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From the Department of Neurology (H.K., N.B., B.B., A.B.), McGill University, Montreal Neurological Institute, Quebec, Canada; and Cognitive Neuroscience and Brain Imaging Laboratory (O.C.), CNRS, Hôpital de la Salpêtrière, Paris, France.
Address correspondence and reprint requests to Dr. Andrea Bernasconi, Montreal Neurological Institute, 3801 University Street, Montreal, Quebec, Canada H3A 2B4 andrea{at}bic.mni.mcgill.ca
Background: We previously demonstrated that shape variants of the hippocampal formation are more prevalent in patients with temporal lobe epilepsy (TLE) than in healthy individuals.
Objective: To categorize sulcal patterns of the basal temporal lobe in TLE compared to healthy controls.
Methods: We studied 51 healthy controls and 69 patients with TLE (37 left, 32 right TLE). Brain sulci were identified and labeled automatically on MRI using an algorithm based on a congregation of neural networks that allows mapping three-dimensional sulcal models on the cortical surface. We used four sulcal patterns classes to categorize the sulcal arrangement in the inferior surface of the temporal lobe in each subject: Type 1, i.e., single-branch, unbroken collateral sulcus (CS) connected with the rhinal sulcus (RS) anteriorly; Type 2, i.e., CS connected with the occipitotemporal sulcus (OTS), but separated from the RS; Type 3, i.e., CS separated from the OTS and RS, which are connected; and Type 4, i.e., CS, OTS and RS separated.
Results: In healthy controls, Type 1 and Type 2 were the patterns seen most frequently. Overall, 82% (42/51) of subjects had the same sulcal pattern in both temporal lobes. Inter-rater reliability for 35 randomly selected subjects indicated excellent agreement (Cohen's Kappa: 0.84). Compared to controls, we found an increased frequency of Type 1 CS in patients with TLE, both in the left (77% vs 47%, p = 0.004) and the right hemispheres (72% vs 41%, p = 0.002). On the other hand, we found a decreased frequency of Type 2 CS in patients with TLE, both in the left (4% vs 31%, p = 0.00002) and the right hemisphere (4% vs 35%, p < 0.00001).
Conclusions: A single-branch, unbroken collateral sulcus is the predominant sulcal pattern found in temporal lobe epilepsy. This "simplified" arrangement may be an indicator of neurodevelopmental deviance associated with this condition.
GLOSSARY: CS= collateral sulcus; OTS= occipitotemporal sulcus; RS= rhinal sulcus; TLE= temporal lobe epilepsy.
Received May 29, 2007. Accepted in final form November 21, 2007.
Funded by a grant from the Canadian Institutes of Health Research (CIHR-MOP 57840). B.B is supported by the German National Merit Foundation, Bonn, Germany.
Disclosure: The authors report no disclosures.
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