Gray matter volume reductions occur in multiple extrahippocampal regions across temporal lobe epilepsy subtypesBrain Imaging Reveals Distinct Patterns in Temporal Lobe Epilepsy

Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology Published August 5, 2026 Study authors: Li Wenhao, Huang Xiang, Huang Kailing, Zhang Yingying, Li Yuming, Liu Peiwen, Cao Danyang, Li Wei, G… PubMed ↗ DOI ↗ Editorial oversight: Dr. Lars van Dijk, PhD · Surgical, Procedural & Diagnostic

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Key Takeaway

Note that TLE is associated with distinct gray matter volume reduction patterns across various extrahippocampal regions.

This meta-analysis and observational cross-sectional study evaluates gray matter volume (GMV) alterations in patients with temporal lobe epilepsy (TLE), including those with hippocampal sclerosis (HS) and MRI-negative TLE (TLE-no). The analysis focuses on identifying morphometric changes across various extrahippocampal regions to differentiate between TLE subtypes.

Key findings indicate GMV reductions in the ipsilateral hippocampus, parahippocampal gyrus, inferior temporal gyrus, fusiform gyrus, insula, lenticular nucleus, cerebellum, and bilateral thalamus. In contrast, patients with TLE-no showed increased GMV in the unilateral amygdala and parahippocampal gyrus. Specific reductions were also noted in the right amygdala and cerebellum when comparing right-sided HS to left-sided HS groups.

The authors note that the results for the TLE-no subgroup are limited by significant heterogeneity. Clinicians should exercise caution when interpreting GMV increases in MRI-negative cases due to this variability. The study provides evidence of distinct morphometric patterns across different TLE subgroups, which may assist in characterizing extrahippocampal involvement beyond the primary hippocampal regions.

How this fits prior evidence

This meta-analysis and observational study expands upon existing knowledge regarding temporal lobe epilepsy by identifying specific extrahippocampal gray matter volume alterations. While previous evidence linked longer epilepsy duration to lower DTI-ALPS index scores, this study provides more granular anatomical detail on GMV reductions in regions such as the insula, cerebellum, and thalamus across different TLE subtypes.

Researchers analyzed imaging data to look at gray matter volume in people with temporal lobe epilepsy (TLE). They specifically compared patients with hippocampal sclerosis (HS) and those with MRI-negative TLE (TLE-no) against healthy individuals. The study aimed to see how these different types of epilepsy affect various regions of the brain.

The findings show that most patients with TLE have a reduction in gray matter in areas like the hippocampus, parahippocampal gyrus, and thalamus. However, the results were different for those without hippocampal sclerosis. In some cases involving MRI-negative TLE, researchers found an increase in gray matter in the amygdala and parahippocampal gyrus.

Because these findings are based on observational data and meta-analyses of imaging, they show a link between brain structure and epilepsy rather than a direct cause. Some results for the MRI-negative group were less certain due to differences among those patients. These findings help doctors better understand how different types of temporal lobe epilepsy affect the brain's physical structure.

What this means for you:

Different types of temporal lobe epilepsy are linked to distinct patterns of gray matter changes in the brain.

Common questions

What did the study find about brain tissue in patients with TLE?

The study found that most people with temporal lobe epilepsy (TLE) showed a reduction in gray matter volume in several areas, including the hippocampus and thalamus. However, some patients without hippocampal sclerosis actually showed an increase in gray matter in the amygdala and parahippocampal gyrus.

How does this research differ between types of temporal lobe epilepsy?

The study looked at two main groups: those with hippocampal sclerosis (HS) and those with MRI-negative TLE. While both groups showed some common reductions in brain tissue, the MRI-negative group showed specific increases in certain areas like the amygdala.

Is this finding a way to treat epilepsy?

No, this study is an observation of brain structure and does not test treatments. It identifies how different types of temporal lobe epilepsy affect the brain's physical makeup. You should speak with your doctor about any changes to your treatment plan.

Study Details

Study typeMeta analysis

EvidenceLevel 1

PublishedJul 2026

PMID42533178

View Original Abstract ↓

OBJECTIVE: To investigate convergent patterns of gray matter volume (GMV) alterations in temporal lobe epilepsy (TLE) and to characterize distinct gray matter atrophy patterns across subtypes of TLE. METHODS: A coordinate-based meta-analysis was performed using anisotropic effect size-based signed differential mapping (AES-SDM). In addition, a complementary single-center observational cross-sectional VBM cohort including patients with hippocampal sclerosis (HS) and MRI-negative TLE (TLE-no) was analyzed to explore subgroup-related GMV alterations compared with healthy controls(HCs). RESULTS: The meta-analysis revealed the most consistent GMV reductions in the ipsilateral hippocampus and parahippocampal, ipsilateral inferior temporal gyrus, ipsilateral fusiform gyrus, ipsilateral insula, ipsilateral lenticular nucleus, ipsilateral cerebellum, and bilateral thalamus in TLE, compared with HCs. GMV increases of the unilateral amygdala and parahippocampal gyrus were observed in TLE without HS. In the observational cross-sectional analysis, patients with unilateral HS showed reduced GMV in the ipsilateral hippocampus, parahippocampal gyrus, fusiform gyrus, temporal gyrus, temporal pole, and thalamus, compared with HCs. Compared with the left HS, the right-sided HS group exhibited GMV atrophy in the right amygdala and cerebellum, alongside longer disease duration. In the Left-sided TLE-no patients, GMV increase was observed in the ipsilateral amygdala and parahippocampal gyrus in TLE-no. CONCLUSIONS: The meta-analysis identified multiple morphometric alterations in extrahippocampal regions in TLE and described GMV alteration patterns across different TLE subgroups. Complementary observational cross-sectional VBM cohort showed partially overlapping spatial patterns. GMV increases in the unilateral amygdala and parahippocampal gyrus were observed in MRI-negative TLE and should be interpreted cautiously, given the heterogeneity of this subgroup.

Gray matter volume reductions occur in multiple extrahippocampal regions across temporal lobe epilepsy subtypesBrain Imaging Reveals Distinct Patterns in Temporal Lobe Epilepsy

How this fits prior evidence

Common questions

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Gray matter volume reductions occur in multiple extrahippocampal regions across temporal lobe epilepsy subtypesBrain Imaging Reveals Distinct Patterns in Temporal Lobe Epilepsy

How this fits prior evidence

Common questions

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