Epilepsy symptoms vary from person to person; some people may have simple staring spells, while others have violent shaking and loss of alertness. The type of seizure depends on the part of the brain affected as well as the cause of the epilepsy.
A petit mal seizure describes a type of seizure that most commonly resembles a staring spell. It is often referred to as an absence seizure because it disturbs brain activity in a way that leads to the “absence” of behavior. It is a brief, usually less than 15 seconds, disturbance of brain function due to abnormal electrical activity in the brain. Petit mal seizures often occur in people under 20 years of age, usually in children ages 6 to 12. They may also occur with other types of seizures, twitches (myoclonus), or the loss of muscle strength (atonic seizures).
A generalized tonic-clonic seizure is a seizure that involves the entire body. The terms seizure, convulsion, or epilepsy are most often associated with generalized tonic-clonic seizures. Generalized tonic-clonic seizures may occur in people of any age. They may occur as a single episode, or as part of a repeated, chronic condition.
All seizures are caused by abnormal electrical activity in the brain. Partial (focal) seizures occur when this electrical activity remains in a limited area of the brain. The seizures can sometimes turn into generalized seizures, which affect the whole brain. This is called secondary generalization. Partial seizures can be simple—not affecting awareness or memory, or complex—affecting awareness of events before, during, and immediately after the seizure, as well as affecting behavior.