Epilepsy

Definition

Epilepsy is a brain disorder involving repeated seizures of any type.

Alternative Names

Causes

Seizures ("fits") are episodes of disturbed brain function that cause changes in attention or behavior. They are caused by abnormal excited electrical signals 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 (for example, 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.

Some seizures are idiopathic, which means the cause can not be identified. Such seizures usually begin between ages 5 and 20, but they can occur at any age. People with this condition have no other neurological problems, but often have a family history of seizures or epilepsy.

Disorders affecting the blood vessels, such as stroke and TIA, are the most common cause of seizures after age 60. Degenerative disorders such as senile dementia Alzheimer type can also lead to seizures.

Some of the more common causes of seizures include:

• Developmental problems, genetic conditions present at birth, or injuries near birth (seizures usually begin in infancy or early childhood)
• Metabolic abnormalities may affect people of any age and may be a result of
  • Diabetes complications
  • Electrolyte imbalances
  • Kidney failure, uremia (toxic accumulation of wastes)
  • Nutritional deficiencies
  • Phenylketonuria (PKU) -- can 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
  • Most common in young adults
  • Seizures usually begin within 2 years after the injury
  • Early seizures (within 2 weeks of injury) do not necessarily mean that chronic (ongoing) seizures (epilepsy) will develop
• Tumors and brain lesions (such as hematomas)
  • May affect any age but are more common after age 30
  • Partial (focal) seizures most common to start with
  • May lead to generalized tonic-clonic seizures
• 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 1.5-5.0% 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