Epilepsy is a chronic medical disorder or condition, usually resulting in unpredictable, unprovoked recurrent seizures that affect a variety of mental and physical functions. It is one of the most common neurological diseases, affecting more than 3 million people in the U.S.1 and about 50 million people worldwide.2 Epilepsy was one of the first brain disorders to be described.3 It was mentioned in ancient Babylon more than 3,000 years ago.3 Through the ages, the strange behavior caused by some seizures has led to the creation of numerous superstitions and prejudices.
The term epilepsy is derived from the Greek word epilam-banein, meaning to attack or seize. People once thought that epileptic individuals were being visited by demons or gods. However, in 400 b.c., the early physician Hippocrates suggested that epilepsy was a disorder of the brain—and he was right.3
A person is considered to have epilepsy when two or more unprovoked seizures occur that can’t be explained by a medical condition such as fever or substance withdrawal. Seizures can be the result of a family tendency toward the disease, or they can occur after a brain injury, but the cause of epilepsy is largely unknown.4 Epileptic seizures are manifested by an abnormal, excessive, and hypersynchronous electrical discharge of neurons in the brain.4
Each distinct form of epilepsy has its own natural history and response to treatment.4 This diversity probably reflects the many different underlying causes of epilepsy and the variety of epilepsy syndromes in which the clinical and pathological characteristics are distinctive and suggest a specific underlying etiologic mechanism.5
There are many kinds of seizures, each with characteristic behavioral changes and electrophysiological disturbances that can usually be detected in scalp electroencephalographic (EEG) recordings.4 A seizure is a transient epileptic event, indicating a disturbance in brain function.4 Having a single seizure does not necessarily mean that a person has epilepsy.4,5 Ten percent of adults experience a seizure sometime during their lifetime.1 Seizures can last from a few seconds to a few minutes. Patients and health care professionals do not always recognize the signs or symptoms, which can include convulsions, a loss of consciousness, blank staring, lip smacking, or jerking movements of the arms and legs.1 A seizure has a clear beginning, middle, and end.
It is necessary to determine the type of seizure in order to focus the diagnostic approach on a particular etiologic factor, to select the appropriate drug therapy, to conduct scientific investigations that require delineation of clinical and EEG phenotypes, and to provide vital information regarding the prognosis.4,5
In 1981, the International League against Epilepsy (ILAE) published a modified version of the International Classification of Epileptic Seizures (ICES), which has continued to be a very useful system.5 This system is based on the clinical features of seizures and associated EEG findings. The etiology or cellular substrate is not considered.
There are three main types of seizures: partial, generalized, and unclassified.5 A modified version of the ICES is presented in Table 1.