Thoma J, Unger V, Kastenbauer E
Laryngol Rhinol Otol (Stuttg). 1982 Aug;61(8):473-6.
While numerous histological findings point towards a possible destruction of inner-ear structures by the Argon-Laser we still miss a satisfactory statement concerning functional impact of stapedectomy or stapedotomy using laser beams. To investigate this we irradiated the promontorium of each of 10 guinea-pigs with laser powers between 0.6 W and 2.2 W ten times for 0.5 s. Then, and on the first, fifth and tenth postoperative day we recorded the brainstem potential evoked by bone-conducted clicks. We found that after the application of laser power up to 1.2 W a reversible threshold shift of up to 20 dB took place. Above powers of 1.2 W a permanent threshold shift was found (Fig. 1). Before sacrificing the animals we recorded the course of temperature in the perilymph during laser irradiation (Fig. 2 and 3). In order to set application limits of power within we consider laser impact functionally critical we compared the temperature increment during single shots and permanent elevation of the temperature above body temperature with values we have found earlier at the human petrous bone (Fig. 2 and 3). This led us to the conclusion that the temperature increment during the shot might be the limiting factor as far as the deterioration of inner-ear function is concerned. This may very well coincide with our hypothesis (Thoma and coworkers, 1981) that the vaporization of endocochlear fluid during the shot is a possible cause of cochlear malfunction after stapedectomy by laser.
尽管众多组织学研究结果表明氩激光可能会对内耳结构造成破坏，但我们仍缺乏关于使用激光束进行镫骨切除术或镫骨造孔术功能影响的令人满意的阐述。为了对此进行研究，我们用功率在0.6瓦至2.2瓦之间的激光对10只豚鼠的每个鼓岬进行了10次照射，每次照射0.5秒。然后，在术后第一天、第五天和第十天，我们记录了骨导短声诱发的脑干电位。我们发现，在施加高达1.2瓦的激光功率后，出现了高达20分贝的可逆阈值偏移。在功率超过1.2瓦时，发现了永久性阈值偏移（图1）。在处死动物之前，我们记录了激光照射期间外淋巴液的温度变化过程（图2和图3）。为了确定我们认为激光影响在功能上至关重要的功率应用限度，我们将单次照射期间的温度增量以及温度永久性升高至高于体温的情况与我们先前在人类岩骨上发现的值进行了比较（图2和图3）。这使我们得出结论，就内耳功能恶化而言，单次照射期间的温度增量可能是限制因素。这很可能与我们的假设（托马及其同事，1981年）相符，即单次照射期间内淋巴液的汽化可能是激光镫骨切除术后耳蜗功能障碍的一个原因。
