As of Tuesday, March 19, 2013
DEAR DOCTOR K: I have a friend with epilepsy. Can you explain what happens in her brain?
DEAR READER: Epilepsy is a condition that causes repeated seizures, but sometimes seizures are not caused by epilepsy. It’s not uncommon, for example, for very young children to have seizures when they get a high fever. Called febrile seizures, they usually occur once or a few times and go away forever.
Seizures are caused by sudden, brief changes in the brain’s electrical activity. Our brains have hundreds of billions of cells. The ones that do the work — the ones that help us to think, remember, see, hear, smell, feel and cause us to move — talk to each other through electrical and chemical signals.
What happens in the brain when someone has a seizure is an electrical firestorm. Brain cells fire uncontrollably at up to four times their normal rate.
There are two main types of seizures. A generalized seizure involves the entire brain. A partial seizure affects only part of the brain — but it can turn into a generalized seizure.
The brain’s electrical activity can be seen on an electroencephalogram (EEG). Metal electrodes attached to the outside of the head detect the brain’s electrical activity and draw the patterns of that activity — patterns commonly called brain waves. (I’ve put an example of a normal EEG, along with what an EEG looks like during a generalized and partial seizure, on my website, AskDoctorK.com.)
Seizures temporarily affect the way a person behaves, moves, thinks or feels. The kind of seizure that you see most often — on TV or in movies — is a generalized, grand mal seizure. It’s very dramatic: A person loses consciousness, falls to the ground and temporarily stops breathing. All body muscles tense up at once for a few seconds; the head and shoulders bend backward. Then, just as suddenly, the arms and legs start jerking and sometimes the face starts twitching. After a few minutes, the person wakes up. However, he or she can be confused and “out of it” for several hours thereafter.
But seizures can be more subtle. A person may just stare blankly and blink their eyes. Nothing is getting through; you can’t reach them. Or a person may suddenly begin to do strange things, such as emptying the contents of a dresser drawer onto the floor. Or a person may suddenly have uncontrollable jerking of one side of the face, an arm or a leg, along with a brief loss of awareness of the world. After a seizure, a person has no memory of the episode.
For most people, seizures can be controlled with medication. If you are with your friend when she has a seizure, call the doctor. A seizure that lasts more than 20 minutes is a medical emergency.
What causes seizures in the first place? We know, for example, that brain scars, tumors or infections can cause seizures. But how they cause the electrical firestorm remains uncertain.
Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.