Left Unilateral Spatial Neglect Research Articles

Neglecting the bottom space: an object-based disorder? A two-case observational study

ABSTRACT Altitudinal neglect is an atypical form of spatial neglect where brain-damaged patients neglect the lower, or sometimes the upper, part of the space. Our understanding of this phenomena is limited, with unknown occurrence across different reference frames, such as distance (peripersonal vs. extrapersonal) and system of reference (egocentric vs. allocentric). Two patients with acute bilateral (P1) or right hemispheric (P2) stroke, with signs of bottom altitudinal neglect, underwent an extensive evaluation of neglect within 10 days post-stroke. Assessments involved altitudinal neglect and unilateral spatial neglect (USN) in peripersonal space, exploring egocentric and allocentric signs and in extrapersonal space. Compared to a control group of 15 healthy age-matched subjects, patients showed allocentric and egocentric left USN in peripersonal space, and mostly allocentric signs of altitudinal neglect. No signs of neglect were evidenced in extrapersonal space. Altitudinal neglect could thus present as an allocentric form of spatial neglect, suggesting that allocentric representations may not only affect the deployment of attentional resources along horizontal dimensions but also operate along vertical dimensions. Future studies should deepen our understanding of altitudinal neglect, eventually leading to further unravel spatial processes that control attention, their corresponding brain mechanisms, and implications for patients’ rehabilitation and functional outcome.

An immersive virtual reality tool for assessing left and right unilateral spatial neglect.

The reported rate of the occurrence of unilateral spatial neglect (USN) is highly variable likely due to the lack of validity and low sensitivity of classical tools used to assess it. Virtual reality (VR) assessments try to overcome these limitations by proposing immersive and complex environments. Nevertheless, existing VR-based tasks are mostly focused only on near space and lack analysis of psychometric properties and/or clinical validation. The present study evaluates the clinical validity and sensitivity of a new immersive VR-based task to assess USN in the extra-personal space and examines the neuronal correlates of deficits of far space exploration. The task was administrated to two groups of patients with right (N = 28) or left (N = 11) hemispheric brain lesions, also undergoing classical paper-and-pencil assessment, as well as a group of healthy participants. Our VR-based task detected 44% of neglect cases compared to 31% by paper-and-pencil tests in the total sample. Importantly, 30% of the patients (with right or left brain lesions) with no clear sign of USN on the paper-and-pencil tests performed outside the normal range in the VR-based task. Voxel lesion-symptom mapping revealed that deficits detected in VR were associated with lesions in insular and temporal cortex, part of the neural network involved in spatial processing. These results show that our immersive VR-based task is efficient and sensitive in detecting mild to strong manifestations of USN affecting the extra-personal space, which may be undetected using standard tools.

Left unilateral spatial neglect of the right hand in a haptic bisection test in a case of callosal disconnection syndrome

Left unilateral spatial neglect of the right hand in a haptic bisection test in a case of callosal disconnection syndrome

Effect of stimulation-driven attention in virtual reality balloon search training of patients with left unilateral spatial neglect after stroke: A randomized crossover study

ABSTRACT Patients with unilateral spatial neglect (USN) commonly experiences stimulus-driven attention deficit characterized by unexpected stimuli detection. We investigated whether virtual reality (VR) balloon search training with the screen background shifted to left space could improve stimulus-driven attention in patients with USN. The participants were divided into two groups: immediate VR group (n = 14) and delayed VR group (n = 14). The immediate VR group first received VR balloon search training, followed by control training, for two weeks each. Delayed VR group received the same training in reverse order. Outcomes were changes in scores on Catherine Bergego Scale (CBS) and reaction time on the modified Posner task (MPT). There was significant improvement in CBS score change after VR balloon retrieval training (all F > 2.71; P < 0.002). In the invalid condition of MPT, significant improvements were shown after VR balloon search training in left-sided reaction time (improvement of stimulation-driven attention). This study shows that VR balloon search training can improve neglect symptoms by using an intensive intervention lasting 2 weeks.

Sensitivity and Specificity of the Brentano Illusion Test in the Detection of Visual Hemi-Field Deficits in Patients with Unilateral Spatial Neglect.

Stroke survivors with right-brain damage (RBD) often present with attentional deficits such as left unilateral spatial neglect. Some patients also present with contralesional visual hemi-field deficits. A late detection of visual hemi-field deficits (VHFD) contributes to hampering neurorehabilitation and functional outcome of patients with neglect. The Brentano Illusion Test (BRIT) may be used for an early detection of VHFD during the neuropsychological assessment. In the present study, we determined the sensitivity and specificity of the BRIT for screening VHFD in patients with neglect. Sixty-four consecutive RBD patients were examined. Forty-five presented with neglect. Of these, 23 presented with VHFD (hemianopia or quadrantanopia) as detected by the Humphrey automated static visual field testing (reference standard). Consecutive patients also included 19 participants without neglect, who did not have any VHFD. The sensitivity and specificity of the BRIT for neglect patients were 78.3% (95% CI: 61.4-95.1) and 90.9 (95% CI: 78.9-100.0), respectively. Positive predictive value (PPV) was 89.6% (95% CI: 76.4-100.0); negative predictive value (NPV) 80.7% (95% CI: 65.2-96.2). No false positives in the group without neglect were identified. We conclude that the BRIT is an effective tool for clinical neuropsychologists to screen for possible VHFD in neglect patients during the neuropsychological assessment, allowing the refinement of the clinical picture in the neuropsychological report. An early detection of VHFD also allows referring the patient to standard diagnostics for a formal visual field examination, right from the first neuropsychological assessment.

Innovative Therapy Combining Neck Muscle Vibration and Transcranial Direct Current Stimulation in Association with Conventional Rehabilitation in Left Unilateral Spatial Neglect Patients: HEMISTIM Protocol for a Randomized Controlled Trial

Unilateral spatial neglect (USN) rehabilitation requires the development of new methods that can be easily integrated into conventional practice. The aim of the HEMISTIM protocol is to assess immediate and long-term recovery induced by an innovative association of left-side neck-muscle vibration (NMV) and anodal transcranial Direct Current Stimulation (tDCS) on the ipsilesional posterior parietal cortex during occupational therapy sessions in patients with left USN. Participants will be randomly assigned to four groups: control, Left-NMV, Left-NMV + sham-tDCS or Left-NMV + anodal-tDCS. NMV and tDCS will be applied during the first 15 min of occupational therapy sessions, three days a week for three weeks. USN will be assessed at baseline, just at the end of the first experimental session, after the first and third weeks of the protocol and three weeks after its ending. Our primary outcome will be the evolution of the functional Catherine Bergego Scale score. Secondary outcome measures include five tests that investigate different neuropsychological aspects of USN. Left NMV, by activating multisensory integration neuronal networks, might enhance effects obtained by conventional therapy since post-effects were shown when it was combined with upper limb movements. We expect to reinforce lasting intermodal recalibration through LTP-like plasticity induced by anodal tDCS.

Full-field input generated from right visual field information for healthy participants reproduces performance simulating left unilateral spatial neglect in line bisection.

Patients with left unilateral spatial neglect (USN) typically place the subjective midpoint to the right of the objective centre when bisecting a horizontal line. This pathological phenomenon may be explained as a result of greater dependence on the right endpoint in the external reference frame (Koyama et al., Brain Cogn, 35, 1997, 271; McIntosh et al., Cogn Brain Res, 25, 2005, 833). Ishiai et al. (Brain, 112, 1989, 1485) reported that once patients with USN fixated on a certain point on the right part of the presented line, they persisted with this point and marked the subjective midpoint there without leftward searches. Ishiai et al.'s interpretation was that the patients saw a totalised line representation that extended equidistantly to the right and left sides, based on the information of the attended rightward extent from the subjective midpoint. Accordingly, we used virtual reality goggles (VRG) and devised a mirror-image viewing (MV) condition that showed a full-field view based on the right visual field information to test whether healthy participants would thereby show neglect-like bisection performance. The participants were 30 healthy adults (22-37 years old; 15 women and 15 men). In this condition, 96.7% (29/30) of participants were judged to exhibit USN-like performance of line bisection, indicating the effectiveness of MV condition to simulate USN. The novelty of the present study lies in the use of a task-specific intervention of neglect-like visuospatial processing during line bisection without attempting to modify the direction of spatial attention. This approach may contribute to the understanding of the pathological visuospatial processing of USN.

Effects of Sentence Line-Break Position on Reading Errors and Eye Movements in Patients with Left Unilateral Spatial Neglect

Effects of Sentence Line-Break Position on Reading Errors and Eye Movements in Patients with Left Unilateral Spatial Neglect

Reaction time analysis in patients with mild left unilateral spatial neglect employing the modified Posner task: vertical and horizontal dimensions.

Unilateral spatial neglect (USN) is a common neurological syndrome that develops after a right hemisphere lesion. By examining the performance of the modified Posner task added to the vertical dimensions of the left and right visual fields, we studied whether the lower left area had different neglect symptoms than the other locations. 41 patients with right hemisphere damage were classified into those with mild USN (USN+ ; n = 20) and without USN (USN- ; n = 21). Twenty older participants made up the healthy control (HC; n = 20) group. All participants recorded deficits in the paper-and-pencil tests established for neglect and reaction times in the modified Posner task. In the paper-and-pencil tests, there was no difference in deficit between the upper and lower left visual fields in any of the groups. According to the modified Posner task, the USN+ group exhibited delays in reaction time in the lower left visual field rather than the upper left visual field. Importantly, reaction times were delayed, and USN symptoms persisted, particularly for the lower left quadrant. Our findings imply that the modified Posner task can accurately uncover neglect symptoms in the case of mild USN.

Effect of motor tasks with left monocular eyeglasses on visual search and line-bisection performance in people with left unilateral spatial neglect

ABSTRACT Training with an eyepatch or eyeglasses is one of the effective approaches for unilateral spatial neglect (USN), and it usually uses a device that covers the right side. However, few approaches are available for the left side. In this study, we examine the effect of motor tasks with left/right monocular eyeglasses on visual search and line-bisection performance in people with left USN. Seven participants with left USN admitted to convalescent hospitals were included. We conducted the Bells test, line-crossing test, and line-bisection test of the behavioral inattention test before/after the motor task. Our analyses focused on the improvement or decline in these assessment scores and the achievement/errors/non-smoothness scores of the motor task. When using the left monocular eyeglasses, the percentages of participants categorized as “improvement,” “unchanged,” and “decline” were 71.4%, 28.6%, and 0%, respectively (when using the right one they were 14.3%, 85.7%, and 0%). In the motor task, when using the left monocular eyeglasses, total achievement scores in five of seven participants were greater than those when using the right one, and they performed efficiently with fewer movement errors. These results suggest that training with left monocular eyeglasses might improve visual search performance in people with left USN.

Development of stimulus-driven attention test for unilateral spatial neglect – Accuracy, reliability, and validity

We developed a simple method to assess stimulus-evoked attention function in unilateral spatial neglect (USN), and examined its accuracy, reliability, and validity. Thirty-one patients with USN and sixteen patients with right hemisphere damage without USN were given a task of reading Japanese characters that suddenly appeared on a display, and a reading or touching task of red Japanese characters that are arranged on the display. The sensitivity and specificity were calculated from the measurement results, and the cutoff value was calculated using the receiver operating characteristic curve. Area under the curve was used to evaluate the discriminatory ability. Reliability was calculated by the intraclass correlation coefficient using the test-retest method. Validity was assessed by correlating the scores of the new method with the scores of the traditional assessment, the behavioral inattention test, and the Catherine Bergego Scale.This new method was able to detect left USN with the same level of accuracy as the conventional assessment and showed moderate or better reliability. In addition, a moderate correlation was found with the conventional assessment, and a higher correlation was observed with items related to perception and cognition in daily life.

The combined approach for post-stroke patients with left arm hemiplegia and general cognitive disorder leading to left unilateral spatial neglect

The combined approach for post-stroke patients with left arm hemiplegia and general cognitive disorder leading to left unilateral spatial neglect

Validity and reliability of standing balance control measurement on the left unilateral spatial neglect model

BACKGROUND: The present study developed a head-mounted display with the visual direction of a web camera modified to the right as a left unilateral spatial neglect (USN) model with respect to postural balance control. AIM: We aimed to estimate the validity and reliability of center of pressure (CoP) measurements in static standing balance (SSB) and dynamic standing balance (DSB) of healthy participants were using the USN model and to examine whether this model's use influenced postural balance control. METHOD: A portable CoP force plate was used to quantify postural balance control in 64 healthy participants as the model. The CoP displacement of the non-USN and USN models in the medial-lateral (ML) and anterior-posterior (AP) planes, CoP length, and bilateral load ratio in SSB and DSB to the right (R) and left (L) were evaluated. RESULTS: Regression analysis indicated that most CoP measurements have excellent concurrent validity. Bland–Altman plots showed good agreement between the non-USN and USN models in the CoP measurements. Test-retest reliability estimation between two times measurements varied in the frontal and sagittal planes. A Comparison of the results demonstrated that the CoP-AP and CoP length changed (-1.40% and 7.67%, respectively) significantly in SSB (P&lt;0.05). Moreover, the CoP-AP changed very significantly in DSB-R and DSB-L (-1.50% and 1.86%, respectively) in opposite directions (P&lt;0.01) when the subjects performed as the model. CONCLUSION: CoP measurements are valid and reliable to quantify standing balance control in both non-USN and USN models that appear to modulate changes in postural adaptation and adjustment.

Measuring Gaze and Arrow Cuing Effects With a Short Test Adapted to Brain Damaged Patients With Unilateral Spatial Neglect: A Preliminary Study.

People with left unilateral spatial neglect (USN) following a right brain lesion show difficulty in orienting their attention toward stimuli presented on the left. However, cuing the stimuli with gaze direction or a pointing arrow can help some of them to compensate for this difficulty. In order to build a tool that helps to identify these patients, we needed a short version of the paradigm classically used to test gaze and arow cuing effects in healthy adults, adapted to the capacities of patients with severe attention deficit. Here, we tested the robustness of the cuing effects measured by such a short version in 48 young adult healthy participants, 46 older healthy participants, 10 patients with left USN following a right brain lesion (USN+), and 10 patients with right brain lesions but no USN (USN–). We observed gaze and arrow cuing effects in all populations, independently of age and presence or absence of a right brain lesion. In the neglect field, the USN+ group showed event greater cuing effect than older healthy participants and the USN– group. We showed that gaze and arrow cuing effects are powerful enough to be detected in a very short test adapted to the capacities of older patients with severe attention deficits, which increases their applicability in rehabilitation settings. We further concluded that our test is a suitable basis to develop a tool that will help neuropsychologists to identify USN patients who respond to gaze and/or arrow cuing in their neglect field.

Mental representation of a line when patients with left unilateral spatial neglect bisect it: A study with an endpoint reproduction task.

Patients with left unilateral spatial neglect (USN) typically place the subjective midpoint to the right of the objective centre. Based on the previous findings (e.g., Ishiai etal. 1989, Brain, 112, 1485), we hypothesized that the patients with left USN may see the representational image of a line that extends equally towards either side of the subjective midpoint depending not upon the information about the leftward extent. The present study tested whether patients with left USN would place the subjective midpoint at the centre of their mental representation of the line. The participants were 10 patients with left USN and 10 neurologically healthy controls. We devised a new 'endpoint reproduction task' using a computer display with a touch panel to seek the representational image when patients with left USN bisect lines and asked the participants to reproduce the location of the right or left endpoint after bisecting lines. The results showed that the representational image of the bisected line depends primarily on the location of the objective right endpoint, not on the location of the objective left endpoint in space. The analyses of the estimated right and left representational extents confirmed our hypotheses that patients with left USN would bisect a line seeing the representational line image that centred across their subjective midpoint. We believe that the findings of the present study with the use of the endpoint reproduction task will contribute to a better understanding of the visuospatial process underlying line bisection of patients with left USN.

Immediate effect of adding mirror visual feedback to lateral weight-shifting training on the standing balance control of the unilateral spatial neglect model.

[Purpose] This study aimed to clarify the immediate effect of adding mirror visual feedback to lateral weight-shifting training on the standing balance control of the left unilateral spatial neglect model. [Participants and Methods] We included 64 healthy participants to create left unilateral spatial neglect models and divided them into four subgroups. Each subgroup received opposite lateral weight-shifting training with or without mirror visual feedback. We then evaluated the static and dynamic standing balance by measuring the center of pressure point alterations in the medial-lateral and anterior-posterior planes. We further evaluated the center of pressure length and bilateral load ratio. [Results] The center of pressure was significantly stable upon performing the eyes-open static standing balance test in the left weight-shifting training subgroup with mirror visual feedback. When participants performed the left dynamic standing balance test, the center of pressure moved significantly rightward and became significantly stable in the right weight-shifting training subgroup with mirror visual feedback. The left load ratio significantly decreased in the right weight-shifting training of subgroups that either did or did not receive mirror visual feedback upon performing the left dynamic standing balance test. [Conclusion] We concluded that adding mirror visual feedback to lateral weight-shifting training affected some measurements of standing balance control of the left unilateral spatial neglect model.

Using Eye Tracking to Identify Left Unilateral Spatial Neglect (USN) in Persons With an Acute Right Hemisphere Stroke

Abstract Date Presented 03/28/20 USN is a common occurrence in right hemisphere stroke survivors. However, no gold standard measure of USN exists. We investigated whether eye tracking is a sensitive measure of left USN in eight people with acute right hemisphere stroke. Eye tracking was found to be more sensitive than paper-and-pencil–based tests and comparable to functional assessments of USN. We suggest that eye tracking may be a quick and effective way to screen for left USN. Primary Author and Speaker: Kelsey Watters Contributing Authors: Gabrielle Escalante, Leora Cherney, Sameer Ashaie

Influence of right versus left unilateral spatial neglect on the functional recovery after rehabilitation in sub-acute stroke patients

ABSTRACT Unilateral spatial neglect (USN) may lead to poor functional rehabilitation outcomes. However, studies investigating the rehabilitation outcomes of right-sided USN are lacking. We aimed to investigate (1) the clinical impacts of USN, including right-sided USN, for stroke patients in sub-acute rehabilitation, and (2) evaluate the differences in clinical characteristics and rehabilitation outcomes between right- and left-sided USN patients. We retrospectively screened the medical records of 297 inpatients at the Tokyo-Bay Rehabilitation Hospital who experienced a cerebrovascular accident with supratentorial lesions between January 1st, 2014 and December 31st, 2016. We performed independent multiple regression analysis in patients with left and right hemisphere damage. The Behavioral Inattention Test was a significant independent variable for predicting the motor, cognitive, and total functional independence measure (FIM), compared to the Stroke Impairment Assessment Set and Mini-Mental State Examination. USN affects motor FIM recovery more than cognitive FIM recovery regardless of the damaged hemisphere. Our study results confirm that both right- and left-sided USN influence the functional recovery of stroke patients. USN occurs, slightly less frequently, following a left hemisphere stroke. However, USN negatively affected rehabilitation outcomes, regardless of the neglected side. Therefore, USN treatment is necessary for patients with left and right hemisphere damage.

Numeric input operation on electronic devices among individuals with visuospatial working memory impairment

ABSTRACT In human–computer interactions, higher-level visuospatial function is likely needed to effectively use the interface. The aim of this study is to clarify whether individuals with visuospatial defects can use electronic devices effectively. We quantitatively and qualitatively analyzed the ability of seven individuals with Bálint syndrome and seven individuals with left-unilateral spatial neglect (USN) to input a digit sequence into a flat touch interface. Control groups consisted of seven individuals with memory deficits and 11 healthy individuals. Participants with Bálint syndrome took longer and had more hesitations than the USN group and the two control groups to input numerical sequences (Steel-Dwass test, p < .01). In addition, participants with Bálint syndrome had a high percentage of hesitations for exploration of the button array on the interface relative to USN and the memory deficit group (Fisher’s exact test, p < .05). Regarding neuropsychological data, participants with Bálint syndrome had a lower score for visuospatial working memory than participants with USN and the memory deficits control group (Steel-Dwass test, p < .01). The results shed some light on the relation between visuospatial working memory deficits and the spatial perception of interface layouts and spatial control during electronic device operation.

A Study on Reading Errors in Left Unilateral Spatial Neglect : The Effect of Lexical Knowledge on Neglect Dyslexia

A Study on Reading Errors in Left Unilateral Spatial Neglect : The Effect of Lexical Knowledge on Neglect Dyslexia