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Developmental abnormalities of the medial temporal lobe in patients with temporal lobe epilepsy
S Lehéricy1, D Dormont, F Sémah
1Department of Neurology, Hôpital de la Salpêtrière, Paris, France.
Purpose:
To evaluate MR temporal lobe malformations and their frequency in patients with temporal lobe epilepsy.
Methods:
Two hundred twenty-two consecutive adult patients with temporal lobe epilepsy of varying severity were investigated with 1.0-T or 1.5-T MR units using three-dimensional T1-weighted acquisition protocol.
Results:
Sixteen patients (7.2%) presented with malformations of the temporal lobe. Four patterns of malformations were encountered: (a) heterotopia (n = 1), lining the temporal horn of the lateral ventricle; (b) focal neocortical dysgenesis (n = 6), which consisted of cortical thickening, poor gray/white matter demarcation, abnormal gyration (n = 5), or limited schizencephaly (n = 1); (c) hippocampal malformations (n = 5), which presented as abnormal hippocampal formation associated with a cyst (n = 2), isolated malformation of the subiculum (n = 1), or bilateral hippocampal malformation (n = 2) consisting of an abnormal shape and a misplaced fimbria; (d) complex malformations of the temporal lobe, combining categories a, b, and c (n = 4). The age at onset, severity of the disease, and occurrence of generalized tonicoclonic seizures were not significantly different between patients with malformations and the entire population of patients with temporal lobe epilepsy.
Conclusion:
MR analysis of temporal lobe malformations allowed a precise determination of the extent of the malformations and the presence or absence of associated hippocampal disease, all of which are of great help in the preoperative evaluation of patients with intractable epilepsy.
Insights
Magnetic resonance imaging (MRI) detected temporal lobe malformations in 7.2% of patients with temporal lobe epilepsy. These malformations aid in preoperative evaluation for intractable epilepsy.
Area of Science:
- Neurology
- Radiology
- Neuroimaging
Background:
- Temporal lobe epilepsy (TLE) is a common neurological disorder.
- Identifying underlying structural abnormalities is crucial for understanding TLE.
- Magnetic resonance imaging (MRI) is a key tool for neuroimaging.
Purpose of the Study:
- To evaluate the frequency and types of temporal lobe malformations in patients with TLE.
- To assess the utility of MRI in characterizing these malformations.
Main Methods:
- A cohort of 222 adult patients with TLE underwent MRI.
- High-resolution, three-dimensional T1-weighted imaging was utilized.
- Malformations were classified into distinct patterns.
Main Results:
- Temporal lobe malformations were identified in 7.2% of patients.
- Four main patterns were observed: heterotopia, focal neocortical dysgenesis, hippocampal malformations, and complex malformations.
- No significant differences in disease onset, severity, or seizure types were found between patients with and without malformations.
Conclusions:
- MRI effectively detects and characterizes temporal lobe malformations in TLE patients.
- Precise determination of malformation extent and associated hippocampal disease is possible.
- Findings are valuable for preoperative evaluation of intractable epilepsy.