This article is about epilepsy in humans. For information on epilepsy in other animals, see Epilepsy in animals. more...
Epilepsy (often referred to as a seizure disorder) is a chronic neurological condition characterized by recurrent unprovoked seizures. The condition is named from the Greek epilepsis ("to take a firm grip on"). It is commonly controlled with medication, although surgical methods are used as well.
The diagnosis of epilepsy requires the presence of recurrent, unprovoked seizures; accordingly, it is usually made based on the medical history. EEG, brain MRI, SPECT, PET, and magnetoencephalography may be useful to discover an etiology for the epilepsy, discover the affected brain region, or classify the epileptic syndrome, but these studies are not useful in making the initial diagnosis.
Long-term video-EEG monitoring for epilepsy is the gold standard for diagnosis, but it is not routinely employed owing to its high cost and inconvenience. It is, however, sometimes used to distinguish psychogenic non-epileptic seizures from epilepsy.
Convulsive or other seizure-like activity, non-epileptic in origin, can be observed in many other medical conditions, including:
- psychogenic non-epileptic seizures (often wrongly called "pseudoseizures")
- syncope (fainting)
- breath-holding spells of childhood
- non-epileptic myoclonus
- hypoglycemia and associated neuroglycopenia
- paroxysmal kinesiogenic dyskinesia
- infantile gratification / masturbation (onanism)
- repetitive behaviors
Neurologists are often called upon to distinguish among the above diagnoses and epilepsy.
Epilepsies are classified five ways:
- By their first cause (or etiology).
- By the observable manifestations of the seizures, known as "semiology."
- By the location in the brain where the seizures originate.
- As a part of discrete, identifiable medical syndromes.
- By the event that triggers the seizures, as in primary reading epilepsy.
All the causes (or etiologies) of epilepsy are not known, but many predisposing factors have been identified, including brain damage resulting from malformations of brain development, head trauma, neurosurgical operations, other penetrating wounds of the brain, brain tumor, high fever, bacterial or viral encephalitis, stroke, intoxication, or acute or inborn disturbances of metabolism. Hereditary or genetic factors also play a role.
Seizures may occur in any person under certain circumstances, including acute illness and drug overdoses, but these provoked seizures are not part of the definition of epilepsy. Epilepsy connotes that an individual has unprovoked seizures which recur over time. In about 50% of all cases, there is no cause for epilepsy that is currently detectable even with state of the art investigations. In about 50% of cases, evidence of a brain injury, scar or malformation is found, to which the epilepsy is attributed. In many, but not all cases, abnormal electrical activity can be detected in the brain with an electroencephalogram (EEG), either during or in between seizures.
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