I recently had a seizure for the first time, what are the chances I will have another one?

DEAR DOCTOR K:

I’m in my mid-30s, and I recently had a seizure for the first time. My doctor recommended anti-epilepsy drugs. Do I really need them? What are the chances I will have another seizure?

DEAR READER:

A seizure is a sudden change in the brain’s normal electrical activity. During a seizure, brain cells “fire” uncontrollably. There are different types of seizures. Some cause a person to lose consciousness and fall to the ground, twitching or jerking. Then it stops, and a person slowly returns to normal consciousness.

Other seizures cause a person to look like he or she is conscious, except that they often are not “taking in” what is happening in the world around them. Or they may behave strangely, stare blankly or blink rapidly. This may last a few minutes, but then people are “with it” again.

About one out of every 10 people will have at least one seizure during their life. Most of these seizures, however, occur during early childhood. When a first seizure happens in adulthood, it’s always cause for concern, and for medical evaluation. You’re probably asking yourself three questions: What caused it? Will it happen again? How can I prevent it?

We know some of the things that cause seizures, and they range from relatively non-serious to very serious. In children, seizures often occur along with high fevers. We used to think that the fevers might be irritating the brain and causing the seizures. In recent years, it’s become clear that infections (particularly a virus I study called human herpesvirus-6) can cause both high fevers and seizures together.

Becoming addicted to some medicines, and alcohol, can cause seizures when a person stops using the substance. For example, people who drink a lot will sometimes have a seizure when they are “drying out” the next morning.

Sometimes, unfortunately, a seizure is the first sign of a brain tumor. This happened to the senior senator from my state of Massachusetts, Edward Kennedy.

Recurrent seizures are caused by epilepsy, a condition that may be the result of past brain injuries: head trauma, brain infections and strokes. Epilepsy also may not have an apparent cause.

Will you have another seizure? It’s impossible to know for sure. Doctors do have guidelines to help them estimate the risk of repeat seizures. The risk estimate is based on a series of tests patients should have after a first seizure:

  • A brain wave test called an electroencephalogram (EEG);
  • An MRI or CT scan to get a picture of the brain;
  • Blood tests.

Your chances of having another seizure after an unprovoked seizure are highest if:

  • You have had a previous stroke or brain injury;
  • Your EEG reveals that you have a seizure disorder;
  • You had the seizure while asleep.

If you fall into any of these categories, you would likely start an anti-convulsant drug right away. Deciding whether or not to take anti-epileptic medication after a first seizure is not straightforward. The best strategy is to work together with your doctor to make the choice that feels right for you — based on an accurate estimate of your future risk.