Efficacy of intracochlear administration of betamethasone on peripheral vestibular disorder in the guinea pig.

We evaluated the effect of steroid hormone on vestibular function in a guinea pig of peripheral vestibular disorder. The right lateral semicircular canal was surgically damaged, and after surgery, animals were treated with 0.1 mg/ml of betamethasone in saline, 1 mg/ml of betamethasone in saline, or saline only, which was administrated directly into the scala tympani by osmotic pump. Rotation tests were performed, and the post-rotatory nystagmus (PRN) ratio (PRN number after counterclockwise rotation/PRN number after clockwise rotation) was calculated. The PRN ratio was recovered to normal at 5 days after treatment in the betamethasone administrated groups, but it did not recover to normal until 14 days after treatment in the saline administrated group. Results indicate that in the vestibular periphery steroid hormones may play an important role in recover of vestibular function.