Classification of the Epilepsies

Classification of the Epilepsies
Purpose: for clinical diagnosis
Transparent language: use words that mean what they say

Co-morbidities
Seizure types
Generalized onset
Unknown onset
Focal
onset

1. Seizure types
Certain that events are epileptic seizures – not referring to distinguishing epileptic versus non-epileptic
In some settings ? classification according to seizure type may be maximum level of diagnosis possible
In other cases ? simply too little information to be able to make a higher level diagnosis
eg. when a patient has only had a single event

Generalized seizures
Originate at some point within and rapidly engage bilaterally distributed networks
Can include cortical and subcortical structures
but not necessarily the entire cortex

Originate within networks limited to one hemisphere
May be discretely localized
or more widely distributed.…
Focal seizures

Notes
Atonic seizures and epileptic spasms would not have level of awareness specified
Pedalling grouped in hyperkinetic rather than automatisms (arbitrary)
Cognitive seizures
impaired language
other cognitive domains
positive features eg déjà vu, hallucinations, perceptual distortions
Emotional seizures: anxiety, fear, joy, etc

Note
When a seizure type begins with ”focal, generalized or absence” then the word “onset” can be presumed

Terms no longer in use
Complex partial
Simple partial
Partial
Psychic
Dyscognitive
Secondarily generalized tonic-clonic

Note
Clarify features of seizures but do not define unique seizure types
Free text descriptors encouraged

Tuberous Sclerosis
GLUT1 deficiency
Unknown
Immune
Infectious
Structural
Metabolic
Genetic

Where unable to make an Epilepsy Syndrome diagnosis or a diagnosis of Etiology
Many examples
Temporal lobe epilepsy
Generalized tonic-clonic seizures in a 5 year old with generalized spike-wave
Both focal impaired awareness seizures and absence seizures in a patient
Cannot tell if tonic-clonic seizure is focal or generalized

Generalized and Focal Epilepsies
Combined focal and generalized epilepsies
Examples
Dravet syndrome
What do with
Multifocal epilepsies?
Hemispheric epilepsies?
? focal
? focal

Epilepsy Syndromes
Seizure types
Generalized onset
Unknown onset
Focal
onset

Old term
‘Idiopathic Generalized Epilepsies’

Genetic versus idiopathic
‘Idiopathic’ = presumed hereditary predisposition
Genetic ≠ inherited
Importance of de novo mutations in both
mild and severe epilepsies
Critical problem of stigma in some parts of the world

Genetic ≠ Gene testing
Usually the mutation is not known
Access to molecular genetic testing not necessary
Diagnosed on clinical research eg. twin, family studies
JME pair; Lennox 1941
CAE pair; Lennox 1950

Co-morbidities
Etiology
Epilepsy types
Focal
Generalized
Combined
Generalized
& Focal
Unknown
Focal
Epilepsy Syndromes
Generalized
Unknown
Immune
Infectious
Structural
Metabolic
Genetic
Genetic

Epilepsy syndromes
There are no approved ILAE epilepsy syndromes

https://www.epilepsydiagnosis.org

Benign
Many epilepsies not benign
CAE – psychosocial impact
BECTS – learning concerns
Replaced by terms:
Self-limited
Pharmacoresponsive
No longer use
Malignant
Catastrophic

Epileptic activity itself
contributes to severe cognitive and behavioral impairment above and beyond that expected from the underlying pathology and that these can worsen over time
Developmental and/or Epileptic encephalopathies
Berg et al 2010

Developmental and/or Epileptic Encephalopathy
For many encephalopathies, there is a developmental component independent of the epileptic encephalopathy
Developmental delay may precede seizure onset
Co-morbidities
eg. cerebral palsy, autism spectrum disorder, intellectual disability
Outcome poor even though seizures stop
eg. KCNQ2, STXBP1 encephalopathies

Developmental and/or Epileptic Encephalopathy
Developmental encephalopathy
May begin in utero
Post birth
Epileptic encephalopathy
Can occur at any age
May have remediable component – right vs wrong AED
Move towards GENE encephalopathy
eg. CDKL5 encephalopathy, SCN2A encephalopathy

Old terms
‘Symptomatic Generalized Epilepsies’
Used for two different groups of disorders
Symptomatic Generalized Epilepsies
Developmental
and/or
Epileptic
Encephalopathies
(Static)
Encephalopathies

ILAE Classification of the Epilepsies
Simplified the framework
Etiology – consider at all stages
Developmental and/or Epileptic Encephalopathies
Self-limited, pharmacoresponsive
Genetic Generalized Epilepsies
Idiopathic Generalized Epilepsies = CAE, JAE, JME, GTCA
Symptomatic Generalized Epiliepsies used for both
? Developmental and Epileptic Encephalopathies
? (static) Encephalopathy with Epilepsy

Impact on Clinical Care and Practice
New classification framework will
Change the approach to diagnosis in the clinic
Be applied to patients and guide management
Updates terminology to reflect
current thinking
Scientific advances