Motor Stroke Research Articles

Anatomical Parameters of tDCS to Modulate the Motor System after Stroke: A Review.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method to modulate the local field potential in neural tissue and consequently, cortical excitability. As tDCS is relatively portable, affordable, and accessible, the applications of tDCS to probe brain–behavior connections have rapidly increased in the last 10 years. One of the most promising applications is the use of tDCS to modulate excitability in the motor cortex after stroke and promote motor recovery. However, the results of clinical studies implementing tDCS to modulate motor excitability have been highly variable, with some studies demonstrating that as many as 50% or more of patients fail to show a response to stimulation. Much effort has therefore been dedicated to understand the sources of variability affecting tDCS efficacy. Possible suspects include the placement of the electrodes, task parameters during stimulation, dosing (current amplitude, duration of stimulation, frequency of stimulation), individual states (e.g., anxiety, motivation, attention), and more. In this review, we first briefly review potential sources of variability specific to stroke motor recovery following tDCS. We then examine how the anatomical variability in tDCS placement [e.g., neural target(s) and montages employed] may alter the neuromodulatory effects that tDCS exerts on the post-stroke motor system.

Abstract WMP109: Characterizing Brain Microstructural Changes in Childhood Arterial Ischemic Stroke Using Multi-shell Diffusion Magnetic Resonance Imaging

Introduction: New imaging markers employing sophisticated models of tissue microstructure may lead to better understanding of neurobiological substrates in childhood arterial ischemic stroke. Methods: Four children with acute unilateral MCA territory ischemic stroke were retrospectively included [two males, age range 2 -16 years]. Parameters of two complementary diffusion modeling techniques: Neurite Orientation Dispersion and Density Imaging (NODDI), and Spherical Mean Technique (SMT) were estimated using two-shell diffusion data acquired at presentation ( b- values = 1000 and 3000 s/mm 2 ). For comparison, diffusion tensor imaging (DTI) parameters were also estimated. Parameter estimates were derived from the acute infarct-affected gray matter, the reconstructed pyramidal tract and the contra-hemispheric homologs. Contrast-to-noise ratios (CNRs) were calculated for each pair of homologous brain regions. Results: In both the acute infarct-affected gray matter, and pyramidal tracts, the multi-shell parameter estimates demonstrated increased intra-cellular volume fraction (F icvf and INVF in figure), predominant reduced extra-cellular microscopic diffusivity (ENMMD and ENTMD in figure), and increased orientation dispersion of the infarct-affected axonal fibers (ODI in figure). These findings were consistent with respective acute stroke histopathological features of cytotoxic edema, narrowed extracellular spaces, and axonal swelling. The CNRs were associated with stroke severity and motor function outcome at follow-up. Conclusion: The parameter estimates derived from multi-shell diffusion data produces robust infarct contrast, and provides histopathologically plausible imaging biomarkers representing brain microstructural changes in acute childhood stroke. Routine clinical introduction of this imaging technique requires further elucidations of its prognostic values in predicting stroke severity and/or motor outcomes.

Erratum to "Are we armed with the right data? Pooled individual data review of biomarkers in people with severe upper limb impairment after stroke".

[This corrects the article DOI: 10.1016/j.nicl.2016.09.015.].

Early clinical predictors of motor function in the upper extremity one month post-stroke.

To investigate factors within 3 days post-stroke that could predict severe impairment in motor function in the upper extremity at one month post-stroke. This cross-sectional study included 104 patients with first-ever stroke and impaired motor function in the upper extremity. Initial impairment in motor function, demographic data, type of stroke and stroke risk factors were chosen as possible predictors. Severe impairment in motor function was defined as ≤ 31p according to the Fugl-Meyer Assessment for Upper Extremity (FMA-UE). Logistic regression was used to predict severe impairment in motor function at one month post-stroke. Three possible prediction models were found, comprising stroke severity combined with grip strength and sex, finger extension or shoulder abduction. Models including grip strength or finger extension gave the most accurate predictions, with overall predictive ability 90.4% (95% confidence interval (95% CI) 0.847-0.961) and sensitivity 92.9% (95% CI 0.851-1.0) and 90.5% (95% CI 0.816-0.979), respectively. Within 3 days post-stroke, severe impairment in motor function in the upper extremity at one month can be predicted using assessment of stroke severity in combination with grip strength, finger extension or shoulder abduction. This may facilitate early planning of rehabilitation for patients with impaired upper extremity in the stroke unit.

Characterization of patients with stroke treated at Lucy Montoro Rehabilitation Center of São José dos Campos

Vascular Accident (CVA) is the neurological event that most affects society in recent years, causing disabilities in the population and death. It can be defined as a set of neurological disorders causing similar symptoms, but with different etiologies. Currently, Lucy Montoro Rehabilitation Center of São José dos Campos is a reference in the treatment of patients neurologically squealed. Thus, the aim of this study was to make an epidemiological survey of the profile of patients affected by CVA in this region and seen at this center. Methods: The records of patients received in this center between September 2011 and December 2014 were used during this research. Patients with hemiplegia caused by other etiologies were not analyzed. Results: Of the 230 valid records for the study, 60% were men and the socio-demographic profile showed that of these, 76% were older than 50 years. Considering the type of event, ischemic stroke was the most prevalent in our sample. It was found the same involvement of body parts affected, right and left 46% and 8% classified into double hemiparesis, since the prevailing motor pattern of the sample was paresis 87%. Conclusion: It was found that the population served by Lucy Montoro Rehabilitation Center of SJC consists most of men above 50 years of age affected by ischemic stroke (right or left) and prevalent paretic motor pattern.

Increased Alpha-Rhythm Dynamic Range Promotes Recovery from Visuospatial Neglect: A Neurofeedback Study.

Despite recent attempts to use electroencephalogram (EEG) neurofeedback (NFB) as a tool for rehabilitation of motor stroke, its potential for improving neurological impairments of attention—such as visuospatial neglect—remains underexplored. It is also unclear to what extent changes in cortical oscillations contribute to the pathophysiology of neglect, or its recovery. Utilizing EEG-NFB, we sought to causally manipulate alpha oscillations in 5 right-hemisphere stroke patients in order to explore their role in visuospatial neglect. Patients trained to reduce alpha oscillations from their right posterior parietal cortex (rPPC) for 20 minutes daily, over 6 days. Patients demonstrated successful NFB learning between training sessions, denoted by improved regulation of alpha oscillations from rPPC. We observed a significant negative correlation between visuospatial search deficits (i.e., cancellation test) and reestablishment of spontaneous alpha-rhythm dynamic range (i.e., its amplitude variability). Our findings support the use of NFB as a tool for investigating neuroplastic recovery after stroke and suggest reinstatement of intact parietal alpha oscillations as a promising target for reversing attentional deficits. Specifically, we demonstrate for the first time the feasibility of EEG-NFB in neglect patients and provide evidence that targeting alpha amplitude variability might constitute a valuable marker for clinical symptoms and self-regulation.

Atypical anticipatory postural adjustments during gait initiation among individuals with sub-acute stroke

Anticipatory postural adjustments, executed prior to gait initiation, help preserve lateral stability when stepping. Atypical patterns of anticipatory activity prior to gait initiation may occur in individuals with unilateral impairment (e.g., stroke). This study aimed to determine the prevalence, correlates, and consequences of atypical anticipatory postural adjustment patterns prior to gait initiation in a sub-acute stroke population. Forty independently-ambulatory individuals with sub-acute stroke stood on two force plates and initiated gait at a self-selected speed. Medio-lateral centre of pressure displacement was calculated and used to define anticipatory postural adjustments (shift in medio-lateral centre of pressure >10mm from baseline). Stroke severity, motor recovery, and functional balance and mobility status were also obtained. Three patterns were identified: single (typical), absent (atypical), and multiple (atypical) anticipatory postural adjustments. Thirty-five percent of trials had atypical anticipatory postural adjustments (absent and multiple). Frequency of absent anticipatory postural adjustments was negatively correlated with walking speed. Multiple anticipatory postural adjustments were more prevalent when leading with the non-paretic than the paretic limb. Trials with multiple anticipatory postural adjustments had longer duration of anticipatory postural adjustment and time to foot-off, and shorter unloading time than trials with single anticipatory postural adjustments. A high prevalence of atypical anticipatory control prior to gait initiation was found in individuals with stroke. Temporal differences were identified with multiple anticipatory postural adjustments, indicating altered gait initiation. These findings provide insight into postural control during gait initiation in individuals with sub-acute stroke, and may inform interventions to improve ambulation in this population.

A novel bilateral lower extremity mirror therapy intervention for individuals with stroke.

Despite improvements made in stroke rehabilitation, motor impairment and gait deficits persist at discharge. New interventions are needed. Mirror therapy has promise as one element of a rehabilitation program. The primary objectives were to 1) describe a bilateral, lower extremity mirror therapy (LE-MT) device and training protocol and 2) investigate the feasibility of LE-MT. A LE-MT device was constructed to train bilateral LE movements for 30 min, 3 times/week for 4 weeks, as an adjunct to physiotherapy in three individuals post-stroke. Sessions were digitally recorded and reviewed to extract feasibility measures; repetitions, rests and session duration. Pre and post measures of gait and motor impairment were taken. Two participants completed 100% of the sessions and a third completed 83% due to a recurrence of pre-existing back pain. Repetitions increased and session duration was maintained. Number of rests decreased for two participants and increased for one participant. Participants reported fatigue and mild muscle soreness but also that the intervention was tolerable. Positive gait changes included increased velocity and decreased variability. LE motor impairment also improved. A bilateral LE-MT adjunct intervention for stroke is feasible and may have positive effects. A history of low back pain should be a precaution.

Evidence-based guidelines on the therapeutic use of transcranial direct current stimulation (tDCS).

A group of European experts was commissioned by the European Chapter of the International Federation of Clinical Neurophysiology to gather knowledge about the state of the art of the therapeutic use of transcranial direct current stimulation (tDCS) from studies published up until September 2016, regarding pain, Parkinson's disease, other movement disorders, motor stroke, poststroke aphasia, multiple sclerosis, epilepsy, consciousness disorders, Alzheimer's disease, tinnitus, depression, schizophrenia, and craving/addiction. The evidence-based analysis included only studies based on repeated tDCS sessions with sham tDCS control procedure; 25 patients or more having received active treatment was required for Class I, while a lower number of 10-24 patients was accepted for Class II studies. Current evidence does not allow making any recommendation of Level A (definite efficacy) for any indication. Level B recommendation (probable efficacy) is proposed for: (i) anodal tDCS of the left primary motor cortex (M1) (with right orbitofrontal cathode) in fibromyalgia; (ii) anodal tDCS of the left dorsolateral prefrontal cortex (DLPFC) (with right orbitofrontal cathode) in major depressive episode without drug resistance; (iii) anodal tDCS of the right DLPFC (with left DLPFC cathode) in addiction/craving. Level C recommendation (possible efficacy) is proposed for anodal tDCS of the left M1 (or contralateral to pain side, with right orbitofrontal cathode) in chronic lower limb neuropathic pain secondary to spinal cord lesion. Conversely, Level B recommendation (probable inefficacy) is conferred on the absence of clinical effects of: (i) anodal tDCS of the left temporal cortex (with right orbitofrontal cathode) in tinnitus; (ii) anodal tDCS of the left DLPFC (with right orbitofrontal cathode) in drug-resistant major depressive episode. It remains to be clarified whether the probable or possible therapeutic effects of tDCS are clinically meaningful and how to optimally perform tDCS in a therapeutic setting. In addition, the easy management and low cost of tDCS devices allow at home use by the patient, but this might raise ethical and legal concerns with regard to potential misuse or overuse. We must be careful to avoid inappropriate applications of this technique by ensuring rigorous training of the professionals and education of the patients.

Early Post Stroke Rehabilitation Load Correlates With Greater Functional Improvement of Hemiparesis

Background: Evidences show that generally stroke patients receiving greater amount of physiotherapy obtain better motor function over time, although this has not been investigated in the early post stroke population. The aim of the present observational retrospective study was to investigate the relationship between the amount of physiotherapy provided to early post acute stroke patients and their motor improvement. Methods: Overall, 846 early stroke patients with hemiparesis, treated with physiotherapy, were retrospectively analyzed. Clinical data at admission as well as functional scales at the first evaluation and at discharge were analyzed. For each patient, a rehabilitation load (resulting from the total number of the 30’ daily consecutive physiotherapy sessions they received) was used as the dose of physiotherapy. Pre and post rehabilitation scales were analyzed and their change (Δ) was correlated with the rehabilitation load. Results: The mean rehabilitation load was ten sessions (range 2 to 56). The scores of Barthel index, Motor Assessment Score, Motricity index for both lower and upper limb, Functional Ambulation Classification, Berg Balance scale and Trunk control test significantly improved from pre to post rehabilitation, and a significant correlation was found between the rehabilitation load and the improvement in Barthel index (P < 0.05), Motor Assessment Score, Motricity Index for upper and lower limb (P < 0.001), Berg Balance scale (P < 0.05) and Trunk control test (P < 0.001). Conclusions: In this study, a significant correlation was found between early post stroke motor rehabilitation dose and greater improvement in functional scales, assessing patient’s independence, balance and paretic limb’s motricity.

Are we armed with the right data? Pooled individual data review of biomarkers in people with severe upper limb impairment after stroke.

To build an understanding of the neurobiology underpinning arm recovery in people with severe arm impairment due to stroke, we conducted a pooled individual data systematic review to: 1) characterize brain biomarkers; 2) determine relationship(s) between biomarkers and motor outcome; and 3) establish relationship(s) between biomarkers and motor recovery. Three electronic databases were searched up to October 2, 2015. Eligible studies included adults with severe arm impairment after stroke. Descriptive statistics were calculated to characterize brain biomarkers, and pooling of individual patient data was performed using mixed-effects linear regression to examine relationships between brain biomarkers and motor outcome and recovery. Thirty-eight articles including individual data from 372 people with severe arm impairment were analysed. The majority of individuals were in the chronic (> 6 months) phase post stroke (51%) and had a subcortical stroke (49%). The presence of a motor evoked potential (indexed by transcranial magnetic stimulation) was the only biomarker related to better motor outcome (p = 0.02). There was no relationship between motor outcome and stroke volume (cm3), location (cortical, subcortical, mixed) or side (left vs. right), and corticospinal tract asymmetry index (extracted from diffusion weighted imaging). Only one study had longitudinal data, thus no data pooling was possible to address change over time (preventing our third objective). Based on the available evidence, motor evoked potentials at rest were the only biomarker that predicted motor outcome in individuals with severe arm impairment following stroke. Given that few biomarkers emerged, this review highlights the need to move beyond currently known biomarkers and identify new indices with sufficient variability and sensitivity to guide recovery models in individuals with severe motor impairments following stroke. PROSPERO: CRD42015026107.

Novel Uses for Botulinum Neurotoxin in Upper Limb Surgery.

Novel Uses for Botulinum Neurotoxin in Upper Limb Surgery.

Rehabilitation of Motor Function after Stroke: A Multiple Systematic Review Focused on Techniques to Stimulate Upper Extremity Recovery.

Stroke is one of the leading causes for disability worldwide. Motor function deficits due to stroke affect the patients' mobility, their limitation in daily life activities, their participation in society and their odds of returning to professional activities. All of these factors contribute to a low overall quality of life. Rehabilitation training is the most effective way to reduce motor impairments in stroke patients. This multiple systematic review focuses both on standard treatment methods and on innovating rehabilitation techniques used to promote upper extremity motor function in stroke patients. A total number of 5712 publications on stroke rehabilitation was systematically reviewed for relevance and quality with regards to upper extremity motor outcome. This procedure yielded 270 publications corresponding to the inclusion criteria of the systematic review. Recent technology-based interventions in stroke rehabilitation including non-invasive brain stimulation, robot-assisted training, and virtual reality immersion are addressed. Finally, a decisional tree based on evidence from the literature and characteristics of stroke patients is proposed. At present, the stroke rehabilitation field faces the challenge to tailor evidence-based treatment strategies to the needs of the individual stroke patient. Interventions can be combined in order to achieve the maximal motor function recovery for each patient. Though the efficacy of some interventions may be under debate, motor skill learning, and some new technological approaches give promising outcome prognosis in stroke motor rehabilitation.

EP 4. Recruitment of premotor cortices in subacute stroke patients – A longitudinal fMRI study

Objective In order to investigate changes in functional representation of hand movement after stroke we used functional magnetic resonance imaging (fMRI) during an active motor task of the affected hand before and after a three week comprehensive motor training. Methods 12 patients in the subacute phase after mild to moderate motor stroke (4.8 ± 2.1 weeks after stroke; age 58.5 ± 12.5 years, NIHSS: 2.4 ± 1.6) underwent a three week (1 hour daily) arm ability training (AAT; Platz et al., 2009 ). Before and after training active hand grip of both hand sides was measured with fMRI while controlling for frequency and force. Accuracy was calculated as deviation from mean amplitude and frequency. In order to compare brain activation with that of healthy controls (HC) representation maps of age-matched subjects were made. To evaluate the correlates of recovery processes we subtracted representation maps of pre- and post-measurement. Correlations of amplitude accuracy with fMRI activation maps were restricted to areas known to be involved in recovery ( Rehme et al., 2012 ). Results Before training performance of patients in the scanner was not as accurate as of controls. These differences decreased after training. Patients not only improved in trained tasks (t(13) = 20.315, p Conclusion Our data underline the importance of the premotor areas for recovered motor performance after stroke. However, the theoretically helpful support of premotor cortices may reach its maximum and performance levels do not attain those of healthy controls although more motor regions are recruited. It has to be evaluated if these recruitments are ineffective – comparable to the fMRI-activations of elder individuals compared to younger subjects ( Loibl et al., 2011 ).

EP 2. Pyramidal tract FA predicts motor outcome in subacute stroke patients after a three week period of arm ability training for ADL-relevant hand motor tests

Objective Outcome prediction after motor stroke for the acute to subacute phase can be consulted for individual therapy modification. For the outcome of severely impaired patients the intactness of the pyramidal tract descending from the lesioned hemisphere (ipsilesional; i ) has been described as an important parameter for upper limb strength as a measure of motor outcome ( Stinear et al., 2012 ). In addition, in chronic stroke fractional anisotrophy (FA) of the pyramidal tract is predictive for hand motor impairment in strength ( Lindenberg et al., 2010 ). In this study we tested whether this does also holds true for the subacute phase and for activity of daily living (ADL) relevant testing of arm activities, i.e. finger and hand dexterity. Methods Thirteen patients after first time stroke (4.7 ± 1.9 weeks after stroke; 9 with left hemispheric lesion; age 60 ± 12.6 years, NIHSS: 2.69±1.8; Edinburg handedness 81.35 ± 34.7) were recruited at the BDH-hospital of Greifswald. They had small lesions (predominantly subcortical; volume: 7.17±15.8 ccl) and mini mental status revealed no severe cognitive impairments (average score 27). Patients underwent a three week course of arm ability training (1 hour per day, 5 days a week) ( Platz et al., 2009 ) in addition to the standard inpatient rehabilitation therapy. MRI and motor performance (Box and Block test; Nine Hole Peg test) were measured before and after training. MRI comprised of high resolution T1-weighted imaging (MPrage-sequence) and a diffusion weighted imaging (64 directions; MDDW-sequence) using a 32 channel head coil with a 3 Tesla MRI scanner (Siemens, Erlangen). The average FA was evaluated for the pyramidal tract between the affected hand area of the primary motor cortex (M1 i ) to the internal capsule and M1i crossing to the contralesional ( c ) pons. FSL was used for calculating average FA over tract. Results Motor tests for the affected hand significantly improved during training (NHP: t = 3.87; p t = 4.58; p i to internal capsule: t = 4.83; p i to pons c : t = 4.83; p i to internal capsule: r = −0.57; p = 0.04; M1 i to pons c : r = −0.87 p = 0.02) and BB (M1 i to internal capsule: r = 0.68; p = 0.01; M1 i to pons c : r = 0.84 p = 0.04). Conclusion Intactness of pyramidal tract is capable for predicting activity of daily living relevant hand motor outcome after comprehensive and specific arm motor training in subacute stroke patients.

A single robotic session that guides or increases movement error in survivors post-chronic stroke: which intervention is best to boost the learning of a timing task?

Purpose: Timing deficits can have a negative impact on the lives of survivors post-chronic stroke. Studies evaluating ways to improve timing post stroke are scarce. The goal of the study was to evaluate the impact of a single session of haptic guidance (HG) and error amplification (EA) robotic training interventions on the improvement of post-stroke timing accuracy.Materials and methods: Thirty-four survivors post-chronic stroke were randomly assigned to HG or EA. Participants played a computerized pinball-like game with their affected hand positioned in a robot that either helped them perform better (HG) or worse (EA) during the task. A baseline and retention phase preceded and followed HG and EA, respectively, in order to assess their efficiency at improving absolute timing errors. The impact of the side of the stroke lesion on the participants’ performance during the timing task was also explored for each training group.Results: An improvement in timing performance was only noted following HG (8.9 ± 4.9 ms versus 7.8 ± 5.3 ms, p = 0.032). Moreover, for the EA group only, participants with a left-sided stroke lesion showed a worsening in performance as compared to those with a right-sided stroke lesion (p = 0.001).Conclusion: Helping survivors post-chronic stroke perform a timing-based task is beneficial to learning. Future studies should explore longer and more frequent HG training sessions in order to further promote post stroke motor recovery.Implications for RehabilitationTiming is crucial for the accomplishment of daily tasks.The number of studies dedicated to improving timing is scarce in the literature, even though timing deficits are common post stroke.This innovative study evaluated the impact of a single session of haptic guidance-HG and error amplification-EA robotic training interventions on improvements in timing accuracy among survivors post chronic stroke.HG robotic training improves timing accuracy more than EA among survivors post chronic stroke.

Falls and Fear of Falling After Stroke: A Case-Control Study

BackgroundFalls are common after stroke, with potentially serious consequences. Few investigations have included age-matched control participants to directly compare fall characteristics between older adults with and without stroke. Further, fear of falling, a significant psychological consequence of falls, has only been examined to a limited degree as a risk factor for future falls in a stroke population. ObjectiveTo compare the fall history between older adults with and without a previous stroke and to identify the determinants of falls and fear of falling in older stroke survivors. DesignCase-control observational study. SettingPrimary teaching hospital. ParticipantsSeventy-five patients with stroke (mean age ± standard deviation, 66 ± 7 years) and 50 age-matched control participants with no previous stroke were tested. MethodsFall history, fear of falling, and physical, cognitive, and psychological function were assessed. A χ2 test was performed to compare characteristics between groups, and logistic regression was performed to determine the risk factors for falls and fear of falling. Main Outcome MeasuresFall events in the past 12 months, Fall Efficacy Scale–International, Berg Balance Scale, Functional Ambulation Category, Fatigue Severity Scale, Montreal Cognitive Assessment, and Patient Healthy Questionnaire–9 were measured for all participants. Fugl-Meyer Motor Assessment was used to quantify severity of stroke motor impairments. ResultsTwenty-three patients and 13 control participants reported at least one fall in the past 12 months (P = .58). Nine participants with stroke had recurrent falls (≥2 falls) compared with none of the control participants (P < .01). Participants with stroke reported greater concern for falling than did nonstroke control participants (P < .01). Female gender was associated with falls in the nonstroke group, whereas falls in the stroke group were not significantly associated with any measured outcomes. Fear of falling in the stroke group was associated with functional ambulation level and balance. Functional ambulation level alone explained 22% of variance in fear of falling in the stroke group. ConclusionsCompared with persons without a stroke, patients with stroke were significantly more likely to experience recurrent falls and fear of falling. Falls in patients with stroke were not explained by any of the outcome measures used, whereas fear of falling was predicted by functional ambulation level. This study has identified potentially modifiable risk factors with which to devise future prevention strategies for falls in patients with stroke. Level of EvidenceIII

Non-Invasive Brain Stimulation Improves Paretic Limb Force Production: A Systematic Review and Meta-Analysis.

Non-invasive brain stimulation (NIBS) facilitates motor improvements post stroke. Transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) are representative NIBS techniques frequently used in stroke motor rehabilitation. Our primary question is: Do these two techniques improve force production capability in paretic limbs? The current systematic review and meta-analysis investigated the effects of tDCS and rTMS on paretic limb force production in stroke survivors. Our comprehensive search identified 23 studies that reported changes in force production following tDCS or rTMS interventions. Each used random assignment and a sham control group. The 23 qualified studies in our meta-analysis generated 29 comparisons: 14 tDCS and 15 rTMS comparisons. Random effects models indicated improvements in paretic limb force after tDCS and rTMS rehabilitation. We found positive effects on force production in the two sets of stimulation protocols: (a) increasing cortical activity in the ipsilesional hemisphere and (b) decreasing cortical activity in the contralesional hemisphere. Moreover, across acute, subacute, and chronic phases, tDCS and rTMS improved force production. Cumulative meta-analytic results revealed that tDCS and rTMS rehabilitation protocols successfully improved paretic limb force production capabilities.

Increased ventral premotor cortex recruitment after arm training in an fMRI study with subacute stroke patients

To investigate therapy associated changes in the cerebral representation of movement after stroke, we used functional magnetic resonance imaging (fMRI) during an active and a passive motor task for the affected and unaffected hand before and after a three week comprehensive hand motor training.Twelve patients in the subacute phase from 2 to 9 weeks after mild to moderate motor stroke were recruited. During fMRI, the active task comprised fist clenching, which was precisely controlled for motor performance by visual feedback of force and frequency. The passive task consisted of wrist flexion-extension of 1Hz frequency by means of a pneumatic driven splint. Arm Ability Training (AAT) was conducted one hour per day over 3 weeks in addition to inward rehabilitative therapy. Performance gain was tested using movements trained with AAT, but also with conventional hand motor tests (Nine-Hole-Peg Test, Box-and-Block Test).Rehabilitation therapy and AAT resulted in considerable improvement of performance in trained tasks and other hand motor functions (e.g., Nine-Hole-Peg Test). FMRI activation in the ventral premotor cortex (vPMC) of the lesioned hemisphere increased over time for the active task only for the affected hand. No such change was present for the passive wrist extension task or the active task with the unaffected hand. In addition, only for the post measurement of the active task performed with the affected hand, bilateral vPMC shows a more pronounced activation than in healthy controls. This finding contradicts the simple “near to normal is good recovery” opinion.

Increased resting state connectivity between ipsilesional motor cortex and contralesional premotor cortex after transcranial direct current stimulation with physical therapy.

Non-invasive stimulation of the brain using transcranial direct current stimulation (tDCS) during motor rehabilitation can improve the recovery of movements in individuals with stroke. However, the neural substrates that underlie the clinical improvements are not well understood. In this proof-of-principle open-label pilot study, five individuals with stroke received 10 sessions of tDCS while undergoing usual care physical/occupational therapy for the arm and hand. Motor impairment as indexed by the Upper Extremity Fugl Meyer assessment was significantly reduced after the intervention. Resting state fMRI connectivity increased between ipsilesional motor cortex and contralesional premotor cortex after the intervention. These findings provide preliminary evidence that the neural underpinnings of tDCS coupled with rehabilitation exercises, may be mediated by interactions between motor and premotor cortex. The latter, of which has been shown to play an important role in the recovery of movements post-stroke. Our data suggest premotor cortex could be tested as a target region for non-invasive brain-stimulation to enhance connectivity between regions that might be beneficial for stroke motor recovery.