Seizure Semiology and Classification Dr Tim Wehner NHNN Epilepsy Daycourse Royal Free Hospital, London 14 Feb 2014

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

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.

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”

Main changes, modifications Language and structure for organizing epilepsies –G–Generalized versus Focal Seizures –“–“Etiology” –D–Diagnostic specificity –N–New recommended terms –O–Organization NO changes to electroclinical syndromes –A–A diagnosis can be made as previously eg Lennox-Gastaut syndrome, childhood absence epilepsy –A–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 Evolving to bilateral, convulsive seizure – Previous terms: partial seizure secondarily generalized; secondarily generalized tonic-clonic seizure – With tonic, clonic or tonic and clonic components

Symptomatogenic areas Left hemisphere, lateral aspect

Symptomatogenic areas Left hemisphere, mesial aspect

Symptomatogenic areas Left Insula

Common lateralising seizure manifestationsSymptomLocalisationSpecificityFrequency* Forced head turn (“version“) Contralateral>90%35-40% Unilateral dystonic posturing Contralateral>90%20-35% “Figure of Four“ Contralateral90% 65% (sGTCS) Postictal nosewiping Ipsilateral>70%10-50% Ictal speech** Nondominant>80%10-20% Ictal automatisms with preserved awareness Nondominant100%5% (Post)ictal dysphasia Dominant>80%20% *In patients referred for presurgical video telemetry

Less common lateralising or localising seizure manifestations SymptomLocalisationSpecificityFrequency Elementary visual auraContralateral occipital>90%? Acoustic auraTemporal, if unilateral then contralateral >90%? Olfactory auraMesiotemporal>70%? Abdominal aura  Automotor sz Temporal 90% 98% Common Ictal aphasiaDominant>80%? Ictal nystagmuscontralateral>95%? Hyperkinetic movements Frontal/frontomesial>80%>10%

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 - Myoclonic - Myoclonic atonic - Myoclonic tonic Clonic Tonic Atonic Seizure types thought to occur within and result from rapid engagement of bilaterally distributed systems

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

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

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

Key References ILAE commission report, Comments by Panayiotopoulos Epilepsia, 52: , 2011 Lüders et al, Epilepsia, 53:405–11, 2012 Berg & Scheffer Epilepsia, 52:1058–62, 2011 Shorvon Epilepsia, 52:1052–57, 2011 Glossary Blume et al, Epilepsia 2001