ABSTRACT
Objective Distortion product otoaconstic emission (DPOAE) was compared withauditory brain－stem response (ABR) in the early diagnosis of gentamicin (GM) ototoxicity. Whetherimpaired hearing could be improved with the glutathione treatment after its withdrawl of injection.Methods40 guinea pigs with normal hearing were randomly divided into 4 groups, 10 in DPOAEgroup, 12 in ABR I group (the usage of GM was stopped when abnormal shift presented in ABR), 12 inABR Ⅱ (group glutathione was injected for 5 after the usage of GM had been stopped), 6 in controlgroup. The guinea pigs in experimental group were injected with GM 100mg/kg per day, while those inthe control group were injected with saline. The DPOAE and ABR were monitored to observe the ampli-tude and the threshold of wave IV. The morphological changes of hair cells were also observed after injec-tion of GM had been stopped for 2 weeks. ResultsIt was averaged at 7d after the injection of GMwhen the changes presented in DPOAE group, while 10d in ABR group. The threshold shift increasedafter the injection had been stopped for 2 weeks in ABR Ⅰ group ( P <0.01) ,while there was no obvi-ous shift in ABR Ⅱ group. The morphological and functional changes of the hair cells were almost thesame. Conclusion GM ototoxicity could be more sensitively observed by DPOAE than ABR. Glu-tathione could prevent further ototoxic effect of GM to the cochlear.
ABSTRACT
In this study, the influence of the duration of opening vestibular window and the application of suction in auditory bulla on cochlear function and ultrastructures were observed by ECochG and scanning and transmission election microscopy in 44 guinea pigs divided into six groups. The results were as follows: (1) The CAP thresholds progressively enhanced as the prolongation of duration in some of outer hair cells in the basal turn occured 180 minutes after total stapedectomy. (2)Significant CAP threshold shift and irreversible pathological changes in some outer hair cells in the basal turn of cochlea were found with continuous suction for 60 minutes in auditory bulla after total stapedectomy. (3)CAP threshold shift without damage of outer hair cells could be fourd with the application of suction for 60 mimutes in auditory bulla before stapedectomy. The results suggested that opening vestibular window for longer time with suction in auditory bulla might be one of the factors to cause postoperative sensorineural hearing loss in total stapedectomy. But the suction noise might not be enough to cause postoperative sensorineural hearing loss in tympanoplasty due to its relatively low intensity.