Epilepsy Syndromes

There are many different types of epilepsy, classified as "epilepsy syndromes." Epilepsy syndromes are disorders characterized by symptoms that include epilepsy. According to the National Institute of Neurological Disorders and Stroke, there are hundreds of different epilepsy syndromes. Each one is classified based on several characteristics, including:

• Age of onset
• Any known associated medical conditions
• Behavior during seizures
• EEG interpretations
• Expected rate of development
• Family history
• Neurological abnormalities
• Possible causes of epilepsy
• Response to treatment
• Seizure type.

Generally, epilepsy syndromes are either classified as idiopathic or symptomatic. Each of these classifications is further subdivided into partial and generalized epilepsies.

Idiopathic Epilepsy Syndromes

By definition, idiopathic epilepsy syndromes have no known cause; often, doctors assume that they are inherited. Idiopathic seizures are generally easier to control and more likely to go into remission than symptomatic seizures.

Idiopathic partial epilepsy syndromes (that start in a particular area of the brain) are not nearly as common as idiopathic generalized epilepsy syndromes, which affect the entire brain. In both of these epilepsy groups:

• Developmental abnormalities are not usually present
• Seizures typically emerge during childhood
• The causes of epilepsy may or may not be genetic.

Examples of common idiopathic epilepsy syndromes include:

• Childhood absence epilepsy: A syndrome involving brief but frequent "staring spells."
• Juvenile absence epilepsy: Similar to childhood absence epilepsy, but begins later (usually between 10 and 17 years of age).
• Juvenile myoclonic epilepsy: A syndrome involving convulsive seizures.

Symptomatic Epilepsy Syndromes

Symptomatic epilepsy syndromes do have a known cause, such as abnormal brain tissue due to genetics, illness, or injury. Symptomatic seizures are difficult to control with medication.

Symptomatic partial epilepsy syndromes are the most common type of adult epilepsy (although they can begin at any age). Most partial (focal) seizures are symptomatic seizures. Causes of epilepsy in such cases are usually the result of a small, contained area of brain damage. Seizure patterns are typically linked to the location of this damage. Symptomatic generalized epilepsies are usually the result of severe brain damage and are therefore commonly associated with a developmental disorder.

Examples of common symptomatic epilepsy syndromes include:

• Frontal lobe epilepsy: A syndrome involving seizures that produce muscle weakness and/or stiffening.
• Infantile spasms (West syndrome): Sudden jerks followed by a stiffening of the whole body. These can begin when a baby is 3 to 12 months old.
• Temporal lobe epilepsy: A syndrome involving seizures that are often hallucinogenic in nature.

Other Epilepsy Syndromes

Cryptogenic epilepsy syndromes have a likely cause (such as a lesion) that doctors cannot exactly uncover during tests. As a result, cryptogenic epilepsies are usually diagnosed as symptomatic.

Special syndromes are conditions that produce seizures, but the condition itself is not epilepsy. Febrile seizures (early childhood seizures provoked by high fever) are the most common example of this. Febrile seizures are not technically defined as an epilepsy syndrome, but they do increase the risk of developing epilepsy later in life.

Resources

Dekker, P.A. (2002). Epilepsy: A manual for medical and clinical officers in Africa. Retrieved March 10, 2010, from http://www.who.int/mental_health/media/en/639.pdf

Epilepsy Action Staff. (n.d.). Epilepsy syndromes. Retrieved March 20, 2010, from http://www.epilepsy.org.au/epilepsy_explained3.asp#special

Holmes, G. L. (2006). Overview of epilepsy syndromes. Retrieved March 20, 2010, from http://professionals.epilepsy.com/page/syndromes.html

National Institute of Neurological Disorders and Stroke Staff. (n.d.) Seizures and epilepsy: Hope through research. Retrieved March 11, 2010, from http://www.ninds.nih.gov/disorders/epilepsy/epilepsy.htm

The Epilepsy Foundation of America^® Staff. (n.d.) Infantile spasms/West syndrome. Retrieved March 21, 2010, from http://www.epilepsyfoundation.org/about/types/syndromes/infantilespasms.cfm