Investigating Peri-Ictal MRI Abnormalities: A Prospective Neuroimaging Study on Status Epilepticus, Seizure Clusters, and Single Seizures

Abstract

Background/Objectives: Brain magnetic resonance imaging (MRI) often reveals acute peri-ictal abnormalities (PMAs) during or shortly after status epilepticus (SE) but also following single seizures (SiS) or clusters of seizures (CS). However, the incidence, characteristics, and progression remain not clearly known. This study aimed to investigate incidence, clinical correlations, and evolution of PMAs in SE, CS, and SiS patients. Methods: This prospective observational study enrolled patients with SE, CS, and SiS who underwent MRI within 120 h of the ictal event. Demographic, clinical, EEG, and MRI data were collected. Patients with PMAs (PMAs+) underwent serial follow-up MRI. Incidence, association with clinical characteristics, and progression of PMAs were analyzed across the three groups. Results: Among 76 patients (30 SE, 22 CS, 24 SiS), PMAs were observed in 31 (41%), with a significant difference between groups (p = 0.011), as PMAs were less frequent in SiS (17%) compared to SE (57%) and CS (45%) patients. Acute symptomatic SE/seizures were significantly more common in PMAs+ compared to PMAs- in the overall cohort (52% vs. 29%; p = 0.045) and in the SiS group (100% vs. 25%; p = 0.031). History of epilepsy was less frequent in PMAs+ in the whole cohort (13% vs. 40%; p = 0.011) and in SE in particular (12% vs. 46%, p = 0.049). No association between PMAs and seizure type, SE duration, etiology, time to MRI, and EEG findings (p > 0.005) was found. The temporal cortex and hippocampus were most frequently affected by PMAs. Follow-up MRI performed in 16 patients showed resolution of PMAs in 75% (5/7 SE, 3/6 CS, 3/3 SiS) within a median time of 24 days (IQR: 8-39). Conclusions: PMAs were more common in SE and CS than in SiS. Acute underlying pathology was frequently associated with PMAs. While duration of ictal activity is an important factor, it was not the sole determinant. Most PMAs resolved, particularly in SiS. Further studies are needed to clarify the pathophysiological mechanism and clinical implications of PMAs.

Keywords: convulsive status epilepticus; epilepsy; non-convulsive status epilepticus; peri-ictal DWI abnormalities; peri-ictal FLAIR abnormalities; transient MRI hyperintensity.

Figure 1

Study flowchart. Ultimately, 15 out of the 91 initially enrolled patients were excluded due to overlap of DWI/FLAIR abnormalities with a concomitant or pre-existing primary brain lesion not related to ictal activity. Follow-up MRI was unavailable for 15 subjects.

Figure 2

Anatomical distribution of peri-ictal MRI abnormalities. The temporal lobe and hippocampus were the most frequently affected regions in SE, CS, and SiS. Thalamic involvement was also frequently observed. In all three groups, the lesions were predominantly unilateral.

Figure 3

Timeline of PMA relapse in patients performing follow-up MRI in the SE, CS, or SiS groups. The figure illustrates the follow-up MRI outcomes for the 16 patients who underwent the procedure (7 SE, 6 CS, 3 SS). Resolution of PMAs was observed in patients 2, 3, 6, 7, 9, 10, 11, 12, 14, and 16 after the first follow-up MRI, while the remaining patients continued to exhibit PMAs. The disappearance of PMAs was demonstrated in patients 1 and 15 after additional MRI scans. Further follow-up was not conducted for four patients due to unavailability (patients 5, 8, and 12) or death (patient 4).