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Network Analysis of Foramen Ovale Electrode Recordings in Drug-resistant Temporal Lobe Epilepsy Patients
Published on: December 18, 2016
Temporal pole MRI abnormalities in temporal lobe epilepsy
Philippe Ryvlin1, Sébastien Coste, Marc Hermier
1Functional Neurology and Epileptology Unit, University Neurological Hospital, Lyon, France.
Abstract:
Magnetic resonance imaging (MRI) demonstrates an abnormal aspect of the temporo-polar region in 1/3 to 2/3 of patients suffering from cryptogenic temporal lobe epilepsy. This abnormal aspect is described as a white matter increased T2 signal, resulting in a loss of gray-white matter demarcation, often associated with atrophy, as recently confirmed by quantitative volumetric measurements. These temporo-polar MRI findings appear to correctly lateralize the epileptogenic temporal lobe with a very high specificity, and have never been reported in extra-temporal lobe epilepsy nor in control subjects. They are usually associated with MRI signs of hippocampal sclerosis, but the two conditions seem to be partly distinct from a pathophysiological point of view. Pathological correlates of temporo-polar white matter increased T2 signal are controversial, but the role of an abnormal myelin seems more likely than that of ectopic neurons. A myelin dysfunction would also be consistent with the correlation observed between lateral temporal hypometabolism and temporo-polar MRI abnormalities. Whether or not these MRI findings are associated with a better seizure outcome following temporal lobectomy remains a debated issue.
Insights
Magnetic resonance imaging (MRI) reveals temporo-polar white matter abnormalities in many patients with cryptogenic temporal lobe epilepsy. These specific MRI findings help lateralize the seizure focus, suggesting potential myelin dysfunction.
Area of Science:
- Neurology
- Radiology
- Neuroimaging
Background:
- Cryptogenic temporal lobe epilepsy (TLE) presents diagnostic challenges.
- Magnetic resonance imaging (MRI) is crucial for identifying subtle brain abnormalities.
- Temporo-polar region involvement is increasingly recognized in TLE.
Purpose of the Study:
- To investigate the characteristics and diagnostic utility of temporo-polar MRI findings in cryptogenic TLE.
- To determine the specificity of these findings for lateralizing the epileptogenic zone.
- To explore potential pathophysiological underpinnings, such as myelin dysfunction.
Main Methods:
- Review of MRI scans from patients with cryptogenic TLE.
- Analysis of temporo-polar white matter T2 signal abnormalities and associated atrophy.
- Comparison with extra-temporal lobe epilepsy and control subjects.
- Correlation with hippocampal sclerosis and metabolic imaging.
Main Results:
- Abnormal temporo-polar white matter T2 signal and loss of gray-white matter demarcation observed in 1/3 to 2/3 of cryptogenic TLE patients.
- High specificity for correctly lateralizing the epileptogenic temporal lobe.
- Findings absent in extra-temporal lobe epilepsy and controls.
- Association with hippocampal sclerosis, but distinct pathophysiology suggested.
- Potential link to myelin dysfunction and lateral temporal hypometabolism.
Conclusions:
- Temporo-polar MRI abnormalities are a specific marker for lateralizing the seizure focus in cryptogenic TLE.
- Myelin dysfunction is a plausible pathophysiological explanation.
- The clinical significance for surgical outcomes requires further investigation.
