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Microstructural status of ipsilesional and contralesional corticospinal tract correlates with motor skill in chronic stroke patients.

ABSTRACT: Greater loss in structural integrity of the ipsilesional corticospinal tract (CST) is associated with poorer motor outcome in patients with hemiparetic stroke. Animal models of stroke have demonstrated that structural remodeling of white matter in the ipsilesional and contralesional hemispheres is associated with improved motor recovery. Accordingly, motor recovery in patients with stroke may relate to the relative strength of CST degeneration and remodeling. This study examined the relationship between microstructural status of brain white matter tracts, indexed by the fractional anisotropy (FA) metric derived from diffusion tensor imaging (DTI) data, and motor skill of the stroke-affected hand in patients with chronic stroke. Voxelwise analysis revealed that motor skill significantly and positively correlated with FA of the ipsilesional and contralesional CST in the patients. Additional voxelwise analyses showed that patients with poorer motor skill had reduced FA of bilateral CST compared to normal control subjects, whereas patients with better motor skill had elevated FA of bilateral CST compared to controls. These findings were confirmed using a DTI-tractography method applied to the CST in both hemispheres. The results of this study suggest that the level of motor skill recovery achieved in patients with hemiparetic stroke relates to microstructural status of the CST in both the ipsilesional and contralesional hemispheres, which may reflect the net effect of degeneration and remodeling of bilateral CST.

SUBMITTER: Schaechter JD

PROVIDER: S-EPMC2780023 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature

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Microstructural status of ipsilesional and contralesional corticospinal tract correlates with motor skill in chronic stroke patients.

Schaechter Judith D JD Fricker Zachary P ZP Perdue Katherine L KL Helmer Karl G KG Vangel Mark G MG Greve Douglas N DN Makris Nikos N

Human brain mapping 20091101 11

Greater loss in structural integrity of the ipsilesional corticospinal tract (CST) is associated with poorer motor outcome in patients with hemiparetic stroke. Animal models of stroke have demonstrated that structural remodeling of white matter in the ipsilesional and contralesional hemispheres is associated with improved motor recovery. Accordingly, motor recovery in patients with stroke may relate to the relative strength of CST degeneration and remodeling. This study examined the relationship ...[more]

PMID: 19370766

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Project description:BackgroundMotor outcome after stroke is associated with reorganisation of cortical networks and corticospinal tract (CST) integrity. However, the relationships between motor severity, CST damage, and functional brain connectivity are not well understood. Here, the main objective was to study the effect of CST damage on the relationship between functional motor network connectivity and hand motor function in two groups of stroke patients: the severely (n=8) and the mildly impaired (n=14).MethodsTwenty-two carotid stroke patients with motor deficits were studied with magnetic resonance imaging (MRI) at 3 weeks, at 3 and 6 months. Healthy subjects (n=28) were scanned once. The CST injury was assessed by fractional anisotropy values. Functional connectivity was studied from a whole-hand grip task fMRI in a cortical and cerebellar motor network. Functional connectivity indexes were computed between these regions at each time point. The relationship between hand motor strength, ipsilesional CST damage and functional connectivity from the primary motor cortex (M1) was investigated using global and partial correlations.FindingsIn mildly impaired patients, cortico-cortical connectivity was disturbed at three weeks but returned to a normal pattern after 3 months. Cortico-cerebellar connectivity was still decreased at 6 months. In severely impaired patients, the cortico-cortical connectivity tended to return to a normal pattern, but the cortico-cerebellar connectivity was totally abolished during the follow-up. In the entire group of patients, the hand motor strength was correlated to the ipsilesional functional connectivity from M1. Partial correlations revealed that these associations were not anymore significant when the impact of CST damage was removed, except for the ipsilesional M1-contralateral cerebellum connectivity.ConclusionFunctional brain connectivity changes can be observed, even in severely impaired patients with no recovery. Upper limb function is mainly explained by the CST damage and by the ipsilesional cortico-cerebellar connectivity.

Project description:BackgroundPreserved integrity of the corticospinal tract (CST) is a marker of good upper-limb behavior and recovery following stroke. However, there is less understanding of neural mechanisms that might help facilitate upper-limb motor recovery in stroke survivors with extensive CST damage.ObjectiveThe purpose of this study was to investigate resting state functional connectivity in chronic stroke survivors with different levels of CST damage and to explore neural correlates of greater upper-limb motor performance in stroke survivors with compromised ipsilesional CST integrity.MethodsThirty chronic stroke survivors (24 males, aged 64.7 ± 10.8 years) participated in this study. Three experimental sessions were conducted to: 1) obtain anatomical (T1, T2) structural (diffusion) and functional (resting state) MRI sequences, 2) determine CST integrity with transcranial magnetic stimulation (TMS) and conduct assessments of upper-limb behavior, and 3) reconfirm CST integrity status. Participants were divided into groups according to the extent of CST damage. Those in the extensive CST damage group did not show TMS evoked responses and had significantly lower ipsilesional fractional anisotropy.ResultsOf the 30 chronic stroke survivors, 12 were categorized as having extensive CST damage. Stroke survivors with extensive CST damage had weaker functional connectivity in the ipsilesional sensorimotor network and greater functional connectivity in the ipsilesional fronto-parietal network compared to those with preserved CST integrity. For participants with extensive CST damage, improved motor performance was associated with greater functional connectivity of the ipsilesional fronto-parietal network and higher fractional anisotropy of the ipsilesional rostral superior longitudinal fasciculus.ConclusionsStroke survivors with extensive CST damage have greater resting state functional connectivity of an ipsilesional fronto-parietal network that appears to be a behaviorally relevant neural mechanism that improves upper-limb motor performance.

Project description:Congenital heart disease (CHD) patients are at risk for neurodevelopmental impairments, including altered motor function. However, little is known about the neuroanatomical correlates of persistent motor deficits in CHD. Thus, we examined the link between corticospinal tract (CST) microstructure and motor function in adolescent and adult CHD patients compared to healthy controls. This study investigated 89 CHD patients (N(adolescents) = 47, N(adults) = 42, mean age = 19.9 years) and 97 age-matched healthy controls (N(adolescents) = 44, N(adults) = 53, mean age = 20.6 years). Diffusion tensor imaging was conducted and fractional anisotropy (FA) of the left and right CST was extracted for each participant. Fine (pegboard) and pure motor (repeated finger, hand and foot movements) performance was evaluated with a standardized test battery. FA and motor performance were correlated and the effect of CHD complexity was tested using multivariate linear regression. Clinically relevant motor impairments (>2SD below normative mean) were evident in 24% of patients and 9% of controls. On average, motor performance was lower in CHD patients compared to controls, particularly in those with more complex CHD (fine motor: p = 0.023; pure motor: p < 0.001). FA CST was lower in patients compared to controls, particularly in those with more complex CHD (left: p < 0.001, right: p = 0.003). There was a significant interaction between CHD complexity and FA CST (left: p = 0.025, right: p = 0.025), indicating that FA correlates significantly with pure motor in patients with severe CHD, while there is only a weak association in moderate CHD and no association in patients with simple CHD and controls. Microstructure of the CST is altered in CHD patients, and is associated with pure motor impairments in patients with severe CHD. This indicates that persistent motor impairments may arise from atypical development of the primary motor pathway in the presence of a complex CHD. Early interventions promoting brain maturation in infancy may prevent persisting impairments across the lifetime.

Dataset Information

Microstructural status of ipsilesional and contralesional corticospinal tract correlates with motor skill in chronic stroke patients.

Publications

Microstructural status of ipsilesional and contralesional corticospinal tract correlates with motor skill in chronic stroke patients.

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