Time-dependent functional role of the contralesional motor cortex after stroke.
Ontology highlight
ABSTRACT:
SUBMITTER: Volz LJ
PROVIDER: S-EPMC5540833 | biostudies-other | 2017
REPOSITORIES: biostudies-other
Similar Datasets
Project description:BackgroundAfter stroke, increases in contralesional primary motor cortex (M1CL) activity and excitability have been reported. In pre-clinical studies, M1CL reorganization is related to the extent of ipsilesional M1 (M1IL) injury, but this has yet to be tested clinically.ObjectivesWe tested the hypothesis that the extent of damage to the ipsilesional M1 and/or its corticospinal tract (CST) determines the magnitude of M1CL reorganization and its relationship to affected hand function in humans recovering from stroke.MethodsThirty-five participants with a single subacute ischemic stroke affecting M1 or CST and hand paresis underwent MRI scans of the brain to measure lesion volume and CST lesion load. Transcranial magnetic stimulation (TMS) of M1IL was used to determine the presence of an electromyographic response (motor evoked potential (MEP+ and MEP-)). M1CL reorganization was determined by TMS applied to M1CL at increasing intensities. Hand function was quantified with the Jebsen Taylor Hand Function Test.ResultsThe extent of M1CL reorganization was related to greater lesion volume in the MEP- group, but not in the MEP+ group. Greater M1CL reorganization was associated with more impaired hand function in MEP- but not MEP+ participants. Absence of an MEP (MEP-), larger lesion volumes and higher lesion loads in CST, particularly in CST fibers originating in M1 were associated with greater impairment of hand function.ConclusionsIn the subacute post-stroke period, stroke volume and M1IL output determine the extent of M1CL reorganization and its relationship to affected hand function, consistent with pre-clinical evidence.ClinicalTrials.gov Identifier: NCT02544503.
| S-EPMC10079613 | biostudies-literature
Project description:Brain lesions caused by cerebral ischemia or hemorrhage lead to a local breakdown of energy homeostasis followed by irreversible cell death and long-term impairment. Importantly, local brain lesions also generate remote functional and structural disturbances, which contribute to the behavioral deficit but also impact the recovery of function. While spontaneous recovery has been associated with endogenous repair mechanisms at the vascular, neural, and immune cell levels, the impact of structural plasticity on sensory-motor dysfunction and recovery thereof remains to be elucidated by longitudinal imaging in a mouse model. Here, we applied behavioral assessments, in vivo fiber tracking, and histological validation in a photothrombotic stroke mouse model. Atlas-based whole-brain structural connectivity analysis and ex vivo histology revealed secondary neurodegeneration in the ipsilesional brain areas, mostly in the dorsal sensorimotor area of the thalamus. Furthermore, we describe for the first time a lesion size-dependent increase in structural connectivity between the contralesional primary motor cortex and thalamus with the ipsilesional cortex. The involvement of the contralesional hemisphere was associated with improved functional recovery relative to lesion size. This study highlights the importance of in vivo fiber tracking and the role of the contralesional hemisphere during spontaneous functional improvement as a potential novel stroke biomarker and therapeutic targets.
| S-EPMC7803721 | biostudies-literature
Project description:It remains uncertain if the contralesional primary sensorimotor cortex (CL_PSMC) contributes to motor recovery after stroke. Here we investigated longitudinal changes in the resting-state functional connectivity (rsFC) of the CL_PSMC and their association with motor recovery. Thirteen patients who had experienced subcortical stroke underwent a series of resting-state fMRI and clinical assessments over a period of 1 year at 5 time points, i.e., within the first week, at 2 weeks, 1 month, 3 months, and 1 year after stroke onset. Thirteen age- and gender-matched healthy subjects were recruited as controls. The CL_PSMC was defined as a region centered at the voxel that had greatest activation during hand motion task. The dynamic changes in the rsFCs of the CL_PSMC within the whole brain were evaluated and correlated with the Motricity Index (MI) scores. Compared with healthy controls, the rsFCs of the CL_PSMC with the bilateral PSMC were initially decreased, then gradually increased, and finally restored to the normal level 1 year later. Moreover, the dynamic change in the inter-hemispheric rsFC between the bilateral PSMC in these patients was positively correlated with the MI scores. However, the intra-hemispheric rsFC of the CL_PSMC was not correlated with the MI scores. This study shows dynamic changes in the rsFCs of the CL_PSMC after stroke and suggests that the increased inter-hemispheric rsFC between the bilateral PSMC may facilitate motor recovery in stroke patients. However, generalization of our findings is limited by the small sample size of our study and needs to be confirmed.
| S-EPMC3885617 | biostudies-literature
Project description:ObjectiveThe nonlesioned motor cortex (M1NL) is thought to be hyperexcitable in patients with subacute or chronic stroke and offers a promising therapeutic target. However, whether M1NL excitability behaves the same for subcortical and cortical strokes is unknown. The aim of the present study was to determine whether cortical, or purely subcortical, strokes have a different effect on M1NL excitability.MethodsWe looked for correlations between the Fugl-Meyer (FM) score and M1NL resting motor threshold (RMTNL) in 34 stroke survivors classified according to lesion location (cortico-subcortical or purely subcortical). In addition to the FM, the Wolf Motor Score and motor power were measured.ResultsFM correlated with RMTNL for subcortical (r = 0.82; p = 0.001) but not for cortical strokes (r = 0.11; p = 0.62). Likewise, Wolf Motor Score (r = -0.62; p = 0.03) and motor power (r = 0.64; p = 0.023) were correlated with RMTNL for the subcortical group, but not for the cortical group.ConclusionWe show that the impact on M1NL depends on lesion location and conclude that protocols aimed at reducing M1NL cortical excitability may be worth exploring for subcortical but not for cortical stroke.
| S-EPMC4540249 | biostudies-literature
Project description:Contralesional dorsal premotor cortex (cPMd) may support residual motor function following stroke. We performed two complementary experiments to explore how cPMd might perform this role in a group of chronic human stroke patients. First, we used paired-coil transcranial magnetic stimulation (TMS) to establish the physiological influence of cPMd on ipsilesional primary motor cortex (iM1) at rest. We found that this influence became less inhibitory/more facilitatory in patients with greater clinical impairment. Second, we applied TMS over cPMd during functional magnetic resonance imaging (fMRI) in these patients to examine the causal influence of cPMd TMS on the whole network of surviving cortical motor areas in either hemisphere and whether these influences changed during affected hand movement. We confirmed that hand grip-related activation in cPMd was greater in more impaired patients. Furthermore, the peak ipsilesional sensorimotor cortex activity shifted posteriorly in more impaired patients. Critical new findings were that concurrent TMS-fMRI results correlated with the level of both clinical impairment and neurophysiological impairment (i.e., less inhibitory/more facilitatory cPMd-iM1 measure at rest as assessed with paired-coil TMS). Specifically, greater clinical and neurophysiological impairment was associated with a stronger facilitatory influence of cPMd TMS on blood oxygenation level-dependent signal in posterior parts of ipsilesional sensorimotor cortex during hand grip, corresponding to the posteriorly shifted sensorimotor activity seen in more impaired patients. cPMd TMS was not found to influence activity in other brain regions in either hemisphere. This state-dependent influence on ipsilesional sensorimotor regions may provide a mechanism by which cPMd supports recovered function after stroke.
| S-EPMC3044467 | biostudies-literature
Project description:BackgroundPrevious studies showed that repetitive transcranial magnetic stimulation (rTMS) reduces spasticity after stroke. However, clinical assessments like the modified Ashworth scale, cannot discriminate stretch reflex-mediated stiffness (spasticity) from passive stiffness components of resistance to muscle stretch. The mechanisms through which rTMS might influence spasticity are also not understood.MethodsWe measured the effects of contralesional motor cortex 1 Hz rTMS (1200 pulses + 50 min physiotherapy: 3×/week, for 4-6 weeks) on spasticity of the wrist flexor muscles in 54 chronic stroke patients using a hand-held dynamometer for objective quantification of the stretch reflex response. In addition, we measured the excitability of three spinal mechanisms thought to be related to post-stroke spasticity: post-activation depression, presynaptic inhibition and reciprocal inhibition before and after the intervention. Effects on motor impairment and function were also assessed using standardized stroke-specific clinical scales.ResultsThe stretch reflex-mediated torque in the wrist flexors was significantly reduced after the intervention, while no change was detected in the passive stiffness. Additionally, there was a significant improvement in the clinical tests of motor impairment and function. There were no significant changes in the excitability of any of the measured spinal mechanisms.ConclusionsWe demonstrated that contralesional motor cortex 1 Hz rTMS and physiotherapy can reduce the stretch reflex-mediated component of resistance to muscle stretch without affecting passive stiffness in chronic stroke. The specific physiological mechanisms driving this spasticity reduction remain unresolved, as no changes were observed in the excitability of the investigated spinal mechanisms.
| S-EPMC10631065 | biostudies-literature
Project description:The net effect of altered interhemispheric interactions between homologous motor cortical areas after unilateral stroke has been previously reported to contribute to residual hemiparesis. Using this framework, we hypothesized that navigated 1 Hz repetitive transcranial magnetic stimulation (rTMS) over the contralesional hemisphere would induce a stronger physiological and behavioural response in patients with residual motor deficit than in healthy subjects, because an imbalance in interhemispheric excitability may underlie motor dysfunction.Navigated rTMS was conducted in 8 chronic stroke patients (67.50±13.77 years) and in 8 comparable normal subjects (57.38±9.61 years). We evaluated motor function (Finger tapping, Nine Hole Peg test, Strength Index and Reaction Time) as well as the excitatory and inhibitory function (resting motor threshold, motor evoked potential amplitude, intra-cortical inhibition and facilitation, and silent period) of the stimulated and non-stimulated motor cortex before and after navigated rTMS.rTMS induced an increase in excitability in the ipsilesional (non-stimulated) motor cortex and led to improved performance in the finger tapping task and pinch force task. These physiological and behavioral effects were more prominent (or robust) in the group of stroke patients than in the control group.Navigated low-frequency rTMS involving precise and consistent targeting of the contralesional hemisphere in stroke patients enhanced the cortical excitability of the ipsilesional hemisphere and the motor response of the hemiparetic hand.
| S-EPMC5384333 | biostudies-other
Project description:The acute phase of stroke is accompanied by functional changes in the activity and interplay of both hemispheres. In healthy subjects, gender is known to impact the functional brain organization. We investigated whether gender influences also acute stroke functional changes. In thirty-five ischemic stroke patients, we evaluated the excitability of the affected (AH) and unaffected hemisphere (UH) by measuring resting and active motor threshold (AMT) and motor-evoked potential amplitude under baseline conditions and after intermittent theta burst stimulation (iTBS) of AH. We also computed an index of the excitability balance between the hemispheres, laterality indexes (LI), to evidence hemispheric asymmetry. AMT differed significantly between AH and UH only in the male group (p = 0.004), not in females (p > 0.200), and both LIAMT and LIRMT were significantly higher in males than in females (respectively p = 0.033 and p = 0.042). LTP-like activity induced by iTBS in AH was more frequent in females. Gender influences the functional excitability changes that take place after human stroke and the level of LTP that can be induced by repetitive stimulation. This knowledge is of high value in the attempt of individualizing to different genders any non-invasive stimulation strategy designed to foster stroke recovery.
| S-EPMC4731507 | biostudies-literature
Project description:Background: During recovery from stroke, the contralesional motor cortex (M1) may undergo maladaptive changes that contribute to impaired interhemispheric inhibition (IHI). Transcranial direct current stimulation (tDCS) with the cathode over contralesional M1 may inhibit this maladaptive plasticity, normalize IHI, and enhance motor recovery. Objective: The objective of this systematic review and meta-analysis was to evaluate available evidence to determine whether cathodal tDCS on contralesional M1 enhances motor re-learning or recovery post-stroke more than sham tDCS. Methods: We searched OVID Medline, Embase, and the Cochrane Central Register of Controlled Trials for participants with stroke (>1 week post-onset) with motor impairment and who received cathodal or sham tDCS to contralesional M1 for one or more sessions. The outcomes included a change in any clinically validated assessment of physical function, activity, or participation, or a change in a movement performance variable (e.g., time, accuracy). A meta-analysis was performed by pooling five randomized controlled trials (RCTs) and comparing the change in Fugl-Meyer upper extremity scores between cathodal and sham tDCS groups. Results: Eleven studies met the inclusion criteria. Qualitatively, four out of five cross-over design studies and three out of six RCTs reported a significant effect of cathodal vs. sham tDCS. In the quantitative synthesis, cathodal tDCS (n = 65) did not significantly reduce motor impairment compared to sham tDCS (n = 67; standardized mean difference = 0.33, z = 1.79, p = 0.07) with a little observed heterogeneity (I 2 = 5%). Conclusions: The effects of cathodal tDCS to contralesional M1 on motor recovery are small and consistent. There may be sub-populations that may respond to this approach; however, further research with larger cohorts is required.
| S-EPMC8083132 | biostudies-literature
Project description:BackgroundDespite improvements in acute stroke therapies and rehabilitation strategies, many stroke patients are left with long-term upper limb motor impairment. We assessed whether an inhibitory repetitive transcranial magnetic stimulation treatment paradigm started within 3 weeks after stroke onset promotes upper limb motor recovery.MethodsWe performed a single-center randomized, sham-controlled clinical trial. Patients with ischemic stroke or intracerebral hemorrhage and unilateral upper limb motor impairment were randomized to 10 daily sessions of active or sham continuous theta-burst stimulation (cTBS) of the contralesional primary motor cortex combined with standard upper limb therapy, started within 3 weeks after stroke onset. The primary outcome was the change in the Action Research Arm Test score from baseline (pretreatment) at 3 months after stroke. Secondary outcomes included the score on the modified Rankin Scale at 3 months and the length of stay at the rehabilitation center. Statistical analyses were performed using mixed models for repeated measures.ResultsWe enrolled 60 patients between April 2017 and February 2021, of whom 29 were randomized to active cTBS and 31 to sham cTBS. One patient randomized to active cTBS withdrew consent before the intervention and was excluded from the analyses. The mean difference in the change in Action Research Arm Test score from baseline at 3 months poststroke was 9.6 points ([95% CI, 1.2-17.9]; P=0.0244) in favor of active cTBS. Active cTBS was associated with better scores on the modified Rankin Scale at 3 months (OR, 0.2 [95% CI, 0.1-0.8]; P=0.0225) and with an 18 days shorter length of stay at the rehabilitation center than sham cTBS ([95% CI, 0.0-36.4]; P=0.0494). There were no serious adverse events.ConclusionsTen daily sessions of cTBS of the contralesional primary motor cortex combined with upper limb training, started within 3 weeks after stroke onset, promote recovery of the upper limb, reduce disability and dependence and leads to earlier discharge from the rehabilitation center.RegistrationURL: https://trialsearch.who.int/; Unique identifier: NTR6133.
| S-EPMC10358447 | biostudies-literature