Types of Epileptic Seizures

Types of Epileptic Seizures

Researchers in epilepsy (called epileptologists) and clinicians worldwide have agreed on a common classification system to describe the various types of seizures. Seizures are classified according to their symptoms (e.g. whether consciousness was altered) and their electroencephalogram (EEG) pattern. Correct classification of the type of seizure is critical for diagnostic and treatment planning purposes (e.g. selection of the most appropriate anti-epileptic medication). The International Classification of Epileptic Seizures (1981; see below) recognizes two general categories of seizures based on the origin of the abnormal electrical discharge. Two broad categories of seizures are recognized, partial and generalized, with each category having different subtypes.

1) Partial seizures (sometimes referred to as Focal or Local seizures) which originate in one location in the brain and then may or may not spread to other brain areas. Partial seizures are further subdivided into simple partial and complex partial. In simple partial seizures consciousness is preserved. In complex partial seizures there is an alteration in consciousness, the person does not recall having the seizure and may be very confused and fatigued in the aftermath. A partial seizure may also progress into a generalized motor seizure.

2) Generalized seizures (once called “grand mal” seizures) begin simultaneously in all areas of the brain. Consciousness is altered and the person may (or may not) show convulsions.

International Classification of Epileptic Seizures (Epilepsia, 1981)

Partial Seizures (seizures that begin in a specific area of the brain)
Simple partial seizures (consciousness is not impaired)
with motor symptoms
with sensory symptoms
with autonomic symptoms
with psychic symptoms
Complex partial seizures (consciousness is impaired)
Simple partial seizures that progress to complex partial seizures
with no other featurres
with features in A1-4 (above)
with automatisms
with impairment of consciousness from the onset
with no other featurres
with features in A1-4 (above)
with automatisms
Generalized seizures (involve both cerebral hemispheres and without local onset)
Absence seizures (what used to be called petit mal)
Myoclonic seizures
Clonic seizures
Tonic seizures
Tonic — clonic seizures
Atonic seizures
Unclassified epileptic seizures (inadequate or incomplete data)