title: Mapping remote subcortical ramifications of injury after ischemic strokes.
abstract: BACKGROUND
  The extent of brain damage in chronic stroke patients is traditionally defined as the necrotic tissue observed on magnetic resonance image (MRI). However, patients often exhibit symptoms suggesting that functional impairment may affect areas beyond the cortical necrotic lesion, for example, when cortical symptoms ensue after subcortical damage. This observation suggests that disconnection or diaschisis can lead to remote cortical dysfunction that can be functionally equivalent to direct cortical lesions. Objective. To directly measure subcortical disconnection after stroke.
  
  
  METHODS
  We describe a principled approach utilizing the whole brain connectome reconstructed from diffusion MRI to evaluate the reduction of apparent white matter fiber density in the hemisphere affected by the stroke compared with the spared hemisphere.
  
  
  RESULTS
  In eight chronic stroke patients, we observed subcortical disconnection extending beyond the location of tissue necrosis and affecting major white matter pathways underlying the necrotic area.
  
  
  CONCLUSIONS
  We suggest that it is possible to detect and quantify previously unappreciated areas of subcortical and cortical disconnection. Specifically, this method can be used to evaluate the relationship between lesion location and symptoms, with emphasis on a connectivity-based approach.
authors.affiliation: Department of Neurology, Medical University of South Carolina, Charleston, SC 29425, USA ; Comprehensive Epilepsy Center, Division of Neurology, Medical University of South Carolina, Charleston, SC 29425, USA.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Bonilha
authors.affiliation: Department of Neurology, Medical University of South Carolina, Charleston, SC 29425, USA.
authors.forename: Travis
authors.initials: T
authors.lastname: Nesland
authors.affiliation: Department of Psychology, University of South Carolina, Columbia, SC 29208, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Rorden
authors.affiliation: Department of Communication Sciences and Disorders, University of South Carolina, Columbia, SC 29208, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Fillmore
authors.affiliation: Department of Neurology, Medical University of South Carolina, Charleston, SC 29425, USA.
authors.forename: Ruwan P
authors.initials: RP
authors.lastname: Ratnayake
authors.affiliation: Department of Communication Sciences and Disorders, University of South Carolina, Columbia, SC 29208, USA.
authors.forename: Julius
authors.initials: J
authors.lastname: Fridriksson
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology*; D002545:Brain Ischemia / Q000473:pathology*; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000473:pathology; D020521:Stroke / Q000473:pathology*