猫慢性蜗外电刺激耳蜗组织病理学改变

Cochlear Histopathological Changes Following Chronic Extracochlear Electrical Stimulation in Kittens

本实验研究了5只猫蜗外电极慢性植入和电刺激引起的耳蜗组织病理学改变。刺激电极球分别固定在圆窗和鼓岬上,用双相平衡的0.4～1.8mA、脉宽100μS电脉冲作1276～1526h的慢性电刺激。光学显微镜检查耳蜗组织病理学改变发现:圆窗和鼓岬电极固定良好;除1耳电极推压圆窗膜与Hook区骨螺旋板粘连外,电极固定部位的圆窗膜均增厚;刺激侧与对照侧耳蜗下基底转内可见不同程度外毛细胞损失、轻度内毛细胞损失和小范围Corti's结构消失;2个刺激侧耳蜗近圆窗2%基底膜长度范围内少量螺旋神经节细胞损失。提示蜗外电极行电刺激虽比蜗内电极安全,但在耳蜗下基底转仍有轻度组织病理学改变.

Histopathological investigation of the cochlea following chronic extracochlear electrical stimulation was carried out in 5 kittens.The auditory nerves were electrically stimulated with round window or tympanic promontory electrodes for periods of 1276—1526 h using charge-balanced biphasic current pulses at charge densities of 1.27—5.73 μC/cm^2·geom·phase.The histopathological changes were examined with a light microscope. The findings were as follow;1.The fixations of round window and tympanic promontory electrodes were very firm.Six round window membranes became thicker in the area which contacted the electrode.One was pushed into the scala tympani and adhered to the spiral lamina of the hook region. 2.There was some outer hair cell loss,mild inner hair cell loss and disappearance of Corti's organ structures in a small area of lower basal turns.3.Decrease of spiral ganglion cell density was found over a 2% basilar membrane length in 2 stimulated cochleas.4.There was no change in normal control cochleas. These results indicate that mild histopatholgical changes occurred even though chronic electrical stimulation was performed with non-invasive extracochlear electrodes.The mechanism behind these changes should be further investigated.