Shigenobu Mihashi

LASER SURGERY IN OTOLARYNGOLOGY: INTERACTION OF CO2 LASER AND SOFT TISSUE*

The sequence of histological change induced by CO2 laser irradiation was discussed in terms of two factors: the physiomechanical factor and the physiochemical factor. At sufficiently high heat energy levels, the immediate findings are characterized by crater formation resulting from rapid vaporization of the water and ejection of the solid component. In the immediate vicinity of the crater edge, the maximum tissue temperature rise is 65 degrees C above the 32 degrees C ambient tissue temperature and it decreases to the primary tissue temperature within a distance of 2 mm. The healing process of CO2 laser induced lesions proceeds with minimal delay. The lymphatic and vascular channels are occluded in the marginal area of coagulation resulting in a marked hemostatic effect. This sealing effect increases the margin of safety in preventing possible dissemination of tumor cells. By selecting the appropriate power, time, and focus cone angle, precise destruction of preselected areas of tissue can be achieved with an extraordinary hemostatic effect without damaging the underlying tissue. These advantages are especially helpful in function-preserving surgery.

A REVIEW OF CO2 LASER SURGERY FOR CARCINOMA OF THE LARYNX

During the period from 1978 to August, 1984, 66 patients with carcinoma of the larynx were treated with the use of CO2 laser at Kurume University Hospital. Results are summarized as follows: 1)Thirty patients who had no previous treatments were treated with laser alone. Of the 30, 3 were Tis cases, 18 were Tla, 7 were Tlb, 2 were T2. Nine patients developed recurrence. 8 patients received second treatments and they are alive with no evidence of disease. The other rejected to have further treatment and died of an intercurrent disease. 2)Thirty-two patients who had no previous treatments were treated with laser and radiotherapy. Of the 32, 10 were T1a cases, 14 were T1b cases, 8 were T2 cases. Seven patients developed recurrence. They were further treated with varying modalities and are alive without any evidence of disease. 3)Four patients were radiation failure. Three of them were rT1a and 1 was rT1b. They were treated with laser alone. Three are alive and the other died of an intercurrent disease. None of the 4 developed local recurrence.