[L. epilepsia fr. Gr. epilēpsia, (epileptic) seizure]
A disease marked by recurrent seizures, i.e., by repeated abnormal electrical discharges within the brain. Epilepsy is found in about 2% or 3% of the population. Its incidence is highest in children under 10 and in older adults (over 70); adolescents and adults are affected less frequently.
The International League Against Epilepsy categorizes epilepsy as partial, generalized, drug-resistant, or unclassified. Partial seizures typically begin with focal or local discharges in one part of the brain (and body); sometimes they may become generalized. When a patient remains awake during a seizure, the seizure is said to be simple and partial. If loss of consciousness occurs after a focal seizure, the seizure is said to be partial and complex. Drug-resistant epilepsy is a failure to control seizures despite adequate trials of two appropriately chosen and administered antiepileptic drugs.
Patients who suffer recurrent episodes of alcohol withdrawal or frequent severe hypoglycemia, hypercalcemia, or similar metabolic illnesses may have repetitive seizures but are not considered to have epilepsy if the seizures stop after their underlying illnesses are treated.
Epilepsy may result from congenital or acquired brain disease. Infants born with lipid storage diseases, tuberous sclerosis, or cortical dysplasia may have recurrent seizures, as may children born with intracranial hemorrhage or anoxic brain injury. Adults may develop epilepsy as a result of strokes, tumors, abscesses, brain trauma, encephalitis, meningitis, or uremia. In many instances the underlying cause is undetermined.
SYMPTOMS AND SIGNS
Symptoms may vary from almost imperceptible alteration in consciousness, as in absence seizures, to dramatic loss of consciousness, tonic-clonic convulsions of all extremities, urinary and fecal incontinence, and amnesia for the event. Some attacks are preceded by an aura, whereas others provide no warning. Other forms are limited to muscular contractions of a localized area or only one side of the body.
SEE: postictal confusion
The diagnosis of epilepsy is made by a careful assessment of the patient's history, augmented by diagnostic studies. Typically, these include blood tests to assess for metabolic disarray, brain imaging by magnetic resonance imaging (MRI) or computed tomography (CT), and electroencephalography. The differential diagnosis of epilepsy includes many other illnesses marked by episodes of loss of consciousness, including pseudoseizures, syncope, transient ischemic attacks, orthostatic hypotension, and narcolepsy.
Therapy is available for the prevention and control of recurrent seizures. Antiepileptic agents include phenytoin or carbamazepine for partial seizures, valproic acid for absence seizures, and any of these agents or phenobarbital, with or without newer drugs, e.g., gabapentin or lamotrigine, for generalized seizures. All these agents may have significant side effects, and many of them have a range of drug-drug interactions.
Surgical therapy to remove an epileptic focus within the brain is used occasionally to manage seizures that have been difficult to control medically. In specialized neurosurgical centers, this may cure or reduce the impact of epilepsy in about 75% of patients.
IMPACT ON HEALTH
Most people with epilepsy do well with standard medical management, but epilepsy increases the risk of death by a factor of 2 or 3 compared to people without recurrent seizures.
SYN: SEE: seizure disorder
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