Effectiveness of transcranial direct current stimulation on hand dexterity in stroke patients: a protocol for a systematic review and meta-analysis.

INTRODUCTION: Hand dexterity is the ability to execute the skilful movements using the hand and fingers. It is commonly impaired poststroke resulting in a profound deterioration in the quality of life for patients with stroke. Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation, which has gained a popularity as an adjunct therapy in recovering motor dysfunction poststroke. Promising results have been gained from applying tDCS in combination with motor rehabilitation, however, the outcome of tDCS on the upper limb motor function poststroke has been varied. Different results are potentially related to the discrepancy of the area of brain stimulation. Therefore, we aim to enhance the application of tDCS to improve its effectiveness in recovering hand dexterity through testing our hypothesis that stimulating the primary motor cortex could improve fine dexterity more than gross dexterity. METHODS AND ANALYSIS: This protocol has been reported according to Preferred Reporting Items for Systematic Review and Meta-Analyses Protocols guidelines. CENTRAL, MEDLINE, EMBASE, SCOPUS, Web of Science and CINAHL databases will be searched with no restriction in language and publication date. The selected studies will be randomised controlled trial investigating the effect of tDCS alone or in combination with motor rehabilitation in improving hand dexterity of patients with stroke with upper limb hemiparesis. The outcomes of interest are fine and gross hand dexterity measures. Two independent reviewers will assess the eligibility of the study, extract data and appraise the methodological quality. The data will be pooled in a meta-analysis if applicable or interpreted narratively. Grading of Recommendations, Assessment, Development and Evaluation approach will be used to assess the overall quality of evidence for the fine and gross dexterity measures. ETHICS AND DISSEMINATION: Ethical approval is not required for this study. The dissemination plan is to publish the results in a peer-review journal and presenting results in a conference. PROSPERO REGISTRATION NUMBER: CRD42021262186.

Do trunk-based left/right judgment tasks elicit motor imagery?

BACKGROUND: Left/right judgment tasks (LRJTs) are used in the management of chronic pain. This use is predicated on their ability to elicit the simulation of movements (i.e. motor imagery), including those where the execution of the same movements induces pain. While established for limb-based LRJTs, the ability of trunk-based LRJTs to elicit motor imagery of trunk movements has not been demonstrated. OBJECTIVE: To establish whether data from a trunk-based LRJT are indicative of motor imagery being elicited for the specific lateralised trunk postures presented. DESIGN: Cross-sectional repeated measures (within-subject experiment). METHODS: Twenty-nine unimpaired and pain-free participants completed a trunk-based LRJT typical of those used in practice. Accordingly, left/right judgements were made to images depicting a human figure with its trunk rotated or side-flexed to the left or right. The extent (amplitude) of this movement was manipulated (small, medium, large). The whole figure was also oriented to different degrees (0°, 45°, 90°, 135°, 180°) and along different axes (sagittal, axial, coronal). RESULTS: Accuracy was higher and response times (RTs) faster (p < 0.001 for both) when lateralised trunk movements depicted had a larger amplitude, contrary to predictions if motor imagery was elicited. Differences in accuracy and RTs depending on the orientation of the whole figure were consistent with previous studies. DISCUSSION: Data were not consistent with motor imagery of lateralised trunk movements being elicited by the trunk-based LRJT. The study presented here questions the value of trunk-based LRJTs in clinical practice.

Yoga practice is associated with superior motor imagery performance.

Yoga is an activity that aims to integrate physical, mental and spiritual elements and is an increasingly popular approach to enhancing physical fitness. The integration of imagery within yoga practice is considered an important component and may be critical in contributing to the benefits of yoga that have been reported. In this study, we tested whether individuals who practice yoga demonstrate superior performance on an objective measure of implicit motor imagery. Thirty-six participants (18 yoga, 18 non-yoga) matched for age, sex and handedness, undertook the hand laterality recognition task; an objective measure of implicit motor imagery performance. Accuracy and response times were gathered and analysed to determine any group differences as well as any differences relating to the typical hallmarks of imagery (i.e. dominance and awkwardness effects) on the task. Response Times (RTs) in the yoga group were significantly faster than controls (p < 0.05) and there was also a trend towards greater accuracy for the Yoga group (p = 0.073). Dominance effects (faster responses to images corresponding with the dominant limb) and Awkwardness effects (faster responses to images corresponding with natural compared with awkward postures) were evident across groups, supporting the participants' use of motor imagery in undertaking the task. Additionally, a Group × Awkwardness interaction (p < 0.05) revealed that the enhanced imagery performance for the yoga group was most pronounced for awkward postures. This is the first study to show that yoga practice is associated with superior motor imagery performance; an association that may be important in explaining the established rehabilitative value of yoga for chronic pain.

SILENCING SHARAPOVA'S GRUNT IMPROVES THE PERCEPTION OF HER SERVE SPEED.

In recent years, grunting has become a familiar although generally unwelcome element of tennis. The behavior is considered to deny opponents the benefit of receiving optimal multi-sensory information in order to plan their own shots. The ability to make accurate serve-speed judgments of identical tennis serves presented on a computer screen, and accompanied by a grunt or not, was assessed among 38 participants (19 men). Accuracy and response time were measured. Analysis compared performance for below versus above average speed serves and for the grunt versus the no grunt condition. Grunting had a disruptive effect on serve-speed perception for below average serves, with most judged incorrectly to be above average. Response times for below average serves were also slower in the grunt condition. Grunting provides a complex perceptual challenge, and greater effort may be attributed to tennis serves with an accompanying grunt.

Motor extinction: a deficit of attention or intention?

Motor extinction refers to a deficit of motor production on the side opposite a brain lesion that either only becomes apparent or disproportionately worsens during bilateral motor activity. It may arise due either to a contralesional deficit in setting the motor activation level (an intentional deficit) or a deficit in contralesional awareness of the sensory consequences of movement (an attentional deficit). In this study, we investigate the nature of motor extinction in a patient (LR) with a right fronto-temporal lesion through the kinematic analysis of unimanual and bimanual circle-drawing movements. While the ipsi- and contralesional limbs performed comparably for unimanual movements, the contralesional limb demonstrated marked bradykinesia and hypometria during bimanual movements. Furthermore, these deficits were not overcome when visual feedback of the contralesional limb was provided (Experiment 1). However, when performing bimanual movements in the presence of a visual template (Experiment 2), LR was able to overcome the contralesional hypometria but not the bradykinesia which proved intractable across both experiments. Both the bradykinesia and hypometria could result from an intentional deficit of motor production. However, in Experiment 2, LR also demonstrated an abnormal level of positional drift in the contralesional limb for bimanual movements indicative of an additional attentional deficit. We conclude that LR's presentation of motor extinction is the result of a primary intentional deficit and a secondary attentional deficit.

When the left hand does not know what the left hand is doing: response mode affects mental rotation of hands.

Mentally simulating a movement is known to share temporal and kinematic characteristics with the execution of the same movement, and this is thought to be reflected in the sharing of neural resources between the two activities. A powerful method of implicitly facilitating such mental simulation (or motor imagery) in individuals is to present them with a picture of a hand and ask them to identify its laterality (i.e. left or right). The mental rotation undertaken in order to complete this hand laterality recognition task (HLRT) provides an effective form of motor imagery, and the task has become an influential tool in clinical and experimental studies. However, performance on the task is modified by numerous factors, and there is a suggestion that the method of response demanded by different versions of the task may have a modulating effect. Here, we compared performance on the HLRT when responding verbally or manually in a group of unimpaired right-handed participants. For manual responses, we also compared performance when participants responded unimanually, using the index and middle fingers of their dominant or non-dominant hand. Performance was poorer for the manual compared to the verbal condition both in terms of accuracy and response time. Furthermore, for manual responses, the requirement to make a response with a specific limb selectively disrupted the ability to recognise an image of the corresponding limb. The disruption is considered to reflect difficulty in concurrently planning two actions with the same limb (manual response and mental rotation). Implications for the interpretation of existing and future studies are discussed.

Caloric vestibular stimulation and postural control in patients with spatial neglect following stroke.

The impact of spatial neglect remains a substantial challenge to patients undergoing rehabilitation following stroke. Beyond the relatively well-described implications for visuospatial function, neglect is increasingly shown to have a negative impact on the wider aspects of sensori-motor performance with corresponding implications for activities including gait and balance. Caloric vestibular stimulation (CVS) administered to the contralesional ear has previously been shown to improve performance in patients with spatial neglect. Here, in Experiment One, we investigated the effect of CVS on clinical measures of spatial neglect and postural control in three groups of patients following stroke; left brain damaged patients (LBD, n = 6), right brain damaged patients without neglect (RBD-, n = 6), and right brain damaged patients with neglect (RBD+ , n = 6). While post-stimulation scores demonstrated an improvement for participants with spatial neglect, further analysis of postural scores indicated that improvement was selective for asymmetrical activities, with symmetrical activities remaining unchanged. We interpret these results with reference to the related problem of extinction which predicts that activities demanding synchronous bilateral activity (symmetrical activities) would cause greater difficulties for patients with neglect. In Experiment Two, we tested a further six RBD+ patients on the same measures following CVS to the ipsilesional (right) ear. There was no significant improvement in perceptual or postural scores. Our findings are supportive of previous studies that demonstrate improvement in perception and movement for patients with spatial neglect following contralesional CVS and suggest that these improvements may have clinical benefits.

Stimulation of the subthalamic nucleus improves velocity of ballistic movements in Parkinson's disease.

High-frequency stimulation of the subthalamic nucleus can markedly improve motor function in patients with Parkinson's disease. However, the underlying mechanisms mediating these improvements are not well understood. In particular, whether motor function is differentially improved in distal or proximal movements is not fully determined. Also, whether reaction time is improved along with other motor parameters is still a matter of debate. Here, we test patients OFF and ON subthalamic nucleus stimulation by capturing simple ballistic movements across four joints using kinematic motion analysis. We show that velocity, but not reaction time, is significantly improved with stimulation. There was no strong differential effect between joints. These results add evidence that deep brain stimulation of the subthalamic nucleus can enhance performance of ballistic movements in Parkinson's disease, and demonstrate that the subthalamic nucleus may be important in driving parameters of motor control after the response has been initiated.

Responsiveness of 2 scales to evaluate lateropulsion or pusher syndrome recovery after stroke.

OBJECTIVES: To analyze responsiveness to change of 2 outcome measures in the lateropulsion population after stroke. Lateropulsion describes an atypical balance problem after stroke where patients actively push themselves toward their paretic side. Secondary aims were to measure the incidence of lateropulsion and evaluate the site of the brain most commonly involved in lateropulsion. DESIGN: Stroke patients were screened for lateropulsion on admission to rehabilitation. Those demonstrating lateropulsion were assessed every 2 weeks using 2 scales to measure progress. Analysis of variance and the standardized response mean (SRM) were used to analyze change for each scale. SETTING: Rehabilitation and geriatric units. PARTICIPANTS: Prospective purposive sample of stroke patients (N=43) demonstrating lateropulsion on admission from a consecutive admission sample of 160. To allow comparison, data from 43 stroke patients who did not display lateropulsion were collected retrospectively, matched on age (±5y) and sex. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Incidence of lateropulsion was calculated as a percentage of stroke patients admitted. Responsiveness to change was measured by using the Burke Lateropulsion Scale (BLS), to quantify severity of lateropulsion, and the Postural Assessment Scale for Stroke (PASS), which measures postural abilities. RESULTS: Of 160 stroke patients, 26.9% displayed lateropulsion (mean age, 72y; 51% men). The BLS and PASS had high levels of measurement responsiveness (BLS SRM =1.48 and 2.24; PASS SRM =1.76 and 1.87) at 4 and 8 weeks, respectively. CONCLUSIONS: The BLS and PASS are responsive scales to monitor progress and recovery during rehabilitation. As more than 25% of stroke patients admitted to rehabilitation may exhibit lateropulsion, these 2 scales could be valuable in monitoring progress and designing future intervention studies.

Variability of angular measurements of head posture within a session, within a day, and over a 7-day period in healthy participants.

Head posture (HP) is used as part of the clinical examination of patients with neck pain to inform diagnosis, plan treatment, and monitor progress. For related information to be interpreted correctly, clinicians need to know how much of the variation in HP between measurements can be attributed to a change in the patient condition and how much is due to measurement error and/or biological variation. The aim of this study was to investigate the variability of angular measurements indicative of forward HP, head extension, and side flexion within a session, within a day, and over a 7-day period. Angles were calculated from 27 participants in three sessions over a period of 7 days through digitization of video images. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) showed that forward HP (ICC between 0.82 and 0.91; SEM between 1.42° and 1.70°) and side flexion (ICC between 0.63 and 0.85; SEM between 0.83° and 1.27°) were stable within a session, within a day, and over a 7-day period. Head extension was found to be less stable (ICC between 0.71 and 0.83; SEM between 2.69° and 3.72°). Time of day did not appear to influence forward HP, side flexion, or head extension.

Modulating wheelchair navigation in patients with spatial neglect.

Patients who have had a stroke resulting in the deficit of visuo-spatial neglect are normally not provided with a powered wheelchair, as they are either considered or found to be unsafe navigating about their environment. As these patients are relatively unlikely to regain functional mobility by walking, the denial of alternative forms of mobility is of particular concern. Modest progress has been made over the past two decades with regards to the rehabilitation of neglect but there have been calls for further research which addresses "real world" measures of independence such as wheelchair navigation. In this study, we investigated the ability of patients with neglect to improve their performance when navigating a powered wheelchair by using theoretically-driven strategies that have shown promise in previous studies (spatial cueing and limb activation). Strategies were applied and tested in the most realistic and practical manner for each individual, based on their abilities and concurrent deficits. Performance was improved by the experimental strategies. The data suggest it is possible to apply theoretically-driven strategies to improve wheelchair navigation in patients with neglect and are supportive of further studies that could lead to improved access to powered mobility by this population in the future.

Reliability and validity of head posture assessment by observation and a four-category scale.

Head posture (HP) is assessed as part of the clinical examination of patients with neck pain using observation and qualitative descriptors. In research, HP is characterised through the measurement of angles and distances between anatomical landmarks. This study investigated whether the assessment of HP as performed in clinical practice is reliable and valid. Ten physiotherapists assessed forward HP, head extension and side-flexion from images of 40 individuals with and without previous experience of neck pain using a four-category scale. The assessment was repeated twice with a 1-week gap. Physiotherapists' ratings were then compared with angular measurements of the same components of HP. K values for intra-rater reliability varied between 0.22 and 0.81 for forward HP, between 0.19 and 0.69 for head extension and between 0.38 and 0.67 for side-flexion. K values for inter-rater reliability were 0.02 for forward HP, 0.07 for head extension and 0.19 for side-flexion. Correlation coefficients between the ratings and the angular measurements varied between -0.16 and -0.49 for forward HP, between -0.17 and 0.68 for head extension and between -0.04 and 0.37 for side-flexion. The assessment of HP by observation and a four-category scale showed poor reliability and validity.

Head posture and neck pain of chronic nontraumatic origin: a comparison between patients and pain-free persons.

OBJECTIVE: To compare standing head posture measurements between patients with nontraumatic neck pain (NP) and pain-free individuals. DESIGN: Single-blind (assessor) cross-sectional study. SETTING: Hospital and general community. PARTICIPANTS: Consecutive patients (n=40) with chronic nontraumatic NP and age- and sex-matched pain-free participants (n=40). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Three angular measurements: the angle between C7, the tragus of the ear, and the horizontal; the angle between the tragus of the ear, the eye, and the horizontal; and the angle between the inferior margins of the right and the left ear and the horizontal were calculated through the digitization of video images. RESULTS: NP patients were found to have a significantly smaller angle between C7, the tragus, and the horizontal, resulting in a more forward head posture than pain-free participants (NP, mean +/- SD, 45.4 degrees +/-6.8 degrees ; pain-free, mean +/- SD, 48.6 degrees +/-7.1 degrees ; P<.05; confidence interval [CI] for the difference between groups, 0.9 degrees -6.3 degrees ). Dividing the population according to age into younger (50y) revealed an interaction, with a statistically significant difference in head posture for younger participants with NP compared with younger pain-free participants (NP, mean +/- SD, 46.1 degrees +/-6.7 degrees ; pain-free, mean +/- SD, 51.8 degrees +/-5.9 degrees ; P<.01; CI for the difference between groups, 1.8 degrees -9.7 degrees ) but no difference for the older group (NP, mean +/- SD, 44.8 degrees +/-7.1 degrees ; pain-free, mean +/- SD, 45.1 degrees +/-6.7 degrees ; P>.05; CI for the difference between groups, -4.9 degrees -4.2 degrees ). No other differences were found between patients and pain-free participants. CONCLUSIONS: Younger patients with chronic nontraumatic NP were shown to have a more forward head posture in standing than matched pain-free participants. However, the difference, although statistically significant, was perhaps too small to be clinically meaningful.

Delay abolishes the obstacle avoidance deficit in unilateral optic ataxia.

Optic ataxic patients have deficits in the visual control of manual reaching and grasping. It has been established previously that these deficits in target-directed behaviour improve following a delay in response. Recently it has been demonstrated that optic ataxic patients also have deficits in taking potential obstacles into account during reaching. The present study was therefore designed to test whether delay would bring an improvement in this behaviour as well. We present experimental data from a patient with unilateral optic ataxia (M.H.). First we document M.H.'s pointing errors, which show a reliable pattern of impairment when pointing to targets in his right visual field, particularly when using his right hand. We then show that a similar pattern of deficits is observable in his ability to negotiate between non-targets: that is, M.H. selectively fails to take account of obstacles in his right visual field, but only while reaching with his right hand. Finally we demonstrate that this obstacle avoidance deficit disappears following a 5s delay in response: under these conditions M.H. now takes account of both non-target objects with either hand. The results are interpreted within the 'two visual streams' model of cortical visual processing.

Motor neglect: implications for movement and rehabilitation following stroke.

PURPOSE: The syndrome of unilateral neglect following stroke is associated with poor outcome and presents significant challenges to those providing therapy for affected individuals. In contrast to a number of reviews which have recently appeared in therapy and rehabilitation journals relating to sensory aspects of neglect, this review focuses on 'motor neglect'. SEARCH STRATEGY: We searched the clinical and scientific literature for papers concerning motor neglect. The search included the databases Web of Science, Pubmed and Cinahl, primarily using the term 'motor neglect'. There was also a large degree of secondary searching involved. DISCUSSION: Motor neglect refers to the under-utilization of a limb opposite a brain lesion that cannot be fully explained by primary sensory and motor deficits. The paper discusses classical descriptions of motor neglect and highlights the difficulties in disentangling motor neglect from hemiparesis. The related problem of motor extinction is introduced as a useful clinical measure of neglect-related movement difficulties and a significant clinical problem in its own right. CONCLUSION: Motor neglect is a relatively under-recognized deficit which may have a significant impact on patient performance and recovery following stroke. We conclude with a discussion of the implications of motor neglect for rehabilitation, including the relative contributions that may be made by Constraint-induced movement therapy and Bilateral movement therapy in managing patients with neglect-related movement problems.