Funai H, Hara M, Nomura Y
Department of Otolaryngology, University of Tokyo, Japan.
Am J Otolaryngol. 1988 Sep-Oct;9(5):244-55. doi: 10.1016/s0196-0709(88)80034-6.
This study was undertaken to elucidate the mechanism that causes sensorineural hearing loss in clinical cases with perilymphatic fistula. Perilymph was experimentally aspirated through the round window membrane in 17 guinea pigs. The extent of cochlear damage was examined electrophysiologically as well as histopathologically. Immediately after aspiration, several types of changes in summating potential (SP) were observed. Two animals without a polarity change of the SP showed only slight threshold changes in both cochlear microphonic and action potentials, and no specific histopathologic changes in the cochlea. Reversed polarity of the SP was observed in three animals, of which one showed a high-amplitude negative SP followed by rapidly progressive hearing loss. Bulging of Reissner's membrane was confirmed histopathologically in this case. The SP disappeared in the remaining 12 animals. In animals with profound electrophysiologic changes, bulging or rupture of Reissner's membrane and damaged hair cells were observed. These findings suggest that an abrupt change in perilymphatic pressure produces morphologic changes in the membranous labyrinth, causing changes in the vibration function of the cochlear partition and in the function of the organ of Corti. Abrupt pressure imbalance may be a causative factor of sensorineural hearing loss in the case of perilymphatic fistula.
本研究旨在阐明临床病例中因外淋巴瘘导致感音神经性听力损失的机制。对17只豚鼠通过圆窗膜实验性抽取外淋巴。从电生理学和组织病理学方面检查耳蜗损伤程度。抽取后立即观察到总和电位（SP）的几种变化类型。两只SP无极性变化的动物，其耳蜗微音电位和动作电位阈值仅出现轻微变化，耳蜗无特异性组织病理学变化。三只动物出现SP极性反转，其中一只出现高振幅负SP并伴有快速进行性听力损失。组织病理学证实该病例中Reissner膜膨出。其余12只动物的SP消失。在电生理学变化严重的动物中，观察到Reissner膜膨出或破裂以及毛细胞受损。这些发现表明，外淋巴压力的突然变化会导致膜迷路的形态学改变，引起耳蜗隔板振动功能和柯蒂器功能的变化。压力突然失衡可能是外淋巴瘘病例中感音神经性听力损失的一个致病因素。
