Postictal punctate hippocampal diffusion restriction: the chicken or the egg?

Area of Science:

• Neurology
• Radiology
• Neuroscience

Background:

• Magnet resonance imaging (MRI) with diffusion-weighted imaging (DWI) is vital for diagnosing cerebral ischemia and epileptic seizures.
• Postictal DWI lesions can mimic ischemia but typically cross vascular territories and are confined to the cortex.
• The hippocampus is a critical brain structure for memory and seizure generation.

Purpose of the Study:

• To investigate the occurrence and characteristics of reversible punctate hippocampal DWI lesions following epileptic seizures.
• To differentiate these postictal lesions from ischemic stroke and transient global amnesia (TGA).
• To highlight the clinical significance of recognizing this imaging finding for patient management.

Main Methods:

• Retrospective analysis of four cases with punctate hippocampal DWI lesions identified during video-electroencephalogram (EEG) monitoring.
• Initial MRI and follow-up MRI performed within days and months, respectively.
• Clinical assessment and video-EEG monitoring for all patients.

Main Results:

• Four patients (3 male/1 female, age 53-78) presented with punctate hippocampal DWI lesions after epileptic seizures.
• Initial diagnosis was ischemic stroke with acute-symptomatic seizures, but follow-up MRIs were normal.
• Video-EEG confirmed epilepsy in one patient and unprovoked seizures in the others, ruling out stroke.

Conclusions:

• Punctate hippocampal DWI lesions can be a postictal phenomenon, mimicking cerebral ischemia.
• Recognition of these reversible lesions is crucial for appropriate therapeutic management.
• Referral for video-EEG monitoring is recommended for inconclusive findings; potential mechanisms include vasogenic edema or venous compression.