Status epilepticus: Viva

Branch 1: Definition and pharmacodynamic rationale

The candidate should define status epilepticus as a continuous seizure or a run of seizures without recovery that lasts long enough to threaten the brain. A strong candidate gives the ILAE operational definition with the two time points, t1 of five minutes beyond which a convulsive seizure is unlikely to self-terminate, and t2 of thirty minutes beyond which neuronal injury can begin, and explains that the window between t1 and t2 is the treatment window. [1]

If the examiner presses on why the first dose must be early and full, the candidate should describe the pharmacodynamic shift. As the seizure runs, the GABA-A receptors on the neuronal surface internalise, so fewer remain for a benzodiazepine to act on, while the excitatory NMDA and AMPA glutamate receptors are recruited to the surface and increase calcium inflow. The candidate should state that this trafficking shift explains the steep decline in benzodiazepine efficacy with time, which is why a full weight-based dose given at five minutes works far better than the same dose at thirty minutes. [4]

Branch 2: The stepwise drug pathway

If asked to run the pathway, the candidate should describe the APLS stepwise ladder. In the first five minutes the priority is the airway, high-flow oxygen, the bedside glucose check, and a first-line benzodiazepine. The candidate should give the dose of lorazepam at 0.1 mg per kg intravenously, to a maximum of 4 mg per dose, or buccal midazolam at 0.15 mg per kg if intravenous access is not available, repeated once after five minutes, with no more than two benzodiazepine doses in total. [2]

For this girl, who is still seizing at twelve minutes after her first benzodiazepine, the candidate should proceed to a second-line agent. The preferred agent is levetiracetam at 40 mg per kg intravenously, to a maximum of 4.5 g over five minutes, or fosphenytoin at 20 mg phenytoin-equivalent per kg, to a maximum of 1500 mg phenytoin-equivalent over ten minutes. The candidate should name the reversible causes, including the missed medication and the viral illness, and state that the antiseizure drug level is checked and the maintenance therapy is reviewed and reinstated. [2]

Branch 3: The refractory case and the trial evidence

If the examiner moves to the refractory case, the candidate should state that seizure persisting beyond thirty minutes or despite adequate first and second-line therapy is refractory status epilepticus. The management is rapid sequence intubation to protect the airway and ventilate, followed by a continuous midazolam, propofol, or thiopentone infusion titrated to burst suppression on the EEG. The candidate should emphasise that continuous EEG monitoring is mandatory from this point, because once the child is paralysed the clinical signs of seizure disappear and only the EEG reveals whether the brain is still seizing. [2]

A strong candidate appraises the trial evidence. The candidate should describe ESETT, which showed levetiracetam, fosphenytoin, and valproate were equally effective, each stopping about half of established seizures, and should name the two paediatric trials, ConSEPT and EcLiPSE, which showed levetiracetam was at least as effective as phenytoin in children with a better safety profile. The candidate should conclude that levetiracetam is the preferred second-line agent in many modern paediatric pathways, that the commonest deviation from guideline care is under-dosing the first benzodiazepine, and that adherence to the stepwise ladder is itself a determinant of outcome. [3]