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Epilepsy Health Center

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Understanding Seizures -- the Basics

What Are Seizures?

A seizure occurs when there’s abnormal electrical activity in the brain. Seizures may go virtually unnoticed. Or, in severe cases, they may produce a change or loss of consciousness and involuntary muscle spasms called convulsions. Seizures usually come on suddenly and vary in duration and severity. A seizure may be a one-time event, or you may have seizures repeatedly. Recurrent seizures are called epilepsy, or a seizure disorder. Less than one in 10 people who has a seizure develops epilepsy.

Experts classify seizures into two general categories and many subtypes based on the pattern of the attack.

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Lennox-Gastaut Syndrome

Lennox-Gastaut syndrome (LGS) is a rare and severe kind of epilepsy that starts in childhood. Children with LGS have seizures often, and they have several different kinds of seizures. This condition is hard to treat, but researchers are looking for new therapies. Finding practical and emotional support is key to help you give your child the best quality of life while facing the challenges and stress this illness brings. The seizures usually start between ages 2 and 6. Children with LGS have learning...

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Generalized seizures involve both sides of the brain from the start of the attack. Common subtypes include tonic-clonic (grand mal) and absence seizures (petit mal). Febrile and infantile spasms are two types of generalized seizures that occur almost exclusively in young children.

Partial (or focal) seizures are the second major seizure type. These begin in a specific area of the brain and may be contained there. Or they may spread to the entire brain.

  • With simple partial seizures, the person remains conscious.
  • Complex partial seizures involve impaired consciousness.

What Causes Seizures?

Often the cause of a seizure is unknown. Many conditions can provoke seizures, including:

WebMD Medical Reference

Reviewed by Richard Senelick, MD on March 01, 2015

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