title: Degree of corticospinal tract damage correlates with motor function after stroke.
abstract: OBJECTIVE
  Direct injury to the corticospinal tract (CST) is a major factor defining motor impairment after stroke. Diffusion tensor imaging (DTI) tractography allows definition of the CST. We sought to determine whether DTI-based assessment of the degree of CST damage correlates with motor impairment at each phase of ischemic stroke.
  
  
  METHODS
  We evaluated patients at the acute (3-7 days), subacute (30 days), and chronic (90 days) phases of ischemic stroke with DTI and clinical motor scores (upper extremity Fugl-Myer test [UE-FM], motor items of the National Institutes of Health Stroke Scale [mNIHSS]). The CST was identified and virtual fiber numbers (FN) were calculated for the affected and contralateral CST. We used Spearman correlation to study the relationship of FN ratio (FNr) (affected/unaffected CST) with motor scores at each time point, and the regression model to study the association of the acute parameters with chronic motor scores.
  
  
  RESULTS
  We studied 23 patients. Mean age was 66.7 (±12) years. FNr correlated with UE-FM score in the acute (r = 0.50, P = 0.032), subacute (r = 0.57, P = 0.007), and chronic (r = 0.67, P = 0.0008) phase, and with mNIHSS in the acute (r = -0.48, P = 0.043), subacute (r = -0.58, P = 0.006), and chronic (r = -0.75, P = 0.0001) phase. The combination of acute NIHSS and FNr significantly predicted chronic UE-FM score (r = 0.74, P = 0.0001).
  
  
  CONCLUSIONS
  DTI-defined degree of CST injury correlates with motor impairment at each phase of ischemic stroke. The combination of baseline FNr and NIHSS predicts motor outcome. DTI-derived CST assessment could become a surrogate marker of motor impairment in the design of neurorestorative clinical trials.
authors.affiliation: Department of Neurology, Henry Ford Hospital Detroit, Michigan.
authors.forename: Stefania
authors.initials: S
authors.lastname: Maraka
authors.affiliation: Department of Neurology, Henry Ford Hospital Detroit, Michigan.
authors.forename: Quan
authors.initials: Q
authors.lastname: Jiang
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School Boston, Massachusetts ; Department of Radiology, Henry Ford Hospital Detroit, Michigan.
authors.forename: Kourosh
authors.initials: K
authors.lastname: Jafari-Khouzani
authors.affiliation: Department of Neurology, Henry Ford Hospital Detroit, Michigan.
authors.forename: Lian
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Neurology, Henry Ford Hospital Detroit, Michigan ; Stroke and Neurovascular Center, Neurosciences Institute, Henry Ford Health System Detroit, Michigan.
authors.forename: Shaneela
authors.initials: S
authors.lastname: Malik
authors.affiliation: Department of Radiology, Henry Ford Hospital Detroit, Michigan ; Department of Computer Science, Wayne State University Detroit, Michigan.
authors.forename: Hajar
authors.initials: H
authors.lastname: Hamidian
authors.affiliation: Department of Public Health Sciences, Henry Ford Health System Detroit, Michigan.
authors.forename: Talan
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Department of Public Health Sciences, Henry Ford Health System Detroit, Michigan.
authors.forename: Mei
authors.initials: M
authors.lastname: Lu
authors.affiliation: Department of Radiology, Henry Ford Hospital Detroit, Michigan.
authors.forename: Hamid
authors.initials: H
authors.lastname: Soltanian-Zadeh
authors.affiliation: Department of Neurology, Henry Ford Hospital Detroit, Michigan.
authors.forename: Michael
authors.initials: M
authors.lastname: Chopp
authors.affiliation: Department of Neurology, Henry Ford Hospital Detroit, Michigan ; Stroke and Neurovascular Center, Neurosciences Institute, Henry Ford Health System Detroit, Michigan.
authors.forename: Panayiotis D
authors.initials: PD
authors.lastname: Mitsias