Seizures

Aseizure is a sudden episode of involuntary muscular contractions and relaxation, often accompanied by a change in sensation, behavior, and level of consciousness. A seizure results when the normal electrical activity of the brain is disturbed, causing the brain cells to become irritated and overactive. Specific conditions that trigger a seizure include epilepsy, encephalitis, a recent or old head injury, high fever in infants and young children, drug and alcohol abuse or withdrawal, eclampsia associated with toxemia of pregnancy, diabetic conditions, and heat stroke.

Seizures are classified as partial or generalized according to the location of the abnormal electrical activity in the brain.

Partial seizures are the most common type, occurring in approximately 80% of individuals who have seizures. With a partial seizure, the abnormal electrical activity is localized into very specific areas of the brain; therefore only the brain functions in those areas are affected.

Partial seizures are further classified as simple or complex, depending on whether the patient's level of consciousness is affected. The symptoms of a simple partial seizure include twitching or jerking in just one part of the body. This type of seizure lasts less than a minute, and the patient remains awake and alert during the seizure. With a complex partial seizure, the patient's level of consciousness is affected, and the patient has little or no memory of the seizure afterward.

The symptoms of this type of seizure include abnormal behavior such as confusion, a glassy stare, aimless wandering, lip smacking or chewing, or fidgeting with clothing, which lasts from a few seconds up to a minute or two. Both a simple and a complex partial seizure can progress to a generalized seizure.

With a generalized seizure, the abnormal electrical activity spreads through the entire brain. The best-known type of generalized seizure is a tonic-clonic seizure (formerly known as a grand mal seizure). With this type of seizure, the patient exhibits tonic-clonic activity followed by a postictal state. During the tonic phase, the patient suddenly loses consciousness and exhibits rigid muscular contractions, which result in odd posturing of the body. Respirations are inhibited, which may cause cyanosis around the mouth and lips. The patient may lose control of the bladder or bowels, resulting in involuntary urination and defecation. The tonic phase lasts up to 30 seconds, followed by the clonic phase. During the clonic phase, the patient's body jerks about violently. The patient's jaw muscles contract, which may cause the patient to bite the tongue or lips. The final phase of the seizure is the postictal state, lasting between 10 and 30 minutes, in which the patient exhibits a depressed level of consciousness, is disoriented, and often has a headache. The patient generally has little or no memory of the seizure and feels confused and exhausted for several hours after the seizure.

In some instances of seizures, particularly in patients with epilepsy, an aura precedes the seizure. An aura is a sensation perceived by the patient that something is about to happen: examples include a strange taste, smell, or sound, a twitch, or a feeling of dizziness or anxiety. An aura provides the patient with a warning signal that a seizure is about to begin.

Although seizures are frightening to observe, they are usually not as bad as they look. Most patients fully recover within a few minutes after the seizure begins. An exception to this is status epilepticus, in which the seizures are prolonged or come in rapid succession without full recovery of consciousness between them. Status epilepticus is a potentially life-threatening situation that requires immediate medical care.