Pharmacological interventions for unilateral spatial neglect after stroke

Spatial neglect treatment: The brain's spatial-motor Aiming systems

Animal and human literature supports spatial-motor "Aiming" bias, a frontal-subcortical syndrome, as a core deficit in spatial neglect. However, spatial neglect treatment studies rarely assess Aiming errors. Two knowledge gaps result: spatial neglect rehabilitation studies fail to capture the impact on motor-exploratory aspects of functional disability. Also, across spatial neglect treatment studies, discrepant treatment effects may also result from sampling different proportions of patients with Aiming bias. We review behavioural evidence for Aiming spatial neglect, and demonstrate the importance of measuring and targeting Aiming bias for treatment, by reviewing literature on Aiming spatial neglect and prism adaptation treatment, and presenting new preliminary data on bromocriptine treatment. Finally, we review neuroanatomical and network disruption that may give rise to Aiming spatial neglect. Because Aiming spatial neglect predicts prism adaptation treatment response, assessment may broaden the ability of rehabilitation research to capture functionally-relevant disability. Frontal brain lesions predict both the presence of Aiming spatial neglect, and a robust response to some spatial neglect interventions. Research is needed that co-stratifies spatial neglect patients by lesion location and Aiming spatial neglect, to personalize spatial neglect rehabilitation and perhaps even open a path to spatial retraining as a means of promoting better mobility after stroke.

Exploring the use of dopaminergic medication to treat hemispatial inattention during in-patient post-stroke neurorehabilitation

Hemispatial inattention (HSI), a lateralised impairment of spatial processing, is a common consequence of stroke. It is a poor prognostic indicator for functional recovery and interferes with the progress during in-patient neurorehabilitation. Dopaminergic medication has shown promise in improving HSI in the chronic post-stroke period but is untested in more acute settings, e.g. during in-patient neurorehabilitation. We audited the use of dopaminergic medication in ten sequential patients with post-stroke HSI, on an open-label exploratory basis. Patients' response to medication was assessed individually, using a three-week Off-On-Off protocol. We employed a mixture of bedside and functional measures, and made a multidisciplinary judgement of efficacy in individual patients. In six out of 10 patients, there was a convincing improvement of HSI while on medication, which reversed when it was paused. There was a mean 57% relative increase in target detection in the star cancellation test on the most affected side (on vs. off medication). In the six responders, medication was therefore continued throughout their admission without adverse effects. The star cancellation test was sensitive to HSI in most patients but in two cases failed to detect changes that were picked up by a functional assessment (Kessler Functional Neglect Assessment Protocol). We found this multidisciplinary approach to be feasible in an in-patient neurorehabilitation setting. We suggest further research to explore the efficacy of dopaminergic medication in improving neurorehabilitation outcomes for patients with post-stroke HSI. We suggest that more detailed N-of-1 assessments of treatment response, with internal blinding, may be a productive approach.

Robot-Assisted Arm Training in Stroke Individuals With Unilateral Spatial Neglect: A Pilot Study

Background: Robot-assisted arm training (RAT) is an innovative exercise-based therapy that provides highly intensive, adaptive, and task-specific training, yet its effects for stroke individuals with unilateral spatial neglect remain to be explored. The study was aimed to investigate the effects of RAT on unilateral spatial neglect, arm motor function, activities of daily living, and social participation after stroke.

Methods: In a pilot randomized controlled trial, individuals with unilateral spatial neglect after right hemisphere stroke were equally allocated to intervention group and control group, 45-min training daily, 5 days/week, for 4 weeks. Outcome measures included the Behavioral Inattention Test-conventional section (BIT-C), Catherine Bergego Scale (CBS), Fugl-Meyer Assessment for Upper Extremity (FMA-UE), Modified Barthel Index (MBI), and World Health Organization Disability Assessment Schedule Version 2.0 (WHODAS 2.0).

Results: From November 2018 to February 2021, 20 stroke patients (mean age 47.40 ± 8.47) were enrolled in the study. Robot-assisted arm training was feasible and safe for individuals with unilateral spatial neglect. Both groups had significant improvements in all outcome measures. Participants assigned to RAT therapy had significantly greater improvements in BIT-C (difference, 7.70; 95% CI, 0.55–14.85, P = 0.04), FMA-UE (difference, 5.10; 95% CI, 1.52–8.68, P = 0.01), and WHODAS 2.0 (difference, −7.30; 95% CI, −12.50 to −2.10, P = 0.01). However, the change scores on CBS and MBI demonstrated no significance between the groups.

Conclusion: Our findings provide preliminary support for introducing robot-assisted arm training to remediate unilateral spatial neglect after stroke. The training program focusing on neglect of contralateral space and affected upper extremity may be effective in neglect symptoms, motor function recovery, and social participation, while not generalizing into improvements in activities of daily living.

Clinical Trial Registration: Chinese Clinical Trial Registry (http://www.chictr.org.cn/) on 17 October 2019, identifier: ChiCTR1900026656.

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.

Evidence-based Umbrella Review of Cognitive Effects of Prefrontal tDCS

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique, which has been increasingly used as an investigational tool in neuroscience. In social and affective neuroscience research, the prefrontal cortex has been primarily targeted, since this brain region is critically involved in complex psychobiological processes subserving both Șhotș and Școldș domains. Although several studies have suggested that prefrontal tDCS can enhance neuropsychological outcomes, meta-analyses have reported conflicting results. Therefore, we aimed to assess the available evidence by performing an umbrella review of meta-analyses. We evaluated the effects of prefrontal active vs sham tDCS on different domains of cognition among healthy and neuropsychiatric individuals. A MeaSurement Tool to Assess Systematic Reviews 2 was employed to evaluate the quality of meta-analyses, and the GRADE system was employed to grade the quality of evidence of every comparison from each meta-analysis. PubMed/MEDLINE, PsycINFO and the Cochrane Database of Systematic Reviews were searched, and 11 meta-analyses were included resulting in 55 comparisons. Only 16 comparisons reported significant effects favoring tDCS, but 13 of them had either very low or low quality of evidence. Of the remaining 39 comparisons which reported non-significant effects, 38 had either very low or low quality of evidence. Meta-analyses were rated as having critically low and low quality. Among several reasons to explain these findings, the lack of consensus and reproducibility in tDCS research is discussed.

Noninvasive Brain Stimulations for Unilateral Spatial Neglect after Stroke: A Systematic Review and Meta-Analysis of Randomized and Nonrandomized Controlled Trials

Background

Unilateral spatial neglect (USN) is the most frequent perceptual disorder after stroke. Noninvasive brain stimulation (NIBS) is a tool that has been used in the rehabilitation process to modify cortical excitability and improve perception and functional capacity.

Objective

To assess the impact of NIBS on USN after stroke.

Methods

An extensive search was conducted up to July 2016. Studies were selected if they were controlled and noncontrolled trials examining transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), and theta burst stimulation (TBS) in USN after stroke, with outcomes measured by standardized USN and functional tests.

Results

Twelve RCTs (273 participants) and 4 non-RCTs (94 participants) proved eligible. We observed a benefit in overall USN measured by the line bisection test with NIBS in comparison to sham (SMD -2.35, 95% CI -3.72, -0.98; p = 0.0001); the rTMS yielded results that were consistent with the overall meta-analysis (SMD -2.82, 95% CI -3.66, -1.98; p = 0.09). The rTMS compared with sham also suggested a benefit in overall USN measured by Motor-Free Visual Perception Test at both 1 Hz (SMD 1.46, 95% CI 0.73, 2.20; p < 0.0001) and 10 Hz (SMD 1.19, 95% CI 0.48, 1.89; p = 0.54). There was also a benefit in overall USN measured by Albert's test and the line crossing test with 1 Hz rTMS compared to sham (SMD 2.04, 95% CI 1.14, 2.95; p < 0.0001).

Conclusions

The results suggest a benefit of NIBS on overall USN, and we conclude that rTMS is more efficacious compared to sham for USN after stroke.

Randomised, double-blind, placebo-controlled crossover study of single-dose guanfacine in unilateral neglect following stroke

OBJECTIVE

Unilateral neglect is a poststroke disorder that impacts negatively on functional outcome and lacks established, effective treatment. This multicomponent syndrome is characterised by a directional bias of attention away from contralesional space, together with impairments in several cognitive domains, including sustained attention and spatial working memory. This study aimed to test the effects of guanfacine, a noradrenergic alpha-2A agonist, on ameliorating aspects of neglect.

METHODS

Thirteen right hemisphere stroke patients with leftward neglect were included in a randomised, double-blind, placebo-controlled proof-of-concept crossover study that examined the effects of a single dose of guanfacine. Patients were tested on a computerised, time-limited cancellation paradigm, as well as tasks that independently assessed sustained attention and spatial working memory.

RESULTS

On guanfacine, there was a statistically significant improvement in the total number of targets found on the cancellation task when compared with placebo (mean improvement of 5, out of a possible 64). However, there was no evidence of a change in neglect patients' directional attention bias. Furthermore, Bayesian statistical analysis revealed reliable evidence against any effects of guanfacine on search organisation and performance on our sustained attention and spatial working memory tasks.

CONCLUSIONS

Guanfacine improves search in neglect by boosting the number of targets found but had no effects on directional bias or search organisation, nor did it improve sustained attention or working memory on independent tasks. Further work is necessary to determine whether longer term treatment with guanfacine may be effective for some neglect patients and whether it affects functional outcome measures.

TRIAL REGISTRATION NUMBER

NCT00955253.

Recent theoretical, neural, and clinical advances in sustained attention research

Models of attention often distinguish among attention subtypes, with classic models separating orienting, switching, and sustaining functions. Compared with other forms of attention, the neurophysiological basis of sustaining attention has received far less notice, yet it is known that momentary failures of sustained attention can have far-ranging negative effects in healthy individuals, and lasting sustained attention deficits are pervasive in clinical populations. In recent years, however, there has been increased interest in characterizing moment-to-moment fluctuations in sustained attention, in addition to the overall vigilance decrement, and understanding how these neurocognitive systems change over the life span and across various clinical populations. The use of novel neuroimaging paradigms and statistical approaches has allowed for better characterization of the neural networks supporting sustained attention and has highlighted dynamic interactions within and across multiple distributed networks that predict behavioral performance. These advances have also provided potential biomarkers to identify individuals with sustained attention deficits. These findings have led to new theoretical models explaining why sustaining focused attention is a challenge for individuals and form the basis for the next generation of sustained attention research, which seeks to accurately diagnose and develop theoretically driven treatments for sustained attention deficits that affect a variety of clinical populations.