What is Epilepsy?

Epilepsy defined, including seizure types.

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Epilepsy is a chronic (long-lasting) medical condition marked by recurrent epileptic seizures. An epileptic seizure is an event of an altered brain function caused by abnormal, or excessive, electrical discharges from brain cells.

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  • Epilepsy affects up to one percent of the population in the United States.
  • There are different types of seizures, different types of epilepsy syndromes, and different causes of epilepsy.
  • In general, medicines can control seizures in about 70 percent of epilepsy patients.
  • For patients with uncontrollable epilepsy, epilepsy surgery can provide a "cure" by eliminating the source of seizures and epilepsy.

Classifying the type of seizure is very important and will help your doctor plan the treatment you need.


Generalized epilepsy involves seizures produced by abnormal electrical activity throughout the brain. The seizures can result from a genetic predisposition in an otherwise healthy person or as a consequence of widespread disturbance of brain function. You may experience different types of generalized seizures or the type may vary from one seizure to another.

Typical Symptoms of Generalized Seizures
Generalized Seizures Typical Symptoms
"Grand Mal" or Generalized Tonic-Clonic Loss of consciousness, rigid muscles, whole-body convulsions; can cause a fall if you are standing
Absence Staring with brief loss of consciousness; fluttering eyelids
Myoclonic Sporadic or repeated, brief jerks of the limbs
Clonic Repetitive, rhythmic jerking movements of head or limbs
Tonic Loss of consciousness, stiffness and rigidity of the whole body; can cause a fall if you are standing
Atonic Loss of muscle tone in head or body; can cause a fall if you are standing

Partial or focal epilepsy involves seizures produced by electrical impulses that start in a relatively small region of the brain. The part of the brain generating the seizures is sometimes called the focus. In simple partial seizures, the patient retains awareness, whereas complex partial seizures cause the patient to lose awareness.

These seizures can vary in type in the same patient, or go from simple partial to complex partial, or even to generalized seizures. Partial seizures imply some localized brain disease caused by head injury, stroke, tumor, scar or developmental anomaly. The cause can sometimes be detected on imaging tests but, in many instances, it remains unknown. Rarely are partial seizures related to a genetic predisposition.

Partial (Focal) Seizures Typical Symptoms
Simple partial (no loss of awareness) Simple motor: Jerking, stiffening confined to one side of head or body
Simple sensory (auras): Unusual sensations affecting vision, hearing, smell, taste or touch, or memory or emotional disturbances; possibility of racing heart, hot and cold feelings
Complex partial (impaired awareness) Staring, unresponsiveness; automatisms such as lip smacking, chewing, fidgeting, and other repetitive, involuntary but coordinated movements
Partial with secondary generalization Milder seizure symptoms listed above lead to loss of consciousness and convulsions

Two other types of attacks can look very much like an epileptic seizure, but are not epileptic in nature because they do not involve abnormal electrical activity in the brain:

  • Non-epileptic seizures can involve loss of consciousness, abnormal movements, jerks and falls. They are usually related to psychological or emotional stress.
  • Convulsive syncope describes fainting from a cardiac or circulatory cause, accompanied by stiffening or jerks that can mimic epilepsy.

Generally, patients with seizures that start in a focal area of the brain, and whose seizures have not been controlled with medicine, are considered for surgery. This region might be small or might involve several lobes of the brain. Typically, a comprehensive pre-surgical evaluation begins with EEG-video monitoring and a high-resolution brain MRI before a patient is recommended for epilepsy surgery.

Learn More About Common Seizures

Some of the common types of seizures are described below.

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