Abstract
Recent findings showed that brain networks far away from a lesion could be altered to adapt changes after stroke. This study examined 13 chronic stroke patients with moderate to severe motor impairment and 13 age-comparable healthy controls using diffusion tensor imaging to investigate the stroke impact on the reorganization of structural connectivity. Each subject's brain was segmented into 68 cortical and 12 subcortical regions of interest (ROIs), and connectivity measures including fractional anisotropy (FA), regional FA (rFA), connection weight (CW) and connection strength (CS) were adopted to compare two subject groups. Correlations between these measures and clinical scores of motor functions (Action Research Arm Test and Fugl-Meyer Assessment for upper extremity) were done. Network-based statistic (NBS) was conducted to identify the connectivity differences between patients and controls from the perspective of whole-brain network. The results showed that both rFAs and CSs demonstrated significant differences between patients and controls in the ipsilesional sensory-motor areas and subcortical network, and bilateral attention and default mode networks. Significant positive correlations were found between the paretic motor functions and the rFAs/CSs of the contralesional medial orbitofrontal cortex (mOFC) and rostral anterior cingulate cortex (rACC), and remained significant even after removing the effect of the ipsilesional corticospinal tract. Additionally, all the connections linked with the contralesional mOFC and rACC showed significantly higher FA/CW values in the stroke patients compared to the healthy controls from the NBS results. These findings indicated that these contralesional prefrontal areas exhibited stronger connections after stroke and strongly related to the residual motor function of the stroke patients.
Highlights
Structural remodeling of white matter associated with the ipsilesional and contralesional sensorimotor areas has been demonstrated in both animal models of stroke [1] and stroke patients [2] and is found to be associated with the level of motor recovery or impairment [2,3,4]
More patients had lesions in the right hemisphere (n = 9) than in the left hemisphere (n = 4), and most of the infarcts were in the territory irrigated by the anterior and middle cerebral arteries
From the Network-based statistic (NBS) results, all the connections linked with the contralesional medial orbitofrontal cortex (mOFC) and rostral anterior cingulate cortex (rACC) showed significantly higher fractional anisotropy (FA)/connection weight (CW) values in the stroke patients compared to the healthy controls (S_Table 2D)
Summary
Structural remodeling of white matter associated with the ipsilesional and contralesional sensorimotor areas has been demonstrated in both animal models of stroke [1] and stroke patients [2] and is found to be associated with the level of motor recovery or impairment [2,3,4]. In addition to the brain tissue damage localized at the periphery of the lesion, recent studies pointed out that the brain network far away from the lesion could be altered [6, 7]. This alteration is suggested as a secondary white matter degeneration which appears in remote regions interconnected, directly or indirectly, with the primary damaged area [6]. More understanding of the entire brain adaptation after a stroke might provide a more comprehensive picture of the interactions between structural connectivity remodeling and post-stroke motor function. Such information may be of value in redefining a potential neural substrate that affects post-stroke motor impairment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
