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 - Northwestern Memorial Hospital - Chicago

Causes & Symptoms


In many generalized epilepsies, the brain looks completely normal and has no structural abnormality to explain the seizure. This type of epilepsy is thought to be caused by a genetic (inherited) predisposition. In some cases, generalized epilepsies are associated with often universal brain abnormalities. These brain abnormalities are sometimes caused by:

  • Brain infections
  • Head injuries
  • Lack of oxygen

Focal epilepsies start from a localized area in the brain, and they are often caused by a lesion (or scar) detectable on the MRI scan. Typical lesions that cause focal epilepsy are:

  • Hippocampal sclerosis (hardening of the hippocampus)
  • Scarring after stroke or trauma
  • Small area of disorganized brain tissue
  • Benign brain tumor
  • Malformed blood vessel

The importance of having a witness during seizures

As the epileptic activity spreads in the brain, patients often lose consciousness and have to rely on witnesses to tell them what happened. Witnesses may describe different symptoms such as a blank stare, fumbling, head turns, limb stiffening and jerking, falls and whole body convulsions. Witnesses play an important role during diagnosis by reporting what symptoms the person exhibited while unconscious. These reports may help pinpoint the area of the brain where the seizure originated.


It is a misconception that a seizure consists of only loss of consciousness and shaking of extremities. Symptoms of seizures vary, depending on the areas of the brain activated by the epileptic activity.

If the entire brain or a large part of the brain is involved in the abnormal brain wave activity from the beginning of the seizure, many patients experience a loss of awareness without any warning. Often times, they can only report the aftermath of the seizures such as a brief time gap, confusion, tongue bite or a fall.

If the seizure starts from a small area of the brain, a person may experience a warning or “aura” at the beginning of the seizure. This aura indicates which area of the brain is involved first by the abnormal electrical activity. Symptoms that may be recalled prior to a seizure include:

  • Numbness
  • Change in vision or hearing
  • Strange smell
  • Rising sensation in the stomach
  • Sudden fear
  • Strange feeling of familiarity
  • Involuntary movements


Last UpdateFebruary 8, 2011


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