Cortical control of postural balance in patients with hemiplegic stroke

Despite its remarkable effect on the activities of daily living, the precise mechanism underlying balance control after stroke remains to be elucidated. In this study, we investigated the cortical activation induced by postural perturbation in 20 patients with stroke using a 50-channel event-related functional near-infrared spectroscopy. A combination of brisk forward and backward movements of a platform without any prior cue was used as an external postural perturbation. Multi-participant analysis of oxygenated hemoglobin signals showed postural perturbation-related cortical activation in the prefrontal cortical areas in both hemispheres as well as the premotor and parietal association cortical areas in the unaffected hemisphere. Regression analysis using the individual Berg Balance Scale as the regressor showed a significant positive correlation between balance ability and the postural perturbation-related changes in oxygenated hemoglobin signals in the supplementary motor areas and prefrontal cortical areas in both hemispheres. Consistent with the previous findings in healthy participants, these findings suggest that the broad cortical network, including the prefrontal, premotor, supplementary motor, and parietal cortical areas in both hemispheres, was essential for balance control even in poststroke patients.     

Cortical reorganization associated with motor recovery in hemiparetic stroke patients

We investigated the cortical activation changes associated with motor recovery in eight hemiparetic patients with cerebral infarct by using functional MRI (fMRI), which was performed at 1.5 T in parallel with finger flexion-extension movements at a fixed rate. The first fMRI was performed when the patient was able to flex and extend fingers of the affected hand against gravity, and the second fMRI was done when the motor function of the affected hand showed definite improvement. The main cortical activation changes that occurred with motor recovery were an increment in the affected and a decrement in the unaffected primary sensori-motor cortex (SMC) activities. In conclusion, it seems that cortical reorganization occurred in parallel with motor recovery in hemiparetic patients with cerebral infarct.     

Cortical reorganization after modified constraint-induced movement therapy in pediatric hemiplegic cerebral palsy

Constraint-induced movement therapy improves motor function in the affected hand of children with hemiplegic cerebral palsy and results in cortical changes in adults with stroke. This study measured clinical improvement and cortical reorganization in a child with hemiplegia who underwent modified constraint-induced movement therapy for 3 weeks. Clinical, functional magnetic resonance imaging and magnetoencephalography measurements were done at baseline, after therapy, and 6 months after therapy. Modified constraint-induced movement therapy resulted in clinical improvement as measured by the Pediatric Motor Activity Log. Functional magnetic resonance imaging showed bilateral sensorimotor activation before and after therapy and a shift in the laterality index from ipsilateral to contralateral hemisphere after therapy. Magnetoencephalography showed increased cortical activation in the ipsilateral motor field and contralateral movement evoked field after therapy. Cortical reorganization was maintained at the 6-month follow-up. This is the first study to demonstrate cortical reorganization after any version of constraint-induced movement therapy in a child with hemiplegia.     

Motor cortex activation is preserved in patients with chronic hemiplegic stroke

Many central nervous system conditions that cause weakness, including many strokes, injure corticospinal tract but leave motor cortex intact. Little is known about the functional properties of surviving cortical regions in this setting, in part because many studies have used probes reliant on the corticospinal tract. We hypothesized that many features of motor cortex function would be preserved when assessed independent of the stroke-affected corticospinal tract. Functional MRI was used to study 11 patients with chronic hemiplegia after unilateral stroke that spared regions of motor cortex. Activation in stroke-affected hemisphere was evaluated using 3 probes independent of affected corticospinal tract: passive finger movement, a hand-related visuomotor stimulus, and tapping by the nonstroke index finger. The site and magnitude of cortical activation were similar when comparing the stroke hemisphere to findings in 19 control subjects. Patients activated each of 8 cortical regions with similar frequency as compared to controls, generally with a smaller activation volume. In some cases, clinical measures correlated with the size or the site of stroke hemisphere activation. The results suggest that, despite stroke producing contralateral hemiplegia, surviving regions of motor cortex actively participate in the same proprioceptive, visuomotor, and bilateral movement control processes seen in control subjects.     

Cortical reorganization in patients with facial palsy

Possible changes in the organization of the cortex in patients with facial palsy, serving as a model of peripheral motor deefferentation, were investigated by using transcranial magnetic stimulation (TMS) and positron emission tomography (PET). With TMS, the size of the area producing muscle-evoked potentials (MEPs) of the abductor pollicis brevis muscle, the sum of MEP amplitudes within this area, and the volume over the mapping area were compared between both hemispheres in 8 patients. With PET, increases in regional cerebral blood flow, measured with the standard H₂ ¹⁵O₂ bolus injection technique, were compared between 6 patients and 6 healthy volunteers during sequential finger opposition. Patients moved the hand ipsilateral to the facial palsy, the control subjects the right hand. Of 9 patients in total, 5 participated in both experiments. With both methods, an enlargement of the hand field contralateral to the facial palsy was found, extending in a lateral direction, into the site of the presumed face area. The PET data showed that the enlargemement of the hand field in the somatosensory cortex (SMC) is part of a widespread cortical reorganization, including the ipsilateral SMC and bilateral secondary motor and sensory areas. We report for the first time, using two different noninvasive methods, that peripheral, mere motor deefferentation is a sufficient stimulus for reorganizational changes in the healthy adult human cortex.     

Cortical reorganization for response regulation with unilateral thalamic stroke detected by functional MRI

To understand neural reorganization of response regulation after stroke, a 54-year-old woman with a chronic left thalamic stroke performed a task requiring decisions about the directionality of an arrow during cerebral functional magnetic resonance imaging. Her performance was compared to 13 matched healthy control subjects. Her behavioral responses were slower but as accurate. Bilateral frontal activations were observed in the right medial frontal gyrus (BA 9), left superior frontal gyrus (BA 45), and left frontal rectus gyrus (BA 11). Activation in the right medial frontal gyrus, along with activity in close proximity to the anterior cingulate cortex, was observed, which may reflect reorganization of activity after the loss of function of the anterior cingulate cortex.     

Cortical reorganization induced by virtual reality therapy in a child with hemiparetic cerebral palsy

Virtual reality (VR) therapy is a new, neurorehabilitation intervention aimed at enhancing motor performance in children with hemiparetic cerebral palsy (CP). This case report investigated the effects of VR therapy on cortical reorganization and associated motor function in an 8-year-old male with hemiparetic CP. Cortical activation and associated motor development were measured before and after VR therapy using functional magnetic resonance imaging (fMRI) and standardized motor tests. Before VR therapy, the bilateral primary sensorimotor cortices (SMCs) and ipsilateral supplementary motor area (SMA) were predominantly activated during affected elbow movement. After VR therapy, the altered activations disappeared and the contralateral SMC was activated. This neuroplastic change was associated with enhanced functional motor skills including reaching, self-feeding, and dressing. These functions were not possible before the intervention. To our knowledge, this is the first fMRI study in the literature that provides evidence for neuroplasticity after VR therapy in a child with hemiparetic CP.     

Evolution of functional reorganization in hemiplegic stroke: a serial positron emission tomographic activation study

We used serial positron emission tomography (PET) to study the evolution of functional brain activity within 12 weeks after a first subcortical stroke. Six hemiplegic stroke patients and three normal subjects were scanned twice (PET 1 and PET 2) by using passive elbow movements as an activation paradigm. Increases of regional cerebral blood flow comparing passive movements and rest and differences of regional cerebral blood flow between PET 1 and PET 2 in patients and normal subjects were assessed by using statistical parametric mapping. In controls, activation was found in the contralateral sensorimotor cortex, supplementary motor area, and bilaterally in the inferior parietal cortex with no differences between PET 1 and PET 2. In stroke patients, at PET 1, activation was observed in the bilateral inferior parietal cortex, contralateral sensorimotor cortex, and ipsilateral dorsolateral prefrontal cortex, supplementary motor area, and cingulate cortex. At PET 2, significant increases of regional cerebral blood flow were found in the contralateral sensorimotor cortex and bilateral inferior parietal cortex. A region that was activated at PET 2 only was found in the ipsilateral premotor area. Recovery from hemiplegia is accompanied by changes of brain activation in sensory and motor systems. These alterations of cerebral activity may be critical for the restoration of motor function.     

Cortical reorganization in deaf children

Topographic mapping of the cerebral cortex of 79 deaf children and a group of matched hearing children was performed, using measures of electroencephalographic coherence, phase, and power. Deaf children manifested higher coherence and lower phase in certain left hemispheric areas, suggesting less neural differentiation; but lower coherence and higher phase in certain right hemispheric areas, suggesting greater differentiation. Deaf children had higher total power in bilateral frontal cortex than did hearing children. The data also suggested compensatory functioning in the visual cortex of the deaf subjects. The pattern of results varied somewhat in relation to cause of deafness. These findings support the hypothesis that prelingual deafness results in a partial reorganization of cerebral cortex.     

Effect of task-oriented training for people with stroke: a meta-analysis focused on repetitive or circuit training

Abstract

Purpose:

The current meta-analysis reviewed evidence for effective task-oriented training focused on repetitive or circuit training after stroke.

Method:

Searches were conducted of randomized, controlled trials using task-oriented training. The quality of each study was assessed using the Physiotherapy Evidence Database (PEDro) scale. Eleven studies were analyzed regarding the magnitude of effect sizes (ESs) and categorized according to extremities focused upon for training, outcome measures, and study variables. This included duration and frequency of training and stroke stage.

Results:

The PEDro scores ranged from 4 to 8 (median?=?7). The overall ES of the 11 studies was large. The effects for lower extremities and both acute/sub-acute and chronic stage stroke were large and significant. Significant effects were also found for gait velocity, gait endurance, balance, timed up and go test, and strength of the lower extremities. There was no significant effect of training focused on upper extremities. Training with a duration of 2?weeks and frequency of 7?days a week had the greatest effects.

Conclusions:

Task-oriented training interventions are useful for improving muscle strength and gait related activities in both acute/sub-acute and chronic stroke patients. Although this meta-analysis provides evidence of task-oriented training for improving functioning after stroke, further studies are necessary to investigate the effects of training on upper extremities and the overall cost-effectiveness of such training.     

Robot-aided sensorimotor arm training improves outcome in patients with chronic stroke

Thirty patients with chronic stroke received 6 weeks of sensorimotor robotic training in a pilot study that targeted motor function of the affected shoulder and elbow. The impairment and disability scores were stable during a 2-month observation/measurement period, improved significantly by program completion, and remained robust in the 3-month follow-up. Task-specific motor training attenuated a chronic neurologic deficit well beyond the expected period for improvement after stroke.     

Motor network reorganization after motor imagery training in stroke patients with moderate to severe upper limb impairment

Background

Motor imagery training (MIT) has been widely used to improve hemiplegic upper limb function in stroke rehabilitation. The effectiveness of MIT is associated with the functional neuroplasticity of the motor network. Currently, brain activation and connectivity changes related to the motor recovery process after MIT are not well understood. Aim: We aimed to investigate the neural mechanisms of MIT in stroke rehabilitation through a longitudinal intervention study design with task-based functional magnetic resonance imaging (fMRI) analysis.

Methods

We recruited 39 stroke patients with moderate to severe upper limb motor impairment and randomly assigned them to either the MIT or control groups. Patients in the MIT group received 4 weeks of MIT therapy plus conventional rehabilitation, while the control group only received conventional rehabilitation. The assessment of Fugl-Meyer Upper Limb Scale (FM-UL) and Barthel Index (BI), and fMRI scanning using a passive hand movement task were conducted on all patients before and after treatment. The changes in brain activation and functional connectivity (FC) were analyzed. Pearson's correlation analysis was conducted to evaluate the association between neural functional changes and motor improvement.

Results

The MIT group achieved higher improvements in FM-UL and BI relative to the control group after the treatment. Passive movement of the affected hand evoked an abnormal bilateral activation pattern in both groups before intervention. A significant Group × Time interaction was found in the contralesional S1 and ipsilesional M1, showing a decrease of activation after intervention specifically in the MIT group, which was negatively correlated with the FM-UL improvement. FC analysis of the ipsilesional M1 displayed the motor network reorganization within the ipsilesional hemisphere, which correlated with the motor score changes.

Conclusions

MIT could help decrease the compensatory activation at both hemispheres and reshape the FC within the ipsilesional hemisphere along with functional recovery in stroke patients.     

Painful hemiplegic shoulder in stroke patients: causes and management

Introduction

The hemiplegic shoulder pain is common after a stroke. Its appearance brings pain and limits daily living activities as well as participation in specific Neuro-rehabilitation programs. All this leads to a worse functional outcome. Good management of patients can reduce both the frequency and intensity of shoulder pain, improving functional outcome.

Development

We conducted a literature search of various databases between 1980 and 2008. The articles were evaluated using the PEDro scoring system. Five evidence levels were established for the conclusions.

Conclusions

Shoulder subluxation, occurs at an early stage after stroke and is associated with subluxation of the shoulder joint and spasticity (mainly subscapularis and pectoralis). Slings prevent subluxation of the shoulder. It is preferable to move within a lower range of motion and without aggression to prevent the occurrence of shoulder pain. The injection of corticosteroids does not improve pain and range of motion in hemiplegic patients, while botulinum toxin combined with physical therapy appears to reduce hemiplegic shoulder pain.     

Effects of task-oriented treadmill-walking training on walking ability of stoke patients

Background: Generally, treadmill-walking training focuses on weight bearing and the speed of walking. However, changes in direction, speed, and slope while walking require adaptation.

Objective: The effects of task-oriented treadmill-walking training (TOTWT) on the walking ability of stroke patients were evaluated.

Methods: Subjects were randomly divided into two groups: the task-oriented treadmill-walking training (TOTWT) group and the conventional treadmill-walking training (CTWT) group. Evaluation was performed before the commencement of the training and again 4 and 8 wk after training was initiated. The OptoGait system measured gait parameters. The Timed Up and Go test and 6-min walk test were also performed.

Results: Within each group, both the TOTWT and the CTWT groups significantly differed before and after the intervention in all tests (P < 0.05); the CTWT group showed greater improvement in all tests following TOTWT (P < 0.05).

Conclusion: TOTWT improves gait and rehabilitation in the stroke-affected limb, and also improves general gait characteristics.     

The role of technology in task-oriented training in persons with subacute stroke: a randomized controlled trial

This trial compares the effects of task-oriented physical therapy (PT) provided with and without the use of rehabilitation technology on locomotor recovery in 63 persons with subacute stroke. Participants in the experimental (EXP) group used a treadmill, a Kinetron isokinetic exerciser, and a limb-load monitor, whereas those in the control (CTL) group did not while engaging in PT 1 h per day, 5 days per week for 2 months. Locomotor recovery was assessed by clinical (gait speed, Fugl Meyer motor leg and arm subscores, the Balance Scale, the Timed Up and Go, and the Barthel ambulation subscore) and laboratory outcomes (gait kinematics and kinetics) pre- and posttherapy and 3 months later. Within groups, gait speed (P < 0.01) and all secondary measures improved posttherapy (P < 0.01-0.05), and improvements in clinical measures were maintained at follow-up, but there was no difference between groups (P > 0.05). When the groups were pooled, the increase in gait speed was associated (r = 0.52, P = 0.003) with an increase in ankle power generation of the affected leg. The results demonstrate that the efficacy of the task-oriented approach is not dependent on rehabilitation technology.