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EPILEPSY CLASSIFICATION

Definition of epilepsy

Epilepsy is a disease of the brain defined by any of the following conditions:

  • At least two unprovoked (or reflex) seizures occurring more than 24 hours apart
  • One unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years
  • Diagnosis of an epilepsy syndrome

Epilepsy is considered to be resolved for individuals who had an age-dependent self-limited epilepsy syndrome but who are now past the applicable age, or for those who have remained seizure-free for the last 10 years, with no seizure medication for the last 5 years.

Classification of epilepsy

Epilepsy classification is undertaken after the criteria for diagnosing epilepsy are met (definition above). Classification is undertaken using a multi-level classification framework, involving classification at three levels - the seizure type, epilepsy type and epilepsy syndrome. Imaging, EEG and other investigations, where available, contribute to optimized classification at all three levels. Where possible, a diagnosis at all three levels should be established. The etiology of the epilepsy should be considered from the outset, and at each step along the diagnostic pathway. Knowing the etiology can inform optimized classification and has important treatment implications for the patient.

Epilepsies are classified as:

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