Reverse frequency-sweep audiometry in patients with retrocochlear and cochlear deafness.
The material consisted of 21 patients with surgically confirmed eighth-nerve tumour and 107 patients with cochlear deafness. 13 (62%) of the patients with eighth-nerve tumour showed separated forward-backward tracings in sweep-frequency audiometry. One of the 13 patients gave an initially normal result but after the test ear had been exposed to 80 dB HL white noise for 3 min, the curves separated. Only 2 (1.9%) of the 107 patients with cochlear deafness had separated curves. Tone decay test revealed a pathological result in 67% of the patients with eighth-nerve tumour and in 26% of the cases with cochlear hearing loss. There is no single pathognomonic test for the diagnosis of retrocochlear and cochlear deafness. Diagnosis must be based on a whole battery of several tests, and among these, reverse frequency-sweep audiometry seems to be a suitable additional adaptation test. If an abnormal result is found in forward-backward sweep-frequency audiometry, a retrocochlear lesion is very probable.
D001299:Audiometry / Q000379:methods*; D001301:Audiometry, Pure-Tone / Q000379:methods*; D003390:Cranial Nerve Neoplasms / Q000175:diagnosis*; D003638:Deafness / Q000175:diagnosis*; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D008875:Middle Aged; D009622:Noise; D000160:Vestibulocochlear Nerve Diseases / Q000175:diagnosis*