Jacksonian Epilepsy, named after Hughlings Jackson, who in 1861 traced its symptoms to their cause, is not a true epilepsy, being due to a local irritation of the cortex (the outermost layer) of the brain.
There is usually an _aura_ before the attack, often a tingling or stabbing pain. The chief symptoms are convulsions of certain limbs or areas of the body, which, save in very severe cases, are confined to one side, and are not attended by loss of consciousness.
The irritation spreads to adjacent areas, as wavelets spread from a stone thrown into a pond, with the result that convulsions of other limbs follow in sequence, all confined to one side.
As every part of the brain is connected to every other part by "association fibres", in very violent attacks of Jacksonian epilepsy the irritation spreads to the other side of the brain also, consciousness is lost, the convulsions become general and bilateral, and the patient presents exactly the same picture as if the attack were due to _grand mal_.
All degrees of violence are seen. The convulsions may consist only of a rapid trembling, or the limb or limbs may be flung about like a flail.
Jackson said: "The convulsion is a brutal development of a man's own movements, a sudden and excessive contention of many of the patient's familiar motions, like winking, speaking, singing, moving, etc." These acts are learned after many attempts, and leave a memory in certain groups of brain cells; irritate those cells, and the memorized acts are performed with convulsive violence.
The convulsions are followed by temporary paralysis of the involved muscles, but power finally returns. As we should expect, this paralysis lasts longest in the muscles first involved, and is slightest in the muscles whose brain-centres were irritated by the nearly exhausted waves. If the disease be untreated, the muscles in time may become totally paralysed, wasted, and useless.
Friends should very carefully note exactly where and how the attack begins, the exact part first involved, and the precise order in which the spasms appear, as this is the only way the doctor can localize the brain injury. The importance of this cannot be overrated.
The consulting surgeon will say if operation is, or is not, advisable, but _operation is the sole remedy for Jacksonian epilepsy_, for the causes that underly its symptoms cannot be reached by medicines.