Status epilepticus: Clinical characteristics and EEG patterns associated with and without MRI diffusion restriction in 69 patients

Abstract

Objective: Incidence and localization of cortical and thalamic peri-ictal diffusion-weighted imaging (DWI) abnormalities were investigated in patients with status epilepticus (SE). Clinical characteristics and EEG features were compared between patients with and without peri-ictal regional DWI restriction. Such correlations are important to improve the understanding of causes and significance of peri-ictal DWI restriction.

Methods: We retrospectively investigated 69 SE-patients treated in our emergency department in whom SE was confirmed by EEG and MRI including DWI was performed.

Results: 19/69 patients presented with peri-ictal DWI restriction: 18/19 with cortical restriction, 13 of them with additional thalamic restriction, and 1/19 with thalamic restriction only. 17/69 patients had DWI restrictions related to other pathologies, so that a possible overlap with peri-ictal DWI restriction could not be determined. In 33/69 patients no peri-ictal DWI restriction was detected. In contrast to SE-patients without DWI restriction, those with peri-ictal DWI restriction always presented with regional/unilateral epileptiform discharges (p<0.001). The EEG of SE-patients with peri-ictal DWI restriction was predominated by circumscribed periodic lateralized epileptiform discharges (PLEDs) (p<0.001) and by repetitive seizure patterns (p=0.009), while PLEDs occurred infrequently and EEG patterns were more variable in extent in patients without DWI restriction. Patients with peri-ictal diffusion had more often a quantitative disorder of consciousness (p=0.05) compared to patients without peri-ictal DWI restriction. No significant differences were found concerning age of patients, preceding generalized tonic-clonic seizures, and mortality.

Significance: Patients with peri-ictal DWI restriction presented with a rather uniform EEG pattern characterized by circumscribed PLEDs possibly resulting from local cortical metabolic disturbances and with intermittent seizure patterns. The frequently observed quantitative disorder of consciousness despite circumscribed EEG patterns could be related to epileptic activity in the temporal lobe and cortico-thalamic synchronization. The higher percentage of bilateral status patterns and subcortical lesions in patients without peri-ictal DWI restrictions suggest a different pathomechanism.

Keywords: DWI restriction; MRI; Mortality; PLEDs; Status epilepticus.