Increasing cognitive demand in assessments of visuo-spatial neglect: Testing the concepts of static and dynamic tests

Virtual reality in clinical evaluation of Unilateral Spatial Neglect, anatomy of current trends: A scoping review

BACKGROUND

Virtual technologies (VR) could respond to several challenges in Unilateral Spatial Neglect (USN) assessment, particularly the lack of sensitivity and ecological validity of traditional paper-and-pencil tests. A scoping review was conducted to explore current trends in this area.

METHODS

PubMed, EMBASE, PsycINFO, Web of Science, IEEE, ACM, and the Cochrane Library were systematically searched for VR USN assessment. The Joanna Briggs Institute methodological guidelines for scoping reviews were used to inform our methodology.

RESULTS

Thirty-one publications were included. There were two populations: healthy adults (n = 349) and post-stroke individuals (n = 903). A classification based on tasks and type of interaction used was proposed. Correlations with paper and pencil tests (PPTs) were often significant when the task structure was similar to PPTs but was lacking for activities with more dynamic components. The ecological validity of the tasks was assessed in comparison with the Catherine Bergego Scale (n = 4) and a real-world navigation task (n = 1). Using VR, USN disorders have been characterized using a wide range of indicators.

CONCLUSIONS

Few studies have addressed ecological validity, yet the use of VR in the assessment of the USN in this scoping review shows an undeniable contribution compared to traditional pencil-paper tests, especially for capturing the patient's behavior toward the far extrapersonal space, essential in daily life.

How have neck muscle vibration effects on visuospatial behavior and spatial neglect been explored? A scoping review

INTRODUCTION

Neck muscle vibration (NMV) has been proposed as a bottom-up intervention to enhance visuospatial exploration in post-stroke patients with unilateral spatial neglect (USN). While some studies report enlarged visual exploration during NMV application, others find no significant impact, highlighting inconsistencies in the literature. The diversity in NMV application methods and the variation in visuospatial outcome measures may contribute to these conflicting findings. This study aimed to overview the methodological approaches used to investigate NMV's effects on visuospatial behavior in USN patients, focusing on aspects beyond sample size and study design.

METHODS

Among the seven databases, studies that applied NMV and assessed visual or perceptual outcomes were included in the analysis. Two independent reviewers screened titles and abstracts to select the studies to analyze. Data about the publication, population, modalities of application, and outcomes were extracted and synthesized.

RESULTS

Twenty-five publications from 1988 to 2023 were included, involving a total of 512 participants, of whom 114 (22.3%) had USN. The presence of USN was assessed based on paper-and-pencil tests. The frequency of NMV was set between 80 and 125 hz. In 22 studies, NMV were applied on the left side of the neck muscles. Six studies proposed multiple NMV sessions, lasting between 5 and 50 minutes/day, 3-5 times/week, for 2-4 weeks. One study included a follow-up period of up to 1.4 years. The tasks during NMV often involved indicating the subjective straight ahead (SSA, n = 8), pointing out targets, or no specific activity (n = 7, each). The SSA and cancellation tests were the most frequent outcomes.

CONCLUSIONS

NMV application modalities varied widely across studies, with only vibration frequency showing consistency. The tasks performed during NMV and the outcome measures were diverse and generally unrelated to activities of daily living. Therefore, NMV effects during more ecologically valid tasks should be explored.

Alpha transcranial alternating current stimulation as add-on to neglect training: a randomized trial

Visuospatial neglect is a common and debilitating condition following unilateral stroke, significantly impacting cognitive functioning and daily life. There is an urgent need for effective treatments that can provide clinically relevant and sustained benefits. In addition to traditional stroke treatment, non-invasive brain stimulation, such as transcranial alternating current stimulation, shows promise as a complementary approach to enhance stroke recovery. In the current study, we aimed to evaluate the additive effects of multi-session transcranial alternating current stimulation at alpha frequency when combined with visual scanning training in chronic stroke patients with visuospatial neglect. In this double-blind randomized controlled trial, we compared the effects of active transcranial alternating current stimulation at alpha frequency to sham (placebo) transcranial alternating current stimulation, both combined with visual scanning training. Both groups received eighteen 40-minute training sessions over a 6-week period. A total of 22 chronic visuospatial neglect patients participated in the study (active group n = 12, sham group n = 10). The median age was 61.0 years, with a median time since stroke of 36.1 months. We assessed the patients at six time-points: at baseline, after the first, ninth and eighteenth training sessions, as well as 1 week and 3 months following the completion of the combined neuromodulation intervention. The primary outcome measure was the change in performance on a visual search task, specifically the star cancellation task. Secondary outcomes included performance on a visual detection task, two line bisection tasks and three tasks evaluating visuospatial neglect in daily living. We found significantly improved visual search (primary outcome) and visual detection performance in the neglected side in the active transcranial alternating current stimulation group, compared to the sham transcranial alternating current stimulation group. We did not observe stimulation effects on line bisection performance nor in daily living. Time effects were observed on all but one outcome measures. Multi-session transcranial alternating current stimulation combined with visual scanning training may be a more effective treatment for chronic visuospatial neglect than visual scanning training alone. These findings provide valuable insights into novel strategies for stroke recovery, even long after the injury, with the aim of enhancing cognitive rehabilitation outcomes and improving the overall quality of life for individuals affected by this condition. Trial registration: ClinicalTrials.gov; registration number: NCT05466487; https://clinicaltrials.gov/ct2/show/NCT05466487.

Cardiac vagal activity changes moderated the association of cognitive and cerebral hemodynamic variations in the prefrontal cortex

Phasic cardiac vagal activity (CVA), reflecting ongoing, moment-to-moment psychophysiological adaptations to environmental changes, can serve as a predictor of individual difference in executive function, particularly executive performance. However, the relationship between phasic CVA and executive function demands requires further validation because of previous inconsistent findings. Moreover, it remains unclear what types of phasic changes of CVA may be adaptive in response to heightened executive demands. This study used the standard N-back task to induce different levels of working memory (WM) load and combined functional Near-Infrared Spectroscopy (fNIRS) with a multipurpose polygraph to investigate the variations of CVA and its interactions with cognitive and prefrontal responses as executive demands increased in fifty-two healthy young subjects. Our results showed phasic decreases in CVA as WM load increased (t (51) = -3.758, p < 0.001, Cohen's d = 0.526). Furthermore, phasic changes of CVA elicited by increased executive demands moderated the association of cognitive and cerebral hemodynamic variations in the prefrontal cortex (B = 0.038, SE = 0.014, p < 0.05). Specifically, as executive demands increased, individuals with larger phasic CVA withdrawal showed a positive relationship between cognitive and hemodynamic variations in the prefrontal cortex (β = 0.281, p = 0.031). No such significant relationship was observed in individuals with smaller phasic CVA withdrawal. The current findings demonstrate a decrease in CVA with increasing executive demands and provide empirical support for the notion that a larger phasic CVA withdrawal can be considered adaptive in situations requiring high executive function demands.

The effect of offline anosognosia for hemispatial neglect on neglect rehabilitation in patients with subacute and chronic right hemispheric brain injury. A retrospective cohort study

CLINICAL TRIALS REGISTRATION NUMBER

NCT05145855.

Application of immersive virtual reality for assessing chronic neglect in individuals with stroke: the immersive virtual road-crossing task

BACKGROUND

Neglect can be a long-term consequence of chronic stroke that can impede an individual's ability to perform daily activities, but chronic and discrete forms can be difficult to detect. We developed and evaluated the "immersive virtual road-crossing task" (iVRoad) to identify and quantify discrete neglect symptoms in chronic stroke patients.

METHOD

The iVRoad task requires crossing virtual intersections and placing a letter in a mailbox placed either on the left or right. We tested three groups using the HTC Vive Pro Eye: (1) chronic right hemisphere stroke patients with (N = 20) and (2) without (N = 20) chronic left-sided neglect, and (3) age and gender-matched healthy controls (N = 20). We analyzed temporal parameters, errors, and head rotation to identify group-specific patterns, and applied questionnaires to measure self-assessed pedestrian behavior and usability.

RESULTS

Overall, the task was well-tolerated by all participants with fewer cybersickness-induced symptoms after the VR exposure than before. Reaction time, left-sided errors, and lateral head movements for traffic from left most clearly distinguished between groups. Neglect patients committed more dangerous crossings, but their self-rated pedestrian behavior did not differ from that of stroke patients without neglect. This demonstrates their reduced awareness of the risks in everyday life and highlights the clinical relevance of the task.

CONCLUSIONS

Our findings suggest that a virtual road crossing task, such as iVRoad, has the potential to identify subtle symptoms of neglect by providing virtual scenarios that more closely resemble the demands and challenges of everyday life. iVRoad is an immersive, naturalistic virtual reality task that can measure clinically relevant behavioral variance and identify discrete neglect symptoms.

Prevalence, Severity and Impact of Visuospatial Neglect in Geriatric Stroke Rehabilitation, a Cross-Sectional Study

OBJECTIVES

Visuospatial neglect (VSN) is a common cognitive deficit of lateralized attention after stroke and can have a negative influence on patients' daily activities, community participation, and caregiver burden. VSN prevalence has been investigated in several mixed-age populations, but rarely in only an older population. As the population in geriatric rehabilitation (GR) is understudied and VSN may influence rehabilitation goals in GR (return home), we examined the prevalence of VSN as well as associations between VSN (severity) and population characteristics and the impact of VSN on functioning, length of stay, and discharge destination after GR.

DESIGN

Multicenter cross-sectional study.

SETTING AND PARTICIPANTS

Stroke patients admitted to GR.

METHODS

Three VSN tests (Star cancelation task, Line bisection task, and Catherine Bergego Scale) were administered in the first 2 weeks of GR admission. To examine VSN severity, a composite score was calculated based on scores of the 3 tests.

RESULTS

A total of 114 stroke patients were included [55.3% female; mean age 80.2 (SD 8.0) years]. VSN prevalence was 47.4%, in which allocentric and egocentric neglect were more prevalent than VSN during activities of daily living. Participants with VSN spent more days in GR compared to participants without VSN (median 68.5 vs 35.5 days) and had fewer home returns. In addition, VSN participants showed less mobility, lower cognitive functioning, and less independence during self-care compared to participants without VSN. Mobility, self-care, cognition, duration of rehabilitation, and home return were negatively associated with VSN severity.

CONCLUSIONS AND IMPLICATIONS

VSN is very prevalent in the GR stroke population. VSN severely hampers older people during daily activities and their rehabilitation process and, therefore, has a major personal and societal impact. Accordingly, systematic assessment of VSN in the early phase of geriatric rehabilitation with multiple VSN screening tests is recommended.

Uncovering the (un)attended: Pupil light responses index persistent biases of spatial attention in neglect

Visuospatial neglect is a frequent and disabling disorder, mostly after stroke, that presents in impaired awareness to stimuli on one side of space. Neglect causes disability and functional dependence, even long after the injury. Improving measurements of the core attentional deficit might hold the key for better understanding of the condition and development of treatment. We present a rapid, pupillometry-based method that assesses automatic biases in (covert) attention, without requiring behavioral responses. We exploit the phenomenon that pupil light responses scale with the degree of covert attention to stimuli, and thereby reveal what draws (no) attention. Participants with left-sided neglect after right-sided lesions following stroke (n = 5), participants with hemianopia/quadrantanopia following stroke (n = 11), and controls (n = 22) were presented with two vertical bars, one of which was white and one of which was black, while fixating the center. We varied which brightness was left and right, respectively across trials. In line with the hypotheses, participants with neglect demonstrated biased pupil light responses to the brightness on the right side. Participants with hemianopia showed similar biases to intact parts of the visual field, whilst controls exhibited no bias. Together, this demonstrates that the pupil light response can reveal not only visual, but also attentional deficits. Strikingly, our pupillometry-based bias estimates were not in agreement with neuropsychological paper-and-pencil assessments conducted on the same day, but were with those administered in an earlier phase post-stroke. Potentially, we pick up on persistent biases in the covert attentional system that participants increasingly compensate for in classical neuropsychological tasks and everyday life. The here proposed method may not only find clinical application, but also advance theory and aid the development of successful restoration therapies by introducing a precise, longitudinally valid, and objective measurement that might not be affected by compensation.

General cognitive decline does not account for older adults' worse emotion recognition and theory of mind

Older adults have both worse general cognition and worse social cognition. A frequent suggestion is that worse social cognition is due to worse general cognition. However, previous studies have often provided contradictory evidence. The current study examined this issue with a more extensive battery of tasks for both forms of cognition. We gave 47 young and 40 older adults three tasks to assess general cognition (processing speed, working memory, fluid intelligence) and three tasks to assess their social cognition (emotion and theory-of-mind). Older adults did worse on all tasks and there were correlations between general and social cognition. Although working memory and fluid intelligence were unique predictors of performance on the Emotion Photos task and the Eyes task, Age Group was a unique predictor on all three social cognition tasks. Thus, there were relations between the two forms of cognition but older adults continued to do worse than young adults even after accounting for general cognition. We argue that this pattern of results is due to some overlap in brain areas mediating general and social cognition, but also independence, and with a differential rate of decline in brain areas dedicated to general cognition versus social cognition.

The mobility assessment course: A ready-to-use dynamic measure of visuospatial neglect

The Mobility Assessment Course (MAC) is a tool to measure visuospatial neglect in a dynamic fashion. Although the MAC has been shown to dissociate between patients with and without neglect, it remains unclear whether it is applicable in clinical settings. We evaluated the MAC regarding its (1) feasibility as a diagnostic tool as part of standard care, (2) construct validity, and (3) underlying constructs and potential confounders. A consecutive sample of stroke patients admitted to inpatient rehabilitation completed the MAC, shape cancellation, line bisection, and/or Catherine Bergego Scale (CBS) as part of the standard assessment. To assess feasibility, we computed the percentage of patients who completed the MAC. Construct validity was tested by evaluating MAC performance between patients with and without neglect and controls. Finally, a regression analysis was conducted to assess underlying constructs and potential confounders of MAC performance (i.e., level of mobility and lesion side). The MAC was completed by 82% of patients (N = 182/223; of whom 145 completed all tasks). Patients with neglect performed worse on the MAC (indicating more severe neglect) compared to patients without neglect and controls. The MAC had a lower sensitivity and higher specificity than paper-and-pencil tasks and the CBS. Performance on shape cancellation, line bisection, and CBS were predictors of MAC performance. Level of mobility and lesion side did not predict MAC scores, indicating that these factors do not confound its reliability. To conclude, the MAC is an easy-to-implement tool to evaluate neglect in a dynamic manner, which can be administered in addition to conventional paper-and-pencil tasks.

Virtual Reality and Eye-Tracking Assessment, and Treatment of Unilateral Spatial Neglect: Systematic Review and Future Prospects

Unilateral spatial neglect (USN) is a disorder characterized by the failure to report, respond to, or orient toward the contralateral side of space to a brain lesion. Current assessment methods often fail to discover milder forms, cannot differentiate between unilateral spatial neglect subtypes and lack ecological validity. There is also a need for treatment methods that target subtypes. Immersive virtual reality (VR) systems in combination with eye-tracking (ET) have the potential to overcome these shortcomings, by providing more naturalistic environments and tasks, with sensitive and detailed measures. This systematic review examines the state of the art of research on these technologies as applied in the assessment and treatment of USN. As we found no studies that combined immersive VR and ET, we reviewed these approaches individually. The review of VR included seven articles, the ET review twelve. The reviews revealed promising results. (1) All included studies found significant group-level differences for several USN measures. In addition, several studies found asymmetric behavior in VR and ET tasks for patients who did not show signs of USN in conventional tests. Particularly promising features were multitasking in complex VR environments and detailed eye-movement analysis. (2) No VR and only a few ET studies attempted to differentiate USN subtypes, although the technologies appeared appropriate. One ET study grouped USN participants using individual heatmaps, and another differentiated between subtypes on drawing tasks. Regarding (3) ecological validity, although no studies tested the prognostic validity of their assessment methods, VR and ET studies utilized naturalistic tasks and stimuli reflecting everyday situations. Technological characteristics, such as the field of view and refresh rate of the head-mounted displays, could be improved, though, to improve ecological validity. We found (4) no studies that utilized VR or ET technologies for USN treatment up until the search date of the 26th of February 2020. In conclusion, VR-ET-based systems show great potential for USN assessment. VR-ET holds great promise for treatment, for example, by monitoring behavior and adapting and tailoring to the individual person's needs and abilities. Future research should consider developing methods for individual subtypes and differential diagnostics to inform individual treatment programs.

Functional neurological disorder: Extending the diagnosis to other disorders, and proposing an alternate disease term—Attentionally-modifiable disorder

BACKGROUND: The term “functional neurological disorder,” or “FND,” applies to disorders whose occurrence of neurological symptoms fluctuate with the patient’s attention to them. However, many other disorders that are not called “FND” nonetheless can also follow this pattern. Consequently, guidelines are unclear for diagnosing “FND.” OBJECTIVE: To review the neurological conditions that follow this pattern, but which have not so far been termed “FND,” to understand their overlap with conditions that have been termed “FND,” and to discuss the rationale for why FND has not been diagnosed for them. METHOD: A systematic review of the PubMed literature registry using the terms “fluctuation,” “inconsistency,” or “attention” did not yield much in the way of these candidate disorders. Consequently, this review instead relied on the author’s personal library of peer-reviewed studies of disorders that have resembled FND but which were not termed this way, due to his longstanding interest in this problem. Consequently, this approach was not systematic and was subjective regarding disease inclusion. RESULTS: This review identified numerous, diverse conditions that generally involve fluctuating neurological symptoms that can vary with the person’s attention to them, but which have not been called “FND.” The literature was unclear for reasons for not referring to “FND” in these instances. CONCLUSION: Most likely because of historical biases, the use of the term “FND” has been unnecessarily restricted. Because at its core FND is an attentionally-influenced disorder that can respond well to behavioral treatments, the field of neurological rehabilitation could benefit by extending the range of conditions that could be considered as “FND” and referred for similar behavioral treatments. Because the term “FND” has been viewed unfavorably by some patients and clinical practitioners and whose treatment is not implied, the alternative term attentionally-modifiable disorder is proposed.

Computer-Based Assessment: Dual-Task Outperforms Large-Screen Cancellation Task in Detecting Contralesional Omissions

Objective: Traditionally, asymmetric spatial processing (i.e., hemispatial neglect) has been assessed with paper-and-pencil tasks, but growing evidence indicates that computer-based methods are a more sensitive assessment modality. It is not known, however, whether simply converting well-established paper-and-pencil methods into a digital format is the best option. The aim of the present study was to compare sensitivity in detecting contralesional omissions of two different computer-based methods: a "digitally converted" cancellation task was compared with a computer-based Visual and Auditory dual-tasking approach, which has already proved to be very sensitive. Methods: Participants included 40 patients with chronic unilateral stroke in either the right hemisphere (RH patients, N = 20) or the left hemisphere (LH patients, N = 20) and 20 age-matched healthy controls. The cancellation task was implemented on a very large format (173 cm × 277 cm) or in a smaller (A4) paper-and-pencil version. The computer-based dual-tasks were implemented on a 15'' monitor and required the detection of unilateral and bilateral briefly presented lateralized targets. Results: Neither version of the cancellation task was able to show spatial bias in RH patients. In contrast, in the Visual dual-task RH patients missed significantly more left-sided targets than controls in both unilateral and bilateral trials. They also missed significantly more left-sided than right-sided targets only in the bilateral trials of the Auditory dual-task. Conclusion: The dual-task setting outperforms the cancellation task approach even when the latter is implemented on a (large) screen. Attentionally demanding methods are useful for revealing mild forms of contralesional visuospatial deficits.

How does the number of targets affect visual search performance in visuospatial neglect?

INTRODUCTION

Impairments in visual search are a common symptom in visuospatial neglect (VSN). The severity of the lateralized attention bias in visual search tasks can vary depending on the number of distractors: the more distractors, the more targets are missed. However, little is known about how the number of targets affect search performance in VSN. The aim of the current study was to examine the effect of the number of targets on hit rate in VSN.

METHODS

We included 23 stroke patients with right-brain damage and VSN, 55 with right-brain damage without VSN, and 49 with left-brain damage without VSN, all admitted for inpatient rehabilitation. In a visual search task, patients had to find and tap targets, presented along with non-targets. The location and number of targets varied from trial to trial, allowing the evaluation of the effects of number and location of targets on hit rate.

RESULTS

VSN patients detected a lower percentage of targets when more targets were present. For patients with right-brain damage without VSN, adding targets only reduced the hit rate of the most contralesional target. No effect of number of targets on hit rate was seen in patients with left-brain damage. Additionally, VSN patients found less contralesional targets than ipsilesional targets, made more delayed revisits, and had an initial rightward bias when compared to the other groups. There were no differences in search time, search consistency, or immediate revisits between groups. There was a moderate positive relation between the hit rate asymmetry score in our search task and conventional paper-and-pencil VSN tasks, and neglect behavior in daily life.

CONCLUSIONS

In VSN patients, a higher number of targets reduces the hit rate. The reduced hit rate in visual search evoked by additional targets should be taken into account when assessing visual search in VSN.

The association between visuospatial neglect and balance and mobility post-stroke onset: A systematic review

BACKGROUND

Although previous narrative reviews have highlighted a potential association between visuospatial neglect (VSN) and balance disorders, to what extent different areas of balance and mobility could be affected is still unclear.

OBJECTIVES

This systematic review updates previous literature findings and systematically reviews sitting balance, standing balance and mobility outcomes.

METHODS

PubMed, Web of Science, ScienceDirect, Naric-Rehabdata, PEDro and the Cochrane Trials Library were systematically searched. Methodological quality was assessed by the National Heart, Lung, and Blood Institute Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. The association between VSN and sitting balance, standing balance and mobility (walking, stair climbing/descending and transfers) was investigated.

RESULTS

In total, 48 studies were included (4595 stroke survivors): at least 1319 (29%) showed symptoms of VSN. VSN was associated with less independence during sitting, with an asymmetric posture toward the affected body side. For standing balance, we revealed a significant negative association between VSN and mediolateral stability and weight shifting, whereas only activities of daily living-related VSN was associated with weight-bearing asymmetry during static stance. While walking, patients with VSN laterally deviated from their path. Results were inconclusive regarding other aspects of mobility. The association between VSN and balance/mobility seemed to decrease over time.

CONCLUSIONS

Despite great heterogeneity in results, this study suggests that stroke survivors with VSN show specific deviations in posture and movement in the mediolateral direction. Although the association between VSN and balance/mobility has been extensively investigated, explanatory studies evaluating underlying mechanisms of the frequently present association are lacking. Future studies should address this by combining clinical and instrumented assessment of balance and gait performance, preferably longitudinally to investigate the associations over time.