Seizures - absence
Red flags
- "Absence" in an adult with no childhood history - typical absence epilepsy almost never begins in adulthood
- Reconsider: focal impaired-awareness seizures (temporal), absence status, autoimmune encephalitis, metabolic
- Prolonged confusional state with fluctuating awareness -> absence status epilepticus (non-convulsive)
- EEG is the only way to make the diagnosis; responds to IV benzodiazepine
- Classically precipitated by an inappropriate sodium-channel blocker or benzodiazepine withdrawal
- Focal features, post-ictal confusion, automatisms lasting >30 s, aura -> focal seizure, not absence, and mandates MRI
- Developmental regression, ataxia or myoclonus -> symptomatic/progressive syndrome, not childhood absence epilepsy
- Atypical absence with slow spike-wave (<2.5 Hz), tonic and atonic seizures, intellectual disability -> Lennox-Gastaut
- Glucose transporter 1 deficiency - early-onset absences (<4 yrs), movement disorder, low CSF glucose -> ketogenic diet, not standard ASM
- Cardiac syncope mimicking blank spells -> ECG, long QT
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