Imaging of Status Epilepticus

MRI plays an increasingly important role in the diagnosis of status epilepticus (SE). Approximately half of patients with SE do not have pre-existing epilepsy, and the cause of de novo SE is frequently unknown. The role of MRI in the identification of causes of SE is invaluable. MRI is often helpful as a diagnostic tool in cases of non-convulsive status epilepticus (NCSE) with ambiguous EEG findings. Thus, MRI is recommended for all patients presenting with de novo SE, patients with known epilepsy with the first episode of SE and NCSE with equivocal EEG. Different peri-ictal MRI (PMA) alterations may be seen during ongoing SE or briefly after its cessation. They commonly present as peri-ictal hyper-perfusion, diffusion restriction and/or FLAIR-hyperintensity affecting specific brain areas such as the cortex, hippocampus, pulvinar of the thalamus, splenium of the corpus callosum, claustrum or cerebellum, frequently in combination, suggesting the existence of a "status epilepticus network". MRI sequences, which are necessary for detecting PMA, include diffusion-weighted imaging, fluid attenuated inversion recovery, T1-weighted imaging with and without contrast application, as well as perfusion sequences such as arterial spin labeling. Recent research suggests that they may serve as biomarkers for predicting an outcome in SE. Patients with PMA seem to have a higher mortality rate compared to those without PMA. However, there is still a substantial knowledge gap and there are many open questions related to imaging in SE. Further prospective quantitative MRI studies with uniform protocols, timing and follow-up periods are needed to answer these important and clinically relevant questions.