Epilepsy
In this condition factsheet:
The Facts on Epilepsy
The name epilepsy comes from the Greek for "to be seized." Sudden, spontaneous seizure is the hallmark of this illness. It may involve falling to the ground and twitching spasmodically, but not always.
As the brain goes about its daily functions, millions of electrical and chemical signals pass from its nerve cells out to the body. These electrochemical messages are necessary for almost everything we do and feel.
Seizures are a sudden and abnormally high discharge of electrical activity among large numbers of nerve cells in the brain. This can result in involuntary and unusually large signals being sent to the muscles.
Epilepsy is one of the most common disorders of the central nervous system, affecting approximately 300,000 people in Canada. About a quarter of people with epilepsy in Canada will be diagnosed before the age of 10, and another third by the age of 19. The diagnosis of epilepsy is only made if there have been at least 2 episodes of unprovoked seizures on different days, or 1 episode of unprovoked seizure with a high chance of having another in the next 10 years. Having an "unprovoked" seizure means that there is no apparent trigger.
Causes of Epilepsy
Epilepsy that first appears in adulthood is often due to some localized damage such as poor blood flow to the brain (including from a stroke), a brain tumour, or a previous head injury. Epilepsy in children can sometimes be brought on by meningitis during infancy or by abnormalities of brain development, but it is often inherited.
We know epilepsy can be passed on genetically, but we don't really understand what's different in the brain of a person with an inherited form of epilepsy. We also don't fully understand what happens to the brain during a seizure. Many people find that particular events tend to trigger seizures. These include:
- cocaine and some other drugs
- alcohol withdrawal
- exposure to flashing or strobe lights
- fever
- hormonal changes
- hyperventilation
- insufficient sleep
- intense exercise
- loud music
- skipping meals or poor nutrition
- starting or abruptly stopping some medications
- strong emotions
Catamenial epilepsy refers to seizures that are timed to the menstrual cycle. These seizures occur most during ovulation or just before menstruation. Seizures are apparently provoked by estrogen and prevented by progesterone. This explains why seizures begin around puberty for some people who menstruate, when estrogen dominates, and may improve after menopause.
Symptoms and Complications of Epilepsy
Before a seizure, many people experience a warning sign called an aura, which may involve a particular smell, feeling, or visual effect. Most seizures will last no more than 1 to 2 minutes. After a seizure, a person may be confused, tired, or sleepy, may experience muscle aches or soreness, and may not remember what happened.
Many people believe that someone having an epileptic seizure is in danger of swallowing their tongue and choking. In reality, this almost never happens. If you try to prop the mouth open of someone who is experiencing a seizure, you can damage their teeth (or lose a finger). If the person is standing, you should usually do nothing; if they are unconscious, roll them on their side with something soft under their head and loosen the top button of their shirt.
An exception is in status epilepticus, when a seizure either keeps going for more than 5 minutes or recurs many times in a short period. It may be provoked after abruptly stopping antiseizure medication. You should call an ambulance if this happens.
Different types of seizures
Epileptic seizures are classified according to their particular characteristics. Classification takes into account where the seizure starts, the person's awareness, and other features of the seizure.
The seizure may be classified based on where it begins in the brain. For example, focal seizures start in one specific area, while generalized seizures can start on both sides of the brain.
The person's awareness during the seizure can also be used to describe and classify the seizure. People may be aware, meaning they don't lose consciousness or have impaired awareness. Other features used to classified seizures include the presence of movements during the seizure.
Epilepsy has a number of sexual and reproductive complications that we don't fully understand. Many epileptic people suffer from erectile dysfunction, dry vagina, painful contractions during sex, or low libido.
About 5% of babies born to people with epilepsy have a birth defect. This compares to about a 2% to 3% chance in the rest of the population. It's known that antiepileptic medications are responsible for at least some of the extra birth defects. The defects can be minor or corrected by surgery (malformed fingers, cleft lip, or palate), but occasionally more serious problems such as spina bifida can occur.
