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The Columbia Electronic Encyclopedia™.
New York: Columbia University Press,
Full Text: The Columbia Electronic Encyclopedia COPYRIGHT 2008 Columbia
University Press. Licensed from Columbia University Press. All rights reserved.
Full Text:
epilepsy, a chronic disorder of cerebral function characterized by periodic convulsive
seizures. There are many conditions that have epileptic seizures. Sudden discharge of
excess electrical activity, which can be either generalized (involving many areas of cells
in the brain) or focal, also known as partial (involving one area of cells in the brain),
initiates the epileptic seizure. Generalized seizures are classified as tonic-clonic (grand
mal), in which there is loss of consciousness and involuntary contraction of all the
muscles of the body, lasting a few minutes; or absence (petit mal), in which there is
clouding of the consciousness for about 1 to 30 sec and no falling, with as many as 100
attacks occurring daily. Partial seizures include Jacksonian epilepsy, characterized by
jerking in the hand and face on the side opposite the brain activity; and psychomotor
seizures, in which there may be localized convulsion with no loss of consciousness, as
well as incoherent speech and various involuntary movements of the body. Often these
are accompanied by a warning cluster of signs and symptoms called an aura. First aid,
such as cushioning the head, is used to prevent the person from self-inflicted injuries
during seizures.
The cause is unknown in over half the cases of epilepsy, especially in those with onset
under age 20. Predisposing factors in other cases include familial history, head injury,
alcohol withdrawal, infections (such as meningitis or by pork tapeworm larvae), and
abnormalities (such as tumors) of the brain.
The recording of brain waves by electroencephalography is an important diagnostic test
for epilepsy. Other diagnostic technologies include CAT scan and magnetic resonance
imaging (MRI). Standard treatment of epilepsy is with antiseizure drugs (also known as
anti-epileptic and anticonvulsive drugs), including carbamazepine, phenytoin, valproic
acid, and others; proper treatment requires a careful analysis of seizure motor activity,
anatomical cause, precipitating factors, age of onset of the disorder, severity, daily
rhythms, and prognosis. Roughly 70% of persons with epilepsy are successfully treated
with drugs, and many people with the disease lead normal lives. Repeated seizures that
lead to unconsciousness, however, appear to be associated with damage to the
hippocampus in the brain and sudden unexpected death.
Some cases of childhood epilepsy (which is often eventually outgrown) have been
successfully treated with surgery or a very high-fat "ketogenic" diet. The diet results in a
natural buildup of ketones in the body, which appear to inhibit the seizures. A number of
different surgical procedures may be used if medication does not control the seizures;
the procedures vary according to the focus of the seizure in the brain, and surgery is not
always appropriate. If a patient with uncontrolled seizures is not a good surgical
candidate, a vagus nerve stimulator or a responsive neurostimulator may be implanted
in some cases. The former is implanted in the chest and connected by a wire to the
vagus nerve (a cranial nerve) in the neck; like a pacemaker, the device regularly
stimulates the nerve to counteract seizures. It also may be activated by the patient in
response to a seizure. The responsive neurostimulator is implanted in the skull, and
wires connect it to brain regions that are the focus of seizures. In reaction to developing
seizure, it electrically stimulates those regions in an effort to stop the seizure. Patients
with such devices take antiseizure medications as well, and these devices typically
reduce but do not eliminate seizures.
See H. Reisner, ed. ​Children with Epilepsy (1988); R. J. Gunnit, ​Living Well with
Epilepsy (1990); O. Devinsky, ​A Guide to Understanding and Living with Epilepsy
(1994); publications of the Epilepsy Foundation of America.
Source Citation​ (MLA 8​th​ Edition)
"epilepsy." ​The Columbia Electronic Encyclopedia™, Columbia University Press,
2016. ​Research in Context,
9026265&it=r&asid=581f354b95f3dce3a744036f7f2512a2. Accessed 5 Dec. 2016.
Gale Document Number: ​ GALE|A69026265