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Epilepsy ll: Types

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Epilepsy can be classified in two main ways, by seizure type and by epilepsy syndromes.

When classified by seizure type, epilepsies fall into four groups. Focal epilepsy happens when seizures begin in one hemisphere.

Generalized epilepsy arises when both hemispheres are involved from the onset.

In combined epilepsy, individuals experience both focal and generalized seizure types during the course of the disorder.

Lastly, in the case of unknown epilepsy, the site of onset cannot be identified.

A second method of classification is by epilepsy syndromes. These are distinct clinical entities defined by consistent patterns of seizure types, age of onset, EEG findings, and progression over time.

Examples include childhood absence epilepsy, which presents with frequent staring spells in children; juvenile myoclonic epilepsy, which begins in adolescence with morning jerks.

Lennox-Gastaut syndrome is another example, characterized by multiple seizure types and associated with developmental impairment.

Overview

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Recurrent seizures, stemming from abnormal electrical activity in the brain, are the defining characteristic of epilepsy, a chronic neurological condition. Because seizure features vary greatly, epilepsy is classified using two systems: by seizure type and by epilepsy syndromes. These classifications enable clinicians to describe seizure patterns and select suitable treatment strategies.

I. Classification by Seizure Type

1. Focal Epilepsy

Focal epilepsy begins in one hemisphere of the brain. Symptoms vary depending on the affected area/areas and may include twitching, tingling, visual disturbances, or altered sensations. Awareness may be maintained in simple focal seizures or impaired in focal dyscognitive seizures. These episodes can spread to both hemispheres, producing generalized convulsions.

2. Generalized Epilepsy

Generalized epilepsy starts in both hemispheres from the onset. It often causes sudden loss of consciousness, accompanied by stiffening and rhythmic jerking. Subtypes include tonic–clonic, absence, myoclonic, and atonic seizures. Absence seizures typically happen in childhood and cause brief staring spells that can disrupt attention.

3. Combined Epilepsy

In some people, both focal and generalized seizures happen together. This condition is known as combined epilepsy and reflects overlapping seizure networks.

4. Unknown Epilepsy

When the seizure’s starting point cannot be identified, the disorder is classified as unknown epilepsy. Further EEG and imaging tests are needed to locate its origin.

II. Classification by Epilepsy Syndromes

Epilepsy can also be grouped by specific syndromes that share patterns of seizure type, age of onset, EEG findings, and disease course.
1. Childhood absence epilepsy presents with frequent staring spells in children.
2. Juvenile myoclonic epilepsy begins in adolescence and causes early-morning jerks.
3. Lennox–Gastaut syndrome is a severe form marked by multiple seizure types and developmental delay. Recognizing these syndromes supports accurate diagnosis and tailored therapy.

Transcript

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Epilepsy Classification

Generalized Epilepsy

Epilepsy Syndromes

Childhood Absence Epilepsy

Juvenile Myoclonic Epilepsy

Lennox Gastaut Syndrome

Combined Epilepsy

Unknown Epilepsy