EEG stages predict treatment response in experimental status epilepticus.

Progression of severity in experimental status epilepticus (SE), defined as refractoriness to first- and second-line abortive agents, may be related to a five-stage progression of electroencephalography (EEG) patterns. This was tested in the lithium-pilocarpine rat SE model. Abortive treatment with diazepam and phenobarbital was given at EEG stages I, III, and V. In stage I, the combination therapy resulted in 100% SE termination. However, stage III corresponded to high treatment resistance (0% abortion) and stage V to an intermediate response (63%). Comparisons of time-to-treatment durations showed overlap between stage I and stage III, despite having markedly different response rates to abortive medications. Therefore, EEG patterns reflect the dynamic pathophysiology of SE and can be used as reliable and specific markers to distinguish treatment-responsive from treatment-refractory SE more accurately than time alone.