Common Types of Seizures

A seizure is a brief disruption of electrical activity in the brain.  Seizures may be convulsions, short periods of unconsciousness, distortion of the senses, or loss of control over movement.  The kind of seizure a person has depends on where in their brain the abnormal activity starts and where it spreads.  There are two primary types of seizures: generalized and partial.

Generalized seizures affect both cerebral hemispheres (sides of the brain) from the beginning of the seizure. They produce loss of consciousness, either briefly or for a longer period of time, and are sub-categorized into two major types:

Tonic clonic, previously known as grand mal seizures, involve loss of consciousness. The person will fall down if standing and then a rhythmic jerking of the head, arms and legs begin. This type of seizure usually ends after one to three minutes and the person may be confused and want to sleep. A headache sometimes occurs and full recovery takes minutes to hours, depending on the individual.

Absence, previously known as petit mal seizures, are lapses of awareness, sometimes with staring, that begin and end abruptly, lasting only a few seconds. There is no warning and no after-effect.

Partial seizures are the most common type of seizure and they originate from a specific area of the brain. Partial seizures are divided into two groups:                                                          Simple partial seizures are generally brief and do not involve loss of consciousness. The person remains aware of the environment, remembers the experience, but may be limited in how he or she can interact while it is in progress. The character of the seizure is affected by the area of the brain. For example, a seizure that begins in a motor area may cause movement of the hand or face. A simple partial seizure can also be a tingling in the hand or face, visual distortions, a sudden feeling of fear, or a peculiar smell, depending on the location of the seizure activity in the brain.               

Complex partial seizures affect consciousness. A person having this type of seizure will be unaware of his surroundings during the seizure. They may wander aimlessly, run, do a series of repetitive movements, pick at clothes, chew, mumble and, to a casual onlooker, appear to be drunk, on drugs or even mentally ill.  After the seizure ends, the person will have little or no memory of the actual seizure or what happened during it.