Epilepsy Classification

Over the last few decades the ILAE classifications for seizures and epilepsies (ILAE-EC) have been updated repeatedly to reflect the substantial progress that has been made in diagnosis and understanding of the etiology of epilepsies and seizures and to correct some of the shortcomings of the terminology used by the original taxonomy from the 1980s. However, these proposals have not been universally accepted or used in routine clinical practice.

Four-dimensional epilepsy classification

A separate classification is known as the “Four-dimensional epilepsy classification” (4D-EC) was developed which includes a seizure classification based exclusively on ictal symptomatology, which has been tested and adapted over the years. The extensive arguments for and against these two classification systems made in the past have mainly focused on the shortcomings of each system, presuming that they are incompatible. As a furthermore detailed discussion of the differences seemed relatively unproductive, we here review and assess the concordance between these two approaches that have evolved over time, to consider whether a classification incorporating the best aspects of the two approaches is feasible.

To facilitate further discussion in this direction Rosenow et al. outlined a concrete proposal showing how such a compromise could be accomplished, the “Integrated Epilepsy Classification”. This consists of five categories derived to different degrees from both of the classification systems: 1) a “Headline” summarizing localization and etiology for the less specialized users, 2) “Seizure type(s)”, 3) “Epilepsy type” (focal, generalized or unknown allowing to add the epilepsy syndrome if available), 4) “Etiology”, and 5) “Comorbidities & patient preferences” ¹⁾.

ILAE 2017 Classification

The Classification of Epilepsies includes several diagnostic levels (steps):

1) from seizure type to epilepsy type (generalized/focal/combined generalized and focal/unknown),

2) diagnosis of epilepsy syndrome

3) etiology (genetic/ structural/ infectious/ metabolic/ immune/unknown). A clinician can use any level of the classification. Operational classification of seizure types is replaced by the previous classification that was grounded on the anatomical basis. Seizures are classified by the onset (focal, generalized or unknown). All types of seizures can be motor or non-motor. Focal seizure may evolve to bilateral tonic-clonic (previously called secondary-generalized). Atonic, clonic, tonic, myoclonic seizures and epileptic spasms can be either of focal or generalized onset. Unclassified type of seizure was introduced. New types of seizures (absence with eyelid myoclonia, myoclonic absence, myoclonic atonic and clonic-tonic-clonic seizures) were added ²⁾.

Miscellaneous

Early seizure

Focal seizure…

Drug resistant epilepsy

Posttraumatic epilepsy

Temporal lobe epilepsy….

see also Pediatric epilepsy.