Thoma J, Unger V, Kastenbauer E
Laryngol Rhinol Otol (Stuttg). 1981 Nov;60(11):587-90.
Laser stapedectomy is looked upon as an operation method which may be less harmful to the inner ear. The purpose of this study was to investigate the course of temperature behind the footplate of isolated human petrous bones while using the Argon Laser. We found that a non-linear relationship exists between the power of the Laser beam, the duration of the impulse and the sudden temperature rise during the impulse. Another, though linear, relationship exists between the energy of the beam and the permanent elevation of temperature in the perilymph during repeated shots. The observation of tiny bubbles beneath the focus on the wall of a plastic tube (which we used as a model for flow studies) led us to assume that the same may be true for the perilymph, too. The bursting of these bubbles was thought to cause a sudden rise of pressure in the inner ear. We were able to measure this Laser-generated sound pressure which reached 59 dB (A) for a beam energy of 1.0 Ws. Very low frequencies, which were not determined by this method, might very well cause damage to the inner ear structures. Finally, we proved that the results found a the isolated petrous bone which we fixed in a 37 degree waterbath can be transferred to in vito conditions: The course of the temperature was investigated in the cochlea of live Guinea pigs and shortly after death without detecting any change of the results.
镫骨切除术被视为一种对内耳危害可能较小的手术方法。本研究的目的是研究在使用氩激光时，离体人颞骨岩部足板后方的温度变化过程。我们发现，激光束功率、脉冲持续时间与脉冲期间温度的突然升高之间存在非线性关系。而在多次照射过程中，光束能量与外淋巴中温度的持续升高之间存在另一种线性关系。在塑料管（我们用作流动研究模型）壁上的焦点下方观察到微小气泡，这使我们推测外淋巴中可能也会出现同样的情况。这些气泡的破裂被认为会导致内耳压力突然升高。我们能够测量这种由激光产生的声压，对于1.0Ws的光束能量，其达到了59dB（A）。这种方法未测定的极低频率很可能会对内耳结构造成损害。最后，我们证明了在37℃水浴中固定的离体颞骨上得到的结果可以推广到体内情况：在活的豚鼠耳蜗以及死后不久对温度变化过程进行了研究，未发现结果有任何变化。
