Integrity of medial temporal structures may predict better improvement of spatial neglect with prism adaptation treatment

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.

No short-term treatment effect of prism adaptation for spatial neglect: An inclusive meta-analysis

Despite 25 years of research on the topic, there is still no consensus on whether prism adaptation is an effective therapy for visuospatial neglect. We have addressed this question through a meta-analysis of the most well-controlled studies on the topic. Our main meta-analytic model included studies with a placebo/sham/treatment-as-usual control group from which data from right hemisphere stroke patients and left-sided neglect could be aggregated. The short-term treatment effects on the two commonly used standard tests for neglect, the conventional Behavioural Inattention Test (BIT-C) and cancellation test scores were combined into one random effect model justified by the fact that 89% of the BIT-C score is determined by cancellation tasks. With this approach, we were able to obtain a larger and more homogeneous dataset than previous meta-analyses: sixteen studies including 430 patients. No evidence for beneficial effects of prism adaptation was found. The secondary meta-analysis including data from the Catherine Bergego Scale, a functional measure of activities of daily living, also found no evidence for the therapeutic effects of prism adaptation, although half as many studies were available for this analysis. The results were consistent after the removal of influential outliers, after studies with high risk-of-bias were excluded, and when an alternative measure of effect size was considered. These results do not support the routine use of prism adaptation as a therapy for spatial neglect.

Prism adaptation therapy in spatial neglect: The importance of connectional anatomy

The meta-analysis conducted by Székely et al. described the lack of beneficial effect of prism adaptation in neglect patients. The authors concluded that the results did "not support the routine use of prism adaptation as a therapy for spatial neglect". However, a possible nuance to this conclusion could be that the response (or lack thereof) of neglect patients to prism adaptation may actually depend on the connectional anatomy of their lesion. We develop this idea in our commentary, in order to offer a more balanced perspective on the implications of the findings obtained by Székely et al.

Association of delirium and spatial neglect in patients with right-hemisphere stroke

BACKGROUND

Delirium, an acute and fluctuating decline in cognitive functioning, increases mortality and length of hospital stays (LOS) and adversely affects functional outcomes. Previous studies suggested that the incidence of delirium may be increased in right-hemisphere strokes. Similarly, spatial neglect, a disabling deficit in unilateral spatial processing, is more common and more severe following a right-sided stroke. Spatial neglect has been established as a risk factor for delirium.

OBJECTIVE

It was hypothesized that functionally relevant spatial neglect and delirium are associated in patients with right-hemisphere stroke during acute inpatient rehabilitation. Data were examined from consecutive unilateral stroke patients evaluated with the 3-minute diagnostic interview for confusion assessment method (3D-CAM) and the Catherine Bergego Scale (CBS) via the Kessler Foundation Neglect Assessment Process (KF-NAP).

DESIGN

A retrospective, cohort study.

SETTING

Data collected in an acute inpatient rehabilitation facility.

PARTICIPANTS

Six hundred twenty six patients with stroke were included.

MAIN OUTCOME MEASURES

The measures were the relative risk of patients with right-hemisphere stroke having delirium when also positive for spatial neglect compared to patients with right-hemisphere stroke without spatial neglect, the incidence of 3D-CAM positive results by stroke hemisphere, and the effect of spatial neglect and delirium on functional outcomes for patients with right-brain stroke patients.

RESULTS

There was a significantly higher risk of delirium in patients with right-hemisphere stroke with spatial neglect compared to patients with right-hemisphere stroke without spatial neglect. The rates of 3D-CAM positive results were not statistically different for left- compared to right-hemisphere strokes. Both delirium and spatial neglect had significant adverse effects on right-hemisphere stroke patients' functional independence.

CONCLUSIONS

The results demonstrate an association between spatial neglect and delirium in patients with right hemisphere stroke in the acute inpatient rehabilitation setting. Because of the negative effect of these impairments on functional outcomes after stroke, prevention, early detection, and targeted treatments should be prioritized for these patients.

Recent advances in treatment of spatial neglect: networks and neuropsychology

INTRODUCTION

Spatial neglect remains an underdiagnosed and undertreated consequence of stroke that imposes significant disability. A growing appreciation of brain networks involved in spatial cognition is helping us to develop a mechanistic understanding of different therapies under development.

AREAS COVERED

This review focuses on neuromodulation of brain networks for the treatment of spatial neglect after stroke, using evidence-based approaches including 1) Cognitive strategies that are more likely to impact frontal lobe executive function networks; 2) Visuomotor adaptation, which may depend on the integrity of parietal and parieto- and subcortical-frontal connections and the presence of a particular subtype of neglect labeled Aiming neglect; 3) Non-invasive brain stimulation that may modulate relative levels of activity of the two hemispheres and depend on corpus callosum connectivity; and 4) Pharmacological modulation that may exert its effect primarily via right-lateralized networks more closely involved in arousal.

EXPERT OPINION

Despite promising results from individual studies, significant methodological heterogeneity between trials weakened conclusions drawn from meta-analyses. Improved classification of spatial neglect subtypes will benefit research and clinical care. Understanding the brain network mechanisms of different treatments and different types of spatial neglect will make possible a precision medicine treatment approach.

Virtual reality-based sensorimotor adaptation shapes subsequent spontaneous and naturalistic stimulus-driven brain activity

Our everyday life summons numerous novel sensorimotor experiences, to which our brain needs to adapt in order to function properly. However, tracking plasticity of naturalistic behavior and associated brain modulations is challenging. Here, we tackled this question implementing a prism adaptation-like training in virtual reality (VRPA) in combination with functional neuroimaging. Three groups of healthy participants (N = 45) underwent VRPA (with a shift either to the left/right side, or with no shift), and performed functional magnetic resonance imaging (fMRI) sessions before and after training. To capture modulations in free-flowing, task-free brain activity, the fMRI sessions included resting-state and free-viewing of naturalistic videos. We found significant decreases in spontaneous functional connectivity between attentional and default mode (DMN)/fronto-parietal networks, only for the adaptation groups, more pronouncedly in the hemisphere contralateral to the induced shift. In addition, VRPA was found to bias visual responses to naturalistic videos: Following rightward adaptation, we found upregulation of visual response in an area in the parieto-occipital sulcus (POS) only in the right hemisphere. Notably, the extent of POS upregulation correlated with the size of the VRPA-induced after-effect measured in behavioral tests. This study demonstrates that a brief VRPA exposure can change large-scale cortical connectivity and correspondingly bias visual responses to naturalistic sensory inputs.

Impacts of Prism Adaptation Treatment on Spatial Neglect and Rehabilitation Outcome: Dosage Matters

We examined whether number of prism adaptation treatment (PAT) sessions in regular clinical practice would predict spatial neglect (SN) improvement and rehabilitation outcomes. We reviewed clinical records from 16 U.S. rehabilitation hospitals where neurological patients were assessed for SN using the Catherine Bergego Scale (CBS) and if SN was detected, and may have received PAT. Multiple linear regression was used to predict CBS Change (indicating SN improvement) in 520 patients who received PAT while considering age, sex, diagnosis, time post diagnosis, CBS at baseline, neglected side of space, and length of stay. Another set of regression models including the same variables and adding Function Independent Measure (FIM®) at admission was used to predict FIM Gains (indicating rehabilitation outcomes) in 1720 patients receiving PAT or not. We found that greater number of PAT sessions predicted greater CBS Change, especially in patients with moderate-to-severe neglect. Number of PAT sessions also positively correlated with Total FIM, Motor FIM, and Cognitive FIM Gains regardless of SN severity classification at baseline. Furthermore, number of PAT sessions predicted CBS Change and FIM Gains among patients completing ≤8 PAT sessions but not among patients with ≥8 sessions, who however, showed greater CBS Change with increased PAT frequency (i.e., fewer days between two consecutive sessions). Receiving more once-daily PAT sessions predicted greater improvement in SN and rehabilitation outcomes. Receiving PAT at a higher frequency for 8 or more sessions predicted better SN improvement. Thus, dosage matters. The study provides practice-based evidence that PAT is appropriate for inpatient rehabilitation.

Visuomotor misalignment induced through immersive virtual reality to improve spatial neglect: a case-series study

One evidence-based treatment for spatial neglect is prism adaptation (PA) treatment. PA after-effects, i.e., the implicit shifts in the arm reaching position toward the neglected side of space after prism removal, are considered fundamental to PA treatment effects. In the present study, the arm reaching position was shifted through a visuomotor misalignment procedure using immersive virtual reality (VR). To examine whether this procedure might have a beneficial impact on spatial neglect, we conducted a multi-baseline experiment in three individuals with chronic left-sided neglect post stroke. Improved spatial neglect was observed in all participants immediately after 5 sessions with two rounds in each. Two participants demonstrated lasting or continuous improvement two weeks later. Participants' pattern of brain lesions did not appear to clearly explain performance differences. The findings suggest that VR-induced visuomotor misalignment may improve spatial neglect immediately after a multi-session treatment course. The optimal number of sessions will be determined by future studies with a larger sample size, which may also elucidate the number of sessions sufficient for sustained improvement in most patients. Further investigations will identify the neural mechanisms underlying VR-induced visuomotor misalignment, which may or may not be identical to PA after-effects.

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.

The Implementation Process of Two Evidence-Based Protocols: A Spatial Neglect Network Initiative

Introduction

Spatial neglect, a neurocognitive disorder of lateralized spatial attention, is prevalent among stroke survivors especially in inpatient rehabilitation facilities (IRFs). The ultimate goal of the project was to improve spatial neglect care in inpatient rehabilitation and trained as many OTs as possible using both tools in their regular practices as the means to achieve our overall objective. Therefore, we conducted a project aimed at implementing two evidence-based protocols, one for assessment (KF-NAP®) and the other for treatment (KF-PAT®), and share the implementation process, which included barriers and facilitators identified during and after the process, and implementation outcomes.

Methods

Sixteen IRFs were involved. The Knowledge-To-Action Cycle was used to describe the process of knowledge inquiry (training), translating knowledge (implementation) and evaluating the use of knowledge in clinical practice (outcomes). Barriers and strategies were reported using the Consolidated Framework for Implementation Research and identified through a survey, after the study concluded.

Results

Thirty-two therapists at the participating sites were trained to some level of the KF-NAP and KF-PAT. Throughout the project and also once after it finished, different barriers were identified by researchers and clinicians, who then determined together actions to eliminate or minimize the barriers. For example, multiple sites reported: "not having time to train other staff at their hospital due to high patient volume and other responsibilities."

Discussion

The project shared our implementation process which demonstrated the importance of using implementation methods and incorporating a researcher-clinician partnership, not only for knowledge generation but also knowledge translation. Frequent communications and exchanging information with stakeholders at different levels, may be determinant to the success of each implementation phase. Further research is needed.

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.

Prism adaptation treatment to address spatial neglect in an intensive rehabilitation program: A randomized pilot and feasibility trial

Spatial neglect (SN) is a common cognitive disorder after brain injury. Prism adaptation treatment (PAT) is one of the promising interventions for SN albeit inconsistent results from previous studies. We carried out a comparison intervention (PAT vs. Sham) and aimed to evaluate the efficacy of PAT on visuospatial symptoms of SN in an inpatient rehabilitation setting that offered a highly intensive comprehensive brain injury rehabilitation program. A total of 34 patients with moderate-to-severe SN secondary to stroke or traumatic brain injury were randomized to the PAT group and the Sham group (an active control group). Both groups received 10 sessions of treatment, over two weeks, in addition to the rehabilitation therapies provided by their rehabilitation care teams. Outcomes were measured using an ecological instrument (the Catherine Bergego Scale) and paper-and-pencil tests (the Bells Test, the Line Bisection Test and the Scene Copying Test). Patients were assessed at baseline, immediately after treatment, two weeks after treatment, and four weeks after treatment. 23 (67.6%) patients completed treatment and all the assessment sessions and were included in the final analyses using mixed linear modeling. While SN symptoms reduced in both groups, we found no difference between the two groups in the degree of improvement. In addition, the average SN recovery rates were 39.1% and 28.6% in the PAT and Sham groups, respectively, but this discrepancy did not reach statistical significance. Thus, the present study suggests that PAT may contribute little to SN care in the context of a highly intensive inpatient rehabilitation program. Further large-scale investigation is required to uncover the mechanisms underlying PAT and Sham in order to refine the treatment or create new interventions.

Improved stability of long-duration sitting in spatial neglect after a single session of prism adaptation

Spatial neglect after right brain stroke affects balance, and improvements in sitting balance after prism adaptation have been demonstrated using short-duration center of pressure (CoP) data. We present long-duration (5 min) CoP and trunk muscles electromyography recordings of a 61-year-old man with left-sided spatial neglect, before and after a single session of prism adaptation. His CoP-derived measures showed improved balance and postural stability in both the anterior-posterior and medial-lateral directions after prism adaptation. Concurrently, asymmetry in neuromuscular activations was reduced. The findings suggest that improved sitting balance may be associated with more symmetrical activation of trunk muscles after prism adaptation.

Exploratory examination of lexical and neuroanatomic correlates of neglect dyslexia

OBJECTIVE

This study examined lexical and neuroanatomic correlates of reading errors in individuals with spatial neglect, defined as a failure to respond to stimuli in the side of space opposite a brain lesion, causing functional disability.

METHOD

One-hundred and ten participants with left spatial neglect after right-hemisphere stroke read aloud a list of 36 words. Reading errors were scored as "contralesional" (error in the left half of the word) or as "other." The influence of lexical processing on neglect dyslexia was studied with a stepwise regression using word frequency, orthographic neighborhood (number of same length neighbors that differ by 1 letter), bigram and trigram counts (number of words with the same 2- and 3-letter combinations), length, concreteness, and imageability as predictors. MRI/CT images of 92 patients were studied in a voxelwise lesion-symptom analysis (VLSM).

RESULTS

Longer length and more trigram neighbors increased, while higher concreteness reduced, the rate of contralesional errors. VLSM revealed lesions in the inferior temporal sulcus, middle temporal and angular gyri, precuneus, temporal pole, and temporo-parietal white matter associated with the rate of contralesional errors.

CONCLUSIONS

Orthographic competitors may decrease word salience, while semantic concreteness may help constrain the selection of available word options when it is based on degraded information from the left side of the word. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Considerations of power and sample size in rehabilitation research

With the current emphasis on power and reproducibility, pressures are rising to increase sample sizes in rehabilitation research in order to reflect more accurate effect estimation and generalizable results. The conventional way of increasing power by enrolling more participants is less feasible in some fields of research. In particular, rehabilitation research faces considerable challenges in achieving this goal. We describe the specific challenges to increasing power by recruiting large sample sizes and obtaining large effects in rehabilitation research. Specifically, we discuss how variability within clinical populations, lack of common standards for selecting appropriate control groups; potentially reduced reliability of measurements of brain function in individuals recovering from a brain injury; biases involved in a priori effect size estimation, and higher budgetary and staffing requirements can influence considerations of sample and effect size in rehabilitation. We also describe solutions to these challenges, such as increased sampling per participant, improving experimental control, appropriate analyses, transparent result reporting and using innovative ways of harnessing the inherent variability of clinical populations. These solutions can improve statistical power and produce reliable and valid results even in the face of limited availability of large samples.

Update on the Clinical Approach to Spatial Neglect

PURPOSE OF REVIEW

Spatial neglect is asymmetric orienting and action after a brain lesion, causing functional disability. It is common after a stroke; however, it is vastly underdocumented and undertreated. This article addresses the implementation gap in identifying and treating spatial neglect, to reduce disability and improve healthcare costs and burden.

RECENT FINDINGS

Professional organizations published recommendations to implement spatial neglect care. Physicians can lead an interdisciplinary team: functionally relevant spatial neglect assessment, evidence-based spatial retraining, and integrated spatial and vision interventions can optimize outcomes. Research also strongly suggests spatial neglect adversely affects motor systems. Spatial neglect therapy might thus "kick-start" rehabilitation and improve paralysis recovery. Clinicians can implement new techniques to detect spatial neglect and lead interdisciplinary teams to promote better, integrated spatial neglect care. Future studies of brain imaging biomarkers to detect spatial neglect, and real-world applicability of prism adaptation treatment, are needed.

Direct Gaze Partially Overcomes Hemispatial Neglect and Captures Spatial Attention

Direct gaze has been shown to be a particularly important social cue, being preferentially processed even when unconsciously perceived. Results from several visual search tasks further suggest that direct gaze modulates attention, showing a faster orientation to faces perceived as looking toward us. The present study aimed to analyze putative modulation of spatial attention by eye gaze direction in patients with unilateral neglect. Eight right hemisphere stroke patients with neglect performed a target cancelation paradigm. Patients were instructed to cross all open-eyed pictures amidst closed eyed distractors. Target images were either in direct or averted gaze. Participants performed significantly better when observing targets with direct gaze supporting the hypothesis that this gaze direction captures attention. These findings further suggest that perception of direct gaze is able to diminish the visuospatial impairment seen in neglect patients.

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.

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.

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.

Disruption of the ascending arousal system and cortical attention networks in post-stroke delirium and spatial neglect

Delirium is an acute attention and cognitive dysfunction, adversely affecting functional outcomes and mortality. As many as half of hospitalized right brain stroke survivors may develop delirium. Further, about 50% of right stroke patients experience spatial neglect, impairing safety and recovery. In this review we explore the brain mechanisms, which may explain the high incidence of delirium and spatial neglect after right-brain stroke. We suggest that brain networks for spatial attention and arousal, composed of ascending projections from the midbrain nuclei and integrating dorsal and ventral cortical and limbic components, may underlie impairments in delirium and spatial neglect. We propose that lateralized deficits in spatial neglect may arise because cortical and limbic components of these functional networks are disproportionally impaired by right-brain strokes, and that spatial neglect may lower the threshold for developing delirium. An improved understanding of the brain basis of delirium and spatial neglect could provide a critical biomarker for initiating preventive care in stroke patients at high risk of hospital morbidity and loss of independence.

Patching for Diplopia Contraindicated in Patients with Brain Injury?

PURPOSE

Patching for double vision is a common palliative treatment for head-trauma patients with acquired strabismus when prisms are not feasible.

METHODS

We review literature on spatial neglect and discuss possible effects of monocular occlusion on spatial attention.

RESULTS

Patching the left eye has been shown to worsen spatial judgments in some brain-injured patients with left neglect by inhibiting the right superior colliculus further impairing contralateral leftward orienting (the Sprague Effect).

CONCLUSIONS

Because more peripheral parts of the visual field increasingly project to the contralateral superior colliculus with the temporal crescent being entirely contralateral, avoiding patching of the temporal crescent was advised, and in most cases can be achieved by taping off the spectacle lens and avoiding an elastic eye patch.

Which perseverative behaviors are symptoms of spatial neglect?

Spatial neglect is a characterized by a failure to attend or make movements towards left-sided stimuli. Common paper-and-pencil tasks to diagnose spatial neglect are sensitive to perseverative errors, including additional marks over already cancelled targets and "scribbling" out a target. Here, we examine whether functionally distinct perseverative behaviors are related to spatial neglect. Line cancellation tasks of 45 healthy controls and 220 right-hemisphere stroke survivors were examined for recurrent marks (RM) and continuous marks (CM) perseverations. We found that RM perseveration correlated with neglect severity, while CM perseveration did not. Examination of lesion profiles for the two groups indicated distinct anatomical correlates, with RM lesions overlapping regions implicated in spatial neglect including the rolandic operculum, superior temporal gyrus, and inferior parietal lobule.

The ecological assessment of unilateral neglect

Conventional paper-and-pencil tests of unilateral neglect are of limited ecological validity. To address this issue, a number of assessment procedures have been proposed to provide clinicians and researchers with more ecologically valid assessments of unilateral neglect, which may be useful to plan rehabilitation and to measure the generalization of the effects of rehabilitation to daily life. We present here an overview of the different assessment measures available in the literature. The most widely used scales are the Behavioural Inattention Test (BIT), the semi-structured scales for assessment of personal and extra-personal neglect, the Subjective Neglect Questionnaire, the Baking Tray Task, the wheelchair obstacle course, the ADL-based neglect battery, and the Catherine Bergego Scale (CBS). The CBS is probably, to date, the most widely used behavioural assessment instrument for unilateral neglect. It has been found to be reliable, valid, and sensitive to change during rehabilitation. It also enables the assessment of awareness of the consequences of unilateral neglect in daily life skills.

Asymmetry in the Collision Judgments of People With Homonymous Field Defects and Left Hemispatial Neglect

PURPOSE

Although the impact of homonymous visual field defects (HFDs) on mobility has been investigated previously, the emphasis has been on obstacle detection. Relatively little is known about HFD patients' ability to judge collisions once an obstacle is detected. We investigated this using a walking simulator.

METHODS

Patients with HFDs (n = 29) and subjects with normal vision (NV; n = 21) were seated in front of a large screen on which a visual simulation of walking was displayed. They made collision judgments for a human figure that appeared for 1 second at lateral offsets from the virtual walking path. A perceived-collision threshold was calculated for right and left sides.

RESULTS

Symmetrical collision thresholds (same on left and right sides) were measured for participants with NV (n = 21), and right (n = 9) and left (n = 7) HFD without hemispatial neglect. Participants with left neglect (n = 10) showed significant asymmetry with thresholds smaller (compared to the NV group and other HFD groups) on the blind (P < 0.001) and larger on the seeing (P = 0.05) sides. Despite the asymmetry, the overall width of the zone of perceived collision risk was not different, suggesting a relatively uniform rightward deviation in judgments of the left neglect group.

CONCLUSIONS

Left neglect was associated with rightward asymmetry in collision judgments, which may cause collisions on the left side even when an obstacle is detected. These behaviors may represent the spatial misperceptions in body midline described previously in patients with left neglect.

Midline Body Actions and Leftward Spatial "Aiming" in Patients with Spatial Neglect

Spatial motor–intentional “Aiming” bias is a dysfunction in initiation/execution of motor–intentional behavior, resulting in hypokinetic and hypometric leftward movements. Aiming bias may contribute to posture, balance, and movement problems and uniquely account for disability in post-stroke spatial neglect. Body movement may modify and even worsen Aiming errors, but therapy techniques, such as visual scanning training, do not take this into account. Here, we evaluated (1) whether instructing neglect patients to move midline body parts improves their ability to explore left space and (2) whether this has a different impact on different patients. A 68-year-old woman with spatial neglect after a right basal ganglia infarct had difficulty orienting to and identifying left-sided objects. She was prompted with four instructions: “look to the left,” “point with your nose to the left,” “point with your [right] hand to the left,” and “stick out your tongue and point it to the left.” She oriented leftward dramatically better when pointing with the tongue/nose, than she did when pointing with the hand. We then tested nine more consecutive patients with spatial neglect using the same instructions. Only four of them made any orienting errors. Only one patient made >50% errors when pointing with the hand, and she did not benefit from pointing with the tongue/nose. We observed that pointing with the tongue could facilitate left-sided orientation in a stroke survivor with spatial neglect. If midline structures are represented more bilaterally, they may be less affected by Aiming bias. Alternatively, moving the body midline may be more permissive for leftward orienting than moving right body parts. We were not able to replicate this effect in another patient; we suspect that the magnitude of this effect may depend upon the degree to which patients have directional akinesia, spatial Where deficits, or cerebellar/frontal cortical lesions. Future research could examine these hypotheses.

Prism adaptation and spatial neglect: the need for dose-finding studies

Spatial neglect is a devastating disorder in 50–70% of right-brain stroke survivors, who have problems attending to, or making movements towards, left-sided stimuli, and experience a high risk of chronic dependence. Prism adaptation is a promising treatment for neglect that involves brief, daily visuo-motor training sessions while wearing optical prisms. Its benefits extend to functional behaviors such as dressing, with effects lasting 6 months or longer. Because one to two sessions of prism adaptation induce adaptive changes in both spatial-motor behavior (Fortis et al., 2011) and brain function (Saj et al., 2013), it is possible stroke patients may benefit from treatment periods shorter than the standard, intensive protocol of ten sessions over two weeks—a protocol that is impractical for either US inpatient or outpatient rehabilitation. Demonstrating the effectiveness of a lower dose will maximize the availability of neglect treatment. We present preliminary data suggesting that four to six sessions of prism treatment may induce a large treatment effect, maintained three to four weeks post-treatment. We call for a systematic, randomized clinical trial to establish the minimal effective dose suitable for stroke intervention.

Presence of Motor-Intentional Aiming Deficit Predicts Functional Improvement of Spatial Neglect With Prism Adaptation

Background Spatial neglect is a debilitating disorder for which there is no agreed on course of rehabilitation. The lack of consensus on treatment may result from systematic differences in the syndrome's characteristics, with spatial cognitive deficits potentially affecting perceptual-attentional "Where" or motor-intentional "Aiming" spatial processing. Heterogeneity of response to treatment might be explained by different treatment impacts on these dissociated deficits: prism adaptation, for example, might reduce Aiming deficits without affecting Where spatial deficits.

OBJECTIVE

Here, we tested the hypothesis that classifying patients by their profile of Where-versus-Aiming spatial deficit would predict response to prism adaptation and specifically that patients with Aiming bias would have better recovery than those with isolated Where bias. Methods We classified the spatial errors of 24 subacute right stroke survivors with left spatial neglect as (1) isolated Where bias, (2) isolated Aiming bias, or (3) both. Participants then completed 2 weeks of prism adaptation treatment. They also completed the Behavioral Inattention Test and Catherine Bergego Scale (CBS) tests of neglect recovery weekly for 6 weeks. Results As hypothesized, participants with only Aiming deficits improved on the CBS, whereas those with only Where deficits did not improve. Participants with both deficits demonstrated intermediate improvement. Conclusion These results support behavioral classification of spatial neglect patients as a potential valuable tool for assigning targeted, effective early rehabilitation.

Advancing the science of spatial neglect rehabilitation: an improved statistical approach with mixed linear modeling

Valid research on neglect rehabilitation demands a statistical approach commensurate with the characteristics of neglect rehabilitation data: neglect arises from impairment in distinct brain networks leading to large between-subject variability in baseline symptoms and recovery trajectories. Studies enrolling medically ill, disabled patients, may suffer from missing, unbalanced data, and small sample sizes. Finally, assessment of rehabilitation requires a description of continuous recovery trajectories. Unfortunately, the statistical method currently employed in most studies of neglect treatment [repeated measures analysis of variance (ANOVA), rANOVA] does not well-address these issues. Here we review an alternative, mixed linear modeling (MLM), that is more appropriate for assessing change over time. MLM better accounts for between-subject heterogeneity in baseline neglect severity and in recovery trajectory. MLM does not require complete or balanced data, nor does it make strict assumptions regarding the data structure. Furthermore, because MLM better models between-subject heterogeneity it often results in increased power to observe treatment effects with smaller samples. After reviewing current practices in the field, and the assumptions of rANOVA, we provide an introduction to MLM. We review its assumptions, uses, advantages, and disadvantages. Using real and simulated data, we illustrate how MLM may improve the ability to detect effects of treatment over ANOVA, particularly with the small samples typical of neglect research. Furthermore, our simulation analyses result in recommendations for the design of future rehabilitation studies. Because between-subject heterogeneity is one important reason why studies of neglect treatments often yield conflicting results, employing statistical procedures that model this heterogeneity more accurately will increase the efficiency of our efforts to find treatments to improve the lives of individuals with neglect.

Prism Adaptation Improves Ego-Centered but Not Allocentric Neglect in Early Rehabilitation Patients

Background and Objective. Unilateral neglect due to parieto-temporo-frontal lesions has a negative impact on the success of rehabilitation, and prism adaptation (PA) enhances recovery from neglect. However, it is unclear if this effect holds also in severely impaired patients and/or in the postacute phase of rehabilitation. Moreover, it is not known whether PA affects all aspects of neglect recovery or ego-centered spatial orientation only. Methods. Sixteen patients in a postacute stage (on average 36 days after a large right cerebrovascular stroke) were entered into a series of single case design studies with 4 measurements: 2 before and 2 after 1 week of PA treatment. All patients had severe neglect (showing trunk, head, and eye deviation; canceling less than 20% of targets in a visual cancellation test). Lesions were transferred to a standard brain to analyze size and location. Results. Patients improved in cued body orientation and in the cancellation task, that is, in ego-centered neglect. However, none of the measures used to evaluate neglect of left side of objects irrespective of their position on the right or left side of the patient (allocentric neglect) showed an improvement. Treatment effects were not influenced by total lesion size, but lesions including the postcentral cortex were related to smaller recovery gains. Conclusion. PA is helpful in treating severely impaired patients in the postacute phase, but the effect is restricted to ego-centered neglect. Lesions in the postcentral cortex (middle occipito-temporal, middle temporal, and posterior parietal areas) seem to limit the effect of PA.