Cochlear Damage Caused by Anaphylatoxin in the Tympanic Cavity

Abstract

Complement is known to be involved in many inflammatory reactions. C4a, C3a and C5a, known as anaphylatoxins, cause especially strong inflammatory reaction. Anaphylatoxins injected into guinea pig carotid arteries cause extreme atrophy of the stria vascularis in the cochlea except in the basal turn ; some cochlear nerves show degeneration, and some cochlea show endolymphatic hydrops. These results have been noted in previous reports. In this study, anaphylatoxins made from guinea pig serum treated with zymosan were injected into the tympanic cavities of 15 male Hartley guinea pigs, weighing about 350 g, all susceptible to preyer's reflex. The temporal bones were fixed in 10% buffered formalin, embedded in celloidin, cut into 13 μ sections and stained with hematoxylin and eosin.
Pathological changes in the inner ears were observed by light microscopy and all the macrophages in the endolymphatic sac were counted. Reissner's membrans were collapsed in some animals (60%). The stria vascularis in the various cochlear turns were extremely atrophied (40%) and some cochlear nerves showed degeneration. There were more macrophages in the endolymphatic sac than in the controls.
These pathological changes were similar to those observed in inner ear diseases in humans.
These results suggest that anaphylatoxins in the middle ear can affect the cochlea.