Neurology &
Neurological Sciences

Stanford Epilepsy Center

Understanding Epilepsy Videos
Robert S. Fisher, M.D., Ph.D.
Maslah Saul MD Professor of Neurology, Stanford

Video List:

Understanding Seizures
The word "seizure" is a general term used to describe the medical condition in which too many brain cells become excited simultaneously.

There are so many kinds of seizures that neurologist are still updating how to classify them. Usually, they classify seizures into two main types: partial seizures and primarily generalized seizures. The difference between these types is in how they begin. Primarily generalized seizures begin with a widespread electrical discharges that involve both sides of the brain at once. On the other hand, partial seizures begin with electrical seizures in one limited area of the brain. All generalized seizures begin with synchronous electrical activity throughout the brain, accompanied by sudden generalized movements or loss of consciousness. However, there are still many different types of generalized seizures.

A tonic-clonic seizure, once called grand mal, is what most people think of when they hear the word "seizure". When someone experiences a tonic-clonic seizure, first they stiffen and lose consciousness, which is the tonic phase. Then they begin jerking and this lasts for several minutes, called the clonic phase. Sometimes, seizures don't have a tonic stiffening and a clonic jerking sequence, but are just tonic seizures or clonic seizures. Other types of generalized seizures include absence seizures, when the sufferer disconnects from the world for a few seconds, and myoclonic seizures which cause jerking, but just for a second or two.

Partial seizures, which began in a single part of the brain, are further described by two important additional criteria. The first is whether awareness, memory and consciousness are preserved during the seizure. If they all are preserved, then the seizure is called simple partial. However, if any are impaired, then the seizure is called complex partial.

The impact of a partial seizure depends on where in the brain it originates and how it spreads. Partial seizures sometimes have an aura, which is a warning that bigger seizures may follow. An aura usually occurs seconds to minutes before a seizure. But some patients can have periods of warning lasting a day or longer. There are many different ways in which people experience an aura. The start of a seizure in one of the temporal lobes can produce unusual feelings, abnormal sensations, or forced thinking. The onset of a complex partial seizure may be heralded by déjà vu, a familiar feeling, or jaimais vu, an unfamiliar feeling. Some patients have auras of sounds, tastes, distorted vision, racing thoughts or smells, like burning rubber.

Physical sensations that can occur as auras include dizziness, headache, lightheadedness and numbness. An upset stomach is a particularly common physical symptom. Auras can include a sense of tingling rising up the body or other strange feelings that are difficult to describe. Distorted emotions, like fear or panic, can also be a seizure warning; however, some complex partial seizures occur without any remembered warning.

Understanding the different types of seizures can be helpful, but many people want more detailed information. The next two videos in this series provide an in-depth look on the effect of partial seizures on different parts of the brain and the different types of generalized seizures.

If you or anyone you know may have seizures, please make sure that they see a physician.

Epilepsy videos made in partnership with and the Epilepsy Therapy Project.

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