Abstract
It is well known for a long time that various drugs and substances injected in the tympanic cavity could enter perilymph through the round window membrane, and many experimental studies have been reported concerning to uptake of steroid in the inner ear by intratympanic instillation. Summing up these studies, 1) concentration of perilymph steroid by intratympanic injection is 24.7-189.6 times higher as compared with intravenous injection, 2) immunohistochemical studies revealed steroid can diffuse and distribute to the spiral ligament, organ of Corti and spiral ganglion in all turns of the cochlea, 3) uptake of steroid in the inner ear can reach the peak level 1 to 3 hours after instillation and, it is not detected 24 hours later. From these reports, intratympanic steroid injection has the advantage that highly-concentrated inner ear uptake can be obtained by a small dose of steroid administration. This is the reason why intratympanic steroid injection becomes to attract attention more recently as a treatment of acute sensorineural hearing loss such as idiopathic sudden sensorineural deafness.
