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]