摘要
为探讨电离辐射所致内耳迟发性损伤的特点和机理，观察了分割剂量６０Ｃｏγ射线照射豚鼠颞骨，当总剂量达６０Ｇｙ后８个月期间内耳功能和形态变化。形态研究应用光镜、扫描电镜与透射电镜，而功能测定采用耳蜗电图（ＥＣｏｃｈＧ）和眼震电图（ＥＮＧ）技术。结果发现：辐射耳照射前ＣＡＰ（复合动作电位）反应阈平均３５．６７±６．７８ｄＢ（ｘ±ｓ），总剂量结束后第一天为４１．１７±７．７６ｄＢ，３个月后４７．００±８．８２ｄＢ，８个月后７１．００±７．６３ｄＢ。放射结束后第一天与照射前比较无统计学差异（Ｐ＞０．０５），３个月后ＣＡＰ反应阈上升，８个月后听觉功能损害更明显（Ｐ＜０．０１）。辐射前眼震持续时间４０．００±５．４４秒，辐射后８个月２２．７１±７．３９秒，差异非常显著（Ｐ＜０．０１）。病理变化特点：耳蜗血管纹萎缩、变性，毛细血管数目减少，血管壁增厚，内皮细胞受损，细胞连接破坏；外毛细胞变性、坏死，底回毛细胞损伤率明显高于二、三回；前庭感觉细胞变性。结果表明：放射治疗剂量可致内耳的迟发性损害，内耳微血管辐射损伤后氧供和新陈代谢障碍可能是主要的致病机理。
To investigate the feature and mechanism of delayed effect of ionizing radiation on the inner ear, the function and structure of the inner ear of the guinea pigs were observed during 8 month′s period after exposure to fractional doses of gamma radiation (2 Gy per day) with a total dose of 60 Gy. Morphological study was performed using light microscopy,transmission and scanning electron microscopy while the function was measured with electrocochleography ( ECochG) and electronystagmography (ENG).The results showed that the mean CAP response threshold was 35.67±6.78dB before radiation, and 41.17±7.76dB,47.00±8.82 dB and 71.00± 7.63 dB at 1st day, 3rd month and 8th months after completion of treatment, respectively. No singnificant change was demonstrated in the auditory respones at the 1st day of radiation ( P >0.05) , but there was obvious hearing loss at 3rd and 8th month ( P <0.01). The nystagmus duration induced by ice water (ENG) was 40.00±5.44 seconds before radiation, 22.71 ±7.93 seconds at 8th month after radiation ( P < 0.01). Histologic examination at 8th month after radiation revealed atrophy and degeneration of stria vasicularis, a reduced number of capillaries, degeneration of endotheliocyte in vessals , outer hair cell and supporting cell of Corti′s organ . The percentage of damaged hair cells in basal turn of the cochlea was significantly higher than those of the upper turn. Degeneration of vestibular hair cell was found. It is suggested that radiation from routine radiotherapy doses may result in a delayed impairment of the inner ear. The main mechanism of the radiation damage may be interference of oxygen supply and metabolism of the inner ear by radiation vascular lesion.
出处
《中华耳鼻咽喉科杂志》
CSCD
1997年第4期222-225,共4页
Chinese Journal of Otorhinolaryngology
关键词
内耳损伤
迟发性损害
电离辐射
Radiation injuries, experimental Gamma rays Cochlea Vestibule
