Ipsilateral motor pathway confirmed by combined brain mapping of a patient with hemiparetic stroke: A case report11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the author(s) or on any organization with which the author(s) is/are associated

Evidence of mirror therapy for recruitment of ipsilateral motor pathways in stroke recovery: A resting fMRI study

Mirror therapy (MT) has been proposed to promote motor recovery post-stroke through activation of mirror neuron system, recruitment of ipsilateral motor pathways, or/and increasing attention toward the affected limb. However, neuroimaging evidence for these mechanisms is still lacking. To uncover the underlying mechanisms, we designed a randomized controlled study and used a voxel-based whole-brain analysis of resting-state fMRI to explore the brain reorganizations induced by MT. Thirty-five stroke patients were randomized to an MT group (n ​= ​16) and a conventional therapy (CT) group (n ​= ​19) for a 4-week intervention. Before and after the intervention, the Fugl-Meyer Assessment Upper Limb subscale (FMA-UL) and resting-state fMRI were collected. A healthy cohort (n ​= ​16) was established for fMRI comparison. The changes in fractional amplitude of low-frequency fluctuation (fALFF) and seed-based functional connectivity were analyzed to investigate the impact of intervention. Results showed that greater FMA-UL improvement in the MT group was associated with the compensatory increase of fALFF in the contralesional precentral gyrus (M1) region and the re-establishment of functional connectivity between the bilateral M1 regions, which facilitate motor signals transmission via the ipsilateral motor pathways from the ipsilesional M1, contralesional M1, to the affected limb. A step-wise linear regression model revealed these two brain reorganization patterns collaboratively contributed to FMA-UL improvement. In conclusion, MT achieved motor rehabilitation primarily by recruitment of the ipsilateral motor pathways. Trial Registration Information: http://www.chictr.org.cn. Unique Identifier. ChiCTR-INR-17013644, submitted on December 2, 2017.

Effect of aging on the cerebral metabolic mechanism of electroacupuncture treatment in rats with traumatic brain injury

Objective

Aging has great influence on the clinical treatment effect of cerebrovascular diseases, and evidence suggests that the effect may be associated with age-related brain plasticity. Electroacupuncture is an effective alternative treatment for traumatic brain injury (TBI). In the present study, we aimed to explore the effect of aging on the cerebral metabolic mechanism of electroacupuncture to provide new evidence for developing age-specific rehabilitation strategies.

Methods

Both aged (18 months) and young (8 weeks) rats with TBI were analyzed. Thirty-two aged rats were randomly divided into four groups: aged model, aged electroacupuncture, aged sham electroacupuncture, and aged control group. Similarly, 32 young rats were also divided into four groups: young model, young electroacupuncture, young sham electroacupuncture, and young control group. Electroacupuncture was applied to "Bai hui" (GV20) and "Qu chi" (LI11) for 8 weeks. CatWalk gait analysis was then performed at 3 days pre- and post-TBI, and at 1, 2, 4, and 8 weeks after intervention to observe motor function recovery. Positron emission computed tomography (PET/CT) was performed at 3 days pre- and post-TBI, and at 2, 4, and 8 weeks after intervention to detect cerebral metabolism.

Results

Gait analysis showed that electroacupuncture improved the forepaw mean intensity in aged rats after 8 weeks of intervention, but after 4 weeks of intervention in young rats. PET/CT revealed increased metabolism in the left (the injured ipsilateral hemisphere) sensorimotor brain areas of aged rats during the electroacupuncture intervention, and increased metabolism in the right (contralateral to injury hemisphere) sensorimotor brain areas of young rats.

Results

This study demonstrated that aged rats required a longer electroacupuncture intervention duration to improve motor function than that of young rats. The influence of aging on the cerebral metabolism of electroacupuncture treatment was mainly focused on a particular hemisphere.

Role of the Contra-Lesional Corticoreticular Tract in Motor Recovery of the Paretic Leg in Stroke: A Mini-Narrative Review

This review discusses the role of the contra-lesional corticoreticular tract (CRT) in motor recovery of the paretic leg in stroke patients by reviewing related diffusion tensor tractography studies. These studies suggest that the contra-lesional CRT can contribute to the motor recovery of the paretic leg in stroke patients, particularly in patients with complete injuries of the ipsilesional corticospinal tract and CRT. Furthermore, a review study reported that the motor recovery of the paretic ankle dorsiflexor, which is mandatory for achieving a good gait pattern without braces in hemiparetic stroke patients, was closely related to the contra-lesional CRT. These results could be clinically important in neuro-rehabilitation. For example, the contra-lesional CRT could be a target for neuromodulation therapies in patients with complete injuries of the ipsilesional corticospinal tract and CRT. On the other hand, only three studies were reviewed in this review and one was a case report. Although the CRT has been suggested to be one of the ipsilateral motor pathways from the contra-lesional cerebral cortex to the paretic limbs in stroke, the role of the CRT has not been elucidated clearly. Therefore, further prospective follow-up studies combining functional neuroimaging and transcranial magnetic stimulation for the paretic leg with diffusion tensor tractography will be useful for elucidating the role of the contra-lesional CRT in stroke patients.

Neural mechanisms mediating cross education: With additional considerations for the ageing brain

CALVERT, G.H.M., and CARSON, R.G. Neural mechanisms mediating cross education: With additional considerations for the ageing brain. NEUROSCI BIOBEHAV REV 21(1) XXX-XXX, 2021. - Cross education (CE) is the process whereby a regimen of unilateral limb training engenders bilateral improvements in motor function. The contralateral gains thus derived may impart therapeutic benefits for patients with unilateral deficits arising from orthopaedic injury or stroke. Despite this prospective therapeutic utility, there is little consensus concerning its mechanistic basis. The precise means through which the neuroanatomical structures and cellular processes that mediate CE may be influenced by age-related neurodegeneration are also almost entirely unknown. Notwithstanding the increased incidence of unilateral impairment in later life, age-related variations in the expression of CE have been examined only infrequently. In this narrative review, we consider several mechanisms which may mediate the expression of CE with specific reference to the ageing CNS. We focus on the adaptive potential of cellular processes that are subserved by a specific set of neuroanatomical pathways including: the corticospinal tract, corticoreticulospinal projections, transcallosal fibres, and thalamocortical radiations. This analysis may inform the development of interventions that exploit the therapeutic utility of CE training in older persons.

An overview of fractional anisotropy as a reliable quantitative measurement for the corticospinal tract (CST) integrity in correlation with a Fugl-Meyer assessment in stroke rehabilitation

[Purpose] Understanding the essential mechanisms in post-stroke recovery not only provides important basic insights into brain function and plasticity but can also guide the development of new therapeutic approaches for stroke patients. This review aims to give an overview of how various variables of Magnetic Resonance-Diffusion Tensor Imaging (MR-DTI) metrics of fractional anisotropy (FA) can be used as a reliable quantitative measurement and indicator of corticospinal tract (CST) changes, particularly in relation to functional motor outcome correlation with a Fugl-Meyer assessment in stroke rehabilitation. [Methods] PubMed electronic database was searched for the relevant literature, using key words of diffusion tensor imaging (dti), corticospinal tract, and stroke. [Results] We reviewed the role of FA in monitoring CST remodeling and its role of predicting motor recovery after stroke. We also discussed the mechanism of CST remodeling and its modulation from the value of FA and FMA-UE. [Conclusion] Heterogeneity of post-stroke brain disorganization and motor impairment is a recognized challenge in the development of accurate indicators of CST integrity. DTI-based FA measurements offer a reliable and evidence-based indicator for CST integrity that would aid in predicting motor recovery within the context of stroke rehabilitation.

Effects of virtual reality training on occupational performance and self-efficacy of patients with stroke: a randomized controlled trial

Background

Virtual reality (VR) has been broadly applied in post-stroke rehabilitation. However, studies on occupational performance and self-efficacy as primary outcomes of stroke rehabilitation using VR are lacking. Thus, this study aims to investigate the effects of VR training on occupational performance and self-efficacy in patients with stroke.

Methods

This was an assessor-blinded, randomized controlled trial. Sixty participants with first-ever stroke (< 1-year onset) underwent rehabilitation in a single acute hospital. Participants were randomly assigned to either the VR group (n = 30) or control group (n = 30). Both groups received dose-matched conventional rehabilitation (i.e., 45 min, five times per week over 3 weeks). The VR group received additional 45-min VR training for five weekdays over 3 weeks. The primary outcome measures were the Canadian Occupational Performance Measure and Stroke Self-Efficacy Questionnaire. Secondary outcome measures included Modified Barthel Index, Fugl-Meyer Assessment-Upper Extremity, and Functional Test for the Hemiplegic Upper Extremity. The assessment was conducted at baseline and after the 3-week intervention.

Results

A total of 52 participants (86.7%) completed the trial. Significant between-group differences in Stroke Self-Efficacy Questionnaire (Median Difference = 8, P = 0.043) and Modified Barthel Index (Median Difference = 10, P = 0.030) were found; however, no significant between-group differences in Canadian Occupational Performance Measure, Fugl-Meyer Assessment-Upper Extremity, and Functional Test for the Hemiplegic Upper Extremity were noted. No serious adverse reactions related to the program were reported.

Conclusions

Additional VR training could help improve the self-efficacy and activities of daily living of patients with stroke; however, it was not superior to conventional training in the improvement of upper limb functions, occupational performance, and satisfaction. Nevertheless, VR could be integrated into conventional rehabilitation programs to enhance self-efficacy of patients after stroke.

Trial registration

This study was successfully registered under the title “Effects of virtual reality training on occupational performance and self-efficacy of patients with stroke” on October 13 2019 and could be located in https://www.chictr.org with the study identifier ChiCTR1900026550.

Motor network recovery in patients with chronic spinal cord compression: a longitudinal study following decompression surgery

OBJECTIVE The authors used functional MRI to assess cortical reorganization of the motor network after chronic spinal cord compression and to characterize the plasticity that occurs following surgical intervention. METHODS A 3-T MRI scanner was used to acquire functional images of the brain in 22 patients with reversible cervical spinal cord compression and 10 control subjects. Controls performed a finger-tapping task on 3 different occasions (baseline, 6-week follow-up, and 6-month follow-up), whereas patients performed the identical task before surgery and again 6 weeks and 6 months after spinal decompression surgery. RESULTS After surgical intervention, an increased percentage blood oxygen level-dependent signal and volume of activation was observed within the contralateral and ipsilateral motor network. The volume of activation of the contralateral primary motor cortex was associated with functional measures both at baseline (r = 0.55, p < 0.01) and 6 months after surgery (r = 0.55, p < 0.01). The percentage blood oxygen level-dependent signal of the ipsilateral supplementary motor area 6 months after surgery was associated with increased function 6 months after surgery (r = 0.48, p < 0.01). CONCLUSIONS Plasticity of the contralateral and ipsilateral motor network plays complementary roles in maintaining neurological function in patients with spinal cord compression and may be critical in the recovery phase following surgery.

Effect of bilateral lower limb strengthening exercise on balance and walking in hemiparetic patients after stroke: a randomized controlled trial

[Purpose] To evaluate the effect of bilateral lower limb strengthening designed to improve balance and walking in stroke patients. [Subjects and Methods] Twenty hemiparetic stroke patients were divided into two groups: a unilateral therapy group (UTG) (n=10) and a bilateral therapy group (BTG) (n=10). The UTG completed strength training only in the paretic lower limb. The BTG completed strength training in the paretic and non-paretic lower limbs. Assessment tools included the functional reach test (FRT), the Berg balance scale (BBS), the timed up and go (TUG) test, and a 10-meter walk test (10MWT). [Results] In both groups, the lower limb strengthening exercise for balance and walking significantly improved the FRT, BBS, TUG, and 10MWT scores. Compared with UTG, the BTG attained significantly improved FRT and BBS scores. [Conclusion] Bilateral therapy using this lower limb strengthening exercise effectively promotes balance in hemiparetic stroke patients.

Activation of less affected corticospinal tract and poor motor outcome in hemiplegic pediatric patients: a diffusion tensor tractography imaging study

The less affected hemisphere is important in motor recovery in mature brains. However, in terms of motor outcome in immature brains, no study has been reported on the less affected corticospinal tract in hemiplegic pediatric patients. Therefore, we examined the relationship between the condition of the less affected corticospinal tract and motor function in hemiplegic pediatric patients. Forty patients with hemiplegia due to perinatal or prenatal injury (13.7 ± 3.0 months) and 40 age-matched typically developing controls were recruited. These patients were divided into two age-matched groups, the high functioning group (20 patients) and the low functioning group (20 patients) using functional level of hemiplegia scale. Diffusion tensor tractography images showed that compared with the control group, the patient group of the less affected corticospinal tract showed significantly increased fiber number and significantly decreased fractional anisotropy value. Significantly increased fiber number and significantly decreased fractional anisotropy value in the low functioning group were observed than in the high functioning group. These findings suggest that activation of the less affected hemisphere presenting as increased fiber number and decreased fractional anisotropy value is related to poor motor function in pediatric hemiplegic patients.

A comparison of different models with motor dysfunction after traumatic brain injury in adult rats

The aim of this study was to evaluate the validity of the model that could produce reproducible and persistent motor weakness and define the accurate tasks and testing parameters for longitudinal assessment of neurological deficits after traumatic brain injury (TBI). We compared the effects of two rat models that suffered different controlled cortical impact (CCI) injury, as well as extensive motor cortex resection model, on behavior recovery and brain morphology. Behavioral tests including the skilled reaching task, limb-use asymmetry test and the grasping test were employed to evaluate neurofunctional recovery from pre- to 12 weeks after the injury. The results demonstrated that all the rats in four groups showed spontaneous functional improvement with the past of time after surgery, especially in rats with mild and moderate CCI injury. At the end of the experiment, the animals' performance reached preoperative base lines on reaching task and limb-use asymmetry test in mild and moderate groups, while severe motor weakness could be observed in rats with severe CCI injury, as well as rats with extended motor cortex resection. Overall, the results of this study indicated that both models with severe CCI injury and extended resection of the motor cortex developed reproducible and long-lasting motor weakness, comparable in severity and duration and identified skilled reaching task, as well as limb-use asymmetry test, as sensitive assessments for slight neurological deficits after brain injury. This will help to provide the basis for further research of the processes after the TBI and development of novel therapies.

Atypical cortical drive during activation of the paretic and nonparetic tibialis anterior is related to gait deficits in chronic stroke

OBJECTIVE

The role of cortical drive in stroke recovery for the lower extremity remains ambiguous. The purpose of this study was to investigate the relationship between cortical drive and gait speed in a group of stroke survivors.

METHODS

Eighteen individuals with stroke were dichotomized into fast or slow walking groups. Transcranial magnetic stimulation (TMS) was used to collect motor evoked potentials (MEPs) from the tibialis anterior of each lower extremity during rest, paretic muscle contractions, and nonparetic muscle contractions. An asymmetry-index (AI) was calculated using motor thresholds and compared between groups. The average MEP of the paretic leg during TMS at maximal intensity (MEP100) for each condition was compared within and between groups.

RESULTS

A significant positive correlation was found between AI and walking speed. Slow-walkers had greater MEP100s during the nonparetic contraction than during the paretic contraction or rest conditions. In contrast, fast-walkers had greatest MEP100s during the paretic contraction.

CONCLUSIONS

Alterations in the balance of corticomotor excitability occur in the lower extremity of individuals with poor motor recovery post-stroke. This atypical cortical drive is dependent on activation of the unaffected hemisphere and contraction of the nonparetic leg.

SIGNIFICANCE

Understanding mechanisms underlying motor function can help to identify specific patient deficits that impair function.

A functional magnetic resonance imaging study on the effect of acupuncture at GB34 (Yanglingquan) on motor-related network in hemiplegic patients

BACKGROUND

Functional disability of stroke patients, especially limb motor function, seriously impacts the quality of life. Although acupuncture at GB34 (Yang-ling-quan) has been shown to be effective on the recovery of motor function, the underlying mechanism has not been well explored.

OBJECTIVE

To explore the central mechanisms of immediate effect of acupuncture at GB34 on motor-related network of stroke patients with hemiplegia.

METHODS

A repeated measures ANOVA method was employed to investigate the effect of acupuncture at GB34 on functional connectivity of motor-related network. Six stroke patients with left hemiplegia were recruited. A left hand motor task fMRI experiment was performed before and right after acupuncture. Sham point acupuncture was taken as control. The most significant fMRI signal changes during motor task in the right precentral gyrus were identified, which was selected as a seed point for connectivity analysis. Then the functional connectivity of this seed point was compared between verum and sham point acupuncture.

RESULTS

Compared to sham, acupuncture at GB34 showed positive interaction effect at right temporal pole, left lingual gyrus, and left cerebellum. While negative interaction effect mainly occurred at contralateral motor cortex and ipsilateral motor cortex of lower limb.

CONCLUSIONS

Acupuncture at GB34 may increase motor-cognition connectivity meanwhile decrease compensation of unaffected motor cortex and homolateral synkinesis, which can definitely promote the rehabilitation of hemiplegia and spasm.

Changes in brain activation in stroke patients after mental practice and physical exercise: a functional MRI study

Mental practice is a new rehabilitation method that refers to the mental rehearsal of motor imagery content with the goal of improving motor performance. However, the relationship between activated regions and motor recovery after mental practice training is not well understood. In this study, 15 patients who suffered a first-ever subcortical stroke with neurological deficits affecting the right hand, but no significant cognitive impairment were recruited. 10 patients underwent mental practice combined with physical practice training, and 5 patients only underwent physical practice training. We observed brain activation regions after 4 weeks of training, and explored the correlation of activation changes with functional recovery of the affected hands. The results showed that, after 4 weeks of mental practice combined with physical training, the Fugl-Meyer assessment score for the affected right hand was significantly increased than that after 4 weeks of practice training alone. Functional MRI showed enhanced activation in the left primary somatosensory cortex, attenuated activation intensity in the right primary motor cortex, and enhanced right cerebellar activation observed during the motor imagery task using the affected right hand after mental practice training. The changes in brain cortical activity were related to functional recovery of the hand. Experimental findings indicate that cortical and cerebellar functional reorganization following mental practice contributed to the improvement of hand function.

Change of the anterior corticospinal tract on the normal side of the brain in chronic stroke patients: Diffusion tensor imaging study

We investigated change of the anterior corticospinal tract (CST) on the normal side of the brain in stroke patients, using diffusion tensor tractography (DTT). We recruited 32 stroke patients and 24 control subjects. Motricity Index and DTT for the whole and anterior CSTs were evaluated. According to findings, the fiber number of the anterior CST on the normal side of the brain of stroke patients was related to poor motor function of the affected extremities.

Tracking post-error adaptation in the motor system by transcranial magnetic stimulation

The commission of an error triggers cognitive control processes dedicated to error correction and prevention. Post-error adjustments leading to response slowing following an error ("post-error slowing"; PES) might be driven by changes in excitability of the motor regions and the corticospinal tract (CST). The time-course of such excitability modulations of the CST leading to PES is largely unknown. To track these presumed excitability changes after an error, single pulse transcranial magnetic stimulation (TMS) was applied to the motor cortex ipsilateral to the responding hand, while participants were performing an Eriksen flanker task. A robotic arm with a movement compensation system was used to maintain the TMS coil in the correct position during the experiment. Magnetic pulses were delivered over the primary motor cortex ipsilateral to the active hand at different intervals (150, 300, 450 ms) after correct and erroneous responses, and the motor-evoked potentials (MEP) of the first dorsal interosseous muscle (FDI) contralateral to the stimulated hemisphere were recorded. MEP amplitude was increased 450 ms after the error. Two additional experiments showed that this increase was neither associated to the correction of the erroneous responses nor to the characteristics of the motor command. To the extent to which the excitability of the motor cortex ipsi- and contralateral to the response hand are inversely related, these results suggest a decrease in the excitability of the active motor cortex after an erroneous response. This modulation of the activity of the CST serves to prevent further premature and erroneous responses. At a more general level, the study shows the power of the TMS technique for the exploration of the temporal evolution of post-error adjustments within the motor system.

Brain connectivity plasticity in the motor network after ischemic stroke

The motor function is controlled by the motor system that comprises a series of cortical and subcortical areas interacting via anatomical connections. The motor function will be disturbed when the stroke lesion impairs either any of these areas or their connections. More and more evidence indicates that the reorganization of the motor network including both areas and their anatomical and functional connectivity might contribute to the motor recovery after stroke. Here, we review recent studies employing models of anatomical, functional, and effective connectivity on neuroimaging data to investigate how ischemic stroke influences the connectivity of motor areas and how changes in connectivity relate to impaired function and functional recovery. We suggest that connectivity changes constitute an important pathophysiological aspect of motor impairment after stroke and important mechanisms of motor recovery. We also demonstrate that therapeutic interventions may facilitate motor recovery after stroke by modulating the connectivity among the motor areas. In conclusion, connectivity analyses improved our understanding of the mechanisms of motor recovery after stroke and may help to design hypothesis-driven treatment strategies and sensitive measures for outcome prediction in stroke patients.

Modeling developmental plasticity after perinatal stroke: defining central therapeutic targets in cerebral palsy

Perinatal stroke is presented as the ideal human model of developmental neuroplasticity. The precise timing, mechanisms, and locations of specific perinatal stroke diseases provide common examples of well defined, focal, perinatal brain injuries. Motor disability (hemiparetic cerebral palsy) constitutes the primary adverse outcome and the focus of models explaining how motor systems develop in health and after early injury. Combining basic science animal work with human applied technology (functional magnetic resonance imaging, diffusion tensor imaging, and transcranial magnetic stimulation), a model of plastic motor development after perinatal stroke is presented. Potential central therapeutic targets are revealed. The means to measure and modulate these targets, including evidence-based rehabilitation therapies and noninvasive brain stimulation, are suggested. Implications for clinical trials and future directions are discussed.

Effects of treadmill training with optic flow on balance and gait in individuals following stroke: randomized controlled trials

OBJECTIVE

This study examined the effects of treadmill training with optic flow on the functional recovery of balance and gait in stroke patients.

DESIGN

Randomized controlled experimental study.

PARTICIPANTS

Thirty patients following stroke were divided randomly into the treadmill with optic flow group (n = 10), treadmill group (n = 10) and control group (n = 10).

INTERVENTIONS

The subjects in the experimental group wore a head-mounted display to receive speed-modulated optic flow during treadmill training for 30 minutes, while those in the treadmill group and control group received treadmill training and regular therapy for the same time, three times a week for four weeks.

MAIN MEASURES

The data were collected using timed up-and-go test, functional reach test, 10-m walk test, and six-minute walk test before and after treatment.

RESULTS

The timed up-and-go test in the treadmill with optic flow group (5.55 ± 2.04) improved significantly greater than the treadmill (1.50 ± 0.93) and control (0.40 ± 0.84) groups. The functional reach test in the treadmill with optic flow group (2.78 ± 1.44) was significantly higher than the control group (0.20 ± 0.16) only. The gait velocity in the treadmill with optic flow group (0.21 ± 0.06) showed a significant decrease compared to the treadmill (0.03 ± 0.02) and control (0.01 ± 0.02) groups. Finally, the six-minute walk test in the treadmill with optic flow group (24.49 ± 11.00) showed significant improvement compared to the treadmill training (4.65 ± 3.25) and control (1.79 ± 3.08) groups.

CONCLUSION

Treadmill using optic flow speed modulation improves the balance and gait significantly in patients with stroke who are able to participate in physical gait training.

Stroke patient with mirror movement of the affected hand due to an ipsilateral motor pathway confirmed by transcranial magnetic stimulation: a case report

A stroke patient with right hemiplegia and mirror movement underwent transcranial magnetic stimulation (TMS) and somatosensory-evoked potential (SEP) testing. The motor-evoked potentials (MEPs) of both abductor pollicis brevis muscles after stimulating the unaffected right hemisphere showed similar latencies, and were potentially produced by corticospinal tracts from the same motor cortex. N(20) responses of SEPs were recorded at C(4)' after contralateral stimulation of the unaffected left median nerve, but not stimulation of the affected right median nerve. The mirror movements and motor recovery might have utilized an ipsilateral motor pathway between the unaffected hemisphere and the affected hand.

Noninvasive cortical stimulation in neurorehabilitation: a review

The purpose of this special communication is to provide an overview of noninvasive cortical stimulation techniques, the types of mechanistic information they can provide, and the ways their use is contributing to our understanding of current models of neurorehabilitation. The focus is primarily on studies using noninvasive cortical stimulation techniques in the human motor system. Noninvasive cortical stimulation techniques are useful tools in the field of neurorehabilitation that are being actively used to test proposed models of functional recovery after neurologic injury. They can provide insight into the physiologic mechanisms of functional recovery and are under investigation as a possible auxiliary intervention to modulate cortical excitability and enhance training effects.

New advances in the rehabilitation of CNS diseases applying rTMS

Transcranial magnetic stimulation (TMS) can directly stimulate the CNS, modifying the brain's plasticity to enhance the behavior of the paretic extremities. Studies with low-frequency repetitive TMS (rTMS) on the intact hemisphere and those with high frequencies on the affected hemisphere could increase the speed of movement in the hand affected by CNS injury. Stimulation of the motor pathway may contribute to faster improvement in patients with spinal cord injury. Symptoms of Parkinson's disease (such as cognition and working memory, neglect syndrome and global aphasia) can be influenced by rTMS. However, the site of stimulation and the parameters of rTMS are different. Processes that contribute to the behavior of rTMS include the modification of brain plasticity, induction of neurogenesis, growth of new fibers in the spinal cord or all of these together. According to previous research, rTMS may be suitable as an add-on therapy to rehabilitation in CNS diseases.

Cortical Reorganization of Hand Motor Function to Primary Sensory Cortex in Hemiparetic Patients With a Primary Motor Cortex Infarct

OBJECTIVE

To show cortical reorganization in hemiparetic patients with a primary motor cortex (M1) infarct including the precentral knob by using functional magnetic resonance imaging (fMRI).

DESIGN

Case-control.

SETTING

Outpatient clinics in the rehabilitation department of a university hospital.

PARTICIPANTS

Two stroke patients and 20 control subjects.

INTERVENTIONS

By using fMRI, we evaluated the hand motor function of 2 hemiparetic stroke patients, who had made some recovery from complete paralysis of the affected hand, and 20 control subjects.

MAIN OUTCOME MEASURES

fMRI was performed by using the blood oxygen level-dependent technique at 1.5 T with a standard head coil. The motor task paradigm consisted of hand grasp-release movements.

RESULTS

The contralateral primary sensorimotor cortex was activated by the hand movements of the control subjects and of the unaffected side of the 2 patients. Only the contralateral (infarct side) primary sensory cortex (S1) was activated by the movements of the affected hand of the 2 patients, a result that was not observed in the control subjects or with the unaffected hand in the stroke patients.

CONCLUSIONS

The hand motor function associated with the infarcted M1 in our patients was reorganized into the S1. These results suggest cortical reorganization in patients with an M1 infarct.