A person is diagnosed with epilepsy if they have had at least two seizures that were not caused by some known and reversible medical condition like alcohol withdrawal or extremely low blood sugar. The seizures in epilepsy may be related to a brain injury or a family tendency, but often the cause is completely unknown. The word "epilepsy" does not indicate anything about the cause of the person's seizures or their severity.
What happens in the brain during a seizure?
- The electrical activity is caused by complex chemical changes that occur in nerve cells.
- Brain cells either excite or inhibit (stop) other brain cells from sending messages. Usually there is a balance of cells that excite and those that can stop these messages. However, when a seizure occurs, there may be too much or too little activity, causing an imbalance between exciting and stopping activity. The chemical changes can lead to surges of electrical activity that cause seizures.
- Seizures are not a disease in themselves. Instead, they are a symptom of many different disorders that can affect the brain. Some seizures can hardly be noticed, while others are totally disabling.
If I have just one or two seizures does that mean I will get epilepsy?
- About half of the people who have one seizure without a clear cause will have another one, usually within 6 months.
- If there is a known cause for your seizure (for example, brain injury or other type of known brain condition), then you are twice as likely to have another seizure.
- If you have two seizures, there's about an 80% chance that you'll have more.
- If your first seizure occurred at the time of an injury or infection in the brain, then you are more likely to develop epilepsy. Often, more seizures don’t occur until weeks or months after the initial injury or infection.
- More seizures are also likely if your doctor finds abnormalities on a neurological examination (tests that are done in a doctor’s office to see how the nervous system is working).
- An EEG test or electroencephalogram (e-LEK-tro_en_SEF-uh_LOG-ram) can look at the electrical activity of the brain and may help predict whether more seizures will occur. Certain patterns on the EEG are typical of epilepsy. If your brain waves show patterns of that type, you are about twice as likely to develop epilepsy.