| Pure tone auditory threshold test is one of commonly used clinical audiology test, operated simply and worth low, universaly used in primary level hospitals.Because of it belonging to subjective audiology test, acoustic immitance which is objective audiometry frequently used to assist. Than we can well understand auditory function of the patient. Auditory neuropathy(AN)was first time named by Starr in 1996, which has the specific clinical characteristics,is one kind of sensorineural hearing loss caused by the injury of acoustic nerve branch of the eighth cranial nerve. Its main otological characteristics are normal evoked otoacoustic emission(EOAE) readings,but obviously abnormal auditory brainstenm responses(ABR),and the speech hearing is worse obviously than the pure tone hearing, and the audiogram is bilateral ascending curve mostly, and pure tone auditory threshold is higher obviously at low frequencies,and acoustic stapedius reflex is absent and the contralateral suppression effect of distortion product otoacoustic emissions(DPOAE)isdisappeared.AN has attracted more and more attention recently.the name of AN and site of AN lession are still need discuss.The pathogeny and pathogenesis of AN are unknown.The effective treatment of AN is still absent.The present subject has been the one of the hotspots in Otorhinolaryngology. In which pure tone auditory threshold is higher obviously at low frequencies,and the speech hearing is worse obviously than the pure tone hearing, is important characteristic of AN.Objective: In this research,we summarized the clinical and audiological characteristics of auditory neuropathy and discussed the significance of pure tone auditory threshold and acoustic immittance in the diagnosis of AN.Then we can best increase diagnose and further to deepen recognition.Methods:By retrospective review of patients from otology clinic from September 2005 to July 2008, we summarized the clinical and pure tone threshold and the examination results by acoustic characteristics of auditory neuropathy ,analyzed the results and discussed the significance of pure tone auditory threshold and acoustic immittance in the diagnosis of AN and the relationship with AN.Results:1. object and clinical manifestationIn all of 51 AN patients, 21patients were male and 30were female. The ratio of both genders was 1:1.43.Most of them came from mountin area and were younger (66.7%).The ages of these first clients were from 12 to 42 years old, averaged at (20.7±6.5)years old.The episode ages of them were from 5 to 31 years old,averaged at (17.3±5.3)years old.Their courses of diseases were from 1/12 to 21 years,averaged at (3.44±3.97)years.50 patients comlained of bilateral gradual hearing loss and can′t discriminate speech correctly,especially in the environment of noise.21 patients (7unilateral,14bilateral ) complained of last or discontinuous tinnitus.And the tone isdifferent. 2patients had the experience of dizziness.2. pure tone auditory threshold and acoustic immittanceThe pure tone audiogram of 55 ears (53.9%)were ascending curve,and the speech hearing is worse obviously than the pure tone hearing. By comparing the degree of the left and right ears′s air conduction threshold of sound, we got that there was not statistically significant between left and right ear in every frequency(P >0.05), excep 0.5 kHz( the right ear super to the left). The degree of hearing loss in each among frequency was significant difference during distinct course of disease of patients(P<0.05),except 4kHz and 8kHz(P>0.05); The degree of hearing loss in each among frequency was not significant difference during distinct age of patient(sP>0.05),except 0.5 kHz. the speech hearing is worse obviously than the pure tone hearing. In the Tympanogram with 51 cases(102 ears) of AN patients, 2 ears were"AD"curve ,1 ear was"C"curve,the remaining were all normal"A"curve. In the result of acoustic stapedial reflex 24 cases homonymy and crossed acoustic reflex were not educed, 27 cases (16 cases were bilateral 11 cases were unilateral) single item and multi-item could be extractable, but the acoustic reflex threshold was raised.All of the ears didn't have the phenomenon of loudness recruitment Conclusion:By the retrospective studies of 51 AN patients, auditory neuropathy commonly onsets in the young (66.7%),averaged at(20.7±6.5)years old.mostly in female.These patients may complain of bilateral, eudipleural and gradual hearing loss and can't discriminate speech correctly.Some of them can accompany tinnitus or dizziness.All of them don't have the obvious exposure history of ototoxic drug or noise.Some of them may have the family history of deafness.The audiogram is bilateral and eudipleural ascending curve mostly(53.9%),The longer of course of disease of the patients ,the worse of the degree of hearing loss in low frequency.The degree of hearing loss were alike in patients of each age stage. The speech hearing is worse obviously than the pure tone hearing;The tympanogram in AN is normal type"A". Acoustic stapedius reflex is absent or the acoustic reflex threshold is raised, and the phenomenon of loudness recruitment isn′t observed in AN.
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