Long-term sensorimotor and therapeutical effects of a mild regime of prism adaptation in spatial neglect. A double-blind RCT essay

Clinical and demographic predictors of unilateral spatial neglect recovery after prism therapy among stroke survivors in the sub-acute phase of recovery

BACKGROUND AND AIMS: Unilateral Spatial Neglect (USN) affects the rehabilitation process and leads to poor outcomes after stroke. Factors that influence USN recovery following prism adaptation therapy have not been investigated. This study investigated predictors of USN recovery after prism therapy at the sub-acute phase of recovery. METHODS: This study was a randomized controlled trial. USN was assessed with the Behavioural Inattention Test and Catherine Bergego scale. Seventy-four patients with USN were divided into control and intervention group (prism). The prism group used 20 dioptre prism lenses for repeated aiming for 12 sessions while the control group used neutral lenses for aiming training. Regression analysis was conducted to establish clinical and sociodemographic factors that influence USN recovery. RESULTS: Gender, age, years of education, race, employment status, handedness, type of stroke, time since stroke and site of stroke (p > 0.005) showed no significant influence on USN recovery following PA treatment. Higher Cognitive function (OR  = 1.52, CI = 1.08-2.14, p =  0.016) and group allocationng (being in the prism group) (OR = 63.10, CI =  9.70-410.59, P < 0.001) were found to significantly influence USN recovery following PA treatment session. CONCLUSIONS: A significant modulating effect on general cognitive ability was found in this study. This suggests that prism adaptation therapy's effect on neural activity and spatial neglect depends on the cognitive function of stroke survivors.Trial registration: Pan African Clinical Trial Registry identifier: PACTR201903732473573.

Functional Resistance Training With Viscous and Elastic Devices: Does Resistance Type Acutely Affect Knee Function?

OBJECTIVE

Functional resistance training (FRT) during walking is an emerging approach for rehabilitating individuals with neuromuscular or orthopedic injuries. During FRT, wearable exoskeleton/braces can target resistance to a weakened leg joint; however, the resistive properties of the training depend on the type of resistive elements used in the device. Hence, this study was designed to examine how the biomechanical and neural effects of functional resistance training differ with viscous and elastic resistances during both treadmill and overground walking.

METHODS

Fourteen able-bodied individuals were trained on two separate sessions with two devices that provided resistance to the knee (viscous and elastic) while walking on a treadmill. We measured gait biomechanics and muscle activation during training, as well as kinematic aftereffects and changes in peripheral fatigue and neural excitability after training.

RESULTS

We found the resistance type differentially altered gait kinetics during training-elastic resistance increased knee extension during stance while viscous resistance primarily affected swing. Also, viscous resistance increased power generation while elastic resistance could increase power absorption. Both devices resulted in significant kinematic and neural aftereffects. However, overground kinematic aftereffects and neural excitability did not differ between devices.

CONCLUSION

Different resistance types can be used to alter gait biomechanics during training. While there were no resistance-specific changes in acute neural adaptation following training, it is still possible that prolonged and repeated training could produce differential effects.

SIGNIFICANCE

Resistance type alters the kinetics of functional resistance training. Prolonged and repeated training sessions on patients will be needed to further measure the effects of these devices.

Quantification and Rehabilitation of Unilateral Spatial Neglect in Immersive Virtual Reality: A Validation Study in Healthy Subjects

Unilateral spatial neglect is a common sensorimotor disorder following the occurrence of a stroke, for which prismatic adaptation is a promising rehabilitation method. However, the use of prisms for rehabilitation often requires the use of specific equipment that may not be available in clinics. To address this limitation, we developed a new software package that allows for the quantification and rehabilitation of unilateral spatial neglect using immersive virtual reality. In this study, we compared the effects of virtual and real prisms in healthy subjects and evaluated the performance of our virtual reality tool (HTC Vive) against a validated motion capture tool. Ten healthy subjects were randomly exposed to virtual and real prisms, and measurements were taken before and after exposure. Our findings indicate that virtual prisms are at least as effective as real prisms in inducing aftereffects (4.39° ± 2.91° with the virtual prisms compared to 4.30° ± 3.49° with the real prisms), but that these effects were not sustained beyond 2 h regardless of exposure modality. The virtual measurements obtained with our software showed excellent metrological qualities (ICC = 0.95, error = 0.52° ± 1.18°), demonstrating its validity and reliability for quantifying deviation during pointing movements. Overall, our results suggest that our virtual reality software (Virtualis, Montpellier, France) could provide an easy and reliable means of quantifying and rehabilitating spatial neglect. Further validation of these results is required in individuals with unilateral spatial neglect.

Functional Resistance Training Differentially Alters Gait Kinetics After Anterior Cruciate Ligament Reconstruction: A Pilot Study

BACKGROUND

Quadriceps weakness is common after anterior cruciate ligament (ACL) reconstruction and can alter gait mechanics. Functional resistance training (FRT) is a novel approach to retraining strength after injury, but it is unclear how it alters gait mechanics. Therefore, we tested how 3 different types of FRT devices: a knee brace resisting extension (unidirectional brace), a knee brace resisting extension and flexion (bidirectional brace), and an elastic band pulling backwards on the ankle (elastic band)-acutely alter gait kinetics in this population.

HYPOTHESIS

The type of FRT device will affect ground-reaction forces (GRFs) during and after the training. Specifically, the uni- and bidirectional braces will increase GRFs when compared with the elastic band.

STUDY DESIGN

Crossover study.

LEVEL OF EVIDENCE

Level 2.

METHODS

A total of 15 individuals with ACL reconstruction received FRT with each device over 3 separate randomized sessions. During training, participants walked on a treadmill while performing a tracking task with visual feedback. Sessions contained 5 training trials (180 seconds each) with rest between. Vertical and anterior-posterior GRFs were assessed on the ACL-reconstructed leg before, during, and after training. Changes in GRFs were compared across devices using 1-dimensional statistical parametric mapping.

RESULTS

Resistance applied via bidirectional brace acutely increased gait kinetics during terminal stance/pre-swing (ie, push-off), while resistance applied via elastic band acutely increased gait kinetics during initial contact/loading (ie, braking). Both braces behaved similarly, but the unidirectional brace was less effective for increasing push-off GRFs.

CONCLUSION

FRT after ACL reconstruction can acutely alter gait kinetics during training. Devices can be applied to selectively alter gait kinetics. However, the long-term effects of FRT after ACL reconstruction with these devices are still unknown.

CLINICAL RELEVANCE

FRT may be applied to alter gait kinetics of the involved limb after ACL reconstruction, depending on the device used.

Using non-invasive transcranial direct current stimulation for neglect and associated attentional deficits following stroke

Neglect is a disabling neuropsychological syndrome that is frequently observed following right-hemispheric stroke. Affected individuals often present with multiple attentional deficits, ranging from reduced orienting towards contralesional space to a generalized impairment in maintaining attention over time. Although a degree of spontaneous recovery occurs in most patients, in some individuals this condition can be treatment-resistant with prominent ongoing non-spatial deficits. Further, there is a large inter-individual variability in response to different therapeutic approaches. Given its potential to alter neuronal excitability and affect neuroplasticity, non-invasive brain stimulation is a promising tool that could potentially be utilized to facilitate recovery. However, there are many outstanding questions regarding its implementation in this heterogeneous patient group. Here we provide a critical overview of the available evidence on the use of non-invasive electrical brain stimulation, focussing on transcranial direct current stimulation (tDCS), to improve neglect and associated attentional deficits after right-hemispheric stroke. At present, there is insufficient robust evidence supporting the clinical use of tDCS to alleviate symptoms of neglect. Future research would benefit from careful study design, enhanced precision of electrical montages, multi-modal approaches exploring predictors of response, tailored dose-control applications and increased efforts to evaluate standalone tDCS versus its incorporation into combination therapy.

Neurorehabilitation through Hippotherapy on Neurofunctional Sequels of Stroke: Effect on Patients' Functional Independence, Sensorimotor/Cognitive Capacities and Quality of Life, and the Quality of Life of Their Caregivers-A Study Protocol

BACKGROUND

Stroke is a high burden illness and the second leading cause of worldwide disability with generally poor recovery rates. Robust benefits of hippotherapy, a novel neurorehabilitation approach, in functional recovery following various severe neurological disabling conditions has been shown. In the present study, we will analyze the effect of a hippotherapy program on the outcome of post-stroke patients in the first year post-stroke.

METHOD

A randomized controlled clinical trial on the effectiveness of hippotherapy (4 weeks/18 weeks hippotherapy/conventional neurorehabilitation) versus conventional neurorehabilitation alone (22 weeks) will be conducted over 48 weeks. In the treated group, one-hour daily hippotherapy sessions will be exclusively conducted during the hippotherapy's cycles, alternated with periods of conventional neurorehabilitation. A test battery will measure both the functional and psychological outcomes. The primary endpoint will be the patient's functional independence. The secondary endpoints will measure the sensorimotor function, autonomy, and quality of life, as well as the caregivers' quality of life.

RESULTS AND CONCLUSION

Individual brain connectome, life history and personality construct influence the brain's functional connectivity and are central to developing optimal tailored neurorehabilitation strategies. According to our current practice, hippotherapy allows the enhancement of substantial neuroplastic changes in the injured brain with significant neurological recovery. The protocol aims to confirm those issues. Trial registration in ClinicalTrials.gov NCT04759326 accessed on 19 February 2021.

Immediate effects of head-mounted display adaptation in cases of unilateral spatial neglect: study of straight-ahead pointing

[Purpose] This study aimed to clarify the effect of an adaptation of a deviation of the visual field in three axes on spatial cognition in patients with unilateral spatial neglect and distorted spatial perception in three dimensions. [Participants and Methods] Fifteen patients with cerebrovascular disease and symptoms of unilateral spatial neglect were included. Forty-eight pointing movements with a camera attached to a head-mounted display changed in three axes were compared with the control condition in which the camera was deflected only in the horizontal plane as with the prism adaptation. The main outcome measures were subjective straight-ahead pointing, line bisection, line cancellation, and star cancellation. [Results] The head-mounted display adaptive therapy was performed under conditions that varied in all three axes. The results indicated that it was possible to deflect the subjective straight-ahead pointing position to the lower left direction. [Conclusion] In contrast to the prism adaptation, which deflects the visual field in a single axis in the horizontal plane, the tri-axial adaptation corrected the median cognition in the left–right direction as well as the cognition of the body center, including the vertical direction.

Functional resistance training methods for targeting patient-specific gait deficits: A review of devices and their effects on muscle activation, neural control, and gait mechanics

BACKGROUND

Injuries to the neuromusculoskeletal system often result in weakness and gait impairments. Functional resistance training during walking-where patients walk while a device increases loading on the leg-is an emerging approach to combat these symptoms. However, there are many methods that can be used to resist the patient, which may alter the biomechanics of the training. Thus, all methods may not address patient-specific deficits.

METHODS

We performed a comprehensive electronic database search to identify articles that acutely (i.e., after a single training session) examined how functional resistance training during walking alters muscle activation, gait biomechanics, and neural plasticity. Only articles that examined these effects during training or following the removal of resistance (i.e., aftereffects) were included.

FINDINGS

We found 41 studies that matched these criteria. Most studies (24) used passive devices (e.g., weighted cuffs or resistance bands) while the remainder used robotic devices. Devices varied on if they were wearable (14) or externally tethered, and the type of resistance they applied (i.e., inertial [14], elastic [8], viscous [7], or customized [12]). Notably, these methods provided device-specific changes in muscle activation, biomechanics, and spatiotemporal and kinematic aftereffects. Some evidence suggests this training results in task-specific increases in neural excitability.

INTERPRETATION

These findings suggest that careful selection of resistive strategies could help target patient-specific strength deficits and gait impairments. Also, many approaches are low-cost and feasible for clinical or in-home use. The results provide new insights for clinicians on selecting an appropriate functional resistance training strategy to target patient-specific needs.

Effects of prismatic adaptation on balance and postural disorders in patients with chronic right stroke: protocol for a multicentre double-blind randomised sham-controlled trial

INTRODUCTION

Patients with right stroke lesion have postural and balance disorders, including weight-bearing asymmetry, more pronounced than patients with left stroke lesion. Spatial cognition disorders post-stroke, such as misperceptions of subjective straight-ahead and subjective longitudinal body axis, are suspected to be involved in these postural and balance disorders. Prismatic adaptation has showed beneficial effects to reduce visuomotor disorders but also an expansion of effects on cognitive functions, including spatial cognition. Preliminary studies with a low level of evidence have suggested positive effects of prismatic adaptation on weight-bearing asymmetry and balance after stroke. The objective is to investigate the effects of this intervention on balance but also on postural disorders, subjective straight-ahead, longitudinal body axis and autonomy in patients with chronic right stroke lesion.

METHODS AND ANALYSIS

In this multicentre randomised double-blind sham-controlled trial, we will include 28 patients aged from 18 to 80 years, with a first right supratentorial stroke lesion at chronic stage (≥12 months) and having a bearing ≥60% of body weight on the right lower limb. Participants will be randomly assigned to the experimental group (performing pointing tasks while wearing glasses shifting optical axis of 10 degrees towards the right side) or to the control group (performing the same procedure while wearing neutral glasses without optical deviation). All participants will receive a 20 min daily session for 2 weeks in addition to conventional rehabilitation. The primary outcome will be the balance measured using the Berg Balance Scale. Secondary outcomes will include weight-bearing asymmetry and parameters of body sway during static posturographic assessments, as well as lateropulsion (measured using the Scale for Contraversive Pushing), subjective straight-ahead, longitudinal body axis and autonomy (measured using the Barthel Index).

ETHICS AND DISSEMINATION

The study has been approved by the ethical review board in France. Findings will be submitted to peer-reviewed journals relative to rehabilitation or stroke.

TRIAL REGISTRATION NUMBER

NCT03154138.

Visual but Not Auditory-Verbal Feedback Induces Aftereffects Following Adaptation to Virtual Prisms

Visuo-motor adaptation with optical prisms that displace the visual scene (prism adaptation, PA) has been widely used to study visuo-motor plasticity in healthy individuals and to decrease the lateralized bias of brain-damaged patients suffering from spatial neglect. Several factors may influence PA aftereffects, such as the degree of optical deviation (generally measured in dioptres of wedge prisms) or the direction of the prismatic shift (leftward vs. rightward). However, the mechanisms through which aftereffects of adaptation in healthy individuals and in neglect affect performance in tasks probing spatial cognition remain controversial. For example, some studies have reported positive effects of PA on auditory neglect, while other studies failed to obtain any changes of performance even in the visual modality. We here tested a new adaptation method in virtual reality to evaluate how sensory parameters influence PA aftereffects. Visual vs. auditory-verbal feedback of optical deviations were contrasted to assess whether rightward deviations influence manual and perceptual judgments in healthy individuals. Our results revealed that altered visual, but not altered auditory-verbal feedback induces aftereffects following adaptation to virtual prisms after 30-degrees of deviation. These findings refine current models of the mechanisms underlying the cognitive effects of virtual PA in emphasizing the importance of visual vs. auditory-verbal feedback during the adaptation phase on visuospatial judgments. Our study also specifies parameters which influence virtual PA and its aftereffect, such as the sensory modality used for the feedback.

Prism Adaptation and Optokinetic Stimulation Comparison in the Rehabilitation of Unilateral Spatial Neglect

Prism adaptation (PA) is one of the most effective treatments for the rehabilitation of unilateral spatial neglect. Optokinetic stimulation (OKS) has also been demonstrated to be effective in ameliorating symptoms of neglect. The aim of this study is to compare the effectiveness of these two methods in a group of neglect patients using a crossover design. A group of 13 post-acute brain-damaged patients with unilateral spatial neglect, who had never been rehabilitated, were treated using PA and OKS. Each treatment was applied for 10 sessions, twice a day, to all patients with both treatments in crossed order (i.e., PA followed by OKS or vice versa). Neuropsychological assessments were performed: before the first (T1), at the end of the first/beginning of the second (T2) and at the end of the second training sessions (T3), and two weeks after the end of treatment (T4). Both procedures produced a significant improvement in clinical tests at T2, independent of the type of training. The results suggest that either PA or OKS induces a significant amelioration of neglect in right brain-damaged patients, mainly in the first block of treatment. Since no differences between treatments were found, they could be applied in clinical practice, according to the requirements of the individual patient.

Does nonviolent communication education improve empathy in French medical students?

OBJECTIVES

To evaluate the impact of nonviolent communication (NVC) training on five aspects of medical students' empathy skills using implicit and explicit measures.

METHODS

312 third-year French medical students were randomly allocated to an intervention group (n = 123) or a control group (n = 189). The intervention group received 2.5 days of NVC training. For each group, empathy-related skills were measured implicitly using three cognitive tests (Visuo-Spatial Perspective Taking, Privileged Knowledge, Empathy for Pain evaluation) and explicitly using two self-rating questionnaires (Jefferson Scale of Physician Empathy, Empathy Quotient). Both groups completed tests and questionnaires before (pre-test) and three months after training (post-test). Responses were collected via online software, and data were analyzed using paired linear mixed models and Bayes Factors.

RESULTS

We found a significant increase in the Jefferson  Scale of Physician Empathy (JSPE) score between pre- and post-tests in the intervention group compared to the control group (linear mixed models: 0.95 points [0.17, 1.73], t₍₁₅₈₎ = 2.39, p < 0.05), and an expected gender effect whereby females had higher JSPE scores (1.57 points [0.72, 2.42], t₍₂₆₂₎ = -3.62, p < 0.001). There was no interaction between these two factors.

CONCLUSIONS

Our results show that brief training in nonviolent communication improves subjective empathy three months after training. These results are promising for the long-term effectiveness of NVC training on medical students' empathy and call for the introduction of NVC training in medical school. Further studies should investigate whether longer training will produce larger and longer-lasting benefits.

Prism Adaptation Treatment Improves Inpatient Rehabilitation Outcome in Individuals With Spatial Neglect: A Retrospective Matched Control Study

Objective

To determine whether prism adaptation treatment (PAT) integrated into the standard of care improves rehabilitation outcome in patients with spatial neglect (SN).

Design

Retrospective matched control study based on information extracted from June 2017-September 2019.

Setting

Inpatient rehabilitation.

Participants

Patients from 14 rehabilitation hospitals scoring >0 on the Catherine Bergego Scale (N=312). The median age was 69.5 years, including 152 (49%) female patients and 275 (88%) patients with stroke.

Interventions

Patients were matched 1:1 by age (±5 years), FIM score at admission (±2 points), and SN severity using the Catherine Bergego Scale (±2 points) and classified into 2 groups: treated (8-12 daily sessions of PAT) vs untreated (no PAT).

Main Outcome Measures

FIM and its minimal clinically important difference (MCID) were the primary outcome variables. Secondary outcome was home discharge.

Results

Analysis included the 312 matched patients (156 per group). FIM scores at discharge were analyzed using repeated-measures analyses of variance. The treated group showed reliably higher scores than the untreated group in Total FIM, F=5.57, P=.020, partial η²=0.035, and Cognitive FIM, F=19.20, P<.001, partial η²=0.110, but not Motor FIM, F=0.35, P=.553, partial η²=0.002. We used conditional logistic regression to examine the odds ratio of reaching MCID in each FIM score and of returning home after discharge. No reliable difference was found between groups in reaching MCID or home discharge.

Conclusions

Patients with SN receiving PAT had better functional and cognitive outcomes, suggesting that integrating PAT into the standard of care is beneficial. However, receiving PAT may not determine home discharge.

Non-pharmacological interventions for spatial neglect or inattention following stroke and other non-progressive brain injury

BACKGROUND

People with spatial neglect after stroke or other brain injury have difficulty attending to one side of space. Various rehabilitation interventions have been used, but evidence of their benefit is unclear.

OBJECTIVES

The main objective was to determine the effects of non-pharmacological interventions for people with spatial neglect after stroke and other adult-acquired non-progressive brain injury.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched October 2020), the Cochrane Central Register of Controlled Trials (CENTRAL; last searched October 2020), MEDLINE (1966 to October 2020), Embase (1980 to October 2020), the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1983 to October 2020), and PsycINFO (1974 to October 2020). We also searched ongoing trials registers and screened reference lists.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of any non-pharmacological intervention specifically aimed at spatial neglect. We excluded studies of general rehabilitation and studies with mixed participant groups, unless separate neglect data were available.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Review authors categorised the interventions into eight broad types deemed to be applicable to clinical practice through iterative discussion: visual interventions, prism adaptation, body awareness interventions, mental function interventions, movement interventions, non-invasive brain stimulation, electrical stimulation, and acupuncture. We assessed the quality of evidence for each outcome using the GRADE approach.

MAIN RESULTS

We included 65 RCTs with 1951 participants, all of which included people with spatial neglect following stroke. Most studies measured outcomes using standardised neglect assessments. Fifty-one studies measured effects on ADL immediately after completion of the intervention period; only 16 reported persisting effects on ADL (our primary outcome). One study (30 participants) reported discharge destination, and one (24 participants) reported depression. No studies reported falls, balance, or quality of life. Only two studies were judged to be entirely at low risk of bias, and all were small, with fewer than 50 participants per group. We found no definitive (phase 3) clinical trials. None of the studies reported any patient or public involvement. Visual interventions versus any control: evidence is very uncertain about the effects of visual interventions for spatial neglect based on measures of persisting functional ability in ADL (2 studies, 55 participants) (standardised mean difference (SMD) -0.04, 95% confidence interval (CI) -0.57 to 0.49); measures of immediate functional ability in ADL; persisting standardised neglect assessments; and immediate neglect assessments. Prism adaptation versus any control: evidence is very uncertain about the effects of prism adaptation for spatial neglect based on measures of persisting functional ability in ADL (2 studies, 39 participants) (SMD -0.29, 95% CI -0.93 to 0.35); measures of immediate functional ability in ADL; persisting standardised neglect assessments; and immediate neglect assessments. Body awareness interventions versus any control: evidence is very uncertain about the effects of body awareness interventions for spatial neglect based on measures of persisting functional ability in ADL (5 studies, 125 participants) (SMD 0.61, 95% CI 0.24 to 0.97); measures of immediate functional ability in ADL; persisting standardised neglect assessments; immediate neglect assessments; and adverse events. Mental function interventions versus any control: we found no trials of mental function interventions for spatial neglect reporting on measures of persisting functional ability in ADL. Evidence is very uncertain about the effects of mental function interventions on spatial neglect based on measures of immediate functional ability in ADL and immediate neglect assessments. Movement interventions versus any control: we found no trials of movement interventions for spatial neglect reporting on measures of persisting functional ability in ADL. Evidence is very uncertain about the effects of body awareness interventions on spatial neglect based on measures of immediate functional ability in ADL and immediate neglect assessments. Non-invasive brain stimulation (NIBS) versus any control: evidence is very uncertain about the effects of NIBS on spatial neglect based on measures of persisting functional ability in ADL (3 studies, 92 participants) (SMD 0.35, 95% CI -0.08 to 0.77); measures of immediate functional ability in ADL; persisting standardised neglect assessments; immediate neglect assessments; and adverse events. Electrical stimulation versus any control: we found no trials of electrical stimulation for spatial neglect reporting on measures of persisting functional ability in ADL. Evidence is very uncertain about the effects of electrical stimulation on spatial neglect based on immediate neglect assessments. Acupuncture versus any control: we found no trials of acupuncture for spatial neglect reporting on measures of persisting functional ability in ADL. Evidence is very uncertain about the effects of acupuncture on spatial neglect based on measures of immediate functional ability in ADL and immediate neglect assessments.

AUTHORS' CONCLUSIONS

The effectiveness of non-pharmacological interventions for spatial neglect in improving functional ability in ADL and increasing independence remains unproven. Many strategies have been proposed to aid rehabilitation of spatial neglect, but none has yet been sufficiently researched through high-quality fully powered randomised trials to establish potential or adverse effects. As a consequence, no rehabilitation approach can be supported or refuted based on current evidence from RCTs. As recommended by a number of national clinical guidelines, clinicians should continue to provide rehabilitation for neglect that enables people to meet their rehabilitation goals. Clinicians and stroke survivors should have the opportunity, and are strongly encouraged, to participate in research. Future studies need to have appropriate high-quality methodological design, delivery, and reporting to enable appraisal and interpretation of results. Future studies also must evaluate outcomes of importance to patients, such as persisting functional ability in ADL. One way to improve the quality of research is to involve people with experience with the condition in designing and running trials.

Patients with lesions to the intraparietal cortex show greater proprioceptive realignment after prism adaptation: Evidence from open-loop pointing and manual straight ahead

Reaching toward a target viewed through laterally refracting prisms results in adaptation of both visual and (limb) proprioceptive spatial representations. Common ways to measure adaptation after-effect are to ask a person to point straight ahead with their eyes closed ("manual straight ahead", MSA), or to a seen target using their unseen hand ("open-loop pointing", OLP). MSA measures changes in proprioception only, whereas OLP measures the combined visual and proprioceptive shift. The behavioural and neurological mechanisms of prism adaptation have come under scrutiny following reports of reduced hemispatial neglect in patients following this procedure. We present evidence suggesting that shifts in proprioceptive spatial representations induced by prism adaptation are larger following lesions to the intraparietal cortex - a brain region that integrates retinotopic visual signals with signals of eye position in the orbit and that is activated during prism adaptation. Six healthy participants and six patients with unilateral intraparietal cortex lesions underwent prism adaptation. After-effects were measured with OLP and MSA. After-effects of control participants were larger when measured with OLP than with MSA, consistent with previous research and with the additional contribution of visual shift to OLP after-effects. However, patients' OLP shifts were not significantly different to their MSA shifts. We conclude that, for the patients, correction of pointing errors during prism adaptation involved proportionally more changes to arm proprioception than for controls. Since lesions to intraparietal cortex led to enhanced realignment of arm proprioceptive representations, our results indirectly suggest that the intraparietal cortex could be key for visual realignment.

Effects of Prism Adaptation for Unilateral Spatial Neglect After Stroke: A Systematic Review and Meta-Analysis

OBJECTIVE

The aim of the study was to assess effects of prism adaptation on unilateral spatial neglect poststroke.

METHODS

Searching databases and referring to randomized controlled trial until December 30, 2019. There were two reviewers who searched some key words such as unilateral spatial neglect and prism adaptation, and only randomized controlled trial was included. There were two evaluators who screened literature and data regarding research design, treatment plan, etc. Assessment tool recommended in Cochrane Reviewers' Handbook 5.1.0 was adopted to assess the risks of bias of randomized controlled trial, and Revman 5.3 software was used for meta-analysis. Mean differences and 95% of confidence intervals were calculated, and heterogeneity was assessed through I2 statistics.

RESULTS

Eight randomized controlled trials were included, involving 244 patients of which 130 in experimental group and 114 in control group. According to meta-analysis results, prism adaptation group scored significantly higher than control group in improving Behavioral Inattention Test (mean difference = 8.99, 95% confidence interval = 0.93 to 17.06, P = 0.03) and Star Cancellation Test (mean difference = 3.04, 95% confidence interval = 0.19 to 5.88, P = 0.04). However, there was no significant statistical difference in Catherine Bergego Scale between groups (mean difference = -0.30, 95% confidence interval = -1.83 to 1.23, P = 0.70). The long-term follow-up visits (over 1 mo) appeared no statistical difference in Behavioral Inattention Test scores between the patients of two groups (mean difference = 8.93, 95% confidence interval = -1.98 to 19.84, P = 0.1).

CONCLUSIONS

Prism adaptation can improve neglect symptoms of patients with unilateral spatial neglect after stroke temporarily.

Visuomotor impairments in complex regional pain syndrome during pointing tasks

ABSTRACT

Complex regional pain syndrome (CRPS) is thought to be characterized by cognitive deficits affecting patients' ability to represent, perceive, and use their affected limb as well as its surrounding space. This has been tested, among others, by straight-ahead tasks testing oneself's egocentric representation, but such experiments lead to inconsistent results. Because spatial cognitive abilities encompass various processes, we completed such evaluations by varying the sensory inputs used to perform the task. Complex regional pain syndrome and matched control participants were asked to assess their own body midline either visually (ie, by means of a moving visual cue) or manually (ie, by straight-ahead pointing with one of their upper limbs) and to reach and point to visual targets at different spatial locations. Although the 2 former tasks only required one single sensory input to be performed (ie, either visual or proprioceptive), the latter task was based on the ability to coordinate perception of the position of one's own limb with visuospatial perception. However, in this latter task, limb position could only be estimated by proprioception, as vision of the limb was prevented. Whereas in the 2 former tasks CRPS participants' performance was not different from that of controls, they made significantly more deviations errors during the visuospatial task, regardless of the limb used to point or the direction of pointing. Results suggest that CRPS patients are not specifically characterized by difficulties in representing their body but, more particularly, in integrating somatic information (ie, proprioception) during visually guided movements of the limb.

Rehabilitation of visual disorders

While there is a long history of rehabilitation for motor deficits following cerebral lesions, less is known about our ability to improve visual deficits. Vision therapy, prisms, occluders, and filters have been advocated for patients with mild traumatic brain injury, on the premise that some of their symptoms may reflect abnormal visual or ocular motor function, but the evidence for their efficacy is modest. For hemianopia, attempts to restore vision have had unimpressive results, though it appears possible to generate blindsight through training. Strategic approaches that train more efficient use of visual search in hemianopia have shown consistent benefit in visual function, while prism aids may help some patients. There are many varieties of alexia. Strategic adaptation of saccades can improve hemianopic alexia, but there has been less work and mixed results for pure alexia, neglect dyslexia, attentional dyslexia, and the central dyslexias. A number of approaches have been tried in prosopagnosia, with recent studies of small groups suggesting that face perception of prosopagnosic subjects can be enhanced through perceptual learning.

Prism adaptation effects in complex regional pain syndrome: A therapo-physiological single case experimental design exploratory report

Complex Regional Pain Syndrome (CRPS) is an invalidating chronic condition that can occur after an acute peripheral lesion. Prism adaptation therapy is regarded as a promising tool to improve chronic pain in this syndrome but the mechanisms which lead to pain amelioration remain unknown. In this exploratory report we performed a retrospective analysis of longitudinal data collected from a single, atypical patient, who showed hyper-attention toward her affected (left) hand. Repeated assessments of pain and spatial neglect made during the course of the prism adaptation treatment revealed differential contributions of the two hands to adaptation-induced pain reduction. Treatment response appeared to be associated with a relative modification of the spatial behaviour of the two hands. This case study provides a new example of pain relief following prismatic deviation away from the pathological side.

Effects of Prism Adaptation on Unilateral Neglect After Stroke: An Updated Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

The aim of this study was to investigate the effects of prism adaptation (PA) on unilateral neglect after stroke.

METHODS

Randomized clinical trials, published up to January 31, 2020, comparing PA with neutral goggles or no goggles were systematically searched and included. Two independent reviewers performed data extraction and assessed the quality of studies using the Physiotherapy Evidence Database scale.

RESULTS

A total of seven randomized trials, involving 211 participants, satisfied the inclusion criteria. There was no significant immediate benefit of PA as measured by Behavioral Inattention Test (BIT) (weighted mean difference [WMD], 5.10; [95% confidence interval (CI), -6.68 to 16.88]), behavioral subset (BIT-B; WMD, 3.40 [95% CI, -3.97 to 10.76), conventional subset (BIT-C; WMD, 9.98 [95% CI, -0.42 to 20.38]), and Catherine Bergego Scale (WMD, -0.52 [95% CI, -1.98 to 0.93]). No statistical difference was observed between PA and control on the long-term effect (BIT: WMD, 1.92 [95% CI, -9.34 to 13.18]; BIT-B: WMD, -3.28 [95% CI, -11.89 to 5.34]; BIT-C: WMD, 2.66 [95% CI, -10.35 to 11.67]; Catherine Bergego Scale: WMD, -1.22 [95% CI, -3.05 to 0.62]).

CONCLUSIONS

PA did not show a greater improvement on neglect symptoms in post-stroke patients with unilateral neglect, compared with placebo or no treatment. These findings do not support the routine use of PA in patients with unilateral neglect after stroke.

Virtual prism adaptation for spatial neglect: A double-blind study

ABSTRACTPrismatic adaptation (PA) with wedge prisms is a non-invasive technique used in the rehabilitation of patients suffering from spatial neglect. Unfortunately, as for many behavioural intervention techniques, it is nearly impossible to achieve adequate blinding using wedge prisms, and the potential benefit of PA in the rehabilitation of neglect remains controversial. In order to study an alternative to wedge prism, we examine whether virtual PA at different degrees of deviation may alleviate signs of neglect in a double-blind design. Fifteen neglect patients participated in three adaptation sessions, which differed by the degree of deviation (0°, 15°, or 30°). Performance in line bisection and item cancellation tasks was measured in virtual reality immediately before and after adaptation. Session allocation was concealed from patients and the examiner. Despite the presence of robust, dose-dependent effects of virtual PA on Open-Loop Pointing (OLP), no transfer to line bisection and item cancellation tests were observed. None of the patients were aware of differences between sessions. Virtual PA did not result in visuo-motor transfer effects despite inducing significant adaptation effects in OLP. Together with recent negative findings of randomized-controlled trials, these findings cast doubt on the general efficacy of PA as a rehabilitation method of spatial neglect.

Hemispheric stroke: Mood disorders

Stroke causes many forms of disability, including emotional and mood disorders. Depression is the most common of these, affecting approximately one-third of stroke patients. Other disorders like mania, bipolar disorder, anxiety disorder, or apathy may also develop following stroke, although they are less common. The development of mood and emotional disorders is dependent on the severity of brain injury, the side of injury, and hemispheric location. Whereas a left hemispheric stroke often results in depression or a catastrophic reaction with anxiety, injury to the right hemisphere has predominantly been associated with the development of emotional indifference (anosodiaphoria) or euphoria. In this chapter, we discuss the mood disorders associated with hemispheric strokes and the neuropsychological mechanisms that might account for the clinical manifestations of these affective disorders.

Vision therapy: Occlusion, prisms, filters, and vestibular exercises for mild traumatic brain injury

A number of treatment approaches have been advocated for persistent visual complaints following mild traumatic brain injury. These include devices such as binasal occlusion, yoked prisms, vertical prisms, and filters, as well as vestibular training. We discuss the rationale and the evidence for each of these approaches. Binasal occlusion has been advocated for visual motion sensitivity, but it is not clear why this should help, and there is no good evidence for its symptomatic efficacy. Base-in prisms can help manage convergence insufficiency, but there are few data on their efficacy. Midline shift is an unproven concept, and while the yoked prisms advocated for its treatment may have some effect on egocentric neglect, their use in mild traumatic brain injury is more questionable. A wide variety of posttraumatic symptoms have been attributed to vertical heterophoria, but this is an unproven concept and there are no controlled data on the use of vertical prisms for mild traumatic brain injury symptoms. Filters could plausibly ameliorate light intolerance but studies are lacking. Better evidence is emerging for the effects of vestibular therapy, with a few randomized controlled trials that included blinded assessments and appropriate statistical analyses. Without more substantial evidence, the use of many of these techniques cannot be recommended and should be regarded as unproven and in some cases implausible.

Unilateral Spatial Neglect After Stroke: Current Insights

INTRODUCTION

Unilateral spatial neglect (USN) is a disorder of contralesional space awareness which often follows unilateral brain lesion. Since USN impairs awareness of contralesional space/body and often of concomitant motor disorders, its presence represents a negative prognostic factor of functional recovery. Thus, the disorder needs to be carefully diagnosed and treated. Here, we attempted to present a clear and concise picture of current insights in the comprehension and rehabilitation of USN.

METHODS

We first provided an updated overview of USN clinical and neuroanatomical features and then highlighted recent progresses in the diagnosis and rehabilitation of the disease. In relation to USN rehabilitation, we conducted a MEDLINE literature research on three of the most promising interventions for USN rehabilitation: prismatic adaptation (PA), non-invasive brain stimulation (NIBS), and virtual reality (VR). The identified studies were classified according to the strength of their methods.

RESULTS

The last years have witnessed a relative decrement of interest in the study of neuropsychological disorders of spatial awareness in USN, but a relative increase in the study of potential interventions for its rehabilitation. Although optimal protocols still need to be defined, high-quality studies have demonstrated the efficacy of PA, TMS and tDCS interventions for the treatment of USN. In addition, preliminary investigations are suggesting the potentials of GVS and VR approaches for USN rehabilitation.

CONCLUSION

Advancing neuropsychological and neuroscience tools to investigate USN pathophysiology is a necessary step to identify effective rehabilitation treatments and to foster our understanding of neurofunctional bases of spatial cognition in the healthy brain.

Frontal lesions predict response to prism adaptation treatment in spatial neglect: A randomised controlled study

Spatial neglect commonly follows right hemisphere stroke. It is defined as impaired contralesional stimulus detection, response, or action, causing functional disability. While prism adaptation treatment is highly promising to promote functional recovery of spatial neglect, not all individuals respond. Consistent with a primary effect of prism adaptation on spatial movements, we previously demonstrated that functional improvement after prism adaptation treatment is linked to frontal lobe lesions. However, that study was a treatment-only study with no randomised control group. The current study randomised individuals with spatial neglect to receive 10 days of prism adaptation treatment or to receive only standard care (control group). Replicating our earlier results, we found that the presence of frontal lesions moderated response to prism adaptation treatment: among prism-treated patients, only those with frontal lesions demonstrated functional improvements in their neglect symptoms. Conversely, among individuals in the standard care control group, the presence of frontal lesions did not modify recovery. These results suggest that further research is needed on how frontal lesions may predict response to prism adaptation treatment. Additionally, the results help elucidate the neural network involved in spatial movement and could be used to aid decisions about treatment.

Prisms adaptation improves haptic object discrimination in hemispatial neglect

Neglect manifestations are typically explored in the visual modality. Although they are less commonly investigated tactile deficits also exist, and the aim of this study was to explore neglect in this modality. A haptic object discrimination task was designed to assess whether or not shape perception is impaired in seven right brain damaged patients with or without neglect. Each patient's performance on the object discrimination task was assessed before and after a brief period of prism adaptation, a bottom-up rehabilitation technique known to improve neglect symptoms. The results suggest that a haptic deficit - in the form of substantially more left errors - is present only in patients with neglect. Following prism adaptation, the left bias error rates in neglect patients were substantially reduced, and were similar to those observed in patients without neglect. Moreover, the haptic processing of the right side of objects also improved slightly. This finding suggests an expansion of the effects of prism adaptation to the unexposed, tactile modality supporting the cross-modal central effect hypothesis.

[Top-down and bottom-up approaches for the treatment of unilateral spatial neglect in stroke patients: A systematic review]

OBJECTIVE

To evaluate the effectiveness of top-down and bottom-up approaches in the rehabilitation of unilateral spatial neglect in stroke patients.

METHODOLOGY

We carried out a systematic review of randomized controlled trials from January of 2013 to March of 2017. The following databases were searched: Scopus, Science Direct, Web of Science, Pubmed and CINHAL. The methodological quality, level of scientific evidence and the strength of recommendation were evaluated.

RESULTS

We included 13 studies (294 subjects): nine studies (188 patients) carried out therapies with a bottom-up approach such us eye patching, virtual reality, optokinetic stimulation, transcranial magnetic stimulation and prism adaption; three studies (94 patients) evaluated therapies with a top-down approach such us visual scanning, sensory feedback and mental practice; one study incorporated both approaches. Nine of these studies showed improvements in spatial neglect scales; five of these used bottom-up approaches, another three used top-down approaches and the remaining study combined both approaches. Disability was evaluated by nine studies, and only three reported improvements. Three studies reported significant improvements in motor function in the intervention groups.

CONCLUSIONS

Top-down and bottom-up approaches could improve unilateral spatial neglect, disability and motor function in patients with stroke.

Regression of left hyperschematia after prism adaptation: A single case study

Prism adaptation (PA) is a promising treatment in the rehabilitation of post-stroke cognitive disorders such as unilateral spatial neglect or constructional deficits. Right brain damage can bring about another representational spatial disorder, termed «hyperschematia», and defined by a left-sided disproportionate expansion of drawings by copy and from memory, and by an overestimation of left lateral extent when a leftward movement is required. This case study aimed at evaluating the effect of PA induced by prismatic lenses creating a shift to the left on hyperschematia signs. A 63-year-old woman with left hyperschematia, consecutive to a right fronto-temporo-parietal hematoma, was exposed to a leftward optical deviation produced by prismatic lenses. An anatomical MRI studied topography of the brain lesion; the patient's lesion was then mapped onto tractography reconstructions of white matter pathways. Results showed that PA significantly reduced the left-sided expansion of drawing by copy and from memory, and the overestimation of left lateral extent, immediately after prism removal and 4 days later, indicating a persistent long lasting cognitive effect. MRI showed a right hemisphere disconnection of the posterior and long segments of the arcuate fasciculus, and of the inferior longitudinal and fronto-occipital fasciculi. Overall, these findings suggest that: i) PA is effective also in hyperschematia by re-orientating spatial attention towards the right side of space, with a relative rightward PA-induced unbalance, and re-setting the spatial representation to the left side of space, contralateral to the side of the lesion; ii) the left misrepresentation of lateral extent may be related to a disconnection between visual coordinates and attentional networks to the frontal lobe.

Effect of prism adaptation on neglect hemianesthesia

Prism adaptation (PA) has proven to be effective in alleviating many signs of unilateral spatial neglect (USN). Generally, the principal improvement after PA treatment was found to be in the high-level cognitive function. Nevertheless, some evidence has also been found for it in somatosensory function. We have aimed to test the influence of PA on neglect hemianesthesia, a condition in which the high-level neglect-related deficit mimics hemianesthesia. Twenty-one USN patients were enrolled in the study. Each patient performed two sessions of PA, one with neutral glasses and one with prism glasses using a cross-over design. Sensitivity on the upper limb was tested using two methods. The first task was the sensibility subtest which was derived from the standard clinical examination. The second was the perceptual and motor electro-cutaneous threshold on the forearms using an electro-cutaneous stimulator. Four neuropsychological tests were used to diagnose USN and to check improvement: Star cancellation, Line bisection, Sentence reading and the Comb & Razor test. Comparing prism with sham conditions, our results show significant improvements in double extinction and in the electro-cutaneous perceptual threshold only for the contralesional hand. No improvement was found for the ipsilesional hand, for the motor threshold, and for neutral glasses. Significant improvement was found in personal neglect. Replication of the task in a subgroup of patients confirmed the primary results. The improvements in somatosensory perception together with the amelioration of personal neglect suggest that PA also has a specific effect on the neglect hemianesthesia.

Pushing attention to one side: Force field adaptation alters neural correlates of orienting and disengagement of spatial attention

Sensorimotor adaptation to wedge prisms can alter the balance of attention between left and right space in healthy adults, and improve symptoms of spatial neglect after stroke. Here we asked whether the orienting of spatial attention to visual stimuli is affected by a different form of sensorimotor adaptation that involves physical perturbations of arm movement, rather than distortion of visual feedback. Healthy participants performed a cued discrimination task before and after they made reaching movements to a central target. A velocity-dependent force field pushed the hand aside during each reach, and required participants to apply compensatory forces toward the opposite side. We used event-related potentials (ERPs) to determine whether electroencephalography (EEG) responses reflecting orienting (cue-locked N1) and disengagement (target-locked P1) of spatial attention are affected by adaptation to force fields. After adaptation, the cue-locked N1 was relatively larger for stimuli presented in the hemispace corresponding to the direction of compensatory hand force. P1 amplitudes evoked by invalidly cued targets presented on the opposite side were reduced. This suggests that force field adaptation boosted attentional orienting responses toward the side of hand forces, and impeded attentional disengagement from that side, mimicking previously reported effects of prism adaptation. Thus, remapping between motor commands and intended movement direction is sufficient to bias ERPs, reflecting changes in the orienting of spatial attention in the absence of visuo-spatial distortion or visuo-proprioceptive mismatch. Findings are relevant to theories of how sensorimotor adaptation can modulate attention, and may open new avenues for treatment of spatial neglect.

Closing the Loop: From Motor Neuroscience to Neurorehabilitation

The fields of human motor control, motor learning, and neurorehabilitation have long been linked by the intuition that understanding how we move (and learn to move) leads to better rehabilitation. In reality, these fields have remained largely separate. Our knowledge of the neural control of movement has expanded, but principles that can directly impact rehabilitation efficacy remain somewhat sparse. This raises two important questions: What can basic studies of motor learning really tell us about rehabilitation, and are we asking the right questions to improve the lives of patients? This review aims to contextualize recent advances in computational and behavioral studies of human motor learning within the framework of neurorehabilitation. We also discuss our views of the current challenges facing rehabilitation and outline potential clinical applications from recent theoretical and basic studies of motor learning and control.

Neuroanatomical and behavioural factors associated with the effectiveness of two weekly sessions of prism adaptation in the treatment of unilateral neglect

Among the different interventions to alleviate the symptoms of unilateral neglect, prism adaptation (PA) appears especially promising. To elucidate the contribution of some neuroanatomical and behavioural factors to PA's effectiveness, we conducted a study combining neuropsychological and lesion mapping methods on a group of 19 neglect patients who underwent two sessions of PA during one week and assessed their improvement relative to the baseline until the following week (7-8 days later). Correlation analyses revealed a significant positive relationship between the magnitude of the proprioceptive after-effect and the improvement at the follow-up session in two perceptual tasks requiring motor responses. Conversely, no correlation was found between the proprioceptive after-effect and the improvement in a perceptual task with no motor involvement. This finding suggests that patients' potential to show a prism-related improvement in motor-related tasks might be indicated by the strength of their proprioceptive response (proprioceptive after-effect). As for the neuroanatomical basis of this relationship, subtraction analyses suggested that patients' improvement in perceptual tasks with high motor involvement might be facilitated by the integrity of temporo-parietal areas and the damage of frontal and subcortical areas.

Prism Adaptation in Rehabilitation? No Additional Effects of Prism Adaptation on Neglect Recovery in the Subacute Phase Poststroke: A Randomized Controlled Trial

Background. Patients with neglect ignore or respond slower to contralesional stimuli. Neglect negatively influences independence in activities of daily living (ADL). Prism adaptation (PA) is one of the most frequently studied treatments, yet there is little evidence regarding positive effects on neglect behavior in ADL. Objective. To assess whether PA in the subacute phase ameliorates neglect in situations of varying complexity. Methods. A total of 70 neglect patients admitted for inpatient stroke rehabilitation received either PA or sham adaptation (SA) for 2 weeks, with full access to standard treatment. There were 7 time-dependent measurements (baseline and 1-4, 6, and 14 weeks after start of treatment). The primary outcome was change of neglect as observed during basic ADL with the Catherine Bergego Scale (CBS). Secondary outcomes were changes in performance on a dynamic multitask (ie, the Mobility Assessment Course [MAC]) and a static paper-and-pencil task (ie, a shape cancellation task [SC]). Results. In all, 34 patients received PA and 35 SA. There were significant time-dependent improvements in performance as measured with the CBS, MAC, and SC (all F > 15.57; P < .001). There was no significant difference in magnitude of improvement between groups on the CBS, MAC, and SC (all F < 2.54; P > .113]. Conclusions. No beneficial effects of PA over SA in the subacute phase poststroke were observed, which was comparable for situations of varying complexity. Heterogeneity of the syndrome, time post–stroke onset, and the content of treatment as usual are discussed. Basic knowledge on subtypes and recovery patterns would aid the development of tailored treatment.

Improvement of Navigation and Representation in Virtual Reality after Prism Adaptation in Neglect Patients

Prism adaptation (PA) is responsible for an expansion of sensori-motor after-effects to cognitive domains for patients with spatial neglect. One important question is whether the cognitive after-effects induced by PA may also concern higher aspects of spatial cognition, such as navigation and topographic memory, which are critical in everyday life. The aim of this study was to assess whether multiple sessions of right PA can affect navigation and topographic memory. Seven right brain-damaged (RBD) patients with chronic neglect were included. We used a virtual supermarket named VAP-S which is an original paradigm, similar to the "shopping list test" during which patients had to purchase items from a list of eight products. Furthermore, in order to assess generalization of PA effects on constructing a spatial map from virtual information, each participant was then asked to draw the map of the virtual supermarket from memory. Regarding navigation performance, significant results were obtained: session duration reduction, fewer numbers of pauses and omissions, more items purchased on the left side and more items purchased over all. A long-lasting effect was noted, up to one month after PA. The representational task performance was also significantly increased for map drawing, with a reduction of the right shift of the symmetry axis of the map, more items drawn on the left side of maps and over all, and more items correctly located on the map. Some of these effects lasted for at least 7 days. These results suggest an expansion of PA benefit to a virtual environment. Crucially, the cognitive benefits induced by PA were noted for complex spatial cognition tasks required in everyday life such as navigation and topographic memory and this improvement was maintained for up to 1 month.