What is Epilepsy?

Legal Definition
Epilepsy is a group of neurological diseases characterized by epileptic seizures. Epileptic seizures are episodes that can vary from brief and nearly undetectable to long periods of vigorous shaking. These episodes can result in physical injuries including occasionally broken bones. In epilepsy, seizures tend to recur, and have no immediate underlying cause. Isolated seizures that are provoked by a specific cause such as poisoning are not deemed to represent epilepsy. People with epilepsy in some areas of the world experience stigma due to the condition.

The cause of most cases of epilepsy is unknown, although some people develop epilepsy as the result of brain injury, stroke, brain tumors, infections of the brain, and birth defects. Known genetic mutations are directly linked to a small proportion of cases. Epileptic seizures are the result of excessive and abnormal nerve cell activity in the cortex of the brain. The diagnosis involves ruling out other conditions that might cause similar symptoms such as fainting and determining if another cause of seizures is present such as alcohol withdrawal or electrolyte problems. This may be partly done by imaging the brain and performing blood tests. Epilepsy can often be confirmed with an electroencephalogram (EEG), but a normal test does not rule out the condition.

Epilepsy that occurs as a result of other issues may be preventable. Seizures are controllable with medication in about 70% of cases. Inexpensive options are often available. In those whose seizures do not respond to medication, then surgery, neurostimulation, or dietary changes may be considered. Not all cases of epilepsy are lifelong, and many people improve to the point that treatment is no longer needed.

As of 2013 about 22 million people have epilepsy. Nearly 80% of cases occur in the developing world. In 2013 it resulted in 116,000 deaths up from 112,000 deaths in 1990. Epilepsy is more common in older people. In the developed world, onset of new cases occurs most frequently in babies and the elderly. In the developing world onset is more common in older children and young adults, due to differences in the frequency of the underlying causes. About 5–10% of people will have an unprovoked seizure by the age of 80, and the chance of experiencing a second seizure is between 40 and 50%. In many areas of the world those with epilepsy either have restrictions placed on their ability to drive or are not permitted to drive until they are free of seizures for a specific length of time. The word epilepsy is from Ancient Greek: ἐπιλαμβάνειν "to seize, possess, or afflict".
-- Wikipedia
Legal Definition
Med. jur. A discase of the brain, which occurs in paroxysms, with uncertain intervals between them.

2. These paroxysms are characterized by the loss of sensation, and convulsive motions of the muscles. When long continued and violent, this disease is very apt to end in dementia. (q. v.) It gradually destroys the memory, and impairs the intellect, and is one of the causes of an unsound mind. 8 Ves. 87. Vide Dig. 50, 16, 123; Id. 21, 1, 4, 5.
-- Bouviers Law Dictionary
Legal Definition
In medical Jurisprudence. A disease of the brain, which occurs in paroxysms with uncertain intervals between them. The disease is generally organic, though it may be functional and symptomatic of irritation in other parts of the body. The attack is characterized by loss of consciousness, sudden failing down, distortion of the eyes and face, grinding or gnashing of the teeth, stertorous respiration, and more or less severe muscular spasms or convulsions.

Epilepsy, though a disease of the brain, is not to be regarded as a form of insanity, in the sense that a person thus afflicted can be said to be permanently insane, for there may be little or no mental aberration in the intervals between the attacks. But the paroxysm is frequently followed by a temporary insanity, varying in particular instances from slight alienation to the most violent mania. In the latter form the affection is known as "epileptic fury." But this generally passes off within a few days. But the course of the principal disease is generally one of deterioration, the brain being gradually more and more deranged in its functions in the intervals of attack, and the memory and intellectual powers in general becoming enfeebled, leading to a greatly impaired state of mental efficiency, or to dementia, or a condition bordering on imbecility. See Aurentz v. Anderson, 3 Pittsb. R. (Pail 310; Lawton v. Sun Mutual Ins. Co., 2 Cush. (Mass.) 517. See Hystero-epilepsy.
-- Black's Law Dictionary