What are focal onset seizures?
Focal onset seizures are seizures that start in one area of the brain. They usually last less than two minutes. Focal onset seizures are different from generalized seizures, which affect all areas of the brain.
Doctors used to call focal onset seizures partial seizures. But in April 2017, the International League Against Epilepsy released new classifications that changed the name from partial seizures to focal onset seizures.
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According to Johns Hopkins Medicine, there are three types of focal onset seizures. Knowing what type of focal onset seizure a person has helps a doctor determine the best treatment.
Focal onset aware seizures
These seizures were formerly known as simple partial seizures or focal seizures without a loss of consciousness. A person with this seizure type doesn’t lose consciousness during the seizure. However, depending on the area of the brain affected, they may have changes in emotion, body movements, or vision.
Jacksonian seizures, or Jacksonian march, are a type of focal onset aware seizure that usually affect only one side of the body. Twitching usually begins in one small area of the body, like a toe, finger, or corner of the mouth, and “marches” to other areas of the body. The person is conscious during a Jacksonian seizure and may not even be aware that a seizure is occurring.
Focal onset impaired awareness seizures
These seizures were formerly known as complex partial seizures or focal dyscognitive seizures. During this type of seizure, a person will experience a loss of consciousness or change in consciousness level. They will not know they had the seizure, and they may stop responding to their environment.
Sometimes, a person’s behavior may be mistaken for not paying attention or even ignoring others when they are actually having a seizure.
Focal onset seizures that secondarily generalize
These seizures may start in one part of the brain and then spread to other parts. Some doctors consider the focal seizure an aura or warning of the generalized seizure that is to come.
This seizure will start in only one area of the brain, but then start to spread. As a result, the person may have convulsions, muscle spasms, or affected muscle tone.