Human Cochlear Pathology in Aminoglycoside Ototoxicity—A Review

The pathological findings due to aminoglycoside ototoxicity in man, as reported in the literature, is reviewed. 21 cases (40 ears) have been studied after serial sectioning, 8 cases (12 ears) have been investigated by the microdissection and surface preparation technique. The combination of both methods provides maximal information. OHCs are primarily affected, followed by IHC loss. Degeneration starts at the basal coil and proceeds towards the apex. The stria vascularis becomes involved in all turns. It is not clear whether stria degeneration is primary or secondary. Supporting cells, nerve fibres and ganglion cells degenerate secondary to hair cell loss. In some cases ingrowth of myelinated nerve fibres in areas with complete destruction of the organ of Corti has been observed. Ototoxic lesions can be asymmetric. Attention is drawn to the audiometric Z-curve in moderate lesions.