Experimental Vestibular Disorder Induced by Tympanic Cavity Drug Infusion

Experimental vestibular disorders of the peripheral type were induced using transtympanic infusion of several drugs. Drugs with high specific gravity such as saturated sodium chroride and pottasium chroride, heavy water, ethylene glycol, glycerine, isosorbid and urea induced direction-changing, positional nystagmus. The nystagmus was directed upward when the head was held with the right or left side down, to the injected side with the nose-up, to the non-injected side with the nose-down position, respectively. Ethyl-alcohol and aceton which have low specific gravities also induced direction-changing, positional nystagmus, although the direction was opposite to that of those drugs with high gravities.Most of these positional nystagmus developed to paralytic nystagmus which directing toward the non-injected side in all head positions or disappeared in three hours. Some animals had a second phase of positional nystagmus before it disappeared. Only pottasium chroride produced irritative nystagmus which directing towared the injected side in all positions and changed to paralytic nystagmus.