title: The corpus callosum and recovery of working memory after epilepsy surgery.
abstract: OBJECTIVE
  For patients with medically intractable focal epilepsy, the benefit of epilepsy surgery must be weighed against the risk of cognitive decline. Clinical factors such as age and presurgical cognitive level partially predict cognitive outcome; yet, little is known about the role of cross-hemispheric white matter pathways in supporting postsurgical recovery of cognitive function. The purpose of this study is to determine whether the presurgical corpus callosum (CC) midsagittal area is associated with pre- to postsurgical change following epilepsy surgery.
  
  
  METHODS
  In this observational study, we retrospectively identified 24 adult patients from an epilepsy resection series who completed preoperative high-resolution T1 -weighted magnetic resonance imaging (MRI) scans, as well as pre- and postsurgical neuropsychological testing. The total area and seven subregional areas of the CC were measured on the midsagittal MRI slice using an automated method. Standardized indices of auditory-verbal working memory and delayed memory were used to probe cognitive change from pre- to postsurgery. CC total and subregional areas were regressed on memory-change scores, after controlling for overall brain volume, age, presurgical memory scores, and duration of epilepsy.
  
  
  RESULTS
  Patients had significantly reduced CC area relative to healthy controls. We found a positive relationship between CC area and change in working memory, but not delayed memory; specifically, the larger the CC, the greater the postsurgical improvement in working memory (β = 0.523; p = 0.009). Effects were strongest in posterior CC subregions. There was no relationship between CC area and presurgical memory scores.
  
  
  CONCLUSIONS
  Findings indicate that larger CC area, measured presurgically, is related to improvement in working memory abilities following epilepsy surgery. This suggests that transcallosal pathways may play an important, yet little understood, role in postsurgical recovery of cognitive functions.
authors: Department of Neurology, Comprehensive Epilepsy Center, New York University School of Medicine, New York, New York, U.S.A.
authors: Karen
authors: K
authors: Blackmon
authors: Heath R
authors: HR
authors: Pardoe
authors: William B
authors: WB
authors: Barr
authors: Babak A
authors: BA
authors: Ardekani
authors: Werner K
authors: WK
authors: Doyle
authors: Orrin
authors: O
authors: Devinsky
authors: Ruben
authors: R
authors: Kuzniecky
authors: Thomas
authors: T
authors: Thesen
mesh_terms: D000293:Adolescent; D000328:Adult; D003337:Corpus Callosum / Q000033:anatomy & histology* / Q000502:physiology*; D004827:Epilepsy / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D020127:Recovery of Function / Q000502:physiology*; D012189:Retrospective Studies; D014888:Wechsler Scales; D055815:Young Adult
keywords: Corpus callosum; Epilepsy; Executive function; MRI; Neuronal plasticity; Short-term memory