Epilepsy and Seizure Disorders
This domain tests classification, semiology and drug choice. Vignettes usually describe the seizure rather than giving the diagnosis, so learn the patterns.
Classification (ILAE 2017)
Seizures are focal, generalised or unknown onset; focal seizures are further divided by awareness. Aetiologies are structural, genetic, infectious, metabolic, immune or unknown. Focal to bilateral tonic-clonic replaces the old term secondary generalised.
Semiology by lobe
- Temporal: epigastric rising aura, deja vu, automatisms, postictal confusion.
- Frontal: brief nocturnal hypermotor seizures with rapid generalisation.
- Occipital: elementary visual hallucinations; parietal: sensory phenomena.
- Juvenile myoclonic epilepsy: morning arm jerks, generalised 3 to 4 Hz polyspike-wave, photoparoxysmal response; valproate is most effective but avoided in women of childbearing age.
- Absence epilepsy: 3 Hz spike-wave, provoked by hyperventilation; ethosuximide is first line.
Status epilepticus
Convulsive status is defined at 5 minutes. Give a benzodiazepine, then a second-line agent such as levetiracetam, fosphenytoin or valproate; refractory cases need anaesthetic doses and intensive care.
Worked example
A 16-year-old boy has jerking of both arms on waking, one generalised tonic-clonic seizure, a normal MRI and an EEG showing 4 Hz polyspike-wave with photoparoxysmal response. This is juvenile myoclonic epilepsy. Management is counselling about sleep deprivation and alcohol, plus valproate in a male patient; the syndrome usually requires long-term treatment.
Traps
Prescribing carbamazepine in juvenile myoclonic epilepsy or absence seizures, which can worsen them; diagnosing epilepsy on a normal EEG; missing psychogenic non-epileptic attacks when prolactin is normal and eyes are closed during the event.