Under normal conditions, discharge from neurons in the brain is random. Seizures are caused by bursts of electricity set off in the brain by neurons that discharge in a coordinated way from the brain. A seizure usually can last anywhere from a few seconds up to several minutes, but, in some serious cases, can last longer.

Signs of a seizure can be subtle or drastic—the affected person could simply stare at nothing for a few seconds, he or she could lose consciousness, could exhibit strange behavior, like speaking nonsense, or could convulse violently.

Though they can vary widely, specific kinds of symptoms can usually be associated with the type of seizure from which a person suffers. Also, an episode can start out as a simpler form of seizure, but can grow worse, becoming another type with more widespread or powerful symptoms.

Seizure types are determined by what body functions are affected and what degree of dysfunction there is to different parts of the body.

Different seizure types include:

Simple Partial Seizures

Also called a focal or local seizure, this type is limited to a specific part of the brain. The awareness of the affected person is not altered, but other symptoms depend on what functions the malfunctioning part of the brain controls. Limited parts of the body might twitch, there may be strange sensations, like tingling, or there may be sensory hallucinations, including strange sights or smells.

Complex Partial Seizures

This type is also limited to specific parts of the brain and can have widely varying symptoms, but, unlike the simple partial seizure, affects the awareness of the person. The affected person often begins to stare off at nothing and may perform odd, meaningless behaviors known as automatisms. These can include fumbling with clothes and making chewing motions. After the seizure, the person may be disoriented.

Tonic Clonic Seizures

Also known as the grand mal seizure, the initial warning sign may be a grunt or other vocalization from the affected person, followed by a slumping over of the body, which briefly becomes rigid (the tonic phase). The person’s body then begins to convulse, which is known as the clonic phase. The patient most often will twitch and undergo rhythmic jerking. The seizure may cause the person to bite down on his or her tongue, so there may also be bleeding from the mouth. The patient may be unable to control secretions, which leads to increased salivation, or “foaming at the mouth.” There may also be a loss of control of bowel or bladder functions, or other injury from the convulsions or from the body striking objects during the seizure.

The victim of a tonic clonic seizure is often sore and tired afterwards and has little or no memory of the experience. The grand mal seizure can be the result of a more limited type of seizure worsening. In that case, it is called a secondarily generalized seizure.

The electrical misfire starts in a specific area of the brain, but the malfunction cascades into larger areas of the brain. This can happen swiftly or slowly.

Absence Seizures

Also known as petit mal seizures, absence seizures occur more often in children and are characterized by brief losses of awareness in which the child stops what he or she is doing and stares off into space, unresponsive. The child may blink rapidly or go limp. Though they only last seconds, petit mals can recur numerous times in one day. Absence seizures should be considered in kids who are considered ‘spacey’ or who have difficulty paying attention.

Myoclonic Seizures

These seizures are characterized by the super-fast jerking of specific portions of the body. They can feel like jumps inside the body, which can affect the limbs, jaw, or other parts of the body. People without epilepsy can feel these types of jerks or twitches, especially when falling asleep or when waking in the morning.

Atonic Seizures

Also known as astatic seizures or drop attacks, these seizures involve a brief loss of consciousness in the affected person. Once it is over, the person is usually unaware of what happened. This severity of this type of seizure can range from appearing to slump or nod briefly before recovering, to the person collapsing.