Visuospatial Hemineglect Research Articles

Effects of a robot intervention on visuospatial hemineglect in postacute stroke patients: a randomized controlled trial

Objective: To evaluate the effects of an intervention using the robot device PARO on visuospatial hemineglect and activities of daily living, and its acceptance during stroke rehabilitation. PARO is an interactive robotic toy with the appearance of a baby seal, which can move, produce sounds, and react to speech and touch. Design: A randomized controlled trial. Setting: Hospital for neurorehabilitation. Subjects: Patients above 60 years old who have suffered their first stroke within the previous three months with left hemineglect (n = 39). Interventions: The PARO group (n = 21) was exposed to PARO over a period of two weeks, three times per week. The participants of the control group (n = 18) were read to aloud. Outcome measure: Visuospatial hemineglect was measured by a cancellation test and a Line Bisection Test, and independence in the activities of daily living was assessed by Scores of Independence Index for Neurological and Geriatric Rehabilitation (SINGER) test. The acceptance of PARO was also evaluated. Data were collected blinded at three times: baseline (T0), after two weeks of interventions (T1), and after additional two weeks as follow-up (T2). Results: Improvement of hemineglect at T1 and T2 was significantly higher in the PARO group (T1: mean (SD) = 6.23 (3.81); T2: mean (SD) = 7.85 (3.68)) compared to the control group (T1: mean (SD) = 2.66 (4.19); T2: mean (SD) = 3.33 (4.16)) (T1: P < 0.05; T2: P < 0.05). Conclusion: The study showed that the use of the PARO is well accepted and can help to improve neglect symptoms in patients with subacute stroke.

Global orientation in space and the lateralization of brain functions.

The functional role of the vestibular system for multisensory orientation and sensorimotor control is reviewed with a special focus on hemispherical lateralization and its consequences for neurological disorders of higher cortical function. The peripheral and central vestibular systems are bilaterally organized with ipsilateral and contralateral ascending pathways and two multisensory cortical networks in the right and left hemisphere. The vestibular cortical system shows a structural and functional lateralization with a dominance of the right hemisphere in right-handers and the left hemisphere in left-handers. Although the vestibular brainstem pathways are evenly distributed at lower pontine level, an increasing lateralization builds up because of an asymmetric number of pontine and mesencephalic crossing fibers from left to right in right-handers. This vestibular lateralization causes more frequent and more severe disorders of higher sensorimotor dysfunction in lesions of the right hemisphere such as in hemispatial neglect and the pusher syndrome. There is evidence that multisensory higher vestibular functions including large-scale spatial orientation, spatial memory and navigation are dominated by the right temporo-parietal cortex. A beneficial result of lateralization of brain functions in healthy individuals is that it enables the individual to produce a global sensorimotor response even in case of a mismatch of the actual right and left sensory inputs. The consequence for neurology, however, is that lesions in the dominant hemisphere cause more frequently and more severe disorders such as the visuo-spatial hemineglect and the pusher syndrome.

Bithalamic Dysfunction in Wernicke’s Encephalopathy

We describe a 65-year-old, nonalcoholic, right-handed female with multiple vascular risk factors who developed transient visuospatial hemineglect and global aphasia after presenting with the classic triad of Wernicke’s encephalopathy (mental status changes, nystagmus/ophthalmoplegia, and ataxia). A brain MRI showed no evidence of acute infarction, but demonstrated signal change in the medial thalami and mammillary bodies. Intravenous thiamine therapy was given, and visuospatial hemineglect and ophthalmoplegia disappeared while the aphasia improved. The occurrence of these acute transient clinical features has not been previously reported in Wernicke’s encephalopathy.

Acute Unilateral Vestibular Failure Does Not Cause Spatial Hemineglect.

ObjectivesVisuo-spatial neglect and vestibular disorders have common clinical findings and involve the same cortical areas. We questioned (1) whether visuo-spatial hemineglect is not only a disorder of spatial attention but may also reflect a disorder of higher cortical vestibular function and (2) whether a vestibular tone imbalance due to an acute peripheral dysfunction can also cause symptoms of neglect or extinction. Therefore, patients with an acute unilateral peripheral vestibular failure (VF) were tested for symptoms of hemineglect.MethodsTwenty-eight patients with acute VF were assessed for signs of vestibular deficits and spatial neglect using clinical measures and various common standardized paper-pencil tests. Neglect severity was evaluated further with the Center of Cancellation method. Pathological neglect test scores were correlated with the degree of vestibular dysfunction determined by the subjective visual vertical and caloric testing.ResultsThree patients showed isolated pathological scores in one or the other neglect test, either ipsilesionally or contralesionally to the VF. None of the patients fulfilled the diagnostic criteria of spatial hemineglect or extinction.ConclusionsA vestibular tone imbalance due to unilateral failure of the vestibular endorgan does not cause spatial hemineglect, but evidence indicates it causes mild attentional deficits in both visual hemifields.

Heminegligencia visuo-espacial: aspectos clínicos, teóricos y tratamiento [Visuospatial neglect: clinical, theoretical and treatment aspects

Objective: A descriptive review of the visuo-spatial hemineglect associated with strokes. Most relevant clinical and theoretical aspects are addressed and the different intervention techniques currently used. Development: The visuo-spatial hemineglect is a multimodal neuropsychological deficit associated with brain lesions, mainly of vascular origin. Their presence implies a slower recovery, increased disability and poor response to rehabilitation. Although spontaneous recovery can occur within the first few weeks or months, the passage of time does not necessarily imply an improvement of symptoms. Currently multiple strategies for rehabilitation have been developed, but very few demonstrate lasting effects over time. Conclusions: The prism adaptation is the technique where best results are obtained, although there are controversies regarding its long-term benefits. The various operations described in the article have a transitory impact and the results do not usually translate into an improvement in activities of daily living. Current trends are betting on the combined application of various techniques.

Heminegligencia visuo-espacial: aspectos clínicos, teóricos y tratamiento

Objective: A descriptive review of the visuo-spatial hemineglect associated with strokes. Most relevant clinical and theoretical aspects are addressed and th...

The Riddle of Style Changes in the Visual Arts after Interference with the Right Brain

We here analyze the paintings and films of several visual artists, who suffered from a well-defined neuropsychological deficit, visuo-spatial hemineglect, following vascular stroke to the right brain. In our analysis we focus in particular on the oeuvre of Lovis Corinth and Luchino Visconti as both major artists continued to be highly productive over many years after their right brain damage. We analyzed their post-stroke paintings and films, indicate several aspects that differ from their pre-stroke work (omissions, use of color, perseveration, deformation), and propose–although both artists come from different times, countries, genres, and styles–that their post-stroke oeuvre reveals important similarities in style. We argue that these changes may be associated with visuo-spatial hemineglect and the right brain. We discuss future avenues of how the neuropsychological investigation of visual artists with and without neglect may allow us to investigate the relationship between brain and art.

Emotionally negative stimuli can overcome attentional deficits in patients with visuo-spatial hemineglect

Left unilateral spatial neglect resulting from right brain damage is characterized by loss of awareness for stimuli in the contralesional side of space, despite intact visual pathways. We examined using fMRI whether patients with neglect are more likely to consciously detect in the neglected hemifield, emotionally negative complex scenes rather than visually similar neutral pictures and if so, what neural mechanisms mediate this effect. Photographs of emotional and neutral scenes taken from the IAPS were presented in a divided visual field paradigm. As expected, the detection rate for emotional stimuli presented in the neglected field was higher than for neutral ones. Successful detection of emotional scenes as opposed to neutral stimuli in the left visual field (LVF) produced activations in the parahippocampal and anterior cingulate areas in the right hemisphere. Detection of emotional stimuli presented in the intact right visual field (RVF) activated a distributed network of structures in the left hemisphere, including anterior and posterior cingulate cortex, insula, as well as visual striate and extrastriate areas. LVF–RVF contrasts for emotional stimuli revealed activations in right and left attention related prefrontal areas whereas RVF–LVF comparison showed activations in the posterior cingulate and extrastriate visual cortex in the left hemisphere. An additional analysis contrasting detected vs. undetected emotional LVF stimuli showed involvement of left anterior cingulate, right frontal and extrastriate areas. We hypothesize that beneficial role of emotion in overcoming neglect is achieved by activation of frontal and limbic lobe networks, which provide a privileged access of emotional stimuli to attention by top-down modulation of processing in the higher-order extrastriate visual areas. Our results point to the importance of top-down regulatory role of the frontal attentional systems, which might enhance visual activations and lead to greater salience of emotional stimuli for perceptual awareness.

An Unusual Cause of Dementia: Essential Diagnostic Elements of Corticobasal Degeneration—A Case Report and Review of the Literature

Corticobasal degeneration (CBD) is an uncommon, sporadic, neurodegenerative disorder of mid- to late-adult life. We describe a further example of the pathologic heterogeneity of this condition. A 71-year-old woman initially presented dysarthria, clumsiness, progressive asymmetric bradykinesia, and rigidity in left arm. Rigidity gradually involved ipsilateral leg; postural instability with falls, blepharospasm, and dysphagia subsequently developed. She has been previously diagnosed as unresponsive Parkinson's Disease. At our clinical examination, she presented left upper-arm-fixed-dystonia, spasticity in left lower limb and pyramidal signs (Babinski and Hoffmann). Brain MRI showed asymmetric cortical atrophy in the right frontotemporal cortex. Neuropsychological examination showed an impairment in visuospatial functioning, frontal-executive dysfunction, and hemineglect. This case demonstrates that association of asymmetrical focal cortical and subcortical features remains the clinical hallmark of this condition. There are no absolute markers for the clinical diagnosis that is complicated by the variability of presentation involving also cognitive symptoms that are reviewed in the paper. Despite the difficulty of diagnosing CBD, somatosensory evoked potentials, motor evoked potentials, long latency reflexes, and correlations between results on electroencephalography (EEG) and electromyography (EMG) provide further support for a CBD diagnosis. These techniques are also used to identify neurophysiological correlates of the neurological signs of the disease.

An Integrative Review of Factors Associated With Falls During Post‐Stroke Rehabilitation

Abstract Purpose: Our aims were to evaluate evidence of risk factors for falls among patients in stroke rehabilitation and to offer recommendations for clinical practice and future research. Method: We conducted an integrative review of the literature published from 1990 to 2009 that describes empirical investigations of risk factors for post‐stroke falls during inpatient rehabilitation. We searched Medline, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsycInfo, and Embase databases, using the search terms “accidental falls,”“fall risk,”“risk factors,”“risk assessment,”“stroke,” and “cerebrovascular disorders.” We extracted information regarding study design, sample, potential risk factors, analytic methods, findings, and limitations from the 14 articles that met our inclusion criteria, and we rated the level of evidence for each study. Findings: Available empirical evidence points to impaired balance, visuospatial hemineglect, and impaired performance of activities of daily living as risk factors for falls during inpatient rehabilitation for stroke. Associations between falls and cognitive function, incontinence, visual field deficits, and stroke type were less clear, while relationships between falls and age, gender, stroke location, and impaired vision and hearing were not supported. Conclusions: The relatively sparse literature pertaining to risk factors for falls among stroke rehabilitation inpatients indicates that deficits affecting balance, perception, and self‐care significantly increase the likelihood of falls. Particularly intriguing is the less well established role of post‐stroke cognition in falls in this population. A conceptual model is needed to guide scientific inquiry and clinical practice in this area. Clinical Relevance: When clinicians in the inpatient stroke rehabilitation setting evaluate which patients are at greatest risk to fall, stroke‐specific risk factors such as impaired balance, visuospatial hemineglect, and self‐care deficits may be better predictors than more general risk factors such as age, incontinence, and sensory impairments. Patients with these stroke‐specific deficits may benefit from the use of aggressive fall prevention interventions.

Is Visuospatial Hemineglect Longitudinally Associated with Postural Imbalance in the Postacute Phase of Stroke?

Introduction. The purpose of this study was to determine the longitudinal association of visuospatial hemineglect with postural imbalance in postacute stroke patients and to establish whether this relationship is confounded by other determinants. Methods. A prospective cohort study of 53 postacute stroke patients consecutively admitted for inpatient rehabilitation was conducted. Transfers and standing balance were assessed with the Berg Balance Scale (BBS) and walking balance with the Functional Ambulation Categories (FAC). Repeated measurements took place at baseline (36.6 ± 10.4 days after stroke) and after 6 and 12 weeks. Visuospatial hemineglect was assessed by an asymmetry index, derived from the Letter and Star Cancellation Tests. Random coefficient analysis was used to analyze the longitudinal impact of visuospatial hemineglect on the BBS and FAC. The association between hemineglect and outcome was corrected for the following potential confounders: age, severity of paresis of the lower leg, sensory deficits, and presence of hypertonia. A covariate was considered to be a confounder if the regression coefficient of hemineglect on outcome changed by >15%. Results. Visuospatial hemineglect was significantly associated with BBS and FAC. The relation between hemineglect and both BBS and FAC was confounded by severity of paresis of the lower limb. After controlling for severity of paresis, hemineglect remained independently associated with BBS, whereas the association with FAC lost significance. Conclusion. Visuospatial hemineglect is an independent covariate that is longitudinally associated with postural imbalance after stroke. These findings suggest that hemineglect is an important factor for controlling static and dynamic standing balance during the first months poststroke.

Effects of Psychostimulants on Alertness and Spatial Bias in Healthy Participants

Converging evidence from neuropsychological and neuroimaging studies suggests that the ability to maintain an alert, ready-to-respond state is mediated by a network of right-hemisphere frontal and parietal cortical areas. This right lateralization may help to explain why visuospatial hemineglect, a cluster of deficits in detecting and responding to contralesional stimuli, is more common and persistent after right-hemisphere lesions. Indeed, it has been hypothesized that this asymmetry reflects a direct, functional link between alertness and spatial attention. In the present study, we investigated whether a pharmacologically induced increase in alertness would influence lateral bias in healthy people. Eighteen healthy participants were each given placebo or the psychostimulant drugs methylphenidate 40 mg or modafinil 400 mg on separate days and completed an hour-long version of the spatially sensitive landmark task. For those participants who demonstrated the expected alerting effect of modafinil, there was a significant Condition by Time interaction, consistent with the effects of the drug resisting time-on-task rightward drifts in spatial bias in the placebo condition. In contrast, no effect of methylphenidate on spatial bias was observed. These results suggest that spatial bias may be modulated by a psychostimulant-induced increase in alertness, supporting the hypothesis of a direct, functional link between right-hemisphere systems controlling alertness and visuospatial attention.

Is Visuospatial Hemineglect Really a Determinant of Postural Control Following Stroke? An Acute-Phase Study

Objective. The purpose of this study was to determine the independent contribution of visuospatial hemineglect to impaired postural control in the acute phase (<2 weeks) of stroke compared with other possible clinical and biological determinants. Methods. This study was conducted in 4 hospitals in the mid-east region of the Netherlands. A total of 78 consecutive patients with a first-ever acute supratentorial stroke was included. Functional balance was measured with the Trunk Impairment Scale, the Trunk Control Test, the Berg Balance Scale, and the Functional Ambulation Categories. Visuospatial hemineglect was assessed by means of an asymmetry index obtained from the Behavioral Inattention Test. The Motricity Index, vibration threshold, sustained attention, and the presence of hemianopia were registered as other possible clinical determinants. Stepwise backward multiple linear regression analysis was performed introducing all selected clinical determinants as well as age and poststroke time as possible biological determinants. Results. Hemineglect was present in 17 patients (21.8%). The groups with and without hemineglect were different for gender and the proportion of right hemisphere strokes, but not for age, type of stroke, or poststroke time. Neglect patients had on average lower scores on all functional balance tests as well as on the clinical assessments. Multivariate linear regression showed that, besides hemineglect, only muscle strength and age independently contributed to impaired balance explaining 65% to 72% of variance of the selected outcomes. Conclusion. This study showed that hemineglect independently contributes to impaired postural control in the acute phase of stroke.

Influence of acquiring reading and writing on visuo-spatial pseudohemineglect

Acquiring and practicing reading and writing, based on a left to right scanning pattern as in Greek–Latin derived cultures, might influence the answers in different visuo-spatial tasks. We compared (independently for each hand) the performance in a visuo-spatial task of line bisection, or two groups of 34 pupils in the first grade and 35 pupils in the third grade, respectively, all right-handed. A significant right pseudohemineglect (in absolute terms) describes the motor response of the left hand in both groups, but of the right hand only in subjects enrolled in the third grade. Promotion in formal education at the beginning of the school ladder seems to be associated in both hands with the advancement of the observed pseudohemineglect phenomenon. The results are integrated into the frame of current explanations and theories concerning visuo-spatial hemineglect and pseudohemineglect.

Extinction of auditory stimuli in hemineglect: Space versus ear

Unilateral extinction of auditory stimuli, a key feature of the neglect syndrome, was investigated in 15 patients with right (11), left (3) or bilateral (1) hemispheric lesions using a verbal dichotic condition, in which each ear received simultaneously one word, and a interaural-time-difference (ITD) diotic condition, in which both ears received both words lateralised by means of ITD. Additional investigations included sound localisation, visuo-spatial attention and general cognitive status. Five patients presented a significant asymmetry in the ITD diotic test, due to a decrease of left hemispace reporting but no asymmetry was found in dichotic listening. Six other patients presented a significant asymmetry in the dichotic test due to a significant decrease of left or right ear reporting, but no asymmetry in diotic listening. Ten of the above patients presented mild to severe deficits in sound localisation and eight signs of visuo-spatial neglect (three with selective asymmetry in the diotic and five in the dichotic task). Four other patients presented a significant asymmetry in both the diotic and dichotic listening tasks. Three of them presented moderate deficits in localisation and all four moderate visuo-spatial neglect. Thus, extinction for left ear and left hemispace can double dissociate, suggesting distinct underlying neural processes. Furthermore, the co-occurrence with sound localisation disturbance and with visuo-spatial hemineglect speaks in favour of the involvement of multisensory attentional representations.

Impact of alertness training on spatial neglect: A behavioural and fMRI study

The effects of a 3-week computerised alertness training on chronic (>3 months) visuospatial hemineglect were investigated prospectively in seven patients by means of neuropsychological tests and functional magnetic resonance imaging (fMRI). Following the alertness training, the group showed improved alertness and a significant improvement in the performance of a neglect test battery over and above any improvement during a 3-week baseline phase. Improvements in the neglect tasks were accompanied by an increase of right hemisphere neural activity in frontal cortex, anterior cingulate cortex, precuneus, cuneus and angular gyrus. These areas have previously been associated with alertness and spatial attention. A similar pattern of increased neural activity was found for the left hemisphere. Four weeks after the end of the training, the patients’ neglect test performance had mostly returned to baseline, while the increases in neural activity bilaterally in frontal areas, in the right anterior cingulate cortex, the right angular gyrus and the left temporoparietal cortex remained. The data show that a 3-week computerised alertness training can improve performance both in alertness and neglect tests and that these behavioural improvements are associated with reactivation in areas associated with alerting and visuospatial attention. The limited stability of these effects over time suggests that a 3-week alertness training alone does not result in long lasting improvements in every patient, but refining the treatment protocol may lead to a more stable amelioration of neglect symptoms.

Cognitive Processes in Saccade Generation

The analysis of saccades offers an opportunity to study a number of different cognitive processes, such as visuospatial attention, working memory, and volitional conflict. A study of saccades in patients with visuospatial hemineglect, who performed a visual search task, showed repeated fixations on targets previously discovered, yet they often failed to retain the information that a particular target had previously been discovered. High-resolution structural brain scanning showed that this abnormality was due either to a lesion in the right intraparietal sulcus or the right inferior frontal lobe. Detailed analysis of the scanpaths suggested that the former location was associated with an accumulating impairment in remapping target locations across saccades or impaired memory of previously inspected target locations, whereas the latter location was more consistent with a failure to inhibit responses to rightward locations. When combined with a spatial bias to the right, such deficits might explain why many neglect patients often reexamine rightward targets, at the expense of items to their left. The functions of the supplementary eye field (SEF), in the medial frontal lobe, in relation to saccade generation are controversial. A series of studies in a patient with a focal lesion of the right SEF has indicated an important role for the SEF in the rapid self-control of saccadic eye movements and in set-switching (i.e., implementing control in situations of response conflict when ongoing saccadic plans have to be changed rapidly), rather than monitoring errors. In a recent fMRI study of normal subjects, it was shown that the SEF is involved in implementing the resolution of any volitional conflict, whereas other presupplementary motor areas are involved in the generation of volitional plans and processing volitional conflict.

Restoration of weight-shifting capacity in patients with postacute stroke: A rehabilitation cohort study

de Haart M, Geurts AC, Dault MC, Nienhuis B, Duysens J. Restoration of weight-shifting capacity in patients with postacute stroke: a rehabilitation cohort study. Arch Phys Med Rehabil 2005;86:755-62. Objectives To identify and interrelate recovery characteristics of voluntary weight shifting after stroke and to examine whether the assessment of weight shifting adds information about balance recovery compared with the assessment of quiet standing. Design Exploratory study using an inception cohort with findings related to reference values from healthy elderly persons. Setting Dutch rehabilitation center. Participants Thirty-six inpatients (mean age, 61.8y; mean time poststroke, 10wk) with a first hemispheric intracerebral infarction or hematoma who were admitted to retrain standing balance and walking. Intervention Individualized therapy. Main outcome measures Center of pressure (COP) displacements were registered during voluntary frontal-plane weight shifting guided by visual COP feedback using a dual-plate force platform. Besides the speed (number of weight shifts) and imprecision (normalized average lateral COP displacement per weight shift), the weight-transfer time asymmetry and the spatiotemporal distribution were determined. Assessments took place as soon as patients could stand unassisted for at least 30 seconds and at 2, 4, 8, and 12 weeks later. Results During the 12-week training period, the stroke patients increased both their speed (2.3 hits/30s; 95% confidence interval [CI], 1.1–3.4) and precision (37.7mm/hit; 95% CI, 10.4–65.0) of weight shifting. Although the speed appeared to stabilize at a suboptimal level after 8 weeks, precision reached normal reference values after 12 weeks. Both older age (≥65y) and the presence of visuospatial hemineglect negatively affected weight-shifting speed but not its relative improvement in time. During the training period, a small degree of weight-transfer time asymmetry persisted (mean change, .07; 95% CI, –.21 to .36), with an average of 23% slower weight shifts toward the paretic leg, but the spatiotemporal distribution remained symmetrical. The correlations between weight-shifting and quiet-standing control at the end of training were moderate (Spearman ρ range, .50–.77). Conclusions Even subjects with severe stroke who are selected for inpatient rehabilitation are able to improve their speed and precision of weight shifting by reducing the weight-transfer time toward both legs in a proportionate manner. The observed correlations between weight shifting and quiet standing indicate that the assessment of weight-shifting capacity provides unique information about balance recovery after stroke.

RTMS of the unaffected hemisphere transiently reduces contralesional visuospatial hemineglect.

To verify the role of interhemispheric influences on manifestations of neglect, the authors investigated the effects of a transient repetitive transcranial magnetic stimulation (rTMS)-induced disruption of the unaffected hemisphere on contralesional visuospatial neglect in two left- and five right-brain-damaged patients. Parietal rTMS of the unaffected hemisphere during the execution of a computerized task of bisected line's length judgment transiently decreased the magnitude of neglect as expressed in the number of errors.

Spatial neglect and paradoxical lesion effects in the cat — A model based on midbrain connectivity

Spatial visual attention in humans and mammals is severely disrupted after deactivation of specific cortical or subcortical regions. Such dysfunction has frequently been associated with impaired unilateral cortical mechanisms. Alternatively, I propose that essential mechanisms of spatial attention are based on the bilateral competition between subcortical midbrain structures. Consequently, visuospatial hemineglect and hemi-extinction arise from unbalanced bilateral competition. I present a simple mathematical model, based on known connectivity of the cat midbrain, that exemplifies the principle of competition through mutual inter-hemispheric inhibition. The model represents a linear, topographic integration of several cortical and subcortical inputs in the two halves of the feline superior colliculus. Such a system reproduced a variety of neglect symptoms and also explained the paradoxical effects observed in some lesion experiments where the consequences of a primary lesion could be reversed through a secondary lesion in structures of the contralateral hemisphere. The model generated predictions for future experiments.