镫骨切除术对豚鼠听力的影响

目的 研究镫骨切除术对豚鼠听功能及形态学的影响,探讨镫骨切除术对听功能改变的影响因素.方法 24只(48耳)豚鼠随机分为两组,每组12只.选定左耳为手术耳,分别进行暴露砧镫关节手术(手术对照、1组),镫骨切除、人工镫骨植入术(镫骨切除术组、2组);行听性脑干反应(ABR)测试并分别于术后1 h、术后1 d各组随机抽出4只豚鼠进行耳蜗中轴切片及扫描电镜检查.结果 手术对照组除波?潜伏期较术前延长外,其余各波潜伏期及波间期、反应阈均无明显改变;镫骨切除术后1 h反应阈明显提高(23.75±3.77 dBSPL);Ⅰ、Ⅱ、Ⅲ、Ⅳ波和Ⅰ～Ⅲ波间期较术前延长.镫骨切除术后Ⅰ、Ⅲ波潜伏期较手术对照组延长,而各波间期无明显差异;各组术后1 d与术后1 h各听力指标无显著性差异.两组耳蜗结构完整,各转螺旋神经节细胞数无显著性差异.镫骨切除术组仅第3排外毛细胞静纤毛部分略有紊乱(术后1 d恢复正常),手术对照组毛细胞形态正常.结论 镫骨切除术可引起豚鼠听力轻度损失,对耳蜗功能的影响小.

Influence of stapedectomy on the hearing of guinea pigs

OBJECTIVE: To compare the influences of stapedectomy and small fenestra stapedotomy on the hearing of guinea pigs. METHODS: Twenty-four (48 ears) guinea pigs were randomized equally into two groups, and the left ears were subjected to stapedectomy and total stapes replacement with a prosthesis, or sham operation (12 ears) to expose the footplate of the stapes and the round window. Each guinea pig was tested by ABR perioperatively. Four guinea pigs were chosen randomly from each group and decapitated for morphological examination by light microscopy and scanning electron microscopy after ABR test. RESULTS: In the sham operation group, the post-operative latencies of each wave, the intervals and the hearing threshold exhibited no significant changes other than prolonged latency of wave I. In stapedectomy group, the hearing threshold increased to 23.75-/+3.77 dBSPL 1 h after operation with significantly prolonged post-operative latencies of all the waves and intervals but for III-IV interval, which was shortened. The latencies of each wave (especially waves I and III) in the stapedectomy group were increased by a greater magnitude than those in the sham operation group, but the intervals were comparable between the two groups. No significant difference was noted in the parameters of ABR either 1 h or 1 day after the operation between the two groups, in which the architecture of cochleas remained intact with similar number of spiral ganglion cells. The stereocilia of the outer hearing cells (OHC) were normal in the sham operation group while in stapedectomy group, slight stereocilia disorder occurred but became normal 1 day after operation. No obvious changes were found in the stereocilia of the inner hearing cell (IHC) in either groups. CONCLUSION: Stapedectomy can induce mild hearing loss without seriously damaging the function of the cochlea in guinea pigs.