Visual neglect: does it exist in children with unilateral brain lesion? A systematic review.

Visual Neglect (VN) is a common neuropsychological disorder in adults with unilateral brain lesion (UBL), characterized by the failure to attend and to report sensory events occurring in one side of space, contralateral to an area of brain damage. Less is known about VN expression in children following brain injury. The aim of this systematic review is to evaluate the presence of VN in UBL children and to identify the best neuropsychological assessment's tool for this population. A comprehensive search of 4 databases (Pubmed, Cochrane Database, SCOPUS, DARE) was undertaken from May 2020 to January 2021. Inclusion criteria were (i) subjects less than 18 years with cerebral lesions and with MRI, (ii) specific neuropsychological assessments for VN, (iii) studies published in English since 2000. A total of 309 articles were found in the initial search but only 10 observational studies met the full inclusion criteria. In these studies, 1051 subjects were evaluated for VN, of them 749 were controls and 302 had brain lesions. The two most common types of neuropsychological tools used in children with unilateral brain damage to assess the presence of VN were target cancellation tests and drawing tests.This review confirms the possibility that children with UBL can develop VN, even if it is not very clear which brain structure's characteristics can increase this risk. Children with right lesion showed visuo-spatial attention deficits focalized on the contralateral side, compatible with diagnosis of VN, while children with left lesion showed more generalized attention difficulties. The overall level of evidence correlating the presence of VN and different types of UBL in children was low and neuropsychological assessment of VN for children are sparse. Some important limitations of this review must be reported: the limited number of studies included, the administration of various types of tests to evaluate VN, the lack of information regarding the cognitive level of children in most of the studies. Further research is needed to understand patterns of VN based on brain structure and time since lesion.Systematic Review Registration: ID on PROSPERO: CRD42021281993.

Unilateral Stroke: Computer-based Assessment Uncovers Non-Lateralized and Contralesional Visuoattentive Deficits.

OBJECTIVE: Patients with unilateral stroke commonly show hemispatial neglect or milder contralesional visuoattentive deficits, but spatially non-lateralized visuoattentive deficits have also been reported. The aim of the present study was to compare spatially lateralized (i.e., contralesional) and non-lateralized (i.e., general) visuoattentive deficits in left and right hemisphere stroke patients. METHOD: Participants included 40 patients with chronic unilateral stroke in either the left hemisphere (LH group, n = 20) or the right hemisphere (RH group, n = 20) and 20 healthy controls. To assess the contralesional deficits, we used a traditional paper-and-pencil cancellation task (the Bells Test) and a Lateralized Targets Computer Task. To assess the non-lateralized deficits, we developed a novel large-screen (173 × 277 cm) computer method, the Ball Rain task, with moving visual stimuli and fast-paced requirements for selective attention. RESULTS: There were no contralesional visuoattentive deficits according to the cancellation task. However, in the Lateralized Targets Computer Task, RH patients missed significantly more left-sided than right-sided targets in bilateral trials. This omission distribution differed significantly from those of the controls and LH patients. In the assessment of non-lateralized attention, RH and LH patients missed significantly more Ball Rain targets than controls in both the left and right hemifields. CONCLUSIONS: Computer-based assessment sensitively reveals various aspects of visuoattentive deficits in unilateral stroke. Patients with either right or left hemisphere stroke demonstrate non-lateralized visual inattention. In right hemisphere stroke, these symptoms can be accompanied by subtle contralesional visuoattentive deficits that have remained unnoticed in cancellation task.

Provocation and prediction of visual peripersonal neglect-like symptoms in preoperative planning and during awake brain surgery.

Neglect is a severe neuropsychological/neurological deficit that usually develops due to lesions of the posterior inferior parietal area of the right hemisphere and is characterized by a lack of attention to the left side. Our case is a proven right-handed, 30-year-old female patient with a low-grade glioma, which was located in the temporo-opercular region and also in the superior temporal gyrus of the right hemisphere. Upon presurgical planning, the motor, language, and visuospatial functions were mapped. In order to achieve this, the protocol for routine magnetic resonance imaging and navigated transcranial magnetic stimulation has been expanded, accordingly.

E-TAN, a technology-enhanced platform with tangible objects for the assessment of visual neglect: A multiple single-case study.

Visual neglect is a frequent and disabling consequence of right brain damage. Traditional paper-and pencil tests of neglect have limited sensitivity and ecological validity. The Baking Tray Task (BTT), instead, approaches real-life situations, because it requires participants to place 16 physical objects on a board. The number of objects placed on the left and right portions of the board provides a clinical index of visual neglect. Here we present E-TAN, a technology-enhanced platform for BTT (E-BTT). E-BTT automatically determines the object locations on the board, and also records the sequence and timing of their placement. We used E-BTT to test 9 patients with right hemisphere damage and compared their performance with that obtained by 115 healthy participants. To this end, we developed a new method of analysis of participants' performance, based on the use of the convex hull described by the objects on the board. This measure provides an estimate of the portion of space processed by each participant and can effectively discriminate neglect patients from patients without neglect. E-TAN allows clinicians to assess visuospatial performance by using a convenient, fast, and relatively automatized procedure, that patients can even perform at home to follow-up the effects of rehabilitation.

Visual and motor neglect: Clinical and neurocognitive aspects.

Attention allows us to prioritize the processing of external information according to our goals, but also to cope with sudden, unforeseen events. Attention processes rely on the coordinated activity of large-scale brain networks. At the cortical level, these systems are mainly organized in fronto-parietal networks, with functional and anatomical asymmetries in favor of the right hemisphere. Dysfunction of these right-lateralized networks often produce severe deficit of spatial attention, such as visual neglect. Other brain-damaged patients avoid moving the limbs contralateral to their brain lesion, even in the absence of sensorimotor deficits (motor neglect). This paper first summarizes past and current evidence on brain networks of attention; then, it presents clinical and experimental findings on visual and motor neglect, and on the possible mechanisms of clinical recovery.

Dynamic Causal Modelling of Active Vision.

In this paper, we draw from recent theoretical work on active perception, which suggests that the brain makes use of an internal (i.e., generative) model to make inferences about the causes of sensations. This view treats visual sensations as consequent on action (i.e., saccades) and implies that visual percepts must be actively constructed via a sequence of eye movements. Oculomotor control calls on a distributed set of brain sources that includes the dorsal and ventral frontoparietal (attention) networks. We argue that connections from the frontal eye fields to ventral parietal sources represent the mapping from "where", fixation location to information derived from "what" representations in the ventral visual stream. During scene construction, this mapping must be learned, putatively through changes in the effective connectivity of these synapses. Here, we test the hypothesis that the coupling between the dorsal frontal cortex and the right temporoparietal cortex is modulated during saccadic interrogation of a simple visual scene. Using dynamic causal modeling for magnetoencephalography with (male and female) human participants, we assess the evidence for changes in effective connectivity by comparing models that allow for this modulation with models that do not. We find strong evidence for modulation of connections between the two attention networks; namely, a disinhibition of the ventral network by its dorsal counterpart.SIGNIFICANCE STATEMENT This work draws from recent theoretical accounts of active vision and provides empirical evidence for changes in synaptic efficacy consistent with these computational models. In brief, we used magnetoencephalography in combination with eye-tracking to assess the neural correlates of a form of short-term memory during a dot cancellation task. Using dynamic causal modeling to quantify changes in effective connectivity, we found evidence that the coupling between the dorsal and ventral attention networks changed during the saccadic interrogation of a simple visual scene. Intuitively, this is consistent with the idea that these neuronal connections may encode beliefs about "what I would see if I looked there", and that this mapping is optimized as new data are obtained with each fixation.

Acute visual impairment as a main presenting symptom of non-convulsive status epilepticus: a case report.

BACKGROUND: Nonconvulsive status epilepticus (NCSE) is a state of ongoing seizure activity without convulsions. The heterogeneous and subtle clinical features of NCSE make diagnosis and treatment challenging. Here, we report a patient with NCSE who showed a main presenting symptom of acute visual impairment, which is a rare and atypical clinical symptom of NCSE. CASE PRESENTATION: A 62-year-old man was admitted to the neurology department after complaining of an inability to see in the right eye for 2 days and progressive headache. He had a history of poststroke epilepsy and vascular dementia. Physical examination revealed right visual field hemianopia, visual neglect and cognitive impairment. T2 and diffusion-weighted magnetic resonance imaging showed high signal intensity in the left temporal, parietal and occipital lobes. Electroencephalography monitoring was performed, which found continuous sharp wave discharges, especially in the regions of the left temporal, parietal and occipital lobes. These findings were most consistent with the diagnosis of NCSE. Thus, a treatment of intravenous pumping of diazepam and an oral antiepileptic drug was added immediately. After that, the visual loss in the patient recovered quickly, and electroencephalography did not find epileptiform waves. On day 11, a follow-up MRI was performed, which showed that the abnormal signals of the left temporal, parietal and occipital lobes were markedly attenuated, and the patient returned to his premorbid state with a modified Rankin Scale score of 3. CONCLUSIONS: Acute visual impairment can be seen in NCSE, and it can be reversed by administering effective antiepileptic treatment. Meanwhile, transient peri-ictal MRI abnormalities can be observed in NCSE.

Perceptual Postural Imbalance and Visual Vertigo.

PURPOSE OF REVIEW: Disorders of posture and balance cause significant patient morbidity, with reduction of quality of life as patients refrain from critical activities of daily living such as walking outside the home and driving. This review describes recent efforts to characterize visual disorders that interact with the neural integrators of positional maintenance and emerging therapies for these disorders. RECENT FINDINGS: Abnormalities of gait and body position sense may be unrecognized by patients but are correlated with focal neurological injury (stroke). Patients with traumatic brain injury can exhibit visual vertigo despite otherwise normal visual functioning. The effect of visual neglect on posture and balance, even in the absence of a demonstrable visual field defect, has been characterized quantitatively through gait analysis and validates the potential therapeutic value of prism treatment in some patients. In addition, the underlying neural dysfunction in visual vertigo has been explored further using functional imaging, and these observations may allow discrimination of patients with structural causes from those whose co-morbid psychosocial disorders may be primarily contributory.

The Computational Anatomy of Visual Neglect.

Visual neglect is a debilitating neuropsychological phenomenon that has many clinical implications and-in cognitive neuroscience-offers an important lesion deficit model. In this article, we describe a computational model of visual neglect based upon active inference. Our objective is to establish a computational and neurophysiological process theory that can be used to disambiguate among the various causes of this important syndrome; namely, a computational neuropsychology of visual neglect. We introduce a Bayes optimal model based upon Markov decision processes that reproduces the visual searches induced by the line cancellation task (used to characterize visual neglect at the bedside). We then consider 3 distinct ways in which the model could be lesioned to reproduce neuropsychological (visual search) deficits. Crucially, these 3 levels of pathology map nicely onto the neuroanatomy of saccadic eye movements and the systems implicated in visual neglect.

Ocular manifestations in patients with cerebrovascular accidents in India: a cross-sectional observational study.

PURPOSE: To assess ophthalmic manifestations in patients with stroke and emphasize the importance of a formal screening for visual problems in stroke patients in hospital and rehabilitation settings. METHODS: This was a cross-sectional study of 50 newly diagnosed patients with stroke with Glasgow Coma Scale (GCS) > 8 examined within 3 days of onset. A detailed ophthalmic examination was performed for each patient including visual acuity, fields, ocular motility, slit lamp and fundus examination, line bisection tests and cranial nerve assessment. Radiological investigations were reviewed and anatomically correlated. RESULTS: A total of 50 patients (41 male and nine female) were included in the study. Mean age of the stroke cohort was 51.36 years. Twenty-nine patients (58%) had a subcortical stroke, while 42% (n = 21) patients had a cortical stroke. Nineteen patients (38%) demonstrated visual field defects. Twenty-one patients (42%) had a gaze palsy. Vertical gaze palsy (n = 8) was more common in cortical stroke, while internuclear ophthalmoplegia (n = 2), horizontal gaze palsies (n = 4) and Parinaud's syndrome (n = 1) were seen more commonly in those with subcortical stroke. Twenty-four percent (n = 12) patients had nystagmus. Twelve percent (n = 6) patients had diplopia. Thirty-eight percent (n = 19) patients had convergence insufficiency. Sixteen patients (32%) complained of visual impairment. Retinal abnormalities were seen in 58% (n = 29) of patients. CONCLUSIONS: Ophthalmic manifestations were seen in 90% of stroke survivors. Their presence in majority of the patients in our cohort suggests that earliest routine ophthalmic examination should be mandatory in all patients with acute stroke.

Occurrence and Recovery of Different Neglect-Related Symptoms in Right Hemisphere Infarct Patients during a 1-Year Follow-Up.

OBJECTIVES: To examine the occurrence of and recovery from visual neglect-related symptoms with the focus on neglect laterality, ipsilateral orienting bias, and slowed processing speed in right hemisphere (RH) infarct patients during a 1-year follow-up. Furthermore, to propose guidelines for assessing processing speed alongside the Behavioural Inattention Test (BIT). METHODS: We studied three RH patient groups: neglect (N+), mild left inattention (MLI+), and non-neglect (N-) patients, and healthy controls. The BIT with some additional analyses was conducted at the acute phase and at 6 and 12 months. RESULTS: The N+ group's BIT score increased and originally lateralized omissions became more evenly distributed during the follow-up. The N+ and MLI+ groups' starting points were more rightward located than the healthy group's at the acute phase and at 6, and partly at 12 months. Patient groups were slower than the controls in performing cancellation tests at the acute phase. The N+ and MLI+ groups remained slower than the controls throughout the follow-up. CONCLUSIONS: During the first year after RH infarct, originally left-sided manifestation of neglect shifted toward milder non-lateralized attentional deficit. Ipsilateral orienting bias and slowed processing speed appeared to be rather persistent neglect-related symptoms both in neglect patients and patients with initially milder inattention. We propose some effortless, tentative ways of examining processing speed and ipsilateral orienting bias alongside the BIT to better recognize these neglect-related symptoms, and highlight the need to assess and treat patients with initially milder inattention, who have been under-recognized and under-treated in clinical work. (JINS, 2018, 24, 617-628).

Visual neglect after left-hemispheric lesions: a voxel-based lesion-symptom mapping study in 121 acute stroke patients.

Visual neglect after left-hemispheric lesion is thought to be less frequent, less severe, and shorter lived than visuospatial attention deficits resulting from right-hemispheric lesions. However, reports exist opposing this assumption, and it is unclear how these findings fit into the current theories of visuospatial processing. Furthermore, only little is known about the exact structure-function relationship between visuospatial attention deficits and left-hemispheric stroke. We investigated neglect in 121 patients with acute left-hemispheric ischemic stroke by following clinical development from within the first 24 h of stroke onset until hospital discharge. Visuospatial attention deficits occurred in 17.4 % (n = 21). Voxel-based lesion-symptom mapping associated visual neglect to the right with lesion in the left superior and middle temporal gyrus, temporal pole, frontal operculum, and insula. Neglect severity, captured by the Center of Cancellation Score of the Bells test, was associated with lesion in the left anterior temporal lobe and the left frontal operculum. The left-hemispheric lesion pattern of neglect thus involves areas of the ventral attention system and partly mirrors the critical regions of the right hemisphere known to be associated with neglect. Based on our prospective analysis on a large cohort of patients with left-hemispheric stroke, this study shows that in a remarkable number of patients, the left hemisphere essentially contributes to an intact representation of space and clarifies the impact of the distinct left-hemispheric structures involved in visuospatial processing.

White matter lesional predictors of chronic visual neglect: a longitudinal study.

Chronic visual neglect prevents brain-damaged patients from returning to an independent and active life. Detecting predictors of persistent neglect as early as possible after the stroke is therefore crucial to plan the relevant interventions. Neglect signs do not only depend on focal brain lesions, but also on dysfunction of large-scale brain networks connected by white matter bundles. We explored the relationship between markers of axonal degeneration occurring after the stroke and visual neglect chronicity. A group of 45 patients with unilateral strokes in the right hemisphere underwent cognitive testing for neglect twice, first at the subacute phase (<3 months after onset) and then at the chronic phase (>1 year). For each patient, magnetic resonance imaging including diffusion sequences was performed at least 4 months after the stroke. After masking each patient's lesion, we used tract-based spatial statistics to obtain a voxel-wise statistical analysis of the fractional anisotropy data. Twenty-seven patients had signs of visual neglect at initial testing. Only 10 of these patients had recovered from neglect at follow-up. When compared with patients without neglect, the group including all subacute neglect patients had decreased fractional anisotropy in the second (II) and third (III) branches of the right superior longitudinal fasciculus, as well as in the splenium of the corpus callosum. The subgroup of chronic patients showed reduced fractional anisotropy in a portion the splenium, the forceps major, which provides interhemispheric communication between regions of the occipital lobe and of the superior parietal lobules. The severity of neglect correlated with fractional anisotropy values in superior longitudinal fasciculus II/III for subacute patients and in its caudal portion for chronic patients. Our results confirm a key role of fronto-parietal disconnection in the emergence and chronic persistence of neglect, and demonstrate an implication of caudal interhemispheric disconnection in chronic neglect. Splenial disconnection may prevent fronto-parietal networks in the left hemisphere from resolving the activity imbalance with their right hemisphere counterparts, thus leading to persistent neglect.

Implicit learning: A way to improve visual search in spatial neglect?

Studies have shown that neglect patients are able to use stimulus regularities to orient faster toward the neglected side, without necessarily being aware of that information, or at the very least without being able to verbalize their knowledge. In order to better control for the involvement of explicit processes, the present study sought to test neglect patients' ability to detect more complex associations between stimuli using tasks similar to those used in implicit learning studies. Our results demonstrate that neglect patients had difficulties implicitly learning complex associations, contrary to what we found with controls. The possible influence of attentional and working memory impairments are discussed.

When brain damage "improves" perception: neglect patients can localize motion-shifted probes better than controls.

When we look at bars flashed against a moving background, we see them displaced in the direction of the upcoming motion (flash-grab illusion). It is still debated whether these motion-induced position shifts are low-level, reflexive consequences of stimulus motion or high-level compensation engaged only when the stimulus is tracked with attention. To investigate whether attention is a causal factor for this striking illusory position shift, we evaluated the flash-grab illusion in six patients with damaged attentional networks in the right hemisphere and signs of left visual neglect and six age-matched controls. With stimuli in the top, right, and bottom visual fields, neglect patients experienced the same amount of illusion as controls. However, patients showed no significant shift when the test was presented in their left hemifield, despite having equally precise judgments. Thus, paradoxically, neglect patients perceived the position of the flash more veridically in their neglected hemifield. These results suggest that impaired attentional processes can reduce the interaction between a moving background and a superimposed stationary flash, and indicate that attention is a critical factor in generating the illusory motion-induced shifts of location.

Can the exploration of left space be induced implicitly in unilateral neglect?

The purpose of the present study was to explore the ability of neglect patients to detect and exploit the predictive value of a cue to respond more quickly and accurately to targets on their contralesional side in a Posner spatial cueing task. The majority of the cues (i.e. 80%) were invalid, indicating that the target would appear on the opposite side, although patients were not informed of this bias. Our results demonstrate that some neglect patients were able to extract the cue's predictability and use it to orient faster toward the left. This cueing effect was present even in patients who were subsequently unable to describe the predictive character of the cues, and thus was not modulated by reportable awareness of the cue-target relation.

Attention-network specific alterations of structural connectivity in the undamaged white matter in acute neglect.

Visual neglect results from dysfunction within the spatial attention network. The structural connectivity in undamaged brain tissue in neglect has barely been investigated until now. In the present study, we explored the microstructural white matter characteristics of the contralesional hemisphere in relation to neglect severity and recovery in acute stroke patients. We compared age-matched healthy subjects and three groups of acute stroke patients (9 ± 0.5 days after stroke): (i) patients with nonrecovered neglect (n = 12); (ii) patients with rapid recovery from initial neglect (within the first week post-stroke, n = 7), (iii) stroke patients without neglect (n = 17). We analyzed the differences between groups in grey and white matter density and fractional anisotropy (FA) and used fiber tracking to identify the affected fibers. Patients with nonrecovered neglect differed from those with rapid recovery by FA-reduction in the left inferior parietal lobe. Fibers passing through this region connect the left-hemispheric analogues of the ventral attention system. Compared with healthy subjects, neglect patients with persisting neglect had FA-reduction in the left superior parietal lobe, optic radiation, and left corpus callosum/cingulum. Fibers passing through these regions connect centers of the left dorsal attention system. FA-reduction in the identified regions correlated with neglect severity. The study shows for the first time white matter changes within the spatial attention system remote from the lesion and correlating with the extent and persistence of neglect. The data support the concept of neglect as disintegration within the whole attention system and illustrate the dynamics of structural-functional correlates in acute stroke.

Use of yoked prisms in patients with acquired brain injury: a retrospective analysis.

PRIMARY OBJECTIVE: The purpose of this retrospective study was to determine the clinical practices for prescribing yoked prisms, as well as to assess related patient responses, in a sample of visually-symptomatic patients having acquired brain injury (ABI). METHODS: The clinical records of individuals with acquired brain injury (ABI) that were assessed for yoked prisms were reviewed retrospectively. This query resulted in 60 patient records for analysis between January 2011 and December 2012. The following diagnostic groups were analysed: homonymous hemianopsia (HH)/homonymous quadranopsia, abnormal egocentric localization (AEL) and visual neglect. RESULTS: HH/homonymous quadranopsia (58.3%) was the primary indication to prescribe yoked prisms, followed by visual neglect/unilateral spatial inattention (USI) (40.0%) and AEL (11.7%). The most common favourable patient responses were increased awareness of their blind visual field and improved gait, mobility and balance. The magnitude and direction of prisms prescribed were dependent upon the subjective responses in patients manifesting AEL. In contrast, base direction was dependent upon the direction of visual field loss in patients with HH/homonymous quadranopsia and visual neglect. CONCLUSIONS: Two-thirds of the present sample population responded favourably to the yoked prisms. The results of the present study should prove useful to clinicians for the successful prescription of yoked prisms as a treatment modality in patients presenting with the above three diagnoses.

Peripheral and bimanual reaching in a stroke survivor with left visual neglect and extinction.

Whether attentional deficits are accompanied by visuomotor impairments following posterior parietal lesions has been debated for quite some time. This single-case study investigated reaching in a stroke survivor (E.B.) with left visual neglect and visual extinction following right temporo-parietal-frontal strokes. Unlike most neglect patients, E.B. did not present left hemiparesis, homonymous hemianopia nor show evidence of motor neglect or extinction allowing us to examine, for the first time, if lateralised attentional deficits co-occur with deficits in peripheral and bimanual reaching. First, we found a classic optic ataxia field effect: E.B.'s accuracy was impaired when reaching to peripheral targets in her neglected left visual field (regardless of the hand used). Second, we found a larger bimanual cost for movement time in E.B. than controls when both hands reached to incongruent locations. E.B.'s visuomotor profile is similar to the one of patients with optic ataxia showing that attentional deficits are accompanied by visuomotor deficits in the affected field.