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Behavioural Neurology
Volume 2014, Article ID 215380, 6 pages
http://dx.doi.org/10.1155/2014/215380
Research Article

Mapping Remote Subcortical Ramifications of Injury after Ischemic Strokes

1Department of Neurology, Medical University of South Carolina, Charleston, SC 29425, USA
2Comprehensive Epilepsy Center, Division of Neurology, Medical University of South Carolina, Charleston, SC 29425, USA
3Department of Psychology, University of South Carolina, Columbia, SC 29208, USA
4Department of Communication Sciences and Disorders, University of South Carolina, Columbia, SC 29208, USA

Received 9 November 2013; Accepted 5 December 2013; Published 24 April 2014

Academic Editor: A. E. Hillis

Copyright © 2014 Leonardo Bonilha et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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.