Subcortical Gray Matter Volume Abnormalities in Temporal Lobe Epilepsy with Hippocampal Atrophy

Area of Science:

• Neurology
• Radiology
• Neuroimaging

Background:

• Hippocampal atrophy (HA) is a key indicator in drug-resistant temporal lobe epilepsy (TLE), often detectable via MRI.
• Quantitative MRI techniques enhance the evaluation of extratemporal gray matter (GM) abnormalities.
• Subcortical GM volume analysis, including hippocampal subfields, is crucial for understanding TLE-HA.

Purpose of the Study:

• To investigate the relationship between subcortical GM volume and TLE-HA.
• To perform hippocampal subfield analysis in patients with TLE-HA.
• To compare subcortical GM volumes between TLE-HA patients and healthy controls.

Main Methods:

• A transversal observational study included 38 patients with TLE-HA and 59 healthy controls.
• Automated techniques were used to obtain subcortical GM volumes (hippocampus, amygdala, basal ganglia) from MRI scans.
• Statistical comparisons were made between the TLE-HA group and the control group.

Main Results:

• Right TLE-HA patients showed no significant subcortical volume loss but had contralateral amygdala enlargement.
• Left TLE-HA patients exhibited contralateral hippocampal amygdala transitional area enlargement.
• No significant volume loss was detected in the contralateral hippocampus or specific hippocampal subfields in either TLE-HA group.

Conclusions:

• Distinct patterns of subcortical volume abnormalities exist in left versus right TLE-HA, potentially reflecting different ictal-side neural network issues.
• Subtle contralateral amygdala enlargement was observed in both TLE-HA groups, possibly contributing to epileptogenic mechanisms.
• Automated analysis did not reveal significant volume abnormalities in the contralateral hippocampus or specific hippocampal subfields.