Abstract
Following operations on the brain in the region of the optic chiasma and infundibulum, patients frequently develop a hyperthermia which is difficult to control and is often fatal. Similar sharp rises in temperature have been obtained in cats and monkeys by placing lesions in the anterior part of the hypothalamus or in the preoptic region. These operations were performed under nembutal anesthesia and the hyperthermia did not appear until the depressing effect of the nembutal had worn off after the lapse of several hours. The technic involved, the location of the lesions, the course of the hyperthermia and its significance for an understanding of the mechanism involved in temperature regulation have been discussed elsewhere. 1 , 2
This investigation was undertaken to study the course of the hyperthermia, when ether instead of nembutal was used as an anesthetic, and the effect of nembutal when injected after a high temperature had been developed. Under ether, lesions were placed bilaterally in the anterior part of the lateral hypothalamus and immediately following the operation the cat was strapped on its side in a comfortable hammock and a continuous record was taken of rectal temperature for the next 20 hours with a Leeds and Northrup Micromax.
Seven out of 11 cats showed postoperative hyperthermia. In one the rectal temperature rose to a high of 104.3° in 450 minutes and in another to 104.8° in 670 minutes. In these 2 cats no nembutal was given. Five others in which the temperature rose more sharply were given nembutal (14 mg per kg) after the temperature had reached levels varying from 104.8 to 106.9. The nembutal caused precipitate drops in temperature in all 5 cats varying in extent from 2.4° to 4.4° (Table I).
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