Electrical stimulation driving functional improvements and cortical changes in subjects with stroke

Neuromuscular electrical stimulation for motor restoration in hemiplegia

Clinical applications of neuromuscular electrical stimulation (NMES) in stroke rehabilitation provide both therapeutic and functional benefits. Therapeutic applications include upper and lower limb motor relearning and reduction of poststroke shoulder pain. There is growing evidence that NMES, especially those approaches that incorporate task-specific strategies, is effective in facilitating upper and lower limb motor relearning. There is also strong evidence that NMES reduces poststroke shoulder subluxation and pain. Functional applications include upper and lower limb neuroprostheses. Lower limb neuroprostheses in the form of peroneal nerve stimulators is effective in enhancing the gait speed of stroke survivors with foot-drop. The development of hand neuroprostheses is in its infancy and must await additional fundamental and technical advances before reaching clinical viability. The limitations of available systems and future developments are discussed.

Impact of early applied upper limb stimulation: the EXPLICIT-stroke programme design

BACKGROUND

Main claims of the literature are that functional recovery of the paretic upper limb is mainly defined within the first month post stroke and that rehabilitation services should preferably be applied intensively and in a task-oriented way within this particular time window. EXplaining PLastICITy after stroke (acronym EXPLICIT-stroke) aims to explore the underlying mechanisms of post stroke upper limb recovery. Two randomized single blinded trials form the core of the programme, investigating the effects of early modified Constraint-Induced Movement Therapy (modified CIMT) and EMG-triggered Neuro-Muscular Stimulation (EMG-NMS) in patients with respectively a favourable or poor probability for recovery of dexterity.

METHODS/DESIGN

180 participants suffering from an acute, first-ever ischemic stroke will be recruited. Functional prognosis at the end of the first week post stroke is used to stratify patient into a poor prognosis group for upper limb recovery (N = 120, A2 project) and a group with a favourable prognosis (N = 60, A1 project). Both groups will be randomized to an experimental arm receiving respectively modified CIMT (favourable prognosis) or EMG-NMS (poor prognosis) for 3 weeks or to a control arm receiving usual care. Primary outcome variable will be the Action Research Arm Test (ARAT), assessed at 1,2,3,4,5, 8, 12 and 26 weeks post stroke. To study the impact of modified CIMT or EMG-NMS on stroke recovery mechanisms i.e. neuroplasticity, compensatory movements and upper limb neuromechanics, 60 patients randomly selected from projects A1 and A2 will undergo TMS, kinematical and haptic robotic measurements within a repeated measurement design. Additionally, 30 patients from the A1 project will undergo fMRI at baseline, 5 and 26 weeks post stroke.

CONCLUSION

EXPLICIT stroke is a 5 year translational research programme which main aim is to investigate the effects of early applied intensive intervention for regaining dexterity and to explore the underlying mechanisms that are involved in regaining upper limb function after stroke. EXPLICIT-stroke will provide an answer to the key question whether therapy induced improvements are due to either a reduction of basic motor impairment by neural repair i.e. restitution of function and/or the use of behavioural compensation strategies i.e. substitution of function.

Effects of somatosensory stimulation on the excitability of the unaffected hemisphere in chronic stroke patients

INTRODUCTION

Somatosensory stimulation of the paretic upper limb enhances motor performance and excitability in the affected hemisphere, and increases activity in the unaffected hemisphere, in chronic stroke patients. We tested the hypothesis that somatosensory stimulation of the paretic hand would lead to changes in excitability of the unaffected hemisphere in these patients, and we investigated the relation between motor function of the paretic hand and excitability of the unaffected hemisphere.

METHODS

Transcranial magnetic stimulation was administered to the unaffected hemisphere of nine chronic stroke patients. Patients were submitted to 2-h somatosensory stimulation in the form of median nerve stimulation and control stimulation using a cross-over design. Baseline Jebsen-Taylor test scores were evaluated. Resting motor threshold, intracortical facilitation, short-interval intracortical inhibition, and visual analog scores for attention, fatigue and drowsiness were measured across conditions.

RESULTS

Better pre-stimulation baseline motor function was correlated with deeper SICI in the unaffected hemisphere. We found no overt changes in any physiological marker after somatosensory stimulation. There was increased drowsiness in the control session, which may have led to changes in intracortical facilitation.

CONCLUSIONS

Our results do not support an overt effect of a single session of somatosensory stimulation of the paretic hand on motor cortical excitability of the unaffected hemisphere as measured by motor threshold, short-interval intracortical inhibition or intracortical facilitation. It remains to be determined if other markers of cortical excitability are modulated by somatosensory stimulation, and whether repeated sessions or lesion location may lead to different effects.

A novel functional electrical stimulation treatment for recovery of hand function in hemiplegia: 12-week pilot study

BACKGROUND

Loss of finger extension is common after stroke and can severely limit hand function. Contralaterally controlled functional electrical stimulation (CCFES) is a new treatment aimed at restoring volitional finger and thumb extension. A previous pilot study showed reductions in hand impairment after 6 weeks of CCFES, but the effect did not persist after end of treatment.

OBJECTIVE

This study aimed to evaluate the feasibility of achieving greater and more persistent gains with CCFES by increasing the treatment period to 12 weeks.

METHODS

CCFES uses neuromuscular electrical stimulation to open the paretic hand in direct proportion to the degree of volitional opening of the unimpaired contralateral hand, which is detected by an instrumented glove. Three subjects with chronic hemiplegia participated in a 12-week CCFES treatment, which consisted of daily CCFES-assisted active repetitive hand-opening exercises and twice weekly functional task practice with CCFES.

RESULTS

Maximum voluntary finger extension increased by 101 degrees and 68 degrees for subjects 1 and 2, respectively, but subject 3 had no improvement in finger extension. Box and Block score increased by 6, 15, and 7 blocks, and upper extremity Fugl-Meyer score increased by 11, 15, and 7 points for subjects 1, 2, and 3, respectively. The finger extension gains declined at the 1-month and 3-month follow-up for subjects 1 and 2, but the gains in Box and Block and Fugl-Meyer scores persisted at follow-up.

CONCLUSIONS

Greater reductions in hand impairment were achieved by extending the treatment period. The effect and its longevity may be related to baseline impairment level.

Impact of EMG-triggered neuromuscular stimulation of the wrist and finger extensors of the paretic hand after stroke: a systematic review of the literature

OBJECTIVE

To assess whether EMG-triggered neuromuscular electrical stimulation (EMG-NMES) applied to the extensor muscles of the forearm improves hand function after stroke.

DESIGN

Systematic review of randomized controlled trials.

METHODS

A computer-aided literature search up to June 2006 identified articles comparing EMG-NMES of the upper extremity with usual care. Methodological quality was rated on the Physiotherapy Evidence Database scale (PEDro), and the Hedges' g model was used to calculate the summary effect sizes (SES) using fixed or random models depending on heterogeneity.

RESULTS

Eight studies, selected out of 192 hits and presenting 157 patients, were included in quantitative and qualitative analyses. The methodological quality ranged from 2 to 6 points. The meta-analysis revealed non-significant effect sizes in favour of EMG-NMES for reaction time, sustained contraction, dexterity measured with the Box and Block manipulation test, synergism measured with the Fugl-Meyer Motor Assessment Scale and manual dexterity measured with the Action Research Arm test.

CONCLUSION

No statistically significant differences in effects were found between EMG-NMES and usual care. Most studies had poor methodological quality, low statistical power and insufficient treatment contrast between experimental and control groups. In addition, all studies except two investigated the effects of EMG-NMES in the chronic phase after stroke, whereas the literature suggests that an early start, within the time window in which functional outcome of the upper limb is not fully defined, is more appropriate.

Cortical effect and functional recovery by the electromyography-triggered neuromuscular stimulation in chronic stroke patients

We investigated the effect of electromyography (EMG)-triggered neuromuscular electrical stimulation (NMES; EMG-stim) on functional recovery of the hemiparetic hand and the related cortical activation pattern in chronic stroke patients. We enrolled 14 stroke patients, who were randomly assigned to the EMG-stim (n=7) or the control groups (n=7). The EMG-stim was applied to the wrist extensor of the EMG-stim group for two sessions (30 min/session) a day, five times per week for 10 weeks. Four functional tests (box and block, strength, the accuracy index, and the on/offset time of muscle contraction) and functional MRI (fMRI) were performed before and after treatment. fMRI was measured at 1.5 T in parallel with timed finger flexion-extension movements at a fixed rate. Following treatment, the EMG-stim group showed a significant improvement in all functional tests. The main cortical activation change with such functional improvement was shifted from the ipsilateral sensorimotor cortex (SMC) to the contralateral SMC. We demonstrated that 10-week EMG-stim can induce functional recovery and change of cortical activation pattern in the hemiparetic hand of chronic stroke patients.

Peripheral repetitive magnetic stimulation induces intracortical inhibition in healthy subjects

OBJECTIVE

Repetitive magnetic stimulation (rMS) is mainly used in transcranial applications. Only a few works have described its potential peripheral use. The aim of this investigation was to determine if conditioning peripheral (paravertebral) rMS of the cervical nerve roots in a group of healthy subjects induces changes in motor cortical excitability.

METHODS

This was measured by means of motor evoked potentials (MEP), motor recruitment curves (RC), intracortical inhibition (ICI) and facilitation, as well as the cortical silent period (CSP) before and after repetitive stimulation. rMS was carried out by applying ten series of stimulation at 120% of resting motor threshold, each lasting 10 seconds with a frequency of 20 Hz. The nerve roots (C7/C8) of the right hand innervating the target muscles (the first dorsal interosseous) were systematically stimulated.

RESULTS

This conditioning rMS caused a significantly longer CSP (p=0.001), increased MEP amplitudes (with a tendency to significance of p=0.06) and raised ICI (p<0.05). These changes were absent on the contralateral side, as well as in the course of RC. In conclusion, previously published results that described a prolonged CSP and increased MEP amplitudes led us to speculate that conditioning peripheral rMS is, like electrical stimulation, capable of influencing motor cortical excitability.

SIGNIFICANCE

rMS might therefore be used in rehabilitative strategies for spasticity, pain or central paresis.

Somatosensory stimulation enhances the effects of training functional hand tasks in patients with chronic stroke

OBJECTIVE

To test the hypothesis that somatosensory stimulation would enhance the effects of training functional hand tasks immediately after practice and 1 day later in chronic subcortical stroke patients.

DESIGN

Single-blinded and randomized, crossover study.

SETTING

Human research laboratory.

PARTICIPANTS

Nine chronic subcortical stroke patients.

INTERVENTIONS

Three separate sessions of motor training preceded by (1) synchronous peripheral nerve stimulation (PNS), (2) no stimulation, or (3) asynchronous PNS.

MAIN OUTCOME MEASURES

Time to complete the Jebsen-Taylor Hand Function Test (JTHFT time) and corticomotor excitability tested with transcranial magnetic stimulation.

RESULTS

After familiarization practice, during which all patients reached a performance plateau, training under the effects of PNS reduced JTHFT time by 10% beyond the post-familiarization plateau. This behavioral gain was accompanied by a specific reduction in GABAergically mediated intracortical inhibition in the motor cortex. These findings were not observed after similar practice under the influence of no stimulation or asynchronous PNS sessions.

CONCLUSIONS

Somatosensory stimulation may enhance the training of functional hand tasks in patients with chronic stroke, possibly through modulation of intracortical GABAergic pathways.

fMRI reliability in subjects with stroke

Functional MRI (fMRI) has become one of the most commonly used neuroimaging tools to assess the cortical effects associated with rehabilitation, learning, or disease recovery in subjects with stroke. Despite this, there has been no systematic study of the reliability of the fMR signal in this population. The purpose of this study was to examine the within- and between-session reliability of fMRI in cortical and cerebellar structures in subjects with stroke during a complex, continuous visual motor task performed with the less affected hand. Nine subjects with stroke underwent four testing trials during two sessions separated by three weeks. Subjects performed a drawing task using an MRI compatible joystick while in the MRI. Methods of analysis evaluated included: percent signal intensity change, active voxel count and a voxel by voxel stat value analysis within and between testing sessions. Reliability was determined with Interclass correlation coefficients (ICC) in the following regions of interest: primary motor (M1), primary sensory (S1), premotor cortex (PMC), medial cerebellum (MCB), and lateral cerebellum (LCB). Results indicate that intensity change has superior reliability to the other methods of analysis (Average ICC across brain regions and trials: intensity change: 0.73, voxel count: 0.58, voxel by voxel: 0.67) and that generally with any analysis method, within-session reliability was higher than between-session, as indicated by higher ICC values across brain regions. Overall, when comparing between-session results, moderate to good reliability was obtained with intensity change (ICC: M1: 0.52, S1: 0.80, SMA: 0.78, PMC: 0.94, MCB: 0.86, and LCB: 0.59). These results show good reliability in subjects with stroke when performing a continuous motor task. These findings give confidence for interpreting fMRI test/retest research in subjects with stroke.

Magnetic resonance-compatible robotic and mechatronics systems for image-guided interventions and rehabilitation: a review study

The continuous technological progress of magnetic resonance imaging (MRI), as well as its widespread clinical use as a highly sensitive tool in diagnostics and advanced brain research, has brought a high demand for the development of magnetic resonance (MR)-compatible robotic/mechatronic systems. Revolutionary robots guided by real-time three-dimensional (3-D)-MRI allow reliable and precise minimally invasive interventions with relatively short recovery times. Dedicated robotic interfaces used in conjunction with fMRI allow neuroscientists to investigate the brain mechanisms of manipulation and motor learning, as well as to improve rehabilitation therapies. This paper gives an overview of the motivation, advantages, technical challenges, and existing prototypes for MR-compatible robotic/mechatronic devices.

Recovery of swallowing function is accompanied by the expansion of the cortical map

To determine whether multiple sessions of electrical stimulation (ES) applied to neck muscles improve swallowing function and whether this improvement is accompanied by cortical reorganization in patients with dysphagia, before-after trials were performed on eight subjects. ES was applied for 1 hour, 5 days a week for 2 weeks. Swallowing function significantly improved after 2 weeks of ES, and this change was found to correlate with cortical reorganization measured by corticobulbar output maps. This study suggests that multiple sessions of ES applied to the neck muscles improve swallowing function via a mechanism involving long-term cortical reorganization.

Neuromodulation by functional electrical stimulation (FES) of limb paralysis after stroke

Functional Electrical Stimulation (FES) in stroke patients has been demonstrated to provide clinical benefits such as improvement in movement, skills, function and decrease of spasticity. Imaging and neurophysiological studies have shown cortical excitability and reorganization. After injury, the parameters of timing, intensity, frequency, and duration of FES are still to be determined. Additional issues that should be determined are whether the changes induced by FES are long-lasting, and which clinical and electrophysiological parameters are important and to what extent.

Neural Correlates of Proprioceptive Integration in the Contralesional Hemisphere of Very Impaired Patients Shortly After a Subcortical Stroke: An fMRI Study

Background. The effects of physiotherapy are difficult to assess in very impaired early stroke patients. Objective. The aim of the study was to characterize the impact of 4 weeks of passive proprioceptive training of the wrist on brain sensorimotor activation after stroke. Methods. Patients with a subcortical ischemic lesion of the pyramidal tract were randomly assigned to a control or a wrist-training group. All patients had a single pure motor hemiplegia with severe motor deficit. The control group (6 patients) underwent standard Bobath rehabilitation. The second, “trained,” group (7 patients) received Bobath rehabilitation plus 4 weeks of proprioceptive training with daily passive calibrated wrist extension. Before and after the training period, patients were examined with validated clinical scales and functional MRI (fMRI) while executing a passive movement versus rest. The effect of standard rehabilitation on sensorimotor activation was assessed in the control group on the wrist, and the effect of standard rehabilitation plus proprioceptive training was assessed in the trained group. The effect of 4-week proprioceptive training alone was statistically evaluated by difference between groups. Results. Standard rehabilitation along with natural recovery mainly led to increases in ipsilesional activation and decreases in contralesional activation. On the contrary, standard rehabilitation and paretic wrist proprioceptive training increased contralesional activation. Proprioceptive training produced change in the supplementary motor area (SMA), prefrontal cortex, and a contralesional network including inferior parietal cortex (lower part of BA 40), secondary sensory cortex, and ventral premotor cortex (PMv). Conclusion. We have demonstrated that purely passive proprioceptive training applied for 4 weeks is able to modify brain sensorimotor activity after a stroke. This training revealed fMRI change in the ventral premotor and parietal cortices of the contralesional hemisphere, which are secondary sensorimotor areas. Recent studies have demonstrated the crucial role of these areas in severely impaired patients. We propose that increased contralesional activity in secondary sensorimotor areas likely facilitates control of recovered motor function by simple proprioceptive integration in those patients with poor recovery.

Neuromuscular Electrical Stimulation During Task-Oriented Exercise Improves Arm Function for an Individual with Proximal Arm Dysfunction After Stroke

This case report examined the effectiveness of a home program using neuromuscular electrical stimulation (NMES) during voluntary task-oriented exercise to achieve functional and impairment improvements for an individual with primarily proximal arm paresis after a stroke. The subject initially achieved a Fugl-Meyer Assessment (FMA) score of 58/66, but she reported minimal functional use of her involved, dominant arm. The 6-wk intervention consisted of NMES-assisted task practice involving repetitive reaching for and manipulation of small objects for three daily 15-min sessions. The subject applied NMES to the deltoid and triceps brachii muscles to augment shoulder flexion and abduction and elbow extension during task practice. Outcome measures included the FMA, the Action Research Arm Test (ARAT), and the Motor Activity Log Quality of Movement subscale (MAL-QOM). The FMA remained unchanged, but the ARAT and MAL-QOM showed improvements, from the beginning to the conclusion of the intervention, that were maintained at 6-wk follow-up.

Effect of finger tracking combined with electrical stimulation on brain reorganization and hand function in subjects with stroke

Synergism of rehabilitative interventions could maximize recovery following stroke. We examined whether the combination of peripherally initiated electrical stimulation of finger extensors and centrally operating finger tracking training could accentuate brain reorganization and its relationship to recovery, beyond the effects of either treatment alone. Twenty subjects with stroke were randomly assigned to an electrical stimulation (ES), tracking training (TR) or combination (CM) group. Each group was trained for ten 1-h sessions over 2-3 weeks. Pretest and posttest measurements consisted of the Box and Block and Jebsen Taylor tests of manual dexterity and a finger tracking test that was performed during functional magnetic resonance imaging (fMRI). fMRI variables included laterality index and BOLD signal intensity of primary motor (M1), primary sensory (S1), sensorimotor (SMC) and premotor (PMC) cortices as well as, supplementary motor area (SMA). ES and CM groups improved on dexterity, whereas the TR group did not. Improvement in the CM group was not greater than the other two groups. Subjects who had an intact M1 showed greater functional improvement than those who had direct involvement of M1. fMRI analysis did not yield significant changes from pretest to posttest. In the CM group only, functional improvement was positively correlated with laterality index change in M1, S1, SMC and PMC, indicating greater ipsilesional control and was negatively correlated with BOLD Signal Intensity change in ipsilesional S1 and SMA, indicating neurophysiological trimming of irrelevant neurons. The correlational results suggest that the combined intervention may be more influential on brain reorganization than either treatment alone but a larger sample size, longer duration of training, or a restricted inclusion of stroke location and volume may be needed to demonstrate a difference in efficacy for producing behavioral changes.

Effect of Sensory-Amplitude Electric Stimulation on Motor Recovery and Gait Kinematics After Stroke: A Randomized Controlled Study

OBJECTIVE

To evaluate the effects of sensory-amplitude electric stimulation (SES) of the paretic leg on motor recovery and gait kinematics of patients with stroke.

DESIGN

Randomized, controlled, double-blind study.

SETTING

Rehabilitation ward and gait laboratory of a university hospital.

PARTICIPANTS

A total of 30 consecutive inpatients with stroke (mean age, 63.2 y), all within 6 months poststroke and without volitional ankle dorsiflexion were studied.

INTERVENTION

Both the SES group (n=15) and the placebo group (n=15) participated in a conventional stroke rehabilitation program 5 days a week for 4 weeks. The SES group also received 30 minutes of SES to the paretic leg without muscle contraction 5 days a week for 4 weeks.

MAIN OUTCOME MEASURES

Brunnstrom stages of motor recovery and time-distance and kinematic characteristics of gait.

RESULTS

Brunnstrom stages improved significantly in both groups (P<.05). In total, 58% of the SES group and 56% of the placebo group gained voluntary ankle dorsiflexion. The between-group difference of percentage change was not significant (P>.05). Gait kinematics was improved in both groups, but the between-group difference was not significant.

CONCLUSIONS

In our patients with stroke, SES of the paretic leg was not superior to placebo in terms of lower-extremity motor recovery and gait kinematics.

Understanding neuroimaging

Neuroimaging is an emergent method of investigation for studying the human brain in healthy and impaired populations. An increasing number of these investigations involve topics important to rehabilitation. Thus, a basic understanding of the more commonly used neuroimaging techniques is important for understanding and interpreting this growing area of research. Included in this article is a description of the signal source, the advantages and limitations of each technique, considerations for study design, and how to interpret cortical imaging data. Particular emphasis is placed on functional magnetic resonance imaging because of its ubiquitous presence in rehabilitation research.

Improving hand function in stroke survivors: a pilot study of contralaterally controlled functional electric stimulation in chronic hemiplegia

OBJECTIVE

To assess the feasibility of a new stroke rehabilitation therapy for the hemiparetic hand.

DESIGN

Case series. Pre- and postintervention assessment with 1- and 3-month follow-ups.

SETTING

Clinical research laboratory of a large public hospital.

PARTICIPANTS

Three subjects with chronic (>6mo postcerebrovascular accident) upper-extremity hemiplegia.

INTERVENTION

Subjects used an electric stimulator to cause the paretic hand extensor muscles to contract and thereby open the hand. Subjects controlled the intensity of the stimulation, and thus the degree of hand opening, by volitionally opening the unimpaired contralateral hand, which was detected by an instrumented glove. For 6 weeks, subjects used the stimulator to perform active repetitive hand-opening exercises 2 hours daily at home and functional tasks 1.5 hours twice a week in the laboratory.

MAIN OUTCOME MEASURES

Maximum voluntary finger extension, maximum voluntary isometric finger-extension moment, finger-movement control, and box and block test (BBT) score at pre- and posttreatment and at 1 month and 3 months posttreatment.

RESULTS

Maximum voluntary finger extension increased from baseline to end of treatment and from the end of treatment to 1-month follow-up in 2 subjects. Maximum voluntary isometric finger-extension moment, finger-movement control, and BBT score increased from baseline to the end of treatment and from the end of treatment to 1-month follow-up in all 3 subjects. The improvements generally declined at 3 months.

CONCLUSIONS

The results suggest a positive effect on motor impairment, meriting further investigation of the intervention.

Prognostic Value of fMRI in Recovery of Hand Function in Subcortical Stroke Patients

The first objective of the study was to determine whether functional magnetic resonance imaging (fMRI) signal was correlated with motor performance at different stages of poststroke recovery. The second objective was to assess the existence of prognostic factors for recovery in early functional MR images. Eight right-handed patients with pure motor deficit secondary to a first lacunar infarct localized on the pyramidal tract were included. This study concerned moderately impaired patients and recovery of handgrip strength and finger-tapping speed. The fMRI task was a calibrated flexion-extension movement. Ten healthy subjects served as a control group. The intensity of the activation in the "classical" motor network (ipsilesional S1M1, ipsilesional ventral premotor cortex [BA 6], contralesional cerebellum) 20 days after stroke was indicative of the performance (positive correlation). The cluster in M1 was posterior and circumscribed to BA 4p. No area was associated with bad performance (negative correlation). No correlation was found 4 and 12 months after stroke. Prognosis factors were evidenced. The higher early the activation in the ipsilesional M1 (BA 4p), S1, and insula, the better the recovery 1 year after stroke. Although the lesions partly deefferented the primary motor cortex, patients who activated the posterior primary motor cortex early had a better recovery of hand function. This suggests that there is benefit in increasing ipsilesional M1 activity shortly after stroke as a rehabilitative approach in mildly impaired patients.

Neuromuscular electrical stimulation versus volitional isometric strength training in children with spastic diplegic cerebral palsy: a preliminary study

BACKGROUND

To date, no reports have investigated neuromuscular electrical stimulation (NMES) to increase muscle force production of children with cerebral palsy (CP) using high-force contractions and low repetitions.

OBJECTIVE

The aims of this study were to determine if isometric NMES or volitional training in children with CP could increase muscle strength and walking speed and to examine the mechanisms that may contribute to increased force production.

METHODS

Eleven children with spastic diplegia were assigned to an NMES training group or to a volitional training group. Participants in the NMES group had electrodes implanted percutaneously to activate the quadriceps femoris and triceps surae muscles. The volitional group trained with maximal effort contractions. Both groups performed a 12-week isometric strength-training program. Maximum voluntary isometric contraction (MVIC) force, voluntary muscle activation, quadriceps and triceps surae cross-sectional area (CSA), and walking speed were measured pre- and post-strength training.

RESULTS

The NMES-trained group had greater increases in normalized force production for both the quadriceps femoris and triceps surae. Similarly, only the NMES group showed an increase in walking speed after training. Changes in voluntary muscle activation explained approximately 67% and 37% of the changes seen in the MVIC of the NMES and volitional groups, respectively. Quadriceps femoris maximum CSA increased significantly for the NMES group only.

CONCLUSIONS

This study was the first to quantitatively show strength gains with the use of NMES in children with CP. These results support the need for future experimental studies that will examine the clinical effectiveness of NMES strength training.

Functional Electrical Stimulation Enhancement of Upper Extremity Functional Recovery During Stroke Rehabilitation: A Pilot Study

Objective. To test if functional electrical stimulation (FES) can enhance the recovery of upper extremity function during early stroke rehabilitation. Methods. Open-label block-randomized trial, begun during inpatient rehabilitation and continued at the patients' home. Patients were assigned to either FES combined with task-specific upper extremity rehabilitation (n = 7) or a control group that received task-specific therapy alone (n = 8) over 12 weeks. Outcome measures . Hand function (Box & Blocks, B&B; Jebsen-Taylor light object lift, J-T) and motor control (modified Fugl-Meyer, mF-M) were video-recorded for both upper extremities at baseline, 4, 8, and 12 weeks. Results. B&B mean score at 12 weeks favored ( P = .049) the FES group (42.3 ± 16.6 blocks) over the control group (26.3 ± 11.0 blocks). The FES group J-T task was 6.7 ± 2.9 seconds and faster ( P = .049) than the 11.8 ± 5.4 seconds of the control group. Mean mF-M score of the FES group at 12 weeks was 49.3 ± 5.1 points out of 54, compared to the control group that scored 40.6 ± 8.2 points ( P = .042). All patients regained hand function. Conclusion. Upper extremity task-oriented training that begins soon after stroke that incorporates FES may improve upper extremity functional use in patients with mild/moderate paresis more than task-oriented training without FES.

Strengthening interventions increase strength and improve activity after stroke: a systematic review

QUESTION

Is strength training after stroke effective (ie, does it increase strength), is it harmful (ie, does it increase spasticity), and is it worthwhile (ie, does it improve activity)?

DESIGN

Systematic review with meta-analysis of randomised trials.

PARTICIPANTS

Stroke participants were categorised as (i) acute, very weak, (ii) acute, weak, (iii) chronic, very weak, or (iv) chronic, weak.

INTERVENTION

Strengthening interventions were defined as interventions that involved attempts at repetitive, effortful muscle contractions and included biofeedback, electrical stimulation, muscle re-education, progressive resistance exercise, and mental practice.

OUTCOME MEASURES

Strength was measured as continuous measures of force or torque or ordinal measures such as manual muscle tests. Spasticity was measured using the modified Ashworth Scale, a custom made scale, or the Pendulum Test. Activity was measured directly, eg, 10-m Walk Test, or the Box and Block Test, or with scales that measured dependence such as the Barthel Index.

RESULTS

21 trials were identified and 15 had data that could be included in a meta-analysis. Effect sizes were calculated as standardised mean differences since various muscles were studied and different outcome measures were used. Across all stroke participants, strengthening interventions had a small positive effect on both strength (SMD 0.33, 95% CI 0.13 to 0.54) and activity (SMD 0.32, 95% CI 0.11 to 0.53). There was very little effect on spasticity (SMD -0.13, 95% CI -0.75 to 0.50).

CONCLUSION

Strengthening interventions increase strength, improve activity, and do not increase spasticity. These findings suggest that strengthening programs should be part of rehabilitation after stroke.

Efficacy of electrical stimulation to increase muscle strength in people with neurological conditions: a systematic review

BACKGROUND AND PURPOSE

Weakness in partially paralysed muscles is a disabling impairment for people with neurological conditions. Strength training programmes are widely administered to address this impairment. There is a common belief that the effectiveness of strength training programmes can be enhanced by the addition of electrical stimulation. The purpose of this systematic review was to assess the efficacy of electrical stimulation for increasing voluntary strength in people with neurological conditions.

METHOD

Eligible randomized trials of electrical stimulation were identified by searches of computerized databases. The search yielded 11,267 abstracts, of which 60 were retrieved. Two assessors independently reviewed full text versions of these articles.

RESULTS

Eighteen studies satisfied the inclusion criteria. These studies involved participants with spina bifida (n = 1), cerebral palsy (n = 1), peripheral nerve lesion (n = 1), multiple sclerosis (n = 1), spinal cord injury (n = 3) and stroke (n = 11). The mean (SD) PEDro score for trial quality was 4.9 (1.0) out of 10. Meta-analyses of studies involving similar patients were not done because of insufficient data or lack of homogeneity. The results of all studies were analysed individually.

CONCLUSION

Several studies suggest a modest beneficial effect of electrical stimulation in patients with stroke. It is not clear whether patients with other types of neurological disabilities benefit from electrical stimulation in the same way.

Neuromuscular electrical stimulation in neurorehabilitation

This review provides a comprehensive overview of the clinical uses of neuromuscular electrical stimulation (NMES) for functional and therapeutic applications in subjects with spinal cord injury or stroke. Functional applications refer to the use of NMES to activate paralyzed muscles in precise sequence and magnitude to directly accomplish functional tasks. In therapeutic applications, NMES may lead to a specific effect that enhances function, but does not directly provide function. The specific neuroprosthetic or "functional" applications reviewed in this article include upper- and lower-limb motor movement for self-care tasks and mobility, respectively, bladder function, and respiratory control. Specific therapeutic applications include motor relearning, reduction of hemiplegic shoulder pain, muscle strengthening, prevention of muscle atrophy, prophylaxis of deep venous thrombosis, improvement of tissue oxygenation and peripheral hemodynamic functioning, and cardiopulmonary conditioning. Perspectives on future developments and clinical applications of NMES are presented.

Transcutaneous electrical stimulation versus traditional dysphagia therapy: a nonconcurrent cohort study

OBJECTIVE

The purpose of this investigation was to critically evaluate the efficacy of electrical stimulation (ES) in treating persons with dysphagia and aspiration.

STUDY DESIGN

Nonconcurrent cohort study.

METHODOLOGY

The charts of 40 consecutive individuals undergoing ES and 40 consecutive persons undergoing traditional dysphagia therapy (TDT) were reviewed. Pre- and post-therapy treatment success was compared utilizing a previously described swallow severity scale. A linear regression analysis was employed to adjust for potential confounding variables.

RESULTS

The swallow severity scale improved from 0.50 to 1.48 in the TDT group (P < 0.05) and from 0.28 to 3.23 in the ES group (P < 0.001). After adjusting for potential confounding factors, persons receiving ES did significantly better in regard to improvement in their swallowing function than persons receiving TDT (P = 0.003).

CONCLUSIONS

The results of this nonconcurrent cohort study suggest that dysphagia therapy with transcutaneous electrical stimulation is superior to traditional dysphagia therapy alone in individuals in a long-term acute care facility.

Functional Imaging of Intervention Effects in Stroke Motor Rehabilitation

OBJECTIVE

To assess intervention-specific effects on cortical reorganization after stroke as shown by available functional neuroimaging studies.

DATA SOURCES

We searched Medline for clinical trials that contained the terms stroke, reorganization, and recovery, as well as either positron-emission tomography and PET, near-infrared spectroscopy and NIRS, single-photon emission tomography and SPECT, or functional magnetic resonance imaging and functional MRI; we reviewed primary and secondary references.

STUDY SELECTION

Articles that reported neuroimaging findings as a result of a specific treatment involving more than 1 subject were included.

DATA EXTRACTION

We included clinical trials that contained the terms stroke, reorganization, and recovery, as well as functional neuroimaging data findings as a result of a specific treatment involving more than 1 subject.

DATA SYNTHESIS

Included studies differed clearly from one another with regard to patient characteristics, intervention protocol, and outcome measures. Most studies used functional magnetic resonance imaging and a motor paradigm. Studies were limited in size.

CONCLUSIONS

Despite the methodologic differences, several common features can be identified based on the reviewed studies. Clinical improvements occurred even late after injury, after subjects were deemed to have reached a recovery plateau. This clinical improvement was accompanied by cortical reorganization that depended on the type of intervention as well as other factors. This review also suggests direction for future research studies.

Neuromuscular Electrical Stimulation Improves Severe Hand Dysfunction for Individuals With Chronic Stroke

Restoring hand function is difficult post-stroke. We sought to determine if applying neuromuscular electrical stimulation (NMES) was beneficial for reducing severe hand impairments. Subjects with chronic stroke (N=8; 3 Fe, 5 M; 58.3 +/- 6.9 y/o) received 10 sessions of NMES using two different methods applied in a counterbalanced order. In one intervention, we applied NMES (active) in a novel fashion using multiple stimulators on the forearm flexors and extensors to assist subjects with grasping and releasing a tennis ball. In the other intervention, the NMES ('passive') stimulated repeated wrist extension and flexion. Motor performance was assessed prior to and immediately following the interventions and at retention. Upper extremity (UE) Fugl-Myer scores significantly improved (p < 0.002) immediately following either intervention. Significant improvement was also observed in the Modified Ashworth Spasticity Scale (MASS) (p < 0.03), immediately following intervention, primarily due to the NMESpassive treatment (p < 0.034). Subjects performed grasping tasks significantly faster (p < 0.0433) following interventions, with performance speeds on dexterous manipulation increasing approximately 10% for NMESactive immediately following intervention, compared to only 0.1% improvement following NMESpassive. Generally, improvements in motor speed remained 10 days following NMESactive intervention, although slightly diminished. In conclusion, severe hand impairment was reduced after a short duration of NMES therapy in this pilot data set for individuals with chronic stroke. NMES-assisted grasping trended towards greater functional benefit than traditional NMES-activation of wrist flexors/extensors.

Imaging motor recovery after stroke

Most patients show improvement in the weeks or months after a stroke. Recovery is incomplete, however, leaving most with significant impairment and disability. Because the brain does not grow back to an appreciable extent, this recovery occurs on the basis of change in function of surviving tissues. Brain mapping studies have characterized a number of processes and principles relevant to recovery from stroke in humans. The findings have potential application to improving therapeutics that aim to restore function after stroke.

Neural drive preservation after detraining following neuromuscular electrical stimulation training

The purpose of the study was to investigate the behaviour of the central nervous system when 5 weeks of neuromuscular electrical stimulation (NMES) training was followed by 5 weeks of detraining. Nineteen males were divided into the neuromuscular electrostimulated group (EG, n=12) and the control group (CG, n=7). The training program consisted of 15 sessions of isometric NMES over a 5-week period. The EG subjects were tested before training (PRE), after 5 weeks of NMES training (POST) and after 5 weeks of detraining (DE) while CG subjects were only tested at PRE and at POST. Soleus (SOL) and gastrocnemii (GAS) maximal H-reflex and M-wave potentials were evoked at rest (i.e., H(max) and M(max), respectively) and during maximal voluntary contraction (MVC) (i.e., H(sup) and M(sup), respectively). SOL and GAS V-wave were recorded by supramaximal stimulation delivered during MVC. SOL and GAS electromyographic (EMG) activity as well as muscle activation were also assessed during MVC. After training, plantar flexor MVC increased significantly by 22% (P<0.001). Torque gains were associated with an increase in muscle activation (P<0.05), SOL and GAS normalized EMG activity (P<0.01 and P<0.05, respectively) and V/M(sup) ratios (P<0.01 and P<0.05, respectively). No significant changes occurred in any of these parameters between POST and DE. H(max)/M(max) and H(sup)/M(sup) ratios for both muscles were unchanged after both the training and detraining periods. In conclusion, the NMES training-induced neural adaptations were maintained after detraining, suggesting that neural changes are long-lasting and did not affect the elements of H-reflex pathways.

MR compatible force sensing system for real-time monitoring of wrist moments during fMRI testing

Functional magnetic resonance imaging (fMRI) of brain function is used in neurorehabilitation to gain insight into the mechanisms of neural recovery following neurological injuries such as stroke. The behavioral paradigms involving the use of force motor tasks utilized in the scanner often lack the ability to control details of motor performance. They are often limited by subjectiveness, lack of repeatability, and complexity that may exclude evaluation of patients with poor function. In this paper we describe a novel MR compatible wrist device that is capable of measuring isometric forces generated at the hand and joint moments along wrist flexion-extension and wrist ulnar-radial deviation axes. Joint moments measured by the system can be visually displayed to the individual and used during target matching block or event related paradigms. Through a small set of pilot testing both inside and outside the MR environment, we have found that the force tracking tasks and performance in the scanner are reproducible, and that high quality force and moment recordings can be made during fMRI studies without compromising the fMRI images. Furthermore, the device recordings are extremely sensitive making it possible for individuals with poor hand and wrist function to be tested.

Neural substrates for motor imagery in severe hemiparesis

BACKGROUND

The beneficial effects of imagined movements on motor learning and performance suggest that motor imagery is functionally close to preparatory and executive motor processes.

OBJECTIVE

The purpose of this study was to examine the cortical processes associated with imagery of movement of the wrist in subjects with severe hemiparesis.

METHODS

During fMRI, subjects with stroke performed alternating blocks of imagining wrist-tracking movements with the hemiparetic hand, active wrist-tracking movements with the unaffected hand, and resting. Control subjects performed the same tasks using an assigned hand. Cortical activation in the primary motor (M1), primary sensory (S1), supplementary motor area (SMA), and pre-SMA regions was determined through a laterality index of active voxels and signal intensity. Ability to imagine was assessed with an Imagery Rating Scale.

RESULTS

All subjects displayed primarily contralateral control during the track condition. Healthy subjects demonstrated contralateral control in all areas during the imagine condition, whereas subjects with stroke displayed primarily contralateral activation in S1 but ipsilateral in M1 and SMA. The percentage change in signal intensity was greater in the ipsilateral hemisphere in subjects with stroke than in the ipsilateral hemisphere in healthy subjects during the imagine condition. Additionally, subjects with self-reported low ability to imagine displayed no difference in activation compared to those with high imagery ability.

CONCLUSIONS

These findings are consistent with other works demonstrating primarily ipsilateral control of the hemiparetic hand in subjects with functional movement and lay the groundwork for further investigation into the ability of mental imagery to affect functionally relevant cortical control in subjects recovering from stroke.

Soleus- and Gastrocnemii-Evoked V-Wave Responses Increase After Neuromuscular Electrical Stimulation Training

The aim of the study was to use combined longitudinal measurements of soleus (SOL) and gastrocnemii evoked V-wave and H-reflex responses to determine the site of adaptations within the central nervous system induced by 5 wk of neuromuscular electrical stimulation (NMES) training of the plantar flexor muscles. Nineteen healthy males subjects were divided into a neuromuscular electrostimulated group ( n = 12) and a control group ( n = 7). The training program consisted of 15 sessions of isometric NMES over a 5-wk period. All subjects were tested before and after the 5-wk period. SOL, lateral gastrocnemius (LG), and medial gastrocnemius (MG) maximal H-reflex and M-wave potentials were evoked at rest (i.e., Hmax and Mmax, respectively) and during maximal voluntary contraction (MVC) (i.e., Hsup and Msup, respectively). During MVC, a supramaximal stimulus was delivered that allowed us to record the V-wave peak-to-peak amplitudes from all three muscles. The SOL, LG, and MG electromyographic (EMG) activity as well as muscle activation (twitch interpolation technique) were also quantified during MVC. After training, plantar flexor MVC increased significantly by 22% ( P < 0.001). Torque gains were accompanied by an increase in muscle activation (+11%, P < 0.05), SOL, LG, and MG normalized EMG activity (+51, +54, and +60%, respectively, P < 0.05) and V/Msup ratios (+81, +76, and +97%, respectively, P < 0.05). Hmax/Mmax and Hsup/Msup ratios for all three muscles were unchanged after training. In conclusion, the increase in voluntary torque after 5 wk of NMES training could be ascribed to an increased volitional drive from the supraspinal centers and/or adaptations occurring at the spinal level.

Electrostimulation for promoting recovery of movement or functional ability after stroke

BACKGROUND

Electrostimulation might improve motor recovery after stroke by providing neuromuscular re-training.

OBJECTIVES

To find if electrostimulation improved functional motor ability, and the ability to undertake activities of daily living.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched August 2005), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2004), MEDLINE (1966 to January 2004), EMBASE (1980 to January 2004), CINAHL (1982 to January 2004), AMED - Allied and Complementary Medicine Database (1985 to January 2004), Physiotherapy Evidence Database (PEDro), REHABDATA and the ISI Science Citation Index (1981 to 2003). We placed a request on the PHYSIO e-mail discussion list and contacted authors of relevant studies to elicit any unpublished or ongoing studies, searched the reference lists of included trials and contacted trialists.

SELECTION CRITERIA

Randomised controlled trials of electrostimulation delivered to the peripheral neuromuscular system which was designed to improve voluntary movement control, functional motor ability and activities of daily living.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial quality and extracted the data.

MAIN RESULTS

Of the 2077 references identified, 24 trials were included in this review. For electrostimulation compared with no treatment this review found that electrostimulation improved some aspects of functional motor ability and some aspects of motor impairment and normality of movement. In addition, there was a significant difference in favour of no treatment compared with electrostimulation for an aspect of functional motor ability. For electrostimulation compared with placebo this review found that electrostimulation improved an aspect of functional motor ability. For electrostimulation compared with conventional physical therapy this review found that electrostimulation improved an aspect of motor impairment. There were no statistically significant differences between electrostimulation and control treatment for all other outcomes. However, these results need to be interpreted with reference to the following: (1) the majority of analyses only contained one trial; (2) variation was found between included trials in time after stroke, level of functional deficit, and dose of electrostimulation; and (3) the possibility of selection and detection bias in the majority of included trials.

AUTHORS' CONCLUSIONS

At present, there are insufficient robust data to inform clinical use of electrostimulation for neuromuscular re-training. Research is needed to address specific questions about the type of electrostimulation that might be most effective, in what dose and at what time after stroke.

Hand Motor Recovery After Stroke: Tuning the Orchestra to Improve Hand Motor Function

The motor deficits after stroke are not only the manifestation of the injured brain region, but rather the expression of the ability of the rest of the brain to maintain function. After a lesion in the primary motor cortex, parallel motor circuits might be activated to generate some alternative input to the spinal motoneurons. These parallel circuits may originate from areas such as the contralateral, undamaged primary motor area, bilateral premotor areas, bilateral supplementary motor areas, bilateral somatosensory areas, cerebellum, and basal ganglia. Most importantly, the efferent, cortico-spinal output pathways must be preserved for a desired behavioral result. Most of the recovery of function after a stroke may represent actual relearning of the skills with the injured brain. The main neural mechanisms underlying this relearning process after stroke involve shifts of distributed contributions across a specific neural network (fundamentally the network engaged in skill learning in the healthy). If these notions are indeed correct, then neuromodulatory approaches, such as transcranial magnetic stimulation, targeting these parallel circuits might be useful to limit injury and promote recovery after a stroke. This paper reviews the stroke characteristics that can predict a good recovery and compensations across brain areas that can be implemented after a stroke to accelerate motor function recovery.

Influence of Electric Somatosensory Stimulation on Paretic-Hand Function in Chronic Stroke

OBJECTIVE

To test the influence of electric somatosensory stimulation on performance of the Jebsen-Taylor Hand Function Test (JTHFT), a widely used assessment of functional hand motor skills, by the paretic arm in patients with chronic stroke.

DESIGN

Initially, patients trained for several sessions until reaching plateau performance on the JTHFT. Subsequently, they entered a crossover randomized study, designed to evaluate the influence of somatosensory stimulation on JTHFT performance.

SETTING

A research laboratory.

PARTICIPANTS

Nine patients with chronic stroke (>/=1.5 y) who acutely had marked weakness (paralysis of the upper extremity is evaluated as equal or below Medical Research Council [MRC] grade 2) followed by improvement to an MRC grade of 4.24+/-0.43 (range, 3.5-4.9) and Fugl-Meyer Assessment (FMA) score of 86.43%+/-2.02% at the time of testing.

INTERVENTIONS

Two hours of electric somatosensory stimulation was applied to the (1) paretic hand, (2) paretic leg, or (3) no stimulation in different sessions, in a randomized order.

MAIN OUTCOME MEASURE

The time required to complete the JTHFT was analyzed by using repeated-measures analysis of variance (ANOVA) with factors time (pre-, postintervention) and intervention (paretic hand, paretic leg, no stimulation) followed by post hoc testing.

RESULTS

Significant effects of intervention and intervention by time interaction (P<.01) on JTHFT time was revealed by repeated-measures ANOVA. Post hoc testing documented improvements in JTHFT time with paretic hand stimulation alone (P<.005), an effect that appeared more prominent in subjects with lower FMA scores.

CONCLUSIONS

Somatosensory stimulation applied to a paretic limb can benefit performance of a functional test in patients with chronic stroke. This result supports the proposal that electric sensory stimulation in combination with training protocols may enhance the benefit of customary neurorehabilitative treatments and possibly motor learning.

Home-based electromyography-triggered stimulation in chronic stroke

OBJECTIVES

(1) To determine the feasibility of a home-based electromyography-triggered neuromuscular stimulation (ETMS) programme; and (2) to determine ETMS efficacy in increasing affected wrist extension and reducing affected arm impairment.

DESIGN

Randomized, controlled, pre-post, cross-over design.

SETTING

Outpatient rehabilitation hospital.

PATIENTS

Twelve chronic stroke patients with palpable muscle contraction in their affected wrist extensors but no movement (7 males; mean age = 59.75 years, age range 44-75 years; mean time since stroke = 52.75 months, range 13-131 months).

INTERVENTION

Subjects were randomly assigned to receive either: (a) ETMS use twice every weekday in 35-min increments during an eight-week period followed by an eight-week home exercise programme (ETMS/home exercise programme) (n=8); or (b) an eight-week home exercise programme followed by use of ETMS twice every weekday in 35-min increments during an eight-week period (home exercise programme) (n=4).

MAIN OUTCOME MEASURES

The Fugl-Meyer, Action Research Arm Test and goniometry.

RESULTS

After home exercise programme participation, subjects showed nominal or no changes on any of the outcome measures. After ETMS, patients showed modest impairment reductions, as shown by the Fugl-Meyer, and no Action Research Arm Test changes. However, both groups showed a 21 degree increase in active affected wrist extension after ETMS use.

CONCLUSION

ETMS use is feasible in the home environment. Neither participation in a traditional home exercise programme nor ETMS use conveyed changes on the Fugl-Meyer or Action Research Arm Test. However, ETMS use increased active affected limb extension. This new movement may provide a potential pathway for subjects to participate in other interventions, such as modified constraint induced therapy.

Back From the Brink: Electromyography-Triggered Stimulation Combined With Modified Constraint-Induced Movement Therapy in Chronic Stroke

OBJECTIVE

To determine the efficacy of a regimen that combines electromyography-triggered neuromuscular stimulation (ETMS) with modified constraint-induced movement therapy (mCIMT) in patients with chronic stroke.

DESIGN

Pre-post, case series.

SETTING

Outpatient rehabilitation hospital.

PARTICIPANTS

Six subjects who had had a stroke more [corrected] than 1 year before the study and who had upper-limb hemiparesis. All subjects were only able to activate the affected wrist extensors.

INTERVENTION

Subjects underwent ETMS twice every weekday in 35-minute increments during an 8-week period. One week after they completed the ETMS regimen, and after the outcome measures were readministered, subjects participated in mCIMT, which consisted of structured therapy sessions that emphasized use of the more affected arm in valued activities. The sessions were held 3 times a week for 10 weeks. The less affected arms were also restrained 5 days a week for 5 hours.

MAIN OUTCOME MEASURES

The Fugl-Meyer Assessment (FMA) of motor recovery, Action Research Arm Test (ARAT), and goniometry.

RESULTS

Subjects had nominal changes on the ARAT (mean change, 0.3), and no functional changes after ETMS. However, they had a mean increase of 21.5 degrees in affected wrist extension and an improved ability to perform the wrist items of the FMA (reflected by a mean increase of 4.1 points on the FMA), which qualified them for mCIMT. After mCIMT, subjects had a 15.5-point change on the FMA, an 11.4-point change on the ARAT, and a new ability to perform valued activities.

CONCLUSIONS

ETMS alone does not result in functional changes. However, it may elicit sufficient active affected wrist and finger extension increases to permit possible participation in mCIMT, which can result in marked functional gains. This study is among the first to show improved function in stroke patients who initially had little hand motor control, and it is among the first to effectively combine 2 singularly efficacious regimens.

Neurochemical effects of exercise and neuromuscular electrical stimulation on brain after stroke: a microdialysis study using rat model

Treadmill exercise and neuromuscular electrical stimulation are common clinical approaches for stroke rehabilitation. Both animal and clinical studies have shown the functional improvements after these interventions. However, the neurochemical effects on the ischemic brain had not been well studied. This study aimed at evaluating the effects of treadmill exercise and neuromuscular electrical stimulation (NMES), and studying their effects during a 2-week training, on the levels of common neurotransmitters (aspartate, glutamate, taurine and gamma-aminobutyric acid (GABA)) in the hippocampus following transient focal cerebral ischemia. Either treadmill exercise or neuromuscular electrical stimulation was prescribed to the rats 24 h after cerebral ischemia whereas Control group remained in cages for 2 weeks. Microdialysis technique was used to collect dialysates from ipsilesional hippocampus in vivo. It was found that the glutamate level was increased significantly during treadmill exercise and then returned to baseline level. Both interventions did not trigger significant effects on aspartate and glutamate basal levels during the 2 weeks. The relatively high taurine level in Control groups may suggest that the interventions might suppress the taurine release in hippocampus. GABA and aspartate levels did not showed significant changes over the 2 weeks in all groups. These results provide insights to explain the neurochemical effects on the ischemic injured brain during the course of rehabilitation.

Drivers of brain plasticity

PURPOSE OF REVIEW

Neural plasticity represents a crucial mechanism of the human brain to adapt to environmental changes in the developing and adult human central nervous system. This property of the central nervous system contributes to learning and functional recovery from neurological diseases such as stroke. Novel interventional approaches have been proposed and are under investigation to modulate neural plasticity, enhance it when it plays an adaptive role and downregulate it when it is considered maladaptive.

RECENT FINDINGS

One of the purposes of research in neurorehabilitation has been to develop interventional approaches to enhance the beneficial effects of training. Procedures like cortical stimulation, administration of central nervous system active drugs and modulation of afferent input have been evaluated as drivers of neural plasticity in healthy subjects and in small groups of patients with stroke. So far, these studies have shown promising results and translation into the clinic is under investigation.

SUMMARY

Cortical stimulation and purposeful changes in afferent input that modulate neural plasticity impact on behavioral markers of performance, learning and functional recovery and represent promising tools in neurorehabilitation.

Improvement of a face perception deficit via subsensory galvanic vestibular stimulation

The remediative effect of galvanic vestibular stimulation (GVS) was investigated in a patient who, following right hemisphere damage, is profoundly unable to recognize faces. We administered a two-alternative forced choice match-to-sample task in which the patient had to choose which of two faces matched a sample face presented directly above, while bipolar, transcutaneous current was applied to the left and right vestibular nerves at a level below the patient's sensory threshold. Performance improved beyond the chance-level observed prestimulation, and relied on reversing the electrode polarity across two separate blocks of trials, such that each mastoid received positive current for one block and then negative charge for the next. Although our study involved only a single case, the data provide preliminary evidence that a deficit in perceptual face matching can be reduced by GVS. This raises the intriguing possibility that other unilateral visual disorders may also respond in such a manner.

Évolution des concepts en rééducation du patient hémiplégique

INTRODUCTION

The author attempts to show the evolution of the ideas guiding the rehabilitation treatment of motricity disorders after a vascular or traumatic brain lesion.

METHOD

Expert opinion based on an uncomprehensive review of the literature, from the databases Reedoc and Medline and from the Institut Lionnois library in Nancy and the Charcot library in Paris.

RESULTS AND DISCUSSION

Many theories and techniques have been proposed. The modern history of this rehabilitation treatment has been marked by a period that stressed control of the abnormal motricity characterizing central motor disorders, sometimes too exclusively. The development of evidence-based medicine in the 1980s undermined certain dogmas. At the same time, the advent of cerebral imaging technology confirmed clinical observations and hypotheses concerning cerebral plasticity. Today, the rehabilitation treatment of these motor disorders uses notions of learning; the diversity and complementarity of the exercises, which must be task-oriented; relative earliness and intensity of therapy; close interactions between sensitivity and motricity; and different concepts as mental imagery, the perception of verticality, or muscle strengthening.

CONCLUSION

To its well-known preventive and palliative roles, rehabilitation treatment has now added a curative role. All the concepts applied today are not new, but the spirit of their application is new. Because we are sure that neurological recovery can be improved, no idea can be rejected at the outset; its effect must be demonstrated. Among the numerous ideas presently proposed, future studies will define the best ones, for the most suitable patient, at the best time.

Modulation of motor cortex excitability by sustained peripheral stimulation: The interaction between the motor cortex and the cerebellum

The excitability of cortical neurons in the motor cortex is determined by their membrane potential and by the level of intracortical inhibition. The excitability of the motor cortex as a whole is a function of single cell excitability, synaptic strength, and the balance between excitatory cells and inhibitory cells. It is now established that a sustained period of somatosensory stimulation increases the excitability of motor cortex areas controlling muscles in those body parts that received the stimulation prior to excitability testing. So far, it has been supposed that the sensorimotor cortex was the anatomical substrate of these excitability changes, which could represent an early change in cortical network function before structural plasticity occurs. Recent experimental studies highlight that the cerebellum, especially the interpositus nucleus, plays a key role in the adaptation of the motor cortex to repeated trains of stimulation. Interpositus neurons, which receive inputs from both sensorimotor cortex and the spinal cord, are involved in somesthetic reflex behaviors and assist the cerebral cortex in transforming sensory signals to motor-oriented commands by acting via the cerebello-thalamo-cortical projections. Moreover, climbing fibers originating in the inferior olivary complex and innervating the nucleus interpositus mediate highly integrated sensorimotor information derived from spinal modules. It appears that the interpositus nucleus is a main subcortical modulator of the excitability changes occurring in the motor cortex, which may be a substrate of early plasticity effective in motor learning and recovery from lesion.

Motor cortex excitability following repetitive electrical stimulation of the common peroneal nerve depends on the voluntary drive

Previously, long-term changes in the motor cortex have been reported after repetitive electrical nerve stimulation (rES) as well as after motor exercise. The purpose of this study was to investigate whether the effects of voluntary motor cortical drive and of rES on the motor cortical output in healthy subjects interact with each other. A 30-min exercise session was performed during the following conditions: rES of the right common peroneal nerve (CPN) during rES at rest (A); voluntary exercise of the right ankle dorsiflexors alone (B); rES combined with voluntary dorsiflexion exercise (C); voluntary exercise of ankle plantar flexors alone (D); and plantar flexion exercise combined with rES (E). Motor evoked potentials (MEPs) were obtained before and after the exercise with a stimulation intensity of 125% of the threshold of the relaxed right tibialis anterior (TA). rES was ON for 1 s and OFF for 2 s in a cycle, and consisted of trains of five pulses, duration 1 ms and frequency 30 Hz, as applied in functional electrical stimulation (FES). MEPs of the TA muscle elicited after the training were increased in A by 38%, in B by 35%, and in C by 66%. In D and E, the MEPs of TA were decreased by 29% and 35%, respectively. The effect was maintained for at least 30 min after the nerve stimulation was completed. Consistent with previous studies (Khaslavskaia et al. (2002) Exp Brain Res 145:309-315), MEPs after the CPN rES are shown to be partly due to increased TA cortical excitability. These results suggest that the effect of FES on motor cortical excitability depends on the concurrent motor cortical drive present at the time of FES, and the combination of these factors modulates neural excitability and probably reorganization. The decrease in motor cortical excitability after plantar flexor exercise probably means that voluntary effort antagonistic to the electrical exercise is stronger and cancels out the effects of rES. Improving FES effects through an agonist voluntary drive implies an enhancement of sensorimotor reorganization through the addition of a voluntary component to a trained movement. Possible mechanisms and implications of these results on the rehabilitation of patients with paralysis and spasticity are discussed.

Functional reorganization of the cerebral motor system after stroke

PURPOSE OF REVIEW

Recovery of function after stroke is now widely considered to be a consequence of central nervous system reorganization. Non-invasive techniques such as functional magnetic resonance imaging, transcranial magnetic stimulation, electroencephalography and magnetoencephalography now allow the study of the working human brain. Studies in stroke patients can now address how cerebral networks in the human brain respond to focal injury and whether these changes are related to functional recovery. This understanding may in turn lead to the development of techniques that will drive cerebral reorganization in a way that promotes functional improvement.

RECENT FINDINGS

The relationship between cerebral reorganization and functional recovery has been examined in both cross-sectional and longitudinal studies. It appears that the motor system reacts to damage in a way that attempts to generate motor output through surviving brain regions and networks. There are changes in cortical excitability after stroke that may provide the substrate whereby the effects of motor practice or experience can be more effective in driving long lasting changes in motor networks. This will be particularly important in intact portions of neural networks subserving motor skills learning.

SUMMARY

Functionally relevant adaptive changes occur in the human brain following focal damage. A greater understanding of how these changes are related to the recovery process will allow the development of novel therapeutic techniques that are based on neurobiological principles and which are designed to minimize impairment in appropriately targeted patients suffering from stroke.