Types of Seizures
More than 30 different seizure types have been identified. Most of these fall into two major categories: focal (or partial) seizures and generalized seizures. Focal seizures occur in just one part of the brain. Generalized seizures are characterized by abnormal neuronal activity on both sides of the brain. However, not every seizure falls into one of these types.
An Introduction to the Types of Seizures
Doctors have described more than 30 different seizure types. Seizures are divided into two major categories -- focal seizures and generalized seizures; however, there are many different variations in each of these categories.
Focal seizures, also called partial seizures, occur in just one part of the brain. About 60 percent of people with epilepsy have focal seizures. These seizures are frequently described by the area of the brain in which they originate. For example, someone might be diagnosed with focal frontal lobe seizures.
Two types of focal seizures are:
- Simple focal seizures
- Complex focal seizures.
Simple Focal Seizure
In a simple focal seizure, the person will remain conscious but experience unusual feelings or sensations that can take many forms. The person may experience sudden and unexplainable feelings of joy, anger, sadness, or nausea. He or she also may hear, smell, taste, see, or feel things that are not real.
Complex Focal Seizure
In a complex focal seizure, the person has a change in or loss of consciousness. His or her consciousness may be altered, producing a dreamlike experience. People having a complex focal seizure may display strange, repetitive behaviors (called automatisms), such as:
- Mouth movements
- Walking in a circle.
More complicated actions, which may seem purposeful, can also occur involuntarily. People may continue activities they started before the seizure began, such as washing dishes in a repetitive, unproductive fashion. These seizures usually last just a few seconds.
Some people with focal seizures, especially complex focal seizures, may experience auras -- unusual sensations that warn of an impending seizure. These auras are actually simple focal seizures in which the person maintains consciousness. The symptoms an individual person has, and the progression of those symptoms, tend to be stereotyped or similar every time.
The symptoms of focal seizures can easily be confused with other disorders. For instance, the dreamlike perceptions associated with a complex focal seizure may be misdiagnosed as migraine headaches, which also may cause a dreamlike state. The strange behavior and sensations caused by focal seizures also can be taken for symptoms of narcolepsy, fainting, or even mental illness. It may take many tests and careful monitoring by an experienced physician to tell the difference between epilepsy and other disorders.