Histopathology of sudden hearing loss.

Eleven temporal bones from eight patients who had clinical histories of sudden hearing loss (SHL) were studied to assess the possible etiopathogenesis. The origin of SHL in seven ears from five patients was obscure, but appeared to be due to multiple causes. Common histopathologic changes in the cochlea, although complex, included atrophy of the organ of Corti and loss of cochlear neurons. Loss of cochlear neurons was the main finding in ears of viral infection. Labyrinthine fibrosis and formation of new bone were seen in two ears associated with vascular insult and in two ears of autoimmune disease. Different histopathologic findings causing SHL were observed even in cases with the same etiology. A case of SHL showing endolymphatic hydrops as the main histopathologic finding is described.