There are many different types of epilepsy that are distinguished by causes, extent, and effects. Among these, there are two major types of epilepsy: generalized epilepsy, in which seizures affect the entire brain, and partial (or focal) epilepsy, in which seizures begin in a specific portion of the brain.

Generalized epilepsies have no defined area in the brain from which the seizures originate. There are two varieties of generalized epilepsies:

• Idiopathic, in which the brain behaves normally between seizures and the cause of seizures is unknown; and
• Symptomatic, in which there is a clear structural abnormality that contributes to the seizures.

The seizures caused by generalized epilepsy include:

• Absence, or petit mal, seizures are characterized by a brief lapse in awareness that lasts a few seconds and causes the person to stare or have twitches in the eyelids or face muscles. These seizures, which may occur up to hundreds of times a day, commonly begin in before age two and end after childhood.
• Tonic-clonic, or grand mal, seizures are characterized by a sudden and complete loss of consciousness and a stiffening the arms and legs that causes the person to fall (called the tonic phase) before a rhythmic jerking (called the clonic phase) begins. When the seizing does not stop, it may become a status epilepticus seizure. This uncontrolled seizing requires immediate medical attention to prevent brain damage or death.
• Tonic seizures are similar to tonic-clonic seizures, but are not followed by a rhythmic jerking of the clonic phase.
• Myoclonic seizuresare generalized seizures that involve very brief, lightning-like jerks of any part of the body without a loss of consciousness.v
• Atonic seizurescause people experiencing them to experience a sudden loss of muscle tone resulting in collapse, sometimes head first, into the ground.

Partial (focal) epilepsy is a condition with a clearly defined focus in the brain from which the seizures originate. While the seizures sometimes are localized, they can spread to become generalized seizures. The seizures caused by these epilepsies, which may spread and become generalized, include:

• Complex partial seizures (psychomotor attacks) which often begin with an aura, or a neurological warning, such as a sense of fear, an unpleasant smell, or change in perception. After the aura, consciousness may be altered; speech stops and the person may perform automatic repetitive movements such as chewing, swallowing, hand fidgeting, or purposeless movement from place to place.
• Simple partial seizures, which affect the motor or sensory areas of the brain, causing jerking movements in the hand or facial muscles, or sensory symptoms such as flashing lights or a buzzing sound, but without altering consciousness.