Use-dependent plasticity of the human motor cortex in health and disease

Using Large-Scale Sensor Data to Test Factors Predictive of Perseverance in Home Movement Rehabilitation: Early Exercise Frequency and Schedule Consistency

Home-based exercises are an important component of stroke rehabilitation but are seldom fully completed. Past studies of exercise perseverance in the general public have suggested the importance of early exercise frequency and schedule consistency (in terms of which days of the week exercises are performed) because they encourage habit formation. To test whether these observations apply after a stroke, we leveraged data from 2,583 users of a sensor-based system (FitMi) developed to motivate movement exercises at home. We grouped users based on their early exercise frequency (defined across the initial 6 weeks of use) and calculated the evolution of habit score (defined as exercise frequency multiplied by exercise duration) across 6 months. We found that habit score decayed exponentially over time but with a slower decay constant for individuals with higher early frequency. Only the group with an early exercise frequency of 4 days/week or more had non-zero habit score at six months. Within each frequency group, dividing individuals into higher and lower consistency subgroups revealed that the higher consistency subgroups had significantly higher habit scores. These results are consistent with previous studies on habit formation in exercise and may help in designing effective home rehabilitation programs after stroke.

Validity and reliability of a finger training tool for assessing metacarpal phalangeal joint ranges of motion in asymptomatic participants

This pilot study aims to evaluate concurrent validity using the goniometer as a reference tool and test-retest reliability of flexion of metacarpal phalangeal joint (MCP) measurements taken from a finger training device (air-guitar system) in healthy participants. There were ten self -reported asymptomatic participants recruited to test the devices. The measurements of all metacarpophangeal joints of the dominant hands were conducted using a finger goniometer and the air-guitar system. Two measuring sessions were conducted on the same day. The concurrent validity of the air-guitar indicated by strong concordance correlation coefficient (0.62-0.90) with the goniometer and mean difference (approximately 1°) between the two instruments are well below the limit of 5°. The test-retest reliability of MCP measurements from the air-guitar glove (0.82-0.99) was acceptable as a clinically meaningful measurement tool as the intraclass correlation coefficients were higher than 0.7. The standard error of measurement and minimal detectable change of the air-guitar are similar to those of the goniometer. The air-guitar tracking features, when used as a home-based therapy tool, may assist in monitoring change of MCP flexion over a time course with good reliability and strongly associated with the measurements from the goniometer.

Optimized Home Rehabilitation Technology Reduces Upper Extremity Impairment Compared to a Conventional Home Exercise Program: A Randomized, Controlled, Single-Blind Trial in Subacute Stroke

BACKGROUND

Upper extremity (UE) stroke rehabilitation requires patients to perform exercises at home, yet patients show limited benefit from paper-based home exercise programs.

OBJECTIVE

To compare the effectiveness of 2 home exercise programs for reducing UE impairment: a paper-based approach and a sensorized exercise system that incorporates recommended design features for home rehabilitation technology.

METHODS

In this single-blind, randomized controlled trial, 27 participants in the subacute phase of stroke were assigned to the sensorized exercise (n = 14) or conventional therapy group (n = 13), though 2 participants in the conventional therapy group were lost to follow-up. Participants were instructed to perform self-guided movement training at home for at least 3 hours/week for 3 consecutive weeks. The sensorized exercise group used FitMi, a computer game with 2 puck-like sensors that encourages movement intensity and auto-progresses users through 40 exercises. The conventional group used a paper book of exercises. The primary outcome measure was the change in Upper Extremity Fugl-Meyer (UEFM) score from baseline to follow-up. Secondary measures included the Modified Ashworth Scale for spasticity (MAS) and the Visual Analog Pain (VAP) scale.

RESULTS

Participants who used FitMi improved by an average of 8.0 ± 4.6 points on the UEFM scale compared to 3.0 ± 6.1 points for the conventional participants, a significant difference (t-test, P = .029). FitMi participants exhibited no significant changes in UE MAS or VAP scores.

CONCLUSIONS

A sensor-based exercise system incorporating a suite of recommended design features significantly and safely reduced UE impairment compared to a paper-based, home exercise program.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03503617.

Feasibility of Wearable Sensing for In-Home Finger Rehabilitation Early After Stroke

Wearable grip sensing shows potential for hand rehabilitation, but few studies have studied feasibility early after stroke. Here, we studied a wearable grip sensor integrated with a musical computer game (MusicGlove). Among the stroke patients admitted to a hospital without limiting complications, 13% had adequate hand function for system use. Eleven subjects used MusicGlove at home over three weeks with a goal of nine hours of use. On average they achieved 4.1 ± 3.2 (SD) hours of use and completed 8627 ± 7500 grips, an amount comparable to users in the chronic phase of stroke measured in a previous study. The rank-order usage data were well fit by distributions that arise in machine failure theory. Users operated the game at high success levels, achieving note-hitting success >75% for 84% of the 1061 songs played. They changed game parameters infrequently (31% of songs), but in a way that logically modulated challenge, consistent with the Challenge Point Hypothesis from motor learning. Thus, a therapy based on wearable grip sensing was feasible for home rehabilitation, but only for a fraction of subacute stroke subjects. Subjects made usage decisions consistent with theoretical models of machine failure and motor learning.

[Efficacy of Music Therapy in Functional Recovery of the Upper Limb After a Stroke: a Systematic Review and Meta-Analysis]

INTRODUCTION

Formal therapeutic interventions based on music have been used in rehabilitation to stimulate the brain functions involved in movement.

OBJECTIVE

The objective of this study was to conduct a systematic review and meta-analysis following the PRISMA recommendations on the effectiveness of music therapy in improving the functionality of the upper limb in patients with hemiparesis secondary to stroke.

METHODS

A search of the Pubmed, clinicaltrials.gov and Cochrane databases was performed in September 2018. The articles included in this review had to meet the following criteria: randomised controlled trials with therapeutic interventions that evaluated improvement in manual dexterity, measured with the box and block test in patients older than 18 years with a residual deficit secondary to an ischaemic or haemorrhagic stroke in the previous months.

RESULTS

Of 371 studies analysed, six were included in the study and subsequent meta-analysis with a total of 149 patients. The musical interventions improved the functionality of the parietal limb in patients with stroke compared with that in controls who received conventional treatment. This effect was statistically significant in the meta-analysis, with a difference in the standardised mean in the box and block test of 0.40 (95% CI 0.09 - 0.72).

CONCLUSIONS

Musical interventions could be beneficial for the functional recovery of the upper extremity. These results are encouraging but a greater number of clinical trials are required to confirm these findings before their subsequent implementation in clinical practice.

Home-based hand rehabilitation after chronic stroke: Randomized, controlled single-blind trial comparing the MusicGlove with a conventional exercise program

Individuals with chronic stroke have limited options for hand rehabilitation at home. Here, we sought to determine the feasibility and efficacy of home-based MusicGlove therapy. Seventeen participants with moderate hand impairment in the chronic phase of stroke were randomized to 3 wk of home-based exercise with either the MusicGlove or conventional tabletop exercises. The primary outcome measure was the change in the Box and Blocks test score from baseline to 1 mo posttreatment. Both groups significantly improved their Box and Blocks test score, but no significant difference was found between groups. The MusicGlove group did exhibit significantly greater improvements than the conventional exercise group in motor activity log quality of movement and amount of use scores 1 mo posttherapy (p = 0.007 and p = 0.04, respectively). Participants significantly increased their use of MusicGlove over time, completing 466 gripping movements per day on average at study end. MusicGlove therapy was not superior to conventional tabletop exercises for the primary end point but was nevertheless feasible and led to a significantly greater increase in self-reported functional use and quality of movement of the impaired hand than conventional home exercises.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; "Influence of Timing on Motor Learning"; NCT01769326; https://clinicaltrials.gov/ct2/show/NCT01769326.

A Multicenter Trial of a Footdrop Stimulator Controlled by a Tilt Sensor

Objectives. To test the efficacy and acceptance of a footdrop stimulator controlled by a tilt sensor. Methods. A nonrandomized, test-retest study of 26 subjects with footdrop of more than 1 year’s duration, resulting from various central nervous system disorders, was performed in 4 centers for at least 3 months. Speed of walking in a straight line, speed around a figure of 8, and physiological cost index (PCI) were measured with and without the device. Hours/day and steps/day using the device were recorded. Results.All but 2 subjects used the tilt sensor at home, rather than a foot switch. Walking speed increased by 15% after 3 months ( n = 26; P < 0.01), 32% after 6 months ( n = 16; P < 0.01), and 47% after 12 months ( n = 8; P < 0.05), while PCI decreased. The number of steps taken per day of use increased significantly over time, and increased speed was directly correlated with usage. Walking speed also increased with the stimulator off, but to a lesser extent, indicating a training effect. Subject feedback from a questionnaire indicated satisfaction with the stimulator. Conclusions. Both efficacy and acceptance of the stimulator were good in a population of subjects with chronic footdrop.

Machine-Based, Self-guided Home Therapy for Individuals With Severe Arm Impairment After Stroke: A Randomized Controlled Trial

BACKGROUND

Few therapeutic options exist for the millions of persons living with severe arm impairment after stroke to increase their dose of arm rehabilitation. This study compared self-guided, high-repetition home therapy with a mechanical device (the resonating arm exerciser [RAE]) to conventional therapy in patients with chronic stroke and explored RAE use for patients with subacute stroke.

METHODS

A total of 16 participants with severe upper-extremity impairment (mean Fugl-Meyer [FM] score = 21.4 ± 8.8 out of 66) >6 months poststroke were randomized to 3 weeks of exercise with the RAE or conventional exercises. The primary outcome measure was FM score 1 month posttherapy. Secondary outcome measures included Motor Activity Log, Visual Analog Pain Scale, and Ashworth Spasticity Scale. After a 1-month break, individuals in the conventional group also received a 3-week course of RAE therapy.

RESULTS

The change in FM score was significant in both the RAE and conventional groups after training (2.6 ± 1.4 and 3.4 ± 2.4, P = .008 and .016, respectively). These improvements were not significant at 1 month. Exercise with the RAE led to significantly greater improvements in distal FM score than conventional therapy at the 1-month follow-up (P = .02). In a separate cohort of patients with subacute stroke, the RAE was found feasible for exercise.

DISCUSSION

In those with severe arm impairment after chronic stroke, home-based training with the RAE was feasible and significantly reduced impairment without increasing pain or spasticity. Gains with the RAE were comparable to those found with conventional training and also included distal arm improvement.

Retraining and assessing hand movement after stroke using the MusicGlove: comparison with conventional hand therapy and isometric grip training

BACKGROUND

It is thought that therapy should be functional, be highly repetitive, and promote afferent input to best stimulate hand motor recovery after stroke, yet patients struggle to access such therapy. We developed the MusicGlove, an instrumented glove that requires the user to practice gripping-like movements and thumb-finger opposition to play a highly engaging, music-based, video game. The purpose of this study was to 1) compare the effect of training with MusicGlove to conventional hand therapy 2) determine if MusicGlove training was more effective than a matched form of isometric hand movement training; and 3) determine if MusicGlove game scores predict clinical outcomes.

METHODS

12 chronic stroke survivors with moderate hemiparesis were randomly assigned to receive MusicGlove, isometric, and conventional hand therapy in a within-subjects design. Each subject participated in six one-hour treatment sessions three times per week for two weeks, for each training type, for a total of 18 treatment sessions. A blinded rater assessed hand impairment before and after each training type and at one-month follow-up including the Box and Blocks (B & B) test as the primary outcome measure. Subjects also completed the Intrinsic Motivation Inventory (IMI).

RESULTS

Subjects improved hand function related to grasping small objects more after MusicGlove compared to conventional training, as measured by the B & B score (improvement of 3.21±3.82 vs. -0.29±2.27 blocks; P=0.010) and the 9 Hole Peg test (improvement of 2.14±2.98 vs. -0.85±1.29 pegs/minute; P=0.005). There was no significant difference between training types in the broader assessment batteries of hand function. Subjects benefited less from isometric therapy than MusicGlove training, but the difference was not significant (P>0.09). Subjects sustained improvements in hand function at a one month follow-up, and found the MusicGlove more motivating than the other two therapies, as measured by the IMI. MusicGlove games scores correlated strongly with the B & B score.

CONCLUSIONS

These results support the hypothesis that hand therapy that is engaging, incorporates high numbers of repetitions of gripping and thumb-finger opposition movements, and promotes afferent input is a promising approach to improving an individual's ability to manipulate small objects. The MusicGlove provides a simple way to access such therapy.

Haptic-based neurorehabilitation in poststroke patients: a feasibility prospective multicentre trial for robotics hand rehabilitation

Background. Haptic robots allow the exploitation of known motor learning mechanisms, representing a valuable option for motor treatment after stroke. The aim of this feasibility multicentre study was to test the clinical efficacy of a haptic prototype, for the recovery of hand function after stroke. Methods. A prospective pilot clinical trial was planned on 15 consecutive patients enrolled in 3 rehabilitation centre in Italy. All the framework features of the haptic robot (e.g., control loop, external communication, and graphic rendering for virtual reality) were implemented into a real-time MATLAB/Simulink environment, controlling a five-bar linkage able to provide forces up to 20 [N] at the end effector, used for finger and hand rehabilitation therapies. Clinical (i.e., Fugl-Meyer upper extremity scale; nine hold pegboard test) and kinematics (i.e., time; velocity; jerk metric; normalized jerk of standard movements) outcomes were assessed before and after treatment to detect changes in patients' motor performance. Reorganization of cortical activation was detected in one patient by fMRI. Results and Conclusions. All patients showed significant improvements in both clinical and kinematic outcomes. Additionally, fMRI results suggest that the proposed approach may promote a better cortical activation in the brain.

The Resonating Arm Exerciser: design and pilot testing of a mechanically passive rehabilitation device that mimics robotic active assistance

Background

Robotic arm therapy devices that incorporate actuated assistance can enhance arm recovery, motivate patients to practice, and allow therapists to deliver semi-autonomous training. However, because such devices are often complex and actively apply forces, they have not achieved widespread use in rehabilitation clinics or at home. This paper describes the design and pilot testing of a simple, mechanically passive device that provides robot-like assistance for active arm training using the principle of mechanical resonance.

Methods

The Resonating Arm Exerciser (RAE) consists of a lever that attaches to the push rim of a wheelchair, a forearm support, and an elastic band that stores energy. Patients push and pull on the lever to roll the wheelchair back and forth by about 20 cm around a neutral position. We performed two separate pilot studies of the device. In the first, we tested whether the predicted resonant properties of RAE amplified a user’s arm mobility by comparing his or her active range of motion (AROM) in the device achieved during a single, sustained push and pull to the AROM achieved during rocking. In a second pilot study designed to test the therapeutic potential of the device, eight participants with chronic stroke (35 ± 24 months since injury) and a mean, stable, initial upper extremity Fugl-Meyer (FM) score of 17 ± 8 / 66 exercised with RAE for eight 45 minute sessions over three weeks. The primary outcome measure was the average AROM measured with a tilt sensor during a one minute test, and the secondary outcome measures were the FM score and the visual analog scale for arm pain.

Results

In the first pilot study, we found people with a severe motor impairment after stroke intuitively found the resonant frequency of the chair, and the mechanical resonance of RAE amplified their arm AROM by a factor of about 2. In the second pilot study, AROM increased by 66% ± 20% (p = 0.003). The mean FM score increase was 8.5 ± 4 pts (p = 0.009). Subjects did not report discomfort or an increase in arm pain with rocking. Improvements were sustained at three months.

Conclusions

These results demonstrate that a simple mechanical device that snaps onto a manual wheelchair can use resonance to assist arm training, and that such training shows potential for safely increasing arm movement ability for people with severe chronic hemiparetic stroke.

Peripheral electrical stimulation triggered by self-paced detection of motor intention enhances motor evoked potentials

This paper proposes the development and experimental tests of a self-paced asynchronous brain-computer interfacing (BCI) system that detects movement related cortical potentials (MRCPs) produced during motor imagination of ankle dorsiflexion and triggers peripheral electrical stimulations timed with the occurrence of MRCPs to induce corticospinal plasticity. MRCPs were detected online from EEG signals in eight healthy subjects with a true positive rate (TPR) of 67.15 ± 7.87% and false positive rate (FPR) of 22.05 ±9.07%. The excitability of the cortical projection to the target muscle (tibialis anterior) was assessed before and after the intervention through motor evoked potentials (MEP) using transcranial magnetic stimulation (TMS). The peak of the evoked potential significantly (P=0.02) increased after the BCI intervention by 53 ± 43% (relative to preintervention measure), although the spinal excitability (tested by stretch reflexes) did not change. These results demonstrate for the first time that it is possible to alter the corticospinal projections to the tibialis anterior muscle by using an asynchronous BCI system based on online motor imagination that triggered peripheral stimulation. This type of repetitive proprioceptive feedback training based on self-generated brain signal decoding may be a requirement for purposeful skill acquisition in intact humans and in the rehabilitation of persons with brain damage.

The cerebellum in maintenance of a motor skill: a hierarchy of brain and spinal cord plasticity underlies H-reflex conditioning

Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex, is a simple model of skill acquisition and involves plasticity in the spinal cord. Previous work showed that the cerebellum is essential for down-conditioning the H-reflex. This study asks whether the cerebellum is also essential for maintaining down-conditioning. After rats decreased the soleus H-reflex over 50 d in response to the down-conditioning protocol, the cerebellar output nuclei dentate and interpositus (DIN) were ablated, and down-conditioning continued for 50-100 more days. In naive (i.e., unconditioned) rats, DIN ablation itself has no significant long-term effect on H-reflex size. During down-conditioning prior to DIN ablation, eight Sprague-Dawley rats decreased the H-reflex to 57% (+/-4 SEM) of control. It rose after ablation, stabilizing within 2 d at about 75% and remaining there until approximately 40 d after ablation. It then rose to approximately 130%, where it remained through the end of study 100 d after ablation. Thus, DIN ablation in down-conditioned rats caused an immediate increase and a delayed increase in the H-reflex. The final result was an H-reflex significantly larger than that prior to down-conditioning. Combined with previous work, these remarkable results suggest that the spinal cord plasticity directly responsible for down-conditioning, which survives only 5-10 d on its own, is maintained by supraspinal plasticity that survives approximately 40 d after loss of cerebellar output. Thus, H-reflex conditioning seems to depend on a hierarchy of brain and spinal cord plasticity to which the cerebellum makes an essential contribution.

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.