Seizures - generalised tonic–clonic
Red flags
- Seizure lasting >5 minutes or repeated without recovery -> status epilepticus, treat immediately
- Failure to regain baseline consciousness within ~20-30 minutes -> consider non-convulsive status
- First seizure with focal neurological signs, papilloedema, or new headache -> structural lesion
- First seizure in pregnancy with hypertension/proteinuria -> eclampsia
- Fever with meningism or reduced consciousness -> CNS infection
- Seizure with cardiac chest pain/arrhythmia preceding -> consider convulsive syncope, not epilepsy
Differential by mechanism
Provoked (acute symptomatic)
- Metabolic: hypoglycaemia, hyponatraemia, hypocalcaemia, uraemia, hepatic encephalopathy
- Toxic/withdrawal: alcohol withdrawal, benzodiazepine withdrawal, sympathomimetics, tricyclic/tramadol/bupropion overdose
- Structural (acute): stroke, traumatic brain injury, subarachnoid haemorrhage
- Infective: meningitis, encephalitis
- Eclampsia
Unprovoked (epilepsy)
- Idiopathic generalised epilepsy (genetic)
- Structural epilepsy - prior stroke, tumour, mesial temporal sclerosis, cortical dysplasia, old trauma
Mimics
- Convulsive syncope - brief myoclonic jerks after loss of consciousness from a cardiac/vasovagal cause, rapid recovery
- Psychogenic non-epileptic seizure - longer duration, fluctuating course, resisted eye opening, pelvic thrusting, preserved awareness of surroundings in some
- Hypoglycaemia alone (no seizure) mimicking post-ictal state
Focused history
- Eyewitness account is essential - onset (sudden vs preceded by aura/prodrome), duration, tonic then clonic pattern, tongue biting (lateral), incontinence, post-ictal confusion/Todd's paresis
- First seizure vs known epilepsy - medication adherence, missed doses, sleep deprivation, alcohol
- Preceding palpitations/chest pain (cardiac cause), preceding aura (focal onset)
- Triggers - flashing lights, sleep deprivation, alcohol withdrawal, fever, missed medication
- Pregnancy status, family history of epilepsy, sudden unexplained death
- Driving and occupational implications (mandatory reporting considerations)
Focused examination
- Full neurological exam once post-ictal period resolves - focal deficit (Todd's paresis vs new lesion)
- Tongue (lateral bite marks), signs of injury from the fall
- Cardiovascular exam - murmurs, irregular rhythm (cardiac cause of collapse)
- Signs of meningism, fever
- Signs of chronic alcohol use, hepatic/renal disease
- Skin (neurocutaneous stigmata if considering a structural epilepsy syndrome)
Investigation strategy
- Bedside glucose immediately
- Bloods: UEC, calcium, magnesium, glucose, LFT, FBE, anticonvulsant levels if applicable, VBG
- ECG in every first seizure - exclude long QT, arrhythmia, structural mimics of "seizure"
- CT brain - first seizure in an adult, focal signs, or failure to return to baseline
- MRI brain (outpatient, unless red flags) - more sensitive for epileptogenic structural lesions (mesial temporal sclerosis, cortical dysplasia, low-grade tumour)
- EEG - supports diagnosis and epilepsy syndrome classification; a normal EEG does not exclude epilepsy
- LP if infective cause suspected once safe
Management
A. Acute
- Protect airway, recovery position once convulsion stops, do not restrain or insert anything in the mouth
- Benzodiazepine if seizure continues beyond 5 minutes (see Status epilepticus note)
- Treat any identified provoking cause (glucose, electrolyte correction, alcohol withdrawal regimen)
B. First unprovoked seizure - starting anticonvulsants is not automatic
- Recurrence risk after a single unprovoked seizure ~40-50% at 2 years; higher with an abnormal EEG, structural lesion on MRI, or nocturnal seizure
- Start anticonvulsant if high recurrence risk (epileptiform EEG, structural lesion, prior brain insult) or after a second unprovoked seizure
- Shared decision-making - factor in occupational/driving implications of a further seizure
C. Provoked (acute symptomatic) seizure
- Treat the cause, not with long-term anticonvulsants - e.g. correct sodium, treat alcohol withdrawal - recurrence risk is low once the provoking factor resolves
D. Choice of anticonvulsant (by epilepsy type, not by default)
- Generalised epilepsy: sodium valproate most effective but avoided in women of childbearing potential (teratogenicity, PBS/TGA restricted access requiring pregnancy prevention program) - levetiracetam or lamotrigine preferred first-line in this group
- Focal-onset epilepsy (including secondarily generalised): levetiracetam, lamotrigine, or carbamazepine
E. Lifestyle and safety
- Driving restriction per state regulations (typically 6-12 months seizure-free depending on jurisdiction and seizure type)
- Sleep hygiene, alcohol moderation, medication adherence counselling
- Contraception and pregnancy planning discussion in women of childbearing age on enzyme-inducing or teratogenic agents
Traps
- Starting long-term anticonvulsants after a single provoked seizure with a clearly reversible cause
- Starting valproate in a woman of childbearing potential without discussing teratogenicity and access restrictions
- Assuming a normal EEG or MRI excludes epilepsy
- Missing convulsive syncope (brief myoclonic jerks after a faint) and diagnosing epilepsy
- Not addressing driving/occupational safety and legal reporting obligations after a first seizure
Talk track
First step is provoked vs unprovoked - correct any acute cause (glucose, electrolytes, alcohol withdrawal) and only start long-term anticonvulsants for unprovoked seizures with high recurrence risk (epileptiform EEG, structural lesion) or after a second unprovoked seizure. Drug choice follows epilepsy type, not habit - avoid valproate in women of childbearing potential. Every first seizure needs a glucose, ECG, and driving safety discussion regardless of what else is found.
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