Seizure Semiology and Classification Dr Tim Wehner NHNN

1. Seizure Semiology and ClassificationDr Tim WehnerNHNN Epilepsy Daycourse Royal Free Hospital, London 14 Feb 2014

2. Summary 1 • Seizure semiology is an expression of activation and disinhibition of cerebral areas • It thus provides some information what cerebral areas are “involved” during a seizure • Video EEG provides objective data on seizure semiology, however for most seizures in most patients information on semiology comes from patient’s and witness’ history • Seizure classification aims to intellectually organise and summarise information about seizure semiology

3. Summary 2 • Seizure classification currently intensily debated in ILAE • Relative consensus exists for seizure types seen in primary generalised epilepsies • ILAE recognizes need to update classification of focal seizures, however no consensus in sight • Why is it important – because we have nothing else to go by.

4. Take home messages • Using obsolete or imprecisely defined terms is of little help • Using defined terms inappropriately is even worse (“absence”) • Patients and relatives should be encouraged to describe what they experience / see during a seizure without using terms such as “aura”, “petit mal”, “grand mal”, “simple partial”, “complex partial”, “deja vu” , “blackout”

5. www.ilae.org

6. 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 www.ilae.org

7. 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.… www.ilae.org

8. 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 • Evolving to bilateral, convulsive seizure • Previous terms: partial seizure secondarily generalized;secondarily generalized tonic-clonic seizure • With tonic, clonic or tonic and clonic components www.ilae.org

9. Symptomatogenic areas Left hemisphere, lateral aspect

10. Symptomatogenic areas Left hemisphere, mesial aspect

11. Symptomatogenic areas Left Insula

12. Common lateralising seizure manifestations *In patients referred for presurgical video telemetry

13. Less common lateralising or localising seizure manifestations

14. 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. www.ilae.org

15. Generalized Seizures Seizure types thought to occur within and result from rapid engagement of bilaterally distributed systems Tonic-clonic (in any combination) Absence - Typical - Atypical - Absence with special features Myoclonic absence Eyelid myoclonia Myoclonic - Myoclonic - Myoclonic atonic - Myoclonic tonic Clonic Tonic Atonic www.ilae.org

16. Recommended terminology for etiology Use terms which mean what they say: Genetic Structural-Metabolic Unknown Previously used terms denoting old concepts: Idiopathic, cryptogenic, symptomatic www.ilae.org

17. 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 www.ilae.org

18. 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. www.ilae.org

19. Unknown • Concept: The nature of the underlying cause is as yet unknown. www.ilae.org

20. 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 www.ilae.org

21. How to classify? • Absence • Aura • Dyscognitive sz • No seizure • Absence is narrowly defined as a seizure with loss of awareness, sudden on- and offset, no postictal state, and 3Hz Spike and Wave complexes in the EEG

22. Elements of a seizure • Subjective experience of the patient • Motor and behavioural manifestations • Awareness, language and cognition • Autonomic manifestations • May coexist in any combination, even in brief seizures, and are a function of how well the patient is assessed during the seizure

23. Key References • ILAE commission report, www.ilae.org • Comments by Panayiotopoulos Epilepsia, 52:2155-60, 2011Lüders et al, Epilepsia, 53:405–11, 2012Berg & Scheffer Epilepsia, 52:1058–62, 2011Shorvon Epilepsia, 52:1052–57, 2011 • Glossary Blume et al, Epilepsia 2001