Temporal pole MRI abnormalities in temporal lobe epilepsy.
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.
Ryvlin
Philippe
P
Functional Neurology and Epileptology Unit, University Neurological Hospital, Lyon, France.
Coste
Sébastien
S
Hermier
Marc
M
Mauguière
François
F
D001284:Atrophy / Q000473:pathology / Q000601:surgery; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000601:surgery; D005442:Flumazenil / Q000493:pharmacokinetics; D018757:GABA Modulators / Q000493:pharmacokinetics; D006801:Humans; D008279:Magnetic Resonance Imaging; D013702:Temporal Lobe / Q000002:abnormalities* / Q000378:metabolism / Q000601:surgery; D014055:Tomography, Emission-Computed
D018757:GABA Modulators; D005442:Flumazenil