A quantitative observation of the efferent fibres across the Corti′s tunnel after intensive impulse noise exposure

Objective To study the damaged extent of efferent fibres across the Corti′s tunnel in guinea pigs after intensive impulse noise exposure.Methods The cochlear AchE(acetylcholinesterase)decoration and a computer assistant quantitative observation of the efferent fibres across the Corti′s tunnel were carried out in three groups of guinea pigs.The guinea pigs of group 3 d and 21 d were fed 3 days and 21 days after exposure of intensive impulse noise,while the normal control group did not receive noise.Results The noise damaged efferent fibres across the Corti′s tunnel mainly took place in the first turn and the second turn of the cochlear.The quantity of the efferent fibres across the Corti′s tunnel in every 0.24 mm length in the first turn and the second turn of the cochlear were(9.6±4.2),(8.8± 3.4) in 3 days group;(11.4±3.2),(10.6±2.5)in 21 days group and(23.2±3.2),(20.7±2.9)in normal control group separately.There were significant statistic difference( P 0 01)between 3 days group and 21 days group with the normal control group.Conclusions The intensive impulse noise could damage efferent fibre across the Corti′s tunnel severely.