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Updated: Mar 5, 2026
Anteromesial Temporal Lobectomy for Medically Intractable Temporal Lobe Epilepsy: An Operative Study
Published on: August 15, 2025
Morphometric MRI features are associated with surgical outcome in mesial temporal lobe epilepsy with hippocampal
Maria Teresa Fernandes Castilho Garcia1, Larissa Botelho Gaça1, Gabriel Barbosa Sandim2
1Unidade de Pesquisa e Tratamento das Epilepsias, Department of Neurology and Neurosurgery of Universidade Federal de São Paulo (UNIFESP), Rua Pedro de Toledo, 650, Vila Clementino, CEP 04039-002, São Paulo, SP, Brazil.
Purpose:
Corticoamygdalohippocampectomy (CAH) improves seizure control, quality of life, and decreases mortality for refractory mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). One-third of patients continue having seizures, and it is pivotal to determine structural abnormalities that might influence the postoperative outcome. Studies indicate that nonhippocampal regions may play a role in the epileptogenic network in MTLE-HS and could generate seizures postoperatively. The aim of this study is to analyze areas of atrophy, not always detected on routine MRI, comparing patients who became seizure free (SF) with those non seizure free (NSF) after CAH, in an attempt to establish possible predictors of surgical outcome.
Methods:
105 patients with refractory MTLE-HS submitted to CAH (59 left MTLE; 46 males) and 47 controls were enrolled. FreeSurfer was performed for cortical thickness and volume estimation comparing patients to controls and SF versus NSF patients. The final sample after post processing procedures resulted in 99 patients.
Results:
Cortical thickness analyses showed reductions in left insula in NSF patients compared to those SF. Significant volume reductions in SF patients were present in bilateral thalami, hippocampi and pars opercularis, left parahippocampal gyrus and right temporal pole. In NSF patients reductions were present bilaterally in thalami, hippocampi, entorhinal cortices, superior frontal and supramarginal gyri; on the left: superior and middle temporal gyri, temporal pole, parahippocampal gyrus, pars opercularis and middle frontal gyrus; and on the right: precentral, superior, middle and inferior temporal gyri. Comparison between SF and NSF patients showed ipsilateral gray matter reductions in the right entorhinal cortex (p=0.003) and contralateral parahippocampal gyrus (p=0.05) in right MTLE-HS. Patients NSF had a longer duration of epilepsy than those SF (p=0.028).
Conclusion:
NSF patients exhibited more extensive areas of atrophy than SF ones. As entorhinal cortex and parahippocampal gyrus are reduced in NSF patients compared to those SF these structures might be implicated in the network responsible for the maintenance of postoperative seizures. Duration of epilepsy is a predictor of seizure outcome.
Insights
Corticoamygdalohippocampectomy (CAH) can improve epilepsy control, but some patients remain seizure-free. This study identified specific brain atrophy patterns, particularly in the entorhinal cortex and parahippocampal gyrus, that predict continued seizures after CAH.
Area of Science:
- Neurosurgery
- Epileptology
- Neuroimaging
Background:
- Corticoamygdalohippocampectomy (CAH) is a treatment for refractory mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS).
- Approximately one-third of patients do not achieve seizure freedom post-CAH.
- Non-hippocampal brain regions may contribute to persistent seizures in MTLE-HS.
Purpose of the Study:
- To identify structural brain abnormalities, beyond routine MRI, that predict surgical outcomes in MTLE-HS patients.
- To compare patterns of atrophy between seizure-free (SF) and non-seizure-free (NSF) patients post-CAH.
- To determine potential predictors of surgical success in MTLE-HS.
Main Methods:
- 105 patients with refractory MTLE-HS underwent CAH; 99 completed the study.
- FreeSurfer software was used for cortical thickness and volume analysis.
- Comparison of brain structures between SF and NSF patient groups, and with controls.
Main Results:
- NSF patients showed greater overall atrophy than SF patients.
- Reductions in the left insula were observed in NSF patients compared to SF patients.
- Specific gray matter reductions in the entorhinal cortex and parahippocampal gyrus were associated with non-seizure freedom.
Conclusions:
- Extensive atrophy, particularly in the entorhinal cortex and parahippocampal gyrus, may indicate a higher likelihood of persistent seizures post-CAH.
- These atrophic regions might be part of the epileptogenic network sustaining postoperative seizures.
- Longer epilepsy duration is a predictor of poorer seizure outcome after CAH.
