Effect of experimental acidosis on nystagmus in rabbits

Vertigo related to acidosis in Meniere's disease has been reported. This study was undertaken to ascertain whether acidosis has any effect on vertigo. Since patients with Meniere's disease usually show unilateral vestibular dysfunction, unilateral intratympanic injection of streptomycin sulfate (SM) was used to induce unilateral vestibular dysfunction in rabbits. Intratympanic SM injections induced vestibular destruction and elicited severe spontaneous nystagmus and ataxia. Then symptoms of acute vestibular upset gradually subsided and eventually disappeared completely. Three weeks after SM injections, in compensated rabbits, NH4Cl injection or CO2 inhalation was used to induce acidosis. Intravenous NH4Cl injection or CO2 inhalation induced nystagmus and ataxia again. In normal rabbits, no nystagmus was induced by NH4Cl injection or by CO2 inhalation. These results suggest that acidosis might be a cause of recurrence of vertigo in patients with unilateral vestibular dysfunction.