title: Asymmetric cortical surface area and morphology changes in mesial temporal lobe epilepsy with hippocampal sclerosis.
abstract: OBJECTIVE
  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 T(1) -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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Molecular and Cellular Therapeutics Department, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Saud
authors.initials: S
authors.lastname: Alhusaini
authors.forename: Colin P
authors.initials: CP
authors.lastname: Doherty
authors.forename: Lena
authors.initials: L
authors.lastname: Palaniyappan
authors.forename: Cathy
authors.initials: C
authors.lastname: Scanlon
authors.forename: Sinead
authors.initials: S
authors.lastname: Maguire
authors.forename: Paul
authors.initials: P
authors.lastname: Brennan
authors.forename: Norman
authors.initials: N
authors.lastname: Delanty
authors.forename: Mary
authors.initials: M
authors.lastname: Fitzsimons
authors.forename: Gianpiero L
authors.initials: GL
authors.lastname: Cavalleri
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000473:pathology*; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000150:complications* / Q000473:pathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012598:Sclerosis / Q000150:complications / Q000473:pathology; D018709:Statistics, Nonparametric