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[ARTICLE] Brain regions important for recovery after severe post-stroke upper limb paresis – Full Text

Abstract

Background The ability to predict outcome after stroke is clinically important for planning treatment and for stratification in restorative clinical trials. In relation to the upper limbs, the main predictor of outcome is initial severity, with patients who present with mild to moderate impairment regaining about 70% of their initial impairment by 3 months post-stroke. However, in those with severe presentations, this proportional recovery applies in only about half, with the other half experiencing poor recovery. The reasons for this failure to recover are not established although the extent of corticospinal tract damage is suggested to be a contributory factor. In this study, we investigated 30 patients with chronic stroke who had presented with severe upper limb impairment and asked whether it was possible to differentiate those with a subsequent good or poor recovery of the upper limb based solely on a T1-weighted structural brain scan.

Methods A support vector machine approach using voxel-wise lesion likelihood values was used to show that it was possible to classify patients as good or poor recoverers with variable accuracy depending on which brain regions were used to perform the classification.

Results While considering damage within a corticospinal tract mask resulted in 73% classification accuracy, using other (non-corticospinal tract) motor areas provided 87% accuracy, and combining both resulted in 90% accuracy.

Conclusion This proof of concept approach highlights the relative importance of different anatomical structures in supporting post-stroke upper limb motor recovery and points towards methodologies that might be used to stratify patients in future restorative clinical trials.

Introduction

Stroke is one of the the most common causes of physical disability worldwide and about 80% of stroke survivors experience impairment of movement on one side of the body.1 Hand and arm impairment in particular is often persistent, disabling and a major contributor to reduced quality of life.2 The main predictor of long-term outcome of upper limb function is the level of initial impairment.3 This can be quantified as the proportional recovery rule which states that by 3 months, patients with stroke will recover about 70% of the initial upper limb motor impairment that has been observed on day 3 post-stroke.4–6 The prediction works extremely well for those presenting with mild to moderate upper limb impairment, but in only about half of those with initially severe upper limb impairment.4–6 In the other half, patients do worse than predicted, that is, there is a failure of proportional recovery. A key question then is, what is the difference between patients with stroke matched for initial severity who go on and have different recovery trajectories? The answer to this will point to the factors that are important for the dynamic process of recovery independent from the causes of initial impairment.

One possibility is the anatomy of the damage may be different in each group. A number of recent studies have proposed that the corticospinal tract (CST) plays a decisive role in this categorical difference7–11 as cortical reorganisation for improved motor function ultimately requires access for cortical motor areas to muscles. However, CST lesion load correlates with initial motor impairment,12 which is the major predictor of long-term outcome. It is therefore reasonable to ask how much CST lesion load can improve prediction of long-term outcome over and above initial severity. Furthermore, most of the patients involved in these studies had suffered from subcortical stroke and recent work has suggested that taking account of cortical damage after stroke can improve prediction of the motor clinical consequences.13 14

In this study, we investigated 30 patients with chronic stroke with a range of lesion locations (cortical and/or subcortical involvement) known to have presented with severe initial upper limb impairment but who had gone on to have quite different recovery trajectories. We applied a support vector machine approach to data representing lesion likelihood derived from structural T1-weighted MRI to answer the following questions. First, how accurately can patients with stroke with severe initial upper limb impairment be classified as having either good or poor recovery using only data extracted from whole brain structural MRI? Second, which brain regions contribute most to the classification? The results have the potential to transform how prediction of long-term upper limb outcome after stroke is achieved in routine clinical practice in future. The ability to easily and accurately predict outcome with standard clinical neuroimaging would have important implications for planning of treatment but also for stratification in future trials of restorative therapies.15[…]

Continue —> Brain regions important for recovery after severe post-stroke upper limb paresis | Journal of Neurology, Neurosurgery & Psychiatry

Figure 1

Figure 1 Data representation. In the figure to the left, a mask corresponding to the corticospinal tract is overlaid on an image obtained through lesion likelihood. Each voxel corresponds to a value between 0 and 1 encoding the probability of being part of injured tissue. The enlarged section of the image in the figure to the right shows that each voxel within a region of interest corresponds to a particular feature in the multivariate analysis. 

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[ARTICLE] Does non-invasive brain stimulation modify hand dexterity? Protocol for a systematic review and meta-analysis – Full Text

 

Abstract

Introduction Dexterity is described as coordinated hand and finger movement for precision tasks. It is essential for day-to-day activities like computer use, writing or buttoning a shirt. Integrity of brain motor networks is crucial to properly execute these fine hand tasks. When these networks are damaged, interventions to enhance recovery are frequently accompanied by unwanted side effects or limited in their effect. Non-invasive brain stimulation (NIBS) are postulated to target affected motor areas and improve hand motor function with few side effects. However, the results across studies vary, and the current literature does not allow us to draw clear conclusions on the use of NIBS to promote hand function recovery. Therefore, we developed a protocol for a systematic review and meta-analysis on the effects of different NIBS technologies on dexterity in diverse populations. This study will potentially help future evidence-based research and guidelines that use these NIBS technologies for recovering hand dexterity.

Methods and analysis This protocol will compare the effects of active versus sham NIBS on precise hand activity. Records will be obtained by searching relevant databases. Included articles will be randomised clinical trials in adults, testing the therapeutic effects of NIBS on continuous dexterity data. Records will be studied for risk of bias. Narrative and quantitative synthesis will be done.

Strengths and limitations of this study

  • This is a novel systematic review and meta-analysis focusing specifically on dexterity.

  • We use continuous data not dependent on the evaluator or participant.

  • This work will potentially help future evidence-based research and guidelines to refine non-invasive brain stimulation.

Introduction

The hand’s somatotopy is extensively represented in the human motor cortex.1 2 Phylogenetically, this relates to the development of corticomotoneuronal cells that specialise in creating patterns of muscle activity that synergises into highly skilled movements.3 This organised hand-and-finger movement to use objects during a specific task is known as dexterity.4 Evolutionary, dexterity played a pivotal role in human survival and is fundamental to actives of daily living, and hence quality of life.5 6

This precision motor movement relies on integration of information from the cerebral cortex, the spinal cord, several neuromusculoskeletal systems and the external world to coordinate finger force control, finger independence, timing and sequence performance.7 During these tasks, multivoxel pattern decoding shows bilateral primary motor cortex activation (M1), which was responsible for muscle recruitment timing and hand movement coordination.8 9 This is related to motor cortex connectivity through the corpus callosum, to motor regions of the cerebellum and white matter integrity.10–15 Adequate motor output translates into successfully executed tasks, like picking up objects, turning over cards, manipulating cutlery, writing, using computer–hand interfaces like smartphones, playing an instrument and performing many other similarly precise skills.16

These motor tasks are negatively impacted when motor output networks are affected, as seen in stroke or Parkinson’s disease.17 18 Therapeutic interventions that restore these damaged motor networks can be vital to restore fine motor movement after injury occurs. Pharmaceutical approaches often lead to adverse effects such as dyskinesias in Parkinson’s disease. Moreover, even after intensive rehabilitation programmes, only about 5%–20% of patients with stroke fully recover their motor function.19–21 Non-invasive brain stimulation (NIBS) techniques, like transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS), are proposed adjuvant or stand-alone interventions to target these affected areas and improve fine motor function.22 23 Briefly, these NIBS interventions are shown to influence the nervous system’s excitability and modulate long-term plasticity, which may be beneficial to the brain’s recovery of functions after injury.24–27

Fine hand motor ability is not studied as much in previous reviews of NIBS. Specifically, one narrative review focuses on rTMS in affected hand recovery poststroke; however, it does not consider the implications of varying International Classification of Functioning, Disability and Health (ICF) domains, data types and rater dependent outcomes, and its interpretability is limited without quantitative synthesis.28–31 The overarching conclusion was supportive of rTMS for paretic hand recovery, though with limited data to support its regular use, and a pressing need to study individualised patient parameters.28 One meta-analysis had positive and significant results when specifically studying the effects of rTMS on finger coordination and hand function after stroke.32 However, while various meta-analysis, and another systematic review, studied upper-limb movement after NIBS in distinct populations, they did not focus on precise hand function, pooled upper-limb outcomes with hand outcomes and presented mixed results.33–38

Motivated by this gap in the evidence for NIBS in dexterity, we will do a systematic review and meta-analysis of the literature on these brain stimulation technologies using outcomes that focus exactly on manual dexterity. These outcomes will be continuous and not dependent on the participant’s or rater’s observation (ie, they will be measured in seconds, or number of blocks/pegs placed, and not by an individual’s interpretation). They will be comprised of multiple domains as defined by the ICF, providing an appreciation of function rather than only condition or disease.29–31 By focusing on the ICF model, we will be able to study dexterity across a larger sample of studies, NIBS techniques and conditions in order to provide a better understanding of brain stimulation efficacy on hand function in various populations.[…]

Continue —. Does non-invasive brain stimulation modify hand dexterity? Protocol for a systematic review and meta-analysis | BMJ Open

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[ARTICLE] Home-based neurologic music therapy for arm hemiparesis following stroke: results from a pilot, feasibility randomized controlled trial – Full Text

 

Continue —> Home-based neurologic music therapy for arm hemiparesis following stroke: results from a pilot, feasibility randomized controlled trialClinical Rehabilitation – Alexander J Street, Wendy L Magee, Andrew Bateman, Michael Parker, Helen Odell-Miller, Jorg Fachner, 2017

figure

Figure 1. Study flow diagram. Data collection occurred at weeks 1, 6, 9, 15 and 18. Cross-over analysis required data from weeks 1, 6, 9 and 15.

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[ARTICLE] Robotic-assisted serious game for motor and cognitive post-stroke rehabilitation – Full Text PDF

 

Abstract

Stroke is a major cause of long-term disability that can cause motor and cognitive impairments. New technologies such as robotic devices and serious games are increasingly being developed to improve post-stroke rehabilitation. The aim of the present project was to develop a ROBiGAME serious game to simultaneously improve motor and cognitive deficits (in particular hemiparesis and hemineglect). In this context, the difficulty level of the game was adapted to each patient’s performance, and this individualized adaptation was addressed as the main challenge of the game development. The game was implemented on the REAplan end-effector rehabilitation robot, which was used in continuous interaction with the game. A preliminary feasibility study of a target pointing game was run in order to validate the game features and parameters. Results showed that the game was perceived as enjoyable, and that patients reported a desire to play the game again. Most of the targets included in the game design were realistic, and they were well perceived by the patients. Results also suggested that the cognitive help strategy could include one visual prompting cue, possibly combined with an auditory cue. It was observed that the motor assistance provided by the robot was well adapted for each patient’s impairments, but the study results led to a suggestion that the triggering conditions should be reviewed. Patients and therapists reported the desire to receive more feedback on the patient’s performances. Nevertheless, more patients and therapists are needed to play the game in order to give further and more comprehensive feedback that will allow for improvements of the serious game. Future steps also include the validation of the motivation assessment module that is currently under development.

Full Text PDF

 

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[Abstract] A Randomized Trial on the Effects of Attentional Focus on Motor Training of the Upper Extremity Using Robotics with Individuals after Chronic Stroke 

 

Highlights

  • Individuals with moderate-to-severe arm impairment after stroke improved motor control after engaging in high-repetition training
  • There were no differences between external focus or internal focus of attention on retention of motor skills after four weeks of arm training for individuals with stroke
  • Individuals with moderate-to-severe arm impairment may not experience the advantages of an external focus during motor training found in healthy individuals
  • Attentional focus is most likely not an active ingredient for retention of trained motor skills for individuals with moderate-to-severe arm impairment

Abstract

Objective

To compare the long-term effects of external focus (EF) versus internal focus (IF) of attention after 4-weeks of arm training. Design: Randomized, repeated measure, mixed ANOVA.

Setting

Outpatient clinic.

Participants

33 individuals with stroke and moderate-to-severe arm impairment living in the community (3 withdrawals).

Interventions

4-week arm training protocol on the InMotion ARM robot (12 sessions).

Main Outcome Measures

Joint independence, Fugl-Meyer Assessment, and Wolf Motor Function Test measured at baseline, discharge, and 4-week follow-up.

Results

There were no between-group effects for attentional focus. Participants in both groups improved significantly on all outcome measures from baseline to discharge and maintained those changes at 4-week follow-up regardless of group assignment [Jt indep-EF, F(1.6, 45.4) = 17.74, p<.0005, partial η2=.39; Jt indep-IF, F(2, 56)= 18.66, p<.0005, partial η2=.40; FMA, F(2, 56) = 27.83, p<.0005, partial η2=.50 ; WMFT, F(2, 56) =14.05, p<.0005, partial η2=.35].

Conclusion

There were no differences in retention of motor skills between EF and IF participants four weeks after arm training, suggesting that individuals with moderate-to-severe arm impairment may not experience the advantages of an EF found in healthy individuals. Attentional focus is most likely not an active ingredient for retention of trained motor skills for individuals with moderate-to-severe arm impairment, whereas dosage and intensity of practice appear to be pivotal. Future studies should investigate the long-term effects of attentional focus for individuals with mild arm impairment.

Source: A Randomized Trial on the Effects of Attentional Focus on Motor Training of the Upper Extremity Using Robotics with Individuals after Chronic Stroke – Archives of Physical Medicine and Rehabilitation

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[Abstract] Effects of Transcranial direct current stimulation with sensory modulation on stroke motor rehabilitation: A randomized controlled trial  

 

Abstract

Objective

To test whether a multi-strategy intervention enhanced recovery immediately and longitudinally in patients with severe to moderate upper extremity (UE) paresis.

Design

Double-blind randomized controlled trial with placebo control.

Setting

An outpatient department of a local medical center.

Participants

People (n = 25) with chronic stroke were randomly assigned to 2 groups. Participants in the transcranial direct current stimulation with sensory modulation (tDCS-SM) and in the control group were 55.3±11.5 (n=14) and 56.9±13.5 (n=11) years old, respectively.

Interventions

8-week intervention. The tDCS-SM group received bilateral tDCS, bilateral cutaneous anesthesia, and high repetitions of passive movements on the paretic hand. The control group received the same passive movements but with sham tDCS and sham anesthesia. During the experiment, all participants continued their regular rehabilitation.

Main outcome measures

Voluntary UE movement, spasticity, UE function, and basic activities of daily living. Outcomes were assessed at baseline, at post-intervention, and at 3- and 6-month follow-ups.

Results

No significant differences were found between groups. However, there was a trend that the voluntary UE movement improved more in the tDCS-SM group than in the control group, with a moderate immediate effect (partial η2, ηp2 = 0.14, p = 0.07) and moderate long-term effects (ηp2 =0.17, p = 0.05 and ηp2 = 0.12, p = 0.10). Compared with the control group, the tDCS-SM group had a trend of a small immediate effect (ηp2 = 0.02 – 0.04) on reducing spasticity but no long-term effect. A trend of small immediate and long-term effects in favor of tDCS-SM was found on UE function and daily function recovery (ηp2= 0.02 – 0.09).

Conclusions

Accompanied with traditional rehabilitation, tDCS-SM had a non-significant trend of having immediate and longitudinal effects on voluntary UE movement recovery in patients with severe to moderate UE paresis after stroke, but its effects on spasticity reduction and functional recovery may be limited. (NCT01847157)

Source: Effects of Transcranial direct current stimulation with sensory modulation on stroke motor rehabilitation: A randomized controlled trial – Archives of Physical Medicine and Rehabilitation

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[Abstract] The Effect of Modified Constraint-Induced Movement Therapy on Spasticity and Motor Function of the Affected Arm in Patients with Chronic Stroke

Purpose: The purpose of this study was to explore the effect of modified constraint-induced movement therapy (CIMT) in a real-world clinical setting on spasticity and functional use of the affected arm and hand in patients with spastic chronic hemiplegia.

Method: A prospective consecutive quasi-experimental study design was used. Twenty patients with spastic hemiplegia (aged 22–67 years) were tested before and after 2-week modified CIMT in an outpatient rehabilitation clinic and at 6 months. The Modified Ashworth Scale (MAS), active range of motion (AROM), grip strength, Motor Activity Log (MAL), Sollerman hand function test, and Box and Block Test (BBT) were used as outcome measures.

Results: Reductions (p<0.05–0.001) in spasticity (MAS) were seen both after the 2-week training period and at 6-month follow-up. Improvements were also seen in AROM (median change of elbow extension 5°, dorsiflexion of hand 10°), grip strength (20 Newton), and functional use after the 2-week training period (MAL: 1 point; Sollerman test: 8 points; BBT: 4 blocks). The improvements persisted at 6-month follow-up, except for scores on the Sollerman hand function test, which improved further.

Conclusion: Our study suggests that modified CIMT in an outpatient clinic may reduce spasticity and increase functional use of the affected arm in spastic chronic hemiplegia, with improvements persisting at 6 months.

Source: The Effect of Modified Constraint-Induced Movement Therapy on Spasticity and Motor Function of the Affected Arm in Patients with Chronic Stroke | Physiotherapy Canada

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[Abstract] Hand therapy interventions, outcomes, and diagnoses evaluated over the last 10 years: A mapping review linking research to practice

 

Abstract

Study Design

Mapping review.

Introduction

Although published literature and evidence to support medical practice is becoming more abundant, it is not known how well available evidence supports the full spectrum of hand therapy practice.

Purpose of the Study

The aim of this mapping review was to identify strengths and/or gaps in the available literature as compared with the hand therapy scope of practice to guide future research.

Methods

A systematic search and screening was conducted to identify evidence published from 2006 to 2015. Descriptive data from 191 studies were extracted, and the diagnoses, interventions, and outcomes used in the literature were compared with the hand therapy scope of practice.

Results

Osteoarthritis, tendon surgeries, and carpal tunnel syndrome were most frequently studied. Exercise, education, and orthotic interventions were most common, each used in more than 100 studies; only 12 studies used activity-based interventions. Primary outcome measures included range of motion, pain/symptoms, strength, and functional status.

Discussion

Abundant high-quality research exists for a portion of the hand therapy scope of practice; however, there is a paucity of evidence for numerous diagnoses and interventions.

Conclusions

More evidence is needed for complex diagnoses and activity-based interventions as well as behavioral and quality-of-care outcomes.

Source: Hand therapy interventions, outcomes, and diagnoses evaluated over the last 10 years: A mapping review linking research to practice – Journal of Hand Therapy

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[BOOK] Chapter 7: After Stroke Movement Impairments: A Review of Current Technologies for Rehabilitation – Full Text

 

 “Physical Disabilities – Therapeutic Implications”, book edited by Uner Tan, ISBN 978-953-51-3248-6, Print ISBN 978-953-51-3247-9, Published: June 14, 2017 under CC BY 3.0 license. © The Author(s)

Chapter 7: After Stroke Movement Impairments: A Review of Current Technologies for Rehabilitation

Abstract

This chapter presents a review of the rehabilitation technologies for people who have suffered a stroke, comparing and analyzing the impact that these technologies have on their recovery in the short and long term. The problematic is presented, and motor impairments for upper and lower limbs are characterized. The goal of this chapter is to show novel trends and research for the assistance and treatment of motor impairment caused by strokes.

1. Introduction

Stroke is the most common acquired neurological disease in the adult population worldwide (15 million every year [1]). Based on recently published studies, incidence of stroke in Europe at the beginning of the twenty-first century ranged from 95 to 290/100,000 per year [37]. Between 2000 and 2010, the relative rate of stroke deaths dropped by 35.8% in the United States and other countries. However, each year stroke affects nearly 800,000 individuals, becoming the first cause of chronic disability and the third cause of death. It is a global public health problem worldwide that generates a significant burden of illness for healthy life years lost due to disability and premature death.

One-third of stroke survivors achieve only a poor functional outcome 5 years after the onset of stroke. Although there is great progress in the management of acute stroke, most of the care to reduce dependence on post-stroke patients depends on rehabilitation. Optimal functional recovery is the ultimate goal of neurorehabilitation after acute brain injury, mainly by optimizing sensorimotor performance in functional actions. New brain imaging techniques are making it clear that the neurological system is continually remodeling throughout life and after damage through experience and learning in response to activity and behavior.

Rehabilitation in stroke patients seeks to minimize the neurological deficit and its complications, encourage family, and facilitate social reintegration of the individual to ultimately improve their quality of life. Stroke rehabilitation is divided into three phases. The acute phase usually extends for the 1st weeks, where patients get treated and stabilized in a hospital and get stabilized. Subacute phase (1–6 months) is the phase where the rehabilitation process is more effective for recovering functions. In chronic phase (after 6 months), rehabilitation is meant to treat and decrease motor sequels.

The potential ability of the brain to readapt after injury is known as neuroplasticity, which is the basic mechanism underlying improvement in functional outcome after stroke. Therefore, one important goal of rehabilitation of stroke patients is the effective use of neuroplasticity for functional recovery [38].

As mentioned before, neural plasticity is the ability of nervous system to reorganize its structure, function, and connections in response to training. The type and extent of neural plasticity is task—specific, highly time-sensitive and strongly influenced by environmental factors as well as motivation and attention.

Current understanding of mechanisms underlying neural plasticity changes after stroke stems from experimental models as well as clinical studies and provides the foundation for evidence-based neurorehabilitation. Evidence accumulated during the past 2 decades together with recent advances in the field of stroke recovery clearly shows that the effects of neurorehabilitation can be enhanced by behavioral manipulations in combination with adjuvant therapies that stimulate the endogenous neural plasticity.

Nowadays, a large toolbox of training-oriented rehabilitation techniques has been developed, which allows the increase of independence and quality of life of the patients and their families [39]. The recovery of function has been shown to depend on the intensity of therapy, repetition of specified-skilled movements directed toward the motor deficits and rewarded with performance-dependent feedback.

The use of technological devices not only helps to increase these aspects but also facilitates the work of therapists in order to enhance the abilities of patients and a higher level of functional recovery. They create environments with a greater amount of sensorimotor stimuli that enhance the neuroplasticity of patients, translating into a successful functional recovery. The use of technological devices can transfer the effects of rehabilitation to the different environments where patients spend their daily life allowing a favorable social reintegration. In this chapter, a review of technologies for rehabilitation of mobility in upper and lower extremity is presented.[…]

Continue —>  After Stroke Movement Impairments: A Review of Current Technologies for Rehabilitation | InTechOpen

Figure 1. Mechanical treatment devices. (a) Armeo Spring and (b) Saebo ReJoyce.

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[ARTICLE] Neural Plasticity in Moderate to Severe Chronic Stroke Following a Device-Assisted Task-Specific Arm/Hand Intervention – Full Text

Currently, hand rehabilitation following stroke tends to focus on mildly impaired individuals, partially due to the inability for severely impaired subjects to sufficiently use the paretic hand. Device-assisted interventions offer a means to include this more severe population and show promising behavioral results. However, the ability for this population to demonstrate neural plasticity, a crucial factor in functional recovery following effective post-stroke interventions, remains unclear. This study aimed to investigate neural changes related to hand function induced by a device-assisted task-specific intervention in individuals with moderate to severe chronic stroke (upper extremity Fugl-Meyer < 30). We examined functional cortical reorganization related to paretic hand opening and gray matter (GM) structural changes using a multimodal imaging approach. Individuals demonstrated a shift in cortical activity related to hand opening from the contralesional to the ipsilesional hemisphere following the intervention. This was driven by decreased activity in contralesional primary sensorimotor cortex and increased activity in ipsilesional secondary motor cortex. Additionally, subjects displayed increased GM density in ipsilesional primary sensorimotor cortex and decreased GM density in contralesional primary sensorimotor cortex. These findings suggest that despite moderate to severe chronic impairments, post-stroke participants maintain ability to show cortical reorganization and GM structural changes following a device-assisted task-specific arm/hand intervention. These changes are similar as those reported in post-stroke individuals with mild impairment, suggesting that residual neural plasticity in more severely impaired individuals may have the potential to support improved hand function.

Introduction

Nearly 800,000 people experience a new or recurrent stroke each year in the US (1). Popular therapies, such as constraint-induced movement therapy (CIMT), utilize intense task-specific practice of the affected limb to improve arm/hand function in acute and chronic stroke with mild impairments (2, 3). Neuroimaging results partially attribute the effectiveness of these arm/hand interventions to cortical reorganization in the ipsilesional hemisphere following training in acute and mild chronic stroke (4). Unfortunately, CIMT requires certain remaining functionality in the paretic hand to execute the tasks, and only about 10% of screened patients are eligible (5), thus disqualifying a large population of individuals with moderate to severe impairments. Recently, studies using device-assisted task-specific interventions specifically targeted toward moderate to severe chronic stroke reported positive clinical results (68). However, these studies primarily focus on clinical measures, but it is widely accepted that neural plasticity is a key factor for determining outcome (911). Consequently, it remains unclear whether moderate to severe chronic stroke [upper extremity Fugl-Meyer Assessment (UEFMA) < 30] maintains the ability to demonstrate neural changes following an arm/hand intervention.

Neural changes induced by task-specific training have been investigated widely using animal models (12). For instance, monkeys or rodents trained on a skilled reach-to-grasp task express enlarged representation of the digits of the hand or forelimb in primary motor cortex (M1) following training as measured by intracortical microstimulation (13, 14). Additionally, rapid local structural changes in the form of dendritic growth, axonal sprouting, myelination, and synaptogenesis occur (1518). Importantly, both cortical and structural reorganization corresponds to motor recovery following rehabilitative training in these animals (19, 20).

The functional neural mechanisms underlying effective task-specific arm/hand interventions in acute and chronic stroke subjects with mild impairments support those seen in the animal literature described above. Several variations of task-specific combined arm/hand interventions, including CIMT, bilateral task-specific training, and hand-specific robot-assisted practice, have shown cortical reorganization such as increased sensorimotor activity and enlarged motor maps in the ipsilesional hemisphere related to the paretic arm/hand (2124). These results suggest increased recruitment of residual resources from the ipsilesional hemisphere and/or decreased recruitment of contralesional resources following training. Although the evidence for a pattern of intervention-driven structural changes remains unclear in humans, several groups have shown increases in gray matter (GM) density in sensorimotor cortices (25), along with increases in fractional anisotropy in ipsilesional corticospinal tract (CST) (26) following task-specific training in acute and chronic stroke individuals with mild impairments.

The extensive nature of neural damage in moderate to severe chronic stroke may result in compensatory mechanisms, such as contralesional or secondary motor area recruitment (27). These individuals show increased contralesional activity when moving their paretic arm, which correlates with impairment (28, 29) and may be related to the extent of damage to the ipsilesional CST (30). This suggests that more impaired individuals may increasingly rely on contralesional corticobulbar tracts such as the corticoreticulospinal tract to activate the paretic limb (29). These tracts lack comparable resolution and innervation to the distal parts of the limb, thus sacrificing functionality at the paretic arm/hand (31). Since this population is largely ignored in current arm/hand interventions, it is unknown whether an arm/hand intervention for these more severely impaired post-stroke individuals will increase recruitment of residual ipsilesional corticospinal resources. These ipsilesional CSTs maintain the primary control of hand and finger extensor muscles (32) and are thus crucial for improved hand function. Task-specific training assisted by a device may reengage and strengthen residual ipsilesional corticospinal resources by training distal hand opening together with overall arm use.

The current study seeks to determine whether individuals with moderate to severe chronic stroke maintain the ability to show cortical reorganization and/or structural changes alongside behavioral improvement following a task-specific intervention. We hypothesize that following a device-assisted task-specific intervention, moderate to severe chronic stroke individuals will show similar functional and structural changes as observed in mildly impaired individuals, demonstrated by (i) a shift in cortical activity related to paretic hand opening from the contralesional hemisphere toward the ipsilesional hemisphere and (ii) an increase in GM density in sensorimotor cortices in the ipsilesional hemisphere.[…]

Continue —> Frontiers | Neural Plasticity in Moderate to Severe Chronic Stroke Following a Device-Assisted Task-Specific Arm/Hand Intervention | Neurology

Figure 5. Statistical maps of gray matter (GM) density changes across all patients. Significant increases (red/yellow) and decreases (Blue) in GM density are depicted on sagittal, coronal, and axial sections (left to right) on Montreal Neurological Institute T1 slices. Sections show the maximum effect on (A) ipsilesioned M1/S1, (B) contralesional M1/S1, and (C) ipsilesional thalamus. Les indicates the side of the lesioned hemisphere. Color maps indicate the t values at every voxel. A statistical threshold was set at p < 0.001 uncorrected.

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