Background: Limbic encephalitis (LE) classically
causes medial temporal lobe T2-hyperintensity on magnetic resonance imaging
(MRI), but this can also occur with seizure activity. Identifying
neuroimaging patterns that can distinguish between LE and seizure activity
may help avoid diagnostic confusion in such challenging cases.
Methods: Through retrospective review of Mayo
Clinic patients who had medial temporal lobe T2-hyperintensity on MRI, we
identified non-LE patients with seizure-related medial temporal lobe
T2-hyperintensity. Their diffusion-weighted imaging (DWI) was reviewed to
look for diffusion restriction patterns potentially unique to seizure
activity. Next, a control cohort of LE patients with medial temporal lobe
T2-hyperintensity was identified, and their DWI was reviewed to see if these
diffusion restriction patterns could help distinguish seizure activity from
LE. Results: We identified 10 non-LE patients who had
medial temporal lobe T2-hyperintensity due to seizure activity; 9/10 had one
of two medial temporal lobe diffusion restriction patterns we uncovered as
being potentially unique to seizure activity. In contrast, only 5/57 LE
patients had one of these diffusion restriction patterns identified, all of
whom had seizures reported. Conclusions: We report
two diffusion restriction patterns that may help distinguish seizure
activity from LE. Recognition of these diffusion restriction patterns should
prompt evaluation for possible seizure activity.
A.3 Use of diffusion-weighted imaging to distinguish seizure-related
change from limbic encephalitis
