Tufts OpenCourseware
Authors: John Morgan, Bonnie F. Zimble

Epilepsy/Seizure Disorders:

Definitions and Classification of Seizure Types

Special Care in Dentistry
John Morgan, DDS
Tufts University School of Dental Medicine, 2008

Study Questions:

  1. Describe the condition of epilepsy.

  2. When do seizures indicate that a person has epilepsy?

  3. What is a seizure?

What is epilepsy?

Epilepsy is defined by the National Institute of Neurological Disorders and Stroke as follows: 

“Epilepsy is a brain disorder in which clusters of nerve cells, or neurons, in the brain sometimes signal abnormally. In epilepsy, the normal pattern of neuronal activity becomes disturbed, causing strange sensations, emotions, and behavior or sometimes convulsions, muscle spasms, and loss of consciousness. Epilepsy is a disorder with many possible causes. Anything that disturbs the normal pattern of neuron activity - from illness to brain damage to abnormal brain development - can lead to seizures. Epilepsy may develop because of an abnormality in brain wiring, an imbalance of nerve signaling chemicals called neurotransmitters, or some combination of these factors. Having a seizure does not necessarily mean that a person has epilepsy. Only when a person has had two or more seizures is he or she considered to have epilepsy. EEGs and brain scans are common diagnostic test for epilepsy.”

What are seizures? 

A seizure is a paroxysmal attack of brain dysfunction, which involves changes in consciousness, motor activity, or sensory phenomena. The attack is accompanied by abnormal and excessive electrical discharge from neurons. The seizure is sometimes preceded by an aura, which provides a warning of the attack. The aura is a symptom produced by the beginning of electrical discharge before the patient loses consciousness.

Classification of Seizure Types 

The International Classification of Seizure Types was first published in 1970 and has since gained wide acceptance. It is based on the clinical presentation of the seizure.

            a. Grand Mal or Generalized Tonic-Clonic Seizures

            b. Petit Mal or generalized absence seizures

            c. Psychomotor or temporal lobe or partial seizure with complex symptomatology

            d. Jacksonian or partial seizure with motor symptoms

            e. Infantile spasms or generalized seizures