Epilepsy — Written Clinical Reasoning

SAQ 1 — Acute Status Epilepticus Management (15 marks, 20 minutes)

Prompt: Outline your immediate and acute management of this patient, addressing airway, first-line pharmacological therapy, second-line therapy, and concurrent investigation for the underlying cause. Justify each step with reference to evidence and guideline thresholds. ^[1]

Case vignette: A 62-year-old man with type 2 diabetes and hypertension and a 40-pack-year smoking history is convulsing on ED arrival, now 12 minutes continuous, with no IV access. Saturation 90%, finger-prick glucose 4.2 mmol/L. Six-month history of morning confusion. ^[1]

Model Answer

Immediate assessment and stabilisation (3 marks): ^[1]

1. This is convulsive status epilepticus (SE) — continuous seizure activity for over 5 minutes. The ILAE 2015 operational definition sets t1 (the treatment threshold) at 5 minutes and t2 (the consequence threshold) at 30 minutes for convulsive SE ^[1]. This patient is at 12 minutes — well into established SE — and the clock is running toward neuronal injury.
2. Airway and oxygen — apply high-flow oxygen (15 L via non-rebreather mask), head tilt, jaw thrust, suction secretions. His saturation of 90 per cent reflects hypoventilation from ongoing seizure activity and airway compromise; rapid seizure termination will restore it.
3. Glucose — finger-prick glucose is 4.2 mmol/L, which is normal; hypoglycaemia is excluded as a cause. Do not delay treatment for further bloods.
4. Call for senior emergency and ICU support — this patient is at high risk of needing intubation.

First-line pharmacological therapy (4 marks): ^[1]

The first-line treatment of SE is a benzodiazepine. The standard adult dose is intravenous lorazepam 0.1 mg/kg (4 mg typical) repeated once at 5 to 10 minutes if seizure activity persists. However, paramedics were unable to establish intravenous access, and this patient has been convulsing for 12 minutes. ^[1]

The correct first-line agent in this situation is intramuscular midazolam 10 mg. The RAMPART trial (Silbergleit et al., NEJM 2012, PMID 22335736) randomised patients to IM midazolam versus IV lorazepam in the prehospital setting and found IM midazolam was superior: 73.4 per cent versus 63.4 per cent seizure-free on ED arrival ^[2]. The reason is that the median time to drug administration was 1.2 minutes for IM midazolam versus 4.8 minutes for IV lorazepam (because establishing IV access in a convulsing patient is slow). The faster administration more than compensated for the slightly slower drug absorption from the IM route.

Establish IV access concurrently with the IM midazolam administration; if the patient is still convulsing at 5 to 10 minutes after the first benzodiazepine dose, give a second benzodiazepine dose — IV lorazepam 4 mg if IV access is now available. ^[1]

Second-line pharmacological therapy (3 marks): ^[1]

If the patient is still convulsing after two benzodiazepine doses (i.e. established benzodiazepine-refractory SE), the next step is a non-benzodiazepine antiepileptic drug. The ESETT trial (Kapur et al., NEJM 2019, PMID 31774955) randomised patients with benzodiazepine-refractory convulsive SE to levetiracetam 60 mg/kg, fosphenytoin 20 mg PE/kg, or valproate 40 mg/kg and found all three were equivalent (47 per cent, 45 per cent, 46 per cent respectively terminating SE and improving consciousness at 60 minutes) ^[3].

For this patient, intravenous levetiracetam 60 mg/kg (approximately 4500 mg over 5 minutes) is a reasonable first choice because it has the most favourable safety profile, minimal drug interactions, and is not an enzyme inducer. Fosphenytoin 20 mg PE/kg would be appropriate if levetiracetam is unavailable or if there is a prior good response to phenytoin; valproate 40 mg/kg should be avoided given his hepatic status is unknown and levetiracetam is equally effective. ^[1]

Refractory SE (anaesthetic infusion) — only if second-line fails: ^[1]

If the patient is still convulsing after the second-line agent (typically beyond 40 minutes), he has refractory SE and requires intubation, mechanical ventilation, anaesthetic infusion (propofol infusion 1-2 mg/kg bolus then 30-200 microgram/kg/min, or midazolam infusion, or thiopentone), continuous EEG monitoring, and ICU admission. ^[1]

Concurrent investigation of the underlying cause (5 marks): ^[1]

New-onset status epilepticus in a 62-year-old demands a structural or metabolic cause search. The investigations and their rationale: ^[1]

Given the 6-month history of morning confusion and a 40-pack-year smoking history, a structural lesion (primary or secondary brain tumour, prior stroke, subdural haematoma) is the leading diagnostic consideration. His type 2 diabetes and hypertension also raise the possibility of cerebrovascular disease. ^[1]