ILAE Commission for Classification and Terminology

Purpose of the International Classification of Seizures and Epilepsies

To provide a common international terminology and classification

Largely for clinical (treatment) purposes

Purpose of classification: to organize items according to their fundamental relationships

2005-2009 Commission Report,Epilepsia 2010;51:676-685

Main changes, modifications Language and structure for organizing epilepsies

Generalized versus Focal Seizures “Etiology” Diagnostic specificity New recommended terms Organization

NO changes to electroclinical syndromes A diagnosis can be made as previously

eg Lennox-Gastaut syndrome, childhood absence epilepsy A diagnosis is not the same as a classification

Focal reconceptualized

For seizures: Focal epileptic seizures are

conceptualized as originating within networks limited to one hemisphere. These may be discretely localized or more widely distributed.…

Focal seizures Blume et al, Epilepsia 2001

Without impairment of consciousness or awareness Previous term: simple partial With observable motor or autonomic components

eg. focal clonic, autonomic, hemiconvulsive With subjective sensory or psychic phenomena

Aura - specific types

Where alteration of cognition is major feature Previous term: complex partial Dyscognitive

Focal seizures Blume et al, Epilepsia 2001

Evolving to bilateral, convulsive seizure Previous terms: partial seizure secondarily

generalized;secondarily generalized tonic-clonic seizure

With tonic, clonic or tonic and clonic components

Generalized - reconceptualized For seizures

Generalized epileptic seizures are conceptualized as originating at some point within, and rapidly engaging, bilaterally distributed networks. …can include cortical and subcortical structures, but not necessarily include the entire cortex.

Generalized SeizuresTonic-clonic (in any combination)Absence

- Typical - Atypical - Absence with special features

Myoclonic absence Eyelid myocloniaMyoclonic

- Myoclonic- Myoclonic atonic- Myoclonic tonic

ClonicTonic Atonic

Seizure types thought to occur within and result from

rapid engagement of bilaterally distributed systems

Recommended terminology for etiologyUse terms which mean what they

say: Genetic Structural-Metabolic Unknown

Previously used terms denoting old concepts:Idiopathic, cryptogenic, symptomatic

Genetic

Concept: the epilepsy is the direct result of a known or inferred genetic defect(s). Seizures are the core symptom of the disorder.

Evidence: Specific molecular genetic studies (well replicated) or evidence from appropriately designed family studies.

Genetic does not exclude the possibility of environmental factors contributing

Structural-Metabolic

Concept: There is a distinct other structural or metabolic condition or disease present. eg. Tuberous sclerosis

Evidence: Must have demonstrated a substantially increased risk of developing epilepsy in association with the condition.

Unknown

Concept: The nature of the underlying cause is as yet unknown.

New recommended terminology

Previously used terms no longer preferred Classification as focal or generalized epilepsies

not always appropriate use when appropriate

Catastrophic - emotionally laden term Benign - does not recognize that co-morbidities

occur, this term is still used in syndrome names Recommended terms Self-limited: high likelihood of spontaneous

remission Pharmacoresponsive

• New terminology and concepts update the classification to be consistent with current understanding of the epilepsies in clinical practice

• Currently there is no biologically based classification of the epilepsies

• Epilepsies can be organized in a flexible, multidimensional way depending on the purpose

eg. by age, etiology, seizure type, EEG abnormality

Future efforts in classification will depend on a biological mechanisms as these are understood

Future developments in the Classification of the

Epilepsies