Hippocampal subfield segmentation in temporal lobe epilepsy: Relation to outcomes

Area of Science:

• Neurology
• Radiology
• Epileptology

Background:

• Temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) is a common cause of refractory seizures.
• Accurate prediction of surgical outcomes in TLE is crucial for patient management.
• Hippocampal subfield volumes and internal architecture (HIA) may offer insights into epilepsy pathology and surgical success.

Purpose of the Study:

• To investigate the relationship between preoperative hippocampal subfield volumes and clinical/surgical outcomes in TLE patients.
• To evaluate the utility of a novel MRI multisequence segmentation technique for assessing hippocampal subfields.
• To determine if HIA ratings correlate with hippocampal subfield volumes and surgical outcomes.

Main Methods:

• 106 TLE patients with HS underwent T1-weighted and T2-weighted MRI.
• An automated algorithm segmented twelve hippocampal subfields.
• 76 patients had amygdalohippocampectomy; seizure outcomes were assessed using ILAE classification.
• HIA ratings were correlated with hippocampal subfield volumes.

Main Results:

• Left TLE patients had smaller contralateral presubiculum and hippocampus-amygdala transition area volumes.
• Right TLE patients showed reduced contralateral hippocampal tail volumes and better outcomes.
• No significant correlations were found between hippocampal subfield volumes and epilepsy duration or age at onset.
• No differences in hippocampal subfield volumes were observed between seizure-free and persistent seizure groups.
• Ipsilateral HIA ratings correlated with hippocampal and subfield volumes, but contralateral ratings did not.

Conclusions:

• Ipsilateral hippocampal subfield volumes do not correlate with TLE chronicity or severity.
• No significant differences in hippocampal subfield volumes or HIA ratings were found between patients with optimal and unfavorable surgical outcomes.
• Advanced MRI analysis of hippocampal architecture has limited predictive value for postoperative outcomes in TLE with HS.