Oda A
Department of Otolaryngology, Tokyo Women's Medical College.
Nihon Jibiinkoka Gakkai Kaiho. 1994 Jan;97(1):112-23. doi: 10.3950/jibiinkoka.97.112.
Although several complications have been reported at present, myringotomy and ventilation tube insertion are frequently used in the treatment of secretory and recurrent otitis media. There have been many studies on histological changes of tympanic membranes (TM) after surgery, however, experimental studies on the mechanical properties of the TM are very few. In animal models, repeated myringotomies were performed on the TM of 39 guinea pigs (Group A), and polyethylene tubes were inserted into the upper anterior quadrants of the TM in 19 guinea pigs (Group B). In Group A two types of incisions, circumferential and radial, were made in the TM. In group B the ventilation tubes were removed after either one week or five weeks. After the final incision or removal of the tubes, structural changes of the TM were examined by otomicroscope once a week for a duration of four weeks. The animals were sacrificed after one week or four weeks and the TM were dissected out, and observed under both light and scanning electron microscopes. A microtesting system was developed to measure the mechanical strength of the TM. This system consists of three components: a microscope, a specimen holder and a force sensor. The specimen was stretched over the hole (500 microm in diameter) of the holder, and was penetrated by a force sensor needle, 130 microns in diameter. The load-displacement curve began ascending when the sensor touched the specimen, and disappeared after breakage. The results were as follows: 1) Repeated myringotomies caused a dramatically thickened TM in not only the operated area, but also the posterior quadrants. The TM in group A were more thickened than those in group B. Tympanosclerosis was observed more frequently in the TM with circumferential incisions as compared to those with radial incisions. Retraction of the TM was observed only in group B. 2) In normal TM, the load-displacement curve showed a linearly ascending curve with some small peaks. The load at breakage was 72.9 mN on average. The load-displacement curve at the thickened area showed a concave ascent without small peaks. The load at breakage ranged from 10 to 660 mN after circumferential incisions, and from 40 to 240 mN after radial incisions. At the tube insertion region, the load at breakage ranged from 53 to 237 mN.
尽管目前已有多种并发症的报道，但鼓膜切开术及置管术仍常用于分泌性中耳炎和复发性中耳炎的治疗。关于术后鼓膜（TM）组织学变化的研究已有很多，然而，关于TM力学性能的实验研究却非常少。在动物模型中，对39只豚鼠的TM进行反复鼓膜切开术（A组），并对19只豚鼠的TM上前象限插入聚乙烯管（B组）。在A组中，在TM上制作了两种类型的切口，即圆周切口和放射状切口。在B组中，通气导管在1周或5周后取出。在最后一次切口或取出导管后，用耳显微镜每周检查一次TM的结构变化，持续四周。在1周或4周后处死动物，取出TM，在光学显微镜和扫描电子显微镜下观察。开发了一种微观测试系统来测量TM的机械强度。该系统由三个部分组成：显微镜、标本夹和力传感器。将标本拉伸在标本夹的孔（直径500微米）上，并用直径130微米的力传感器针穿透。当传感器接触标本时，载荷-位移曲线开始上升，并在破裂后消失。结果如下：1）反复鼓膜切开术不仅使手术区域的TM显著增厚，后象限的TM也增厚。A组的TM比B组增厚更明显。与放射状切口相比，圆周切口的TM中耳鼓室硬化更常见。仅在B组观察到TM内陷。2）在正常TM中，载荷-位移曲线呈线性上升曲线，有一些小峰值。平均破裂载荷为72.9 mN。增厚区域的载荷-位移曲线呈凹形上升，无小峰值。圆周切口后破裂载荷范围为10至660 mN，放射状切口后为40至240 mN。在置管区域，破裂载荷范围为53至237 mN。
