacks are believed to be caused by many potassium ions from the endolymph entering the perilymphatic space upon rupture of the membraneous labyrinth due to hydrops in Meniere's disease (Schuknecht, 1972).
At the beginning of an attack, irritative nystagmus, or nystagmus directed towards the ill side, was observed in 3 of 5 patients with Meniere's disease. Worsened hearing, increse of body sway during standing with eyes closed, increase of deviation towards the ill side in writing test with eyes covered, positional nystagmus of the direction changing type towards the upper ear and changing of DP to the intact ear side from DP to the ill side were observed in the pendular rotation test just before an attack of vertigo in one patient with Meniere's disease. Those findings were assumed to have been induced by hypofunction of the labyrinth due to acute progression of hydrops in Meniere's disease.
