| AimAuditory neuropathy (AN) first 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. The most important audiological characteristic of AN patients is that auditory brainstem responses (ABR) are absent or abnormal severely, but evoked otoacoustic emissions (EOAE) are normally recorded. AN is different from other common sensorineural deafness, which has the specific hearing impairment. AN has attracted attention more and more recently. The name of AN and site of AN lesion are still need discuss. The pathogeny and pathogenesis of AN are unknown. The effect treatment of AN is still absent. In this research, we summarized the clinical and audiological characteristics ofauditory neuropathy and discussed the significance of pure tone auditory threshold, acoustic immittance, ABR and distortion product otoacoustic emissions (DPOAE) in the diagnosis of AN. We also investigated the vestibular function disorder in AN patients and complicated AN in other nervous system diseases. Finally, we analysised the relationship between nervous system diseases and AN.MethodBy the retrospective studies of 134 AN patients including 4 complicated AN patients with nervous system hereditary disease from the department of neurology, we summarized their clinical dates, results of audiometry and other electrophysiological examinations. These results were compared with the results of audiometry of 30 common sensorineural deafness patients (49 ears) and 30 young subjects (60 ears) with normal hearing.Results1. Objects and clinical characteristics In all of the 134 AN patients, 48 patients were male and 86 were female. The ratio of both genders was 1:1.79. They mostly came from countryside, and 34.3% of them came from mountain area. Most of them were younger, and the ages of these first clients were from 1/6 to 48 years old, averaged at (20.0+8.45) years old. 13 patients (9.7%) were from 1/6 to 10 years old, 66 patients (49.3%) were from 11 to 20 years old, 41 patients (30.6%) were from 21 to 30 years old, and 14 patients (10.4%) were from 31 to 48 years old. The episode ages of them were from neonate to 39 years old, averaged at (17.1+7.89) years old. Their courses of diseases were from 1/6 to 15 years, averaged at (3.7+4.87) years. The courses of diseases of 59 patients (44.0%) were from half to 2 years. 133 patients (99.2%)complained of bilateral gradual hearing loss, and can't discriminate speech correctly, especially in the environment of noise. 10 children were found by their parents from a child. 61 patients (45.5%) complained of last or discontinuous tinnitus. 15 patients had the experience of dizziness, and 11 patients of inertia and walking lability. 11 patients had weak sight for unknown reason. 9 patients had the family history of deafness. All of them didn't have the exposure history of noise or ototoxic drug.2. The pure tone auditory threshold and acoustic immittance audiometry In 120 AN patients (240 ears), the pure tone audiogram of 167 ears (69.6%) were ascending curve, 45 ears (18.8%) were updown basin curve, 23 ears (9.6%) were flat curve, and other 5 ears (2.1%) were descending curve. Classified by the average pure tone threshold at low frequencies (0.125, 0.25 and 0.5 kHz), 17 patients (14.2%) were mild hearing loss (26-40 dB HL), 35 patients (29.2%) were moderate hearing loss (41-55 dB HL), 42 patients (35.0%) were moderate severe hearing loss (56-70 dB HL), 20 patients (16.6%) were severe hearing loss (71-90 dB HL), and 6 patients (5.0%) were profound hearing loss (>90 dB HL). The pure tone auditory threshold of the AN group was higher (6.9+6.17 and 7.8+6.37 dB HL separately) obviously (P<0.05) than the sensorineural deafness group at low frequencies (0.125 and 0.25 kHz), but lower (12.5+7.13, 27.2+7.72, 42.6+7.63 and 39.7+7.84 dB HL separately) obviously (P<0.05) at intermediate frequencies (1.0 and 2.0 kHz) and high frequencies (4.0 and 8.0 kHz). The... |
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