The scope and techniques of surgery become progressively more complex. However, the tools of the surgeon are relatively few, and they are chiefly mechanical: traditional scalpel, scissors, saws, and drills. More or less recent innovations are the electrical high-frequency knife (Bovie), which provides cauterization when used to cut or ablate tissue, and freezing techniques and ultrasound energy, which are used for specialized applications. Though not strictly considered surgical tools, penetrating ionizing X-rays and γ-rays have vast applications in cancer therapy.

Lasers in Surgery

Minute and reproducible inner-ear lesions were produced in surviving guinea pigs by using an argon laser. Preselected areas, mainly in the cochlea, were irradiated for 0.5-30 seconds at power densities at the focal spot of around 1 to 2 kW/cm2. the laser beam did not perforate the otic capsule but produced superficial changes. Beneath the impact point in the bone, a rounded lesion was observed in the vascular stria. Damage to the organ of Corti of varying extent occurred, depending on the energy dosage delivered. the organ of Corti in the impact area was characterized by either a complete loss or a reduced number of lipid granules in the Hensen cells. Hair-cell changes covering about one-third of a coil were frequently noted. Variations in the appearance of the cilia after irradiation are presented. Expansions of the tips of the cilia on the outer hair cells are described. the outer hair cells proved to be more affected by the laser irradiation than the inner hair cells. Scanning electron microscopy and p...

The laser as a tool in inner-ear surgery.

In guinea pigs the cochlea microphonics (CM) were recorded during and after argon laser stapedotomy. Short termed drastic depression of CM was observed. This effect involved the entire frequency range of the cochlea. The recovery was mostly complete and often started already during laser irradiation or at the end of the laser exposure. A marked sensitivity loss of the cochlea only occurred with large stapedotomy holes followed by massive perilymph leakage. A momentary heat related instability of the entire stapes is suggested to cause the CM depression. In addition we observed a thermoacoustic effect on the CM. This laser evoked response seems to cause no harm to the cochlea.

Influence of Argon Laser Stapedotomy on Cochlear Potentials I: Alteration of Cochlear Microphonics (CM)

The influence of argon laser stapedotomy on inner ear function was investigated in guinea pigs. The cochlear microphonics (CM) and the compound action potential (CAP) served as parameters for the functional status of the cochlear. Transitory depression of both potentials was found during and after laser stapedotomy. The time course of CM and CAP depression and recovery is compared to endocochlear temperature changes. Possible implications for clinical use are discussed.

Influence of argon laser stapedotomy on inner ear function and temperature.

The influence of the argon laser on inner-ear function during and after laser stapedotomy was investigated in guinea pigs, using the compound action potential (CAP) as parameter. With the onset of the argon laser impact, the CAP is depressed or even extinguished up to 10 s. The temporal course of subsequent CAP recovery is similar to that of endocochlear temperature recovery after laser stapedotomy, so that a direct influence of temperature increase and CAP decrease is probable. No permanent attenuation of CAP amplitude was found after a single laser perforation of the stapes footplate.

K Vogel

Papers

The transmission of a high-power ruby laser beam through bone.

Effect of high-power ruby laser irradiation on peripheral nerve.