Observations on Decerebration by Embolism

Abstract

Langley, 1 Mellanby, 2 and Edkins and Murray 3 have used intracarotid injection of starch as a method of decerebration for cats or rabbits. Observations in this laboratory on more than 40 dogs “decerebrated” with starch suspension (10%, 0.5 cc. per kg. or 2 cc. total; opposite carotid tied before injection) showed irregular results. While superficial resemblance to decerebrates as regards muscle tone pattern, etc., was not infrequent, the method appeared unreliable, a result naturally to be expected in view of the inevitably large role played by chance in the ultimate distribution of the embolizing particles. About one in 4 of the animals ceased breathing after injection.

Lycopodium spores, comparatively much less variable in size, more stable chemically 4 and on the average larger, are particles more readily identifiable in microscopic sections. The spore is a 3-sided pyramid with convex base. 5 Four spores are formed from a sphere of radius 21 microns. 4 There are about 95,000 spores per mg. against about 10,000,000 for rice starch. 4 Inclusion in lycopodium suspension of lampblack, 6 red oxide of iron, or the less permanent soluble dyes, methylene blue, crystal violet or diazine green, has enabled us to locate with moderate accuracy in gross sections the distribution of embolic material in the brain, so that its irregularity is plain, and the functional variation from animal to animal explicable. Attempts to explain functional results on an anatomical basis have proved interesting. Thus in an embolized dog, still breathing, but with relaxed limbs, the irregular posterior distribution of the embolic mixture extended to the pons-medulla junction and might conceivably have cut off the blood supply of the nuclei of Deiters.