Epilepsy - Causes
The brain contains a mass of neurons (nerve cells) that constantly communicate with each other. They communicate in two ways: by sending certain chemicals back and forth, and by the passage of electric currents among them. Under certain conditions, those electric currents can be disrupted. Instead of traveling smoothly between neurons, they go out of control.
When this happens, messages traveling through the brain are wildly disrupted. The brain begins to send out irregular and unpredictable messages to the rest of the body. Muscles throughout the body begin to contract and relax in random patterns. These changes bring about the symptoms of epilepsy.
- Aura:
- A set of warning signals that an epileptic attack is about to begin.
- Clonic phase:
- The stage of a grand mal attack in which muscles alternately contract and relax.
- Electroencephalogram (EEG):
- A test used to measure electrical activity of the brain to see if the brain is functioning normally.
- Grand mal:
- An alternative term used for tonic-clonic epilepsy.
- Idiopathic epilepsy:
- A form of epilepsy for which no cause is known.
- Neuron:
- A nerve cell.
- Petit mal:
- An alternative term used for absence epilepsy.
- Seizure:
- A convulsion; a series of involuntary muscular movements that alternate between contractions and relaxations.
- Symptomatic epilepsy:
- A form of epilepsy for which some specific cause is known.
- Tonic phase:
- The stage of a grand mal attack in which muscles become rigid and fixed.
Epilepsy is usually classified as symptomatic or idiopathic (pronounced ih-dee-uh-PA-thik). Symptomatic epilepsy is a form of the condition for which a cause is known. For example, a person may receive a blow to the head. The injury may cause damage that leads to the development of epilepsy. Some conditions that can cause symptomatic epilepsy include:
- Serious infections of the central nervous system
- Heat stroke (see heat disorders entry)
- An abscess (open sore) in the brain
- Rabies, tetanus, and malaria (see entries)
- Toxic (poisonous) materials, such as lead or alcohol
- Damage to the brain or skull (see head injury entry)
- Drug allergy
- Stroke (see stroke entry)
Idiopathic epilepsy is epilepsy for which no specific cause has been identified. Some authorities believe that idiopathic epilepsy is caused by damage to a newborn baby's brain during delivery.
About 75 percent of all cases of epilepsy are idiopathic. Individuals with this condition usually experience their first seizure between the ages of two and fourteen. Symptomatic epilepsy usually does not appear until later in life, after the age of twenty-five.
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