Cisplatin-induced ototoxicity: Morphological evidence of spontaneous outerhair cell recovery in albino guinea pigs?

Cisplatin is frequently used in the treatment of various forms of malignanc ies. Its therapeutic efficacy, however, is limited by the occurrence of sen sorineural hearing loss. Little is known about the course of hearing loss o ver longer time intervals after cessation of cisplatin administration. Infr equently, recovery of hearing has been described in animals and humans. Ste ngs et al. (1997) treated guinea pigs with cisplatin at a daily dose of 1.5 mg/kg for 8 consecutive days and subsequently studied cochlear function af ter survival times varying from 1 day to 16 weeks. Spontaneous improvement of the hair cell-related potentials (cochlear microphonics and summating po tentials) was observed starting 2 weeks after cessation of treatment. In th e present study we examined light microscopically the cochleas used in the study of Stengs et al. (1997). One day after cessation of cisplatin adminis tration outer hair cell (OHC) loss in the basal cochlear turn averaged 66%. In the 1-week survival group, OHC counts were similar to those of the 1-da y survival group. In the 4-week survival group, however, a relatively small loss of OHCs was found in the basal cochlear turn; OHC loss averaged only 15%. A similar loss was found after 8 weeks. In the 16-week survival group, OHC loss in the basal turn increased to 48%. but this was not statisticall y significant. Our histological observations are in line with the electroph ysiological data from the same animals. Our findings suggest that OHCs reco ver from cisplatin-induced damage 1-4 weeks after treatment. However, the r esults do not allow a conclusion as to whether the observed recovery is due to the formation of new OHCs or to (self-)repair of damaged OHCs. (C) 2000 Elsevier Science B.V. All rights reserved.