Epilepsy Health Article

Definition

Epilepsy is a chronic (persistent) disorder of the nervous system. The primary symptoms of this disease are periodic or recurring seizures that are triggered by sudden episodes of abnormal electrical activity in the brain. The term "seizure" refers to any unusual body functions or activities that are under the control of the nervous system.

Description

The word epilepsy is derived from the Greek term for seizure. Seizures can involve a combination of sensations, muscle contractions, and other abnormal body functions. Seizures may appear spontaneously—without any apparent cause—or can be triggered by a specific type of stimulus such as a flashing light. Specific cases of epilepsy may result from known causes, such as brain injury, or may have no apparent cause (referred to as ideopathic epilepsy). Ideopathic epilepsy may be initiated by a combination of genetic and environmental factors.

An epileptic seizure involves a transient (temporary) episode of abnormal electrical activity in the brain. During a seizure, many nerve cells within a specific region of the brain may begin to fire at the same time. This activity may then spread out over other parts of the brain. In addition to abnormal physical symptoms, seizures can bring on emotions ranging from fear, anger, and rage, to joy or happiness. During a seizure, patients may experience disorientation, spontaneous sensations of sounds, smells, visions, and distorted visual perception—such as misshapen objects and places.

Epilepsy can be caused by some event or condition that results in damage to the brain such as strokes, tumors, abscesses, trauma (physical injury), or infections such as meningitis. Epilepsy can also be triggered by inherited (genetic) factors or some form of injury or trauma at birth. Epilepsy cases that seem to have no readily identifiable cause are referred to as "idiopathic" cases in medical terminology. Symptoms of this disease can appear at any age. Seizures can damage and destroy brain cells and scar tissue can develop in the section of brain tissue where seizures originate.

There are many forms of epileptic seizures. The parts of the body that are affected by a seizure and the distinctive characteristics, duration and severity of the symptoms can distinguish each type of epilepsy. Patients can experience more than one type of seizure. The nature of the symptoms depends on where in the brain the seizure originated and how much of the brain is involved. Seizures can be classified as either "generalized" or "partial." Partial seizures involve abnormal activity in a specific region of the brain.

Generalized (also called tonic-clonic) seizures last about two minutes and are the result of abnormal electrical activity that spreads out over both sides or hemispheres of the brain. They were formerly referred to as grand mal seizures. The patient will usually lose consciousness and fall during the episode. The term "tonic" refers to the first phase of a generalized seizure in which the body muscles become taunt or stiff. This is followed by strong, rhythmic muscular contractions (convulsions) of the "clonic" phase. Sometimes a patient's breathing may be hampered by a brief stoppage of the respiratory muscles, causing the skin to develop a bluish tinge due to lack of oxygen.

Epileptic seizures can also be classified as "complex" or "simple." Complex seizures generally involve a loss of consciousness, whereas simple seizures do not. Simple partial seizures can begin as a localized (focal) seizure and then evolve into a secondary generalized episode in which the initial abnormal electrical activity spreads to involve other parts of the brain. Patients may actually remember the physical and psychological events that occur during a simple seizure, such as the types of movement, emotions, and sensations, but frequently are completely unaware of the event. Partial seizures are more common in adults.

An absence seizure (once called petit mal) typically results in brief periods of "lack of awareness" and some abnormal muscle movement. The patient generally remains conscious during the seizure episode, but may become absent-minded and unresponsive. They may also appear to be starring. Absence seizures last about 5–10 seconds.

How seizures affect a person's memory depends where in the brain seizures occur. Seizures can interfere with learning, storage, and retrieval of new information. For example, a form of epilepsy that produces seizures in the temporal lobe of the brain can cause a serious deterioration (loss) of memory function. Early treatment can help prevent or reduce memory loss.

In some forms of epilepsy, seizures can be triggered by a particular mental—or cognitive—activity. For example, the simple activity of reading aloud can trigger a seizure in patients with reading epilepsy. Symptoms include face muscle spasms. In medical terms, this type of epilepsy is referred to as idiopathic localization-related epilepsy. This means that seizures occur in one part of the brain (in this case, the temporal lobes) and that there is no apparent cause that brought on the disease.