Experiments were carried out to compare the effectiveness of
dexamethasone, a
barbiturate, and hypothermy on experimental
cerebral edema caused by
CO2 laser in dogs. Experimental brain lesions were created over the right frontal cortex of the dogs through the intact dura mater with
CO2 laser energy (40 W impact, 0.5 second duration, for a total time of 4 seconds on a 12.5 mm surface). Animals were divided into four groups and treated with
dexamethasone, a
barbiturate, hypothermy, and a
crystalloid (control group). The brains were examined 48 hours after injury. Histologically all brain lesions showed three distinct layers with a vaporized center bordered by a zone of coagulation
necrosis surrounded by
edema. The main finding in the surrounding coagulation and edematous layers was dilatation of the vessels.
Hemorrhage was sometimes observed mainly in the edematous layer. The effect of these
therapies on the
laser lesion and the effectiveness of these
therapies on surrounding
cerebral edema were evaluated by both light and electron microscopy. The control group showed significantly greater
edema than the
dexamethasone group. There was only a minimal difference between the control group and the
barbiturate group, and there was no significant difference in amount of
edema between control group and the hypothermy group. There was less
edema in the
dexamethasone group than in the other ones. These data suggest that
dexamethasone inhibits
edema in
CO2 laser lesions with the same efficacy as shown in the treatment of vasogenic
edema.