White Matter Integrity Is a Stronger Predictor of Motor Function Than BOLD Response in Patients With Stroke

• Type of Material: Article
• Authors: Mingguo Qiu, Third Military Medical University; Warren G. Darling, University of Iowa; Robert J. Morecraft, University of South Dakota; Chun Chun Ni, Emory University; Justin Rajendra, Emory University; Andrew John Butler, Emory University
• Language: English
• Date: 2011
• Publisher: SAGE Publications (UK and US)
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © The Author(s) 2011
• Final Published Version (URL): http://nnr.sagepub.com/content/25/3/275
• Title of Journal or Parent Work: Neurorehabilitation and Neural Repair
• ISSN: 1545-9683
• Volume: 25
• Issue: 3
• Start Page: 275
• End Page: 284
• Grant/Funding Information: This study was sponsored by the National Institutes of Health (Grant Number NCCAM R21 AT-002138-03 to AJB) and NSFC (30670595).
• Keywords: laterality index; diffusion tensor imaging; fractional anisotropy; magnetic resonance imaging; motor functional outcome
• Research Categories: Biology, Neuroscience; Health Sciences, Rehabilitation and Therapy

Abstract

Objective: Neuroimaging techniques, such as diffusion tensor imaging (DTI) and blood oxygenation level–dependent (BOLD) functional magnetic resonance imaging (fMRI), provide insights into the functional reorganization of the cortical motor system after stroke. This study explores the relationship between upper extremity motor function, white matter integrity, and BOLD response of cortical motor areas. Methods: Seventeen patients met study inclusion criteria; of these 12 completed DTI assessment of white matter integrity and 9 completed fMRI assessment of motor-related activation. Primary clinical outcome measures were the Wolf Motor Function Test (WMFT) and the upper limb portion of the Fugl-Meyer (FM) motor assessment. Structural integrity of the posterior limb of the internal capsule was assessed by examining the fractional anisotropy (FA) asymmetry in the PLIC. Laterality index of motor cortical areas was measured as the BOLD response in each patient during a finger pinch task. Linear regression analyses were performed to determine whether clinical outcome was associated with structural or functional MRI measures. Results: There were strong relationships between clinical outcome measures and FA asymmetry (eg, FM score [R2 = .655, P = .001] and WMFT asymmetry score [R2 = .651, P < .002]) but relationships with fMRI measures were weaker. Conclusion: Clinical motor function is more closely related to the white matter integrity of the internal capsule than to BOLD response of motor areas in patients 3 to 9 months after stroke. Thus, use of DTI to assess white matter integrity in the internal capsule may provide more useful information than fMRI to interpret motor deficits following supratentorial brain injury.