FULL-LENGTH ORIGINAL RESEARCH
Asymmetric cortical surface area and morphology changes in mesial temporal lobe epilepsy with hippocampal sclerosis
Article first published online: 17 APR 2012
Wiley Periodicals, Inc. © 2012 International League Against Epilepsy
Volume 53, Issue 6, pages 995–1003, June 2012
How to Cite
Alhusaini, S., Doherty, C. P., Palaniyappan, L., Scanlon, C., Maguire, S., Brennan, P., Delanty, N., Fitzsimons, M. and Cavalleri, G. L. (2012), Asymmetric cortical surface area and morphology changes in mesial temporal lobe epilepsy with hippocampal sclerosis. Epilepsia, 53: 995–1003. doi: 10.1111/j.1528-1167.2012.03457.x
- Issue published online: 1 JUN 2012
- Article first published online: 17 APR 2012
- Accepted February 20, 2012; Early View publication April 17, 2012.
- Magnetic resonance imaging;
- Surface area;
- Geometric distortion;
- Cortical thickness
Purpose: To date, magnetic resonance imaging (MRI)–based studies of the cerebral cortex in mesial temporal lobe epilepsy (MTLE) have focused primarily on investigating cortical volume and thickness. However, volume is a composite of surface area and thickness, each reflecting distinct neurobiologic and genetic processes. The goal of this study was to investigate cerebral cortex (1) surface area, (2) surface geometric distortion, and (3) thickness in MTLE with hippocampal sclerosis (HS).
Methods: Seventy patients with “sporadic” unilateral MTLE + HS and 40 healthy controls underwent T1-weighted MRI. Processing MR images using an automated cortical surface reconstruction method (FreeSurfer), we quantified cortical surface area, surface geometric distortion (metric distortion), and thickness at each vertex across the entire cortex. Differences between patients and controls were determined using generalized linear models. Separate linear regression models were employed to assess the relationship between cortical surface area and hippocampal volume as well as a series of important clinical features of the condition.
Key Findings: We detected an asymmetric reduction in cortical surface area, predominantly in ipsilateral mesial and anterior temporal lobe subregions, of patients with MTLE + HS. Changes in surface geometric features were also evident and closely mirrored surface area patterns. In contrast, cortical thinning appeared dispersed across the cortex bilaterally. The regression models revealed that ipsilateral hippocampal volume was a significant predictor of temporal lobe surface area changes.
Significance: Our findings indicate that contraction in surface area, rather than cortical thinning, explains ipsilateral mesial and anterior temporal lobe atrophy in patients with MTLE with HS. Furthermore, the alterations in surface geometry indicate folding abnormality involving the same regions. Cortical surface changes may represent sequelae of the disease or deviant cortical development.