Epilepsy - Introduction

Introduction

Epilepsy is a brain disorder involving repeated, spontaneous seizures of any type. There are different types of epilepsy but what they all share are recurrent seizures caused by an uncontrolled electrical discharge from nerve cells in the cerebral cortex. This part of the brain controls higher mental functions, general movement, the functions of the internal organs in the abdominal cavity, perception, and behavioral reactions.

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Seizures

Seizures are a symptom of epilepsy. Seizures ("fits," convulsions) are episodes of disturbed brain function that cause changes in neuromuscular function, attention, or behavior. They are caused by abnormally excited electrical signals in the brain.

A single seizure may be related to a specific medical problem (such as brain tumor or withdrawal from alcohol). If repeated seizures do not recur after this underlying problem has been corrected, the person does not have epilepsy.

A single, first seizure that cannot be explained by a temporary medical problem has about a 25% chance of returning. After a second seizure occurs, there is about a 70% chance of future seizures and the diagnosis of epilepsy.

Types of Epilepsy

Epilepsy is generally classified into two main categories based on seizure type:

• Partial (also called focal or localized) seizures. These seizures are more common than generalized seizures and occur in one or more specific locations in the brain. In some cases, partial seizures can spread to wide regions of the brain. They are likely to develop from specific injuries, but in most cases the exact origins are unknown (idiopathic).
• Generalized seizures. These seizures typically occur in both sides of the brain. Many forms of these seizures are genetically based. There is usually normal neurologic function between episodes.