Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of E.N.T

Background:Chronic unilateral hearing impairment causes imbalanced auditory input to the brain that triggers cortical reorganization. The effect of sensorineural hearing loss on the central auditory system has been thoroughly studied while there is a paucity of research on the effect of conductive hearing loss (CHL), on the central auditory system of humans. objective:The aim of this study was to assess the N1-P2 cortical auditory evoked response potential (CAEP) in adult individuals with chronic acquired unilateral CHL when stimulating the affected ear. subjects andmethods:This study included 108 participants of both genders: 54 patients with unilateral chronic CHL who were compared to well-matched 54 healthy subjects as controls. All were subjected to history taking, otologic examination, basic audiological evaluation, and bone conduction N1-P2 cortical auditory evoked response potential. results:The affected ears of the CHL cases showed highly statistically significant shorter bone conduction CAEPs N1, P2, N1-P2 latencies but not P1 and showed highly statistically significant larger bone conduction N1, P2, N1P2, amplitude than the tested ears of the control group. Both N1 and P2 latency decreased and the N1 amplitude, P2 amplitude, and N1 P2 amplitude increased,as the degree of CHL increased. Neither the age of the patients, the side of CHL, or the duration of the CHL affect either the amplitude or latency of CAEP.Cases with tinnitus had statistically significant delayed latency of CAEP except for the P1 latency and the N1 P2 latency difference and had statistically significantly smaller amplitude than those without tinnitus

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