Classification

General considerations

• The International League Against Epilepsy (ILAE) recommends a multilevel approach to classifying epilepsy.

• Etiology and comorbidities should be considered at each level of classification.

Levels of classification

• For level 1, first determine the seizure type (see “Classification of seizures” above).

• For level 2, then determine the epilepsy type, which can be:

  • Focal

    • The lobe from which seizures originate should be determined.

    • Epilepsy with focal-to-bilateral tonic-clonic seizures is classified as focal.

  • Generalized: diagnosed in patients with generalized-onset seizures as evidenced by generalized ictal activity (e.g., 3 Hz spike-wave activity in absence seizures) and/or typical interictal discharges on EEG.

  • Combined generalized and focal: diagnosed in patients who have both focal-onset and generalized-onset seizures (seen, e.g., in Dravet syndrome and Lennox-Gastaut syndrome)

  • Unknown: diagnosed if there is not enough clinical information to classify seizures as focal, generalized, or combined

• For level 3, consider epilepsy syndromes (see “Focal seizures and syndromes” and “Generalized epilepsy in childhood” for discussion of specific syndromes)