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Published on: August 5, 2014
Internal structural changes in the hippocampus observed on 3-tesla MRI in patients with mesial temporal lobe epilepsy
Takahiro Mitsueda-Ono1, Akio Ikeda, Nobukatsu Sawamoto
1Department of Neurology, Kyoto University Graduate School of Medicine, Japan.
Objective:
Hippocampal sclerosis (HS) is observed in many intractable, mesial temporal lobe epilepsy (MTLE) patients. We aimed to delineate the internal structural changes (ISC) shown as loss of internal architecture in the hippocampus on 3-Tesla magnetic resonance imaging (3T-MRI) due to its higher spatial resolution.
Methods:
We studied 12 MTLE patients who exhibited unilateral HS on conventional 1.5 Tesla-MRI. Using 3T-MRI, high resolution T2-weighted coronal images of the hippocampus were investigated by visual inspection without the use of detailed clinical information. In addition, tissue samples obtained from four patients who underwent epilepsy surgery were analyzed histopathologically.
Results:
In addition to hippocampal atrophy (HA) in the abnormal side, blurring of the low-intensity streak, i.e., ISC, in the hippocampus was seen in 12 patients and atrophy or high signal intensity was observed in Ammon's horn or the dentate gyrus in nine patients. After four patients underwent epilepsy surgery, tissue samples showed astrogliosis and a loss of pyramidal neurons in the hippocampal body, concordant with ISC or HA on MRI examination.
Conclusion:
High-resolution MRI suggests that minute internal structural changes in the hippocampus reflect neuronal cell loss or gliosis, possibly in the early stage, and also show laterality of changes more sensitively. Different internal structural changes could further subclassify HS and may predict the surgical outcomes of seizure control based on the clinicopathological correlation.
Insights
High-resolution 3-Tesla MRI reveals subtle internal structural changes in the hippocampus, indicating neuronal loss or gliosis in mesial temporal lobe epilepsy (MTLE) patients with hippocampal sclerosis (HS). These findings may help classify HS and predict surgical outcomes.
Area of Science:
- Neurology
- Radiology
- Pathology
Background:
- Hippocampal sclerosis (HS) is a common cause of intractable mesial temporal lobe epilepsy (MTLE).
- Conventional MRI often shows hippocampal atrophy (HA) in affected individuals.
- Higher spatial resolution MRI may offer more detailed insights into HS pathology.
Purpose of the Study:
- To delineate internal structural changes (ISC) in the hippocampus using 3-Tesla MRI (3T-MRI) in MTLE patients with HS.
- To correlate MRI findings with histopathological analysis.
- To explore the potential of 3T-MRI in subclassifying HS and predicting surgical outcomes.
Main Methods:
- Studied 12 MTLE patients with unilateral HS on 1.5T-MRI.
- Acquired high-resolution T2-weighted coronal 3T-MRI images of the hippocampus.
- Visually inspected MRI images and analyzed histopathology from four surgically treated patients.
Main Results:
- All 12 patients showed blurring of the low-intensity streak (ISC) in the hippocampus, alongside HA.
- Nine patients exhibited atrophy or high signal intensity in the Ammon's horn or dentate gyrus.
- Histopathology confirmed astrogliosis and neuronal loss, correlating with MRI findings of ISC and HA.
Conclusions:
- High-resolution 3T-MRI can detect subtle hippocampal structural changes indicative of neuronal loss or gliosis, potentially in early stages of HS.
- These changes are sensitive in showing laterality.
- Further subclassification of HS and prediction of surgical outcomes may be possible through detailed analysis of internal structural changes and clinicopathological correlation.
