Epilepsy is the fourth most common neurological diseaseTrusted Source after migraines, stroke, and Alzheimer’s.
Seizures can cause a range of symptoms, from momentarily staring blankly to loss of awareness and uncontrollable twitching. Some seizures can be milder than others, but even minor seizures can be dangerous if they occur during activities like swimming or driving.
Here’s what you need to know:
In 2017, the International League Against Epilepsy (ILAE) revised its classification of seizures from two primary groups to three, a change based on three key features of seizures:
- where seizures begin in the brain
- level of awareness during a seizure
- other features of the seizures, like motor skills and auras
These three seizure types are:
- focal onset
- unknown onset
Focal seizures — previously called partial seizures — originate in neuronal networks but are limited to part of one cerebral hemisphere.
Focal seizures account for about 60 percent of all epileptic seizures. They last one to two minutes and have milder symptoms that someone may be able to work through, like continuing to do the dishes.
Symptoms may include:
- motor, sensory, and even psychic (like deja vu) abnormalities
- sudden, inexplicable feelings of joy, anger, sadness, or nausea
- automatisms like repetitive blinking, twitching, smacking, chewing, swallowing, or walking in circles
- auras, or a sense of warning or awareness of an oncoming seizure
Generalized seizures originate in bilateral distributed neuronal networks. They can begin as focal, then become generalized.
These seizures can cause:
- loss of consciousness
- severe muscle contractions
More than 30 percent of people with epilepsy experience generalized seizures.
They can be identified more specifically by these subcategories:
- Tonic. This type is characterized by stiffening muscles primarily in the arms, legs, and back.
- Clonic. Clonic seizures involve repetitive jerking movements across both sides of the body.
- Myoclonic. In this type, jerking or twitching movements occur in the arms, legs, or upper body.
- Atonic. Atonic seizures involve a loss of muscle tone and definition, ultimately leading to falls or an inability to hold the up head.
- Tonic-clonic. Tonic-clonic seizures are sometimes called grand mal seizures. They can include a combination of these varied symptoms.
Unknown (or epileptic spasm)
The origin of these seizures is unknown. They manifest by sudden extension or flexion of the extremities. Moreover, they can reoccur in clusters.
Up to 20 percent of people with epilepsy experience nonepileptic seizures (NES), which present like epileptic seizures, but aren’t associated with the typical electrical discharge found in the brain.