A lecture on the pathology and treatment of epilepsy / by George Johnson.

  • Johnson, George, 1818-1896.
Date:
1868
Catalogue details

Licence: Public Domain Mark

Credit: A lecture on the pathology and treatment of epilepsy / by George Johnson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    or upon the surface of the brain, which happily is a much less frequent accident. A number of facts point to the conclusion, that both the loss of con- sciousness and the convulsions of epilepsy are the result of sudden and ex- treme anemia of the brain. In man, and in most, if not in all, warm-blooded animals, a rapid and very copious haemorrhage usually causes convulsions. Kussmaul and Tenner state (On Epileptic Convulsions from Hcemorrhage, New Sydenham Society, 1859) that, in numerous cases of dogs, cats, and rabbits, they observed, without a single exception, violent and general convulsions preceding death from loss of blood. In order to produce this result, the haemorrhage must be rapid. If it occur slowly, so that the vital powers are gradually consumed, death then occurs with swooning, drowsiness, and delirium, without convulsions. The same observers found that an interruption in the supply of blood to the head of a rabbit, by ligature or compression of the arteries, pro- duces epileptic fits as surely as haemorrhage does. In about one hun- dred rabbits, they ligatured or compressed the carotids and subclavians, from which, be it remembered, the vertebrals proceed, and in every in- stance except that of one very old, lean, and feeble rabbit, convulsions occurred. In order to produce convulsions, it was necessary to elose all the four arteries which supply the brain. If but one carotid or one subclavian remained pervious, the animal was enfeebled and more or less paralysed, but not convulsed. And, again, if, during the height of a convulsion, the ligature is removed from one carotid, the convulsions generally cease immediately, and there is a sudden change from the most frightful spasm to complete relaxation of the muscles. The de- scription of the convulsions thus artificially produced in these animals, shows that they were essentially the same as epileptic convulsions in the human subject. There was the dilated pupil, the tonic spasm, quickly succeeded by clonic convulsion, so violent, as to throw the animal for- cibly forwards to a distance of one or two feet, and sometimes even over the shoulders of the experimenter. These experiments suffice to show the fallacy of the explanation which Dr. Brown-Sequard and others have given of the clonic convulsions in man. It has been supposed that the clonic convulsions are a consequence of the circulation of black blood which results from the tonic spasm of the respiratory muscles. Now it is manifest that, in these animals with ligatured arteries, no black blood could reach their brain. In them, therefore, the clonic convulsion, as well as the preceding tonic spasm, must be due to want of blood, and not to the altered quality of blood in the brain.