Decerebration in the Dog by Complete Temporary Anemia of the Brain

Abstract

In many investigations, it is desirable to perform experiments upon animals in the absence of anesthetics. The usual procedure is that of Sherrington, namely, to decerebrate surgically under ether, to stop the anesthesia, and to proceed at once with the experiment. 1 Under such conditions, profound shock and the depression due to the residual anesthetic agent throw some doubt on the reliability of the results. A more delicate method of decerebration has been devised for the cat by Pollock and Davis. 2 In this method, an anemic decerebration is produced by ligation of the basilar and carotid arteries under ether anesthesia. In the dog, the inaccessibility of the basilar artery makes this a difficult method.

It has been shown that the nerve cells of the brain stem are much more resistant to anemia than are those of the cerebral hemispheres, 3 It is therefore possible to produce extensive cerebral damage by a period of anemia which will allow the cells of the brain stem to recover. Guthrie, Pike and Stewart 4 and Gildea and Cobb 5 studied the effects of temporary occlusion of the 4 chief cerebral vessels in the neck under ether anesthesia, and were unable to predict the severity of the destruction produced by a given period of such occlusion. The variability in their results was due primarily to their failure to interrupt the flow in the spinal arteries, which is not constant from animal to animal. A further uncertainty must have resulted from variations in the depth of anesthesia just prior to the occlusion of the cerebral vessels.

We have devised a method of decerebration depending upon complete temporary anemia of the brain of the dog in the absence of anesthetics. A preliminary surgical procedure is used, consisting in removal of both laminæ and spine of the second cervical vertebra and ligation of both vertebral arteries. After an interval of one to 2 weeks, the dog is given one to 2 mg of atropin sulfate to prevent vagal cardiac inhibition, and placed, back down, on the table.