ABSTRACT
Objective:To investigate the relationship between hearing loss and acoustic neuroma(AN),the tests of pure tone audiometry,acoustic emissions impedance audiometry,audiometry brainstem response(ABR)and evoked otoacoustic emissions(EOAE)wee measured in 14 patients (16 ears)from March 1999 to December 2000.Methods:Fourteen patients (16 ears)with acoustic neuroma (8 males and 6 females,ranging in age from 21 to 72 years old)were diagnosed by CT or MRI scaning,and final confirmed by surgery and pathology.In the auditory tests ,efferent suppression test was curried out only in 4 ears with recordable emissions,promontory stimulation test (PST)was examined only in 5 ears with severe or profound deafness (hearing loss≥80dB SPL)who have no both measurable ABR and recordable EOAE.Results:It was found that 2 ears (12.5%,2/16)of the AN ears showed neural impairment,6 ears (37.5%,6/16)were cochlear impairment and 8 ears (50.0%,8/16)were cochlear-retrocochlear impairment.All of 4 tumors ears with EOAE emission have a disorders of efferent function.Conclusion:EOAE test had significant value for evaluation of the status of cochlear function (at the level of outer hair cells)in AN patients.The retrocochlear auditory nerve function of AN patients were evaluated by the tests of ABR combined PST which showed significant value.Results showed that the hearing impairment of AN have different levels of the peripheral auditory system according to auditory tests,including cochlear,eighth cranial nerve and efferent nerve level at the same or independently.
ABSTRACT
Objective: To investigate the impairment status of vestibular and limb peripheral nerve of patients with auditory neuropathy, improve the understanding of auditory neuropathy in general. Method: Vestibular function tests and nerve conduction velocity (NCV) examinatoin were performed on 28 young patients with auditory neuropathy which confirmed by clinical auditory tests diagnosis from March 1999 to November 2000. There were 14 males and 14 females, ranging in age from 22 to 28 years old. Results: Vestibular dysfunction was encountered in 22 of 28 (78.57%) suffering from auditory neuropathy. Limb peripheral nerve impairment was found in 11 of 28 patients (39.29%) of auditory neuropathy. The caloric responses were normal symmetric responses in 6 of 28 (21.43%,6/28), and weaken bilaterally in 20 of 28 (71.43%,20/28)respectively. On the NCV examination, both motor conduction velocity (MVC) and sensory conduction velocity (SCV) were normal in 17 (60.71%,17/28), abnormal in 4 (14.29%,4/28). Four cases showed abnormal MCV and SCV. And pure MCV abnormality and pure SCV abnormality were found on 4 and 3 cases respectively. Conclusion: The pathological process affecting the auditory nerve may also affect the vestibular nerve and other peripheral nerve. This seemed possible in view of fact that auditory neuropathy may affect one nerve (mononeuropathy) or multiple nerves (polyneuropathy).