title: Assessing the integrity of corticospinal pathways from primary and secondary cortical motor areas after stroke.
abstract: OBJECTIVE
  Aside from the primary motor cortex, the corticospinal tract (CST) also receives fibers from dorsal and ventral premotor cortices and supplementary motor area, all of which might potentially contribute to motor function after stroke. We sought to quantify the microstructural integrity of CST originating from the hand representations in these 4 motor cortices separately and examined how these values related to hand motor impairment.
  
  
  METHODS
  Probabilistic tractography from functional MRI-defined cortical sites demonstrated continuous CST originating from hand representations within each motor area in a group of healthy subjects. Microstructural integrity for each tract was calculated using fractional anisotropy at the level of the posterior limb of the internal capsule in a group of patients with chronic stroke.
  
  
  RESULTS
  Fractional anisotropy was reduced in all 4 CSTs in the affected hemisphere. Grip strength correlated with the integrity of the CSTs originating from primary motor and dorsal premotor cortices, whereas, in a multiple regression model, the latter improved the ability of primary motor cortex CST to explain variability in grip strength.
  
  
  CONCLUSIONS
  Handgrip critically depends on the CST originating in primary motor cortex but microstructural integrity of CST originating from premotor cortices appears to play a role in supporting motor function after stroke.
authors: Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. rschulz@uke.de
authors: Robert
authors: R
authors: Schulz
authors: Chang-Hyun
authors: CH
authors: Park
authors: Marie-Hélène
authors: MH
authors: Boudrias
authors: Christian
authors: C
authors: Gerloff
authors: Friedhelm C
authors: FC
authors: Hummel
authors: Nick S
authors: NS
authors: Ward
mesh_terms: D016880:Anisotropy; D001921:Brain / Q000473:pathology; D002908:Chronic Disease; D056324:Diffusion Tensor Imaging / Q000379:methods; D018737:Hand Strength; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D020772:Internal Capsule / Q000503:physiopathology; D015233:Models, Statistical; D009044:Motor Cortex / Q000473:pathology*; D011712:Pyramidal Tracts / Q000473:pathology*; D020521:Stroke / Q000473:pathology*