Pathophysiology of the Ototoxicity of Cis‐Diamminedichloroplatinum

Abstract

The electrophysiologic and histopathologic changes in the inner ear caused by the administration of cis-diamminedichloroplatinum (CP) were studied in guinea pigs. The endocochlear DC potential (EP) gradually decreased after the i.v. injection of CP and reached approximately O mV on the 4th day, but the EP did not become negative. The cochlear microphonics also diminished and could not be recorded on the 4th day. The negative potential of the organ of Corti remained in the normal range during the experiment. A large negative summating potential (SP) was observed 1 day after injection, but the amplitude of the negative SP became small on the 2nd day. Light microscopic examination demonstrated that the outer hair cells are destroyed in the basal turn of the cochlea and are preserved in the upper turns, while the inner hair cells are almost completely preserved in all turns. The stria vascularis was slightly atrophic. Severe collapse of Reissner''s membrane was observed in the basal turn.