Epilepsy is a common neurological disorder that affects 2.7 million people in the United States, making it one of the most common disorders of the nervous system - impacting people of all ages, races and ethnic backgrounds.

A seizure is generated by abnormal electrical discharges from brain cells, a kind of misfiring that disrupts normal function, producing anything from a change in a person's consciousness to uncontrolled movements and/or sensations. Epilepsy is a condition characterized by recurring seizures.

The disease remains a mystery to scientists in many ways, although many strides have been made in recent years, as new antiepileptic medications have become available and advanced brain imaging technologies have brought new hope to many.

There are many potential causes of epilepsy. Tumors, strokes and brain damage from illness or injury can all cause epilepsy. There are genetic causes of epilepsy as well. In some cases, however, the source of the disorder is not understood.

There are many different types of seizures, and people with epilepsy may experience one or more types. The kind of seizure a person has depends on which part and how much of the brain is affected by the electrical disturbance that produces seizures.

Different types of seizures

Seizures are generally divided into two different types. There are generalized seizures and partial seizures. A generalized seizure occurs when a burst of electrical energy sweeps through the whole brain at once, causing a loss of consciousness, falls, convulsions (also called "tonic clonic seizures") or muscle spasms.

Often people with seizures describe a warning or a change in feeling or movement at the beginning of the seizure. The warning is sometimes called an aura and is a partial seizure. The following explains the terminology and describes more specifically the different kinds of seizures.

Partial Seizures

Focal seizures take place when abnormal electrical brain function occurs in one or more areas on one side of the brain. Focal seizures may also be called partial seizures. With focal seizures, particularly with complex focal seizures, a person may experience an aura before the seizure occurs. An aura is a strange feeling, either consisting of visual changes, hearing abnormalities or changes in the sense of smell. Two types of focal seizures include the following:

  • Simple partial seizures
    The seizures typically last less than one minute. The person may show different symptoms depending upon which area of the brain is involved. If the abnormal electrical brain function is in the occipital lobe (the back part of the brain that is involved with vision), sight may be altered. If the abnormal brain function is in the frontal lobe (the front part of the brain that is involved with muscle or motor movement), the person's muscles are typically affected. The seizure activity is limited to an isolated muscle group, such as the fingers, or to larger muscles in the arms and legs. Consciousness is not lost in this type of seizure. The person may also experience sweating, nausea or become pale.
  • Complex partial seizures
    This type of seizure commonly occurs in the temporal lobe of the brain, the area of the brain that controls emotion and memory function. This seizure usually lasts between one to two minutes. Consciousness is usually lost during these seizures and a variety of behaviors can occur. These behaviors may include gagging, lip smacking, running, screaming, crying and/or laughing. When the person regains consciousness, they may complain of being tired or sleepy after the seizure. This is called the postictal period.
  • Secondarily generalized seizures
    This type of seizure begins in one part of the brain, either as a simple partial seizure or complex partial, and then spreads to involve both sides of the brain where consciousness is lost. Clinically, it looks exactly like the generalized tonic clonic seizure listed below.

Generalized Seizures

Generalized seizures involve both sides of the brain. There is loss of consciousness after the seizure occurs. Types of generalized seizures include the following:

  • Absence seizures (also called petit mal seizures)
    These seizures are characterized by a brief altered state of consciousness and staring episodes. Typically, the person's posture is maintained during the seizure. The mouth or face may move or the eyes may blink. The seizure usually lasts no longer than 30 seconds. When the seizure is over, the person may not recall what just occurred and may go on with their activities, acting as though nothing happened. These seizures may occur several times a day. This type of seizure is sometimes mistaken for a learning problem or behavioral problem. Absence seizures almost always start between ages 4 to 12 years.
  • Atonic (also called drop attacks)
    With atonic seizures, there is a sudden loss of muscle tone and the person may fall from a standing position or suddenly drop their head. During the seizure, the person is limp and unresponsive.
  • Tonic
    Stiffening or contraction in a fixed posture, often with abduction of the shoulders and partial flexion of the elbows; usual duration 10 to 20 seconds,but often cluster; EEG pattern of rapid, diffuse polyspikes, often following a slow wave.
  • Generalized tonic-clonic seizures (GTC or also called grand mal seizures)
    This seizure is characterized by five distinct phases that occur. The body, arms, and legs will flex (contract), extend (straighten out), and tremor (shake), followed by a clonic period (contraction and relaxation of the muscles) and the postictal period. During the postictal period, the person may be sleepy, have problems with vision or speech, and may have a bad headache, fatigue, or body aches.
  • Myoclonic seizures
    This type of seizure refers to quick movements or sudden jerking of a group of muscles. These seizures tend to occur in clusters, meaning that they may occur several times a day, or for several days in a row.

Non-Epileptic Seizures

The BWH Bromfield Epilepsy Program has extensive experience in identifying and treating non-epileptic seizures. The symptoms of the two conditions are very similar. As with epileptic seizures, those who experience a non-epileptic seizure experience a variety of similar abnormal movements, such as falling or shaking, unconsciousness, or other symptoms. Due to the similar symptoms, physicians will often use medications designed to treat epilepsy to treat non-epileptic seizures. This is usually ineffective and may even increase the frequency of these non-epileptic seizures. The multidisciplinary team at the BWH Bromfield Epilepsy Program, however, can use the video EEG monitoring program to safely investigate the possibility that a patient is experiencing non-epileptic seizures and adjust their treatment accordingly, thereby improving their quality of life.

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