Transcript Concepts in classification and their Relevance to Epilepsy

THE ORGANIZATION OF THE
EPILEPSIES 2010
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 Seizures
Tonic-clonic (in any combination)
Absence
- Typical
- Atypical
- Absence with special features
Myoclonic absence
Eyelid myoclonia
Myoclonic
Seizure types thought to
- Myoclonic
occur within and result from
- Myoclonic atonic
rapid engagement of
- Myoclonic tonic
bilaterally distributed systems
Clonic
Tonic
Atonic
Recommended terminology for
etiology
Use 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
Future developments in the
Classification of the Epilepsies
• 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