What Causes Epilepsy?

There are many causes of epilepsy. Generally speaking, the causes of epilepsy can be classified into three broad categories:

  • Genetic: Inherited due to genetic predisposition, called “idiopathic” or “primary” epilepsy
  • Other: Acquired due to some form of brain injury or improper development, called “symptomatic” or “secondary” epilepsy
  • Cryptogenic: Acquired due to an unknown cause

Genetic Causes of Epilepsy

A mutation in a person’s genes can put him or her at risk of developing epilepsy. Often, these are the genes that control the excitability of nerve cells (neurons) in the brain. However, many people with genetic mutations may never develop epilepsy. Experts believe that, in many cases, genetic predisposition combined with environmental conditions lead to epilepsy. About 30 to 40 percent of epilepsy is caused by genetic predisposition. First-degree relatives of people with inherited epilepsy have a two- to four-fold increased risk for epilepsy. Although there is some increased risk, it is important to remember that the overall risk of epilepsy in other family members is still low.

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Other Causes of Epilepsy

  • Head trauma: Some people develop epilepsy after a car accident or other traumatic head injury.
  • Brain conditions: Brain conditions, such as vascular malformations, brain tumors, and strokes, can damage the brain. That brain damage can cause epilepsy. Damage from a stroke is the leading cause of epilepsy in adults over the age of 35.
  • Prenatal brain damage: Babies are very sensitive to brain damage while they are in their mother’s womb. Certain factors can lead to brain damage that can result in epilepsy or other conditions (like cerebral palsy). Some of these factors are oxygen deficiencies, poor nutrition, and infection in the mother.
  • Infectious diseases: Meningitis, viral encephalitis, and HIV/AIDs all have the potential to cause epilepsy.
  • Developmental disorders: Some people with developmental disorders, like autism or neurofibromatosis (NF), also have epilepsy.

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Cryptogenic Epilepsy

In about half of all cases of epilepsy, doctors are unable to pinpoint an exact, identifiable cause. When doctors don’t know the cause of epilepsy or can’t determine the cause with certainty, they consider it “cryptogenic” epilepsy. That means the cause is hidden.

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