Epilepsy

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Overview, Causes, & Risk Factors

Epilepsy is a disorder involving repeated seizures of any type. Seizures ("fits") are episodes of disturbed brain function that cause changes in attention and/or behavior. They are caused by abnormal electrical excitation in the brain.

Sometimes, seizures are related to a temporary condition, such as exposure to drugs, withdrawal from certain drugs, or abnormal levels of sodium or glucose in the blood. In such cases, repeated seizures may not recur once the underlying problem is corrected.

In other cases, injury to the brain (e.g., stroke or head injury) causes brain tissue to be abnormally excitable. In some people, an inherited abnormality affects nerve cells in the brain, which leads to seizures. In some cases, no cause at all can be identified.

Some of the more common causes of seizures include:

• Idiopathic (no identifiable cause)
  • usually begin between ages 5 to 20
  • can occur at any age
  • no other neurologic abnormalities present
  • often a family history of epilepsy or seizures
• Developmental or genetic conditions present at birth, or injuries near birth -- in this case, the seizures usually begin in infancy or early childhood
• Metabolic abnormalities
  • may affect people of any age
  • diabetes mellitus complications
  • electrolyte imbalances
  • kidney failure, uremia (toxic accumulation of wastes)
  • nutritional deficiencies
  • phenylketonuria (PKU) -- can rarely cause seizures in infants
  • other metabolic diseases, such as inborn error of metabolism
  • use of cocaine, amphetamines, alcohol or certain other recreational drugs
  • withdrawal from alcohol
  • withdrawal from drugs, particularly barbiturates and benzodiazepines
• Brain injury
  • may affect any age, highest incidence in young adults
  • most likely to occur if the brain membranes are damaged
  • seizures usually begin within 2 years after the injury
  • early seizures (within 2 weeks of injury) -- do not necessarily indicate that chronic seizures (epilepsy) will develop
• Tumors and brain lesions that occupy space (such as hematomas)
  • may affect any age, more common after age 30
  • partial (focal) seizures most common initially
  • may progress to generalized tonic-clonic seizures
• Disorders affecting the blood vessels (such as stroke and TIA)
  • most common cause of seizures after age 60
• Degenerative disorders (senile dementia Alzheimer type, or similar organic brain syndromes)
  • mostly affect older people
• Infections
  • may affect people of all ages
  • may be a reversible cause of seizures
  • brain infections like meningitis and encephalitis can produce seizures
  • brain abscess
  • acute severe infections of any part of the body
  • chronic infections (such as neurosyphilis)
  • complications of AIDS or other immune disorders

Seizure disorders affect about 0.5% of the population. Approximately 1.5 to 5.0% of the population may have a seizure in their lifetime. Epilepsy can affect people of any age.

Risk factors include a family history of epilepsy, head injury, or other condition that causes damage to the brain.

The following factors may present a risk for worsening of seizures in a person with a previously well-controlled seizure disorder:

• Pregnancy
• Lack of sleep
• Skipping doses of epilepsy medications
• Use of alcohol or other recreational drugs
• Certain prescribed medications
• Illness