Right Hemisphere Stroke Research Articles

Long-term cognitive outcomes after decompressive hemicraniectomy for right-hemisphere large middle cerebral artery ischemic stroke.

Decompressive hemicraniectomy (DH) improves survival and functional outcome in large middle cerebral artery (MCA) infarcts. However, long-term cognitive outcomes after DH remain underexplored. In a cohort of patients with large right-hemisphere MCA infarction undergoing DH, we assessed the rates of long-term cognitive impairment over 3-year follow-up. We prospectively evaluated consecutive patients included in the Lille Decompressive Surgery Database (May 2005-April 2022) undergoing DH according to existing guidelines for large hemisphere MCA infarction. We included patients with right-sided stroke andscreened with the Mini-Mental State Examination (MMSE) in at least one of the prespecified follow-ups (3-month, 1-year, 3-year). Cognitive impairment was defined as an MMSE score < 24. We included only right-hemisphere strokes to avoid testing biases related to severe aphasia. We compared clinical and neuroimaging data in patients with and without cognitive impairment. Three hundred four patients underwent DH during the study period. Among 3-month survivors, 95 had a right-hemisphere stroke and underwent at least one cognitive screening (median age = 51 years, 56.8% men). Forty-four patients (46.3%) exhibited cognitive impairment at least once during the 3-year follow-up. Baseline characteristics did not significantly differ between patients with and without cognitive impairment. Regarding long-term temporal trends, cognitive impairment was observed in 23 of 76 (30.3%), 25 of 80 (31.3%), and 19 of 66 (28.8%) patients at 3-month, 1-year, and 3-year follow-up, respectively, and it was associated with higher rates of functional disability (all p < 0.05). The persistently high rates of cognitive impairment after DH highlight the importance of cognitive monitoring to improve the long-term management of survivors.

Anterior circulation acute ischemic stroke due to vertebral artery ostial stenosis in a patient with congenital internal carotid artery agenesis: a case report

BackgroundCongenital agenesis of internal carotid artery (ICA) is a rare cerebrovascular variation entity. Most cases of congenital ICA agenesis are asymptomatic and discovered incidentally. Congenital ICA agenesis presenting as ischemic stroke is even rare.Case presentationAn 80-year-old male patient was admitted to our hospital due to sudden dysarthria and left limb weakness for 3.5 h. Based on emergency physical examination and head computed tomography (CT) scan results, acute ischemic stroke (AIS) of right cerebral hemisphere was suspected. Following intravenous thrombolysis with recombinant tissue plasminogen activator, right congenital agenesis of ICA was confirmed by CT and digital subtraction angiography. Additionally, there was a severe right vertebral artery ostial (VAO) stenosis. After ruling out common causes of AIS such as haematological diseases, arterial dissection, organic heart disease, immunological abnormality and underlying possible malignancies, we hypothesize that the severe stenosis of the right VAO may have contributed to the development of AIS in this case.ConclusionsWe present a case of right congenital ICA agenesis in which severe stenosis of the right VAO may have played a role in the development of AIS. This case underscores a rare scenario where a lesion in the posterior circulation leads to an infarction in the anterior circulation in the setting of congenital ICA agenesis.

The impact of rehabilitation on the recovery of executive functions in stroke patients with different location of the ischemic focus.

Cognitive dysfunction is part of the clinical picture of stroke. Most of the executive dysfunctions are diagnosed in the early stage of rehabilitation, a few weeks after the vascular incident. Coexistence of executive dysfunctions with other disorders in stroke patients may hinder patient's functions, slow down the rehabilitation process, and disrupt self-awareness, interpersonal communication, and professional activity in everyday life. Ninety patients after ischemic stroke were examined (right hemisphere stroke: N = 33, left hemisphere stroke: N = 57). The study group (N = 45) consisted of patients rehabilitated in the Department of Rehabilitation and Physical Medicine of the University Teaching Hospital of the Military Medical Academy in Lodz, Łódź, Poland, in whom a comprehensive neurorehabilitation program was implemented, consisting of motor and neuropsychological rehabilitation. The control group (N = 45) consisted of patients awaiting admission to the department, who were covered by comprehensive environmental rehabilitation including exercise therapy and neuropsychological therapy. Executive function was measured with 3 popular diagnostic tools: the Wisconsin Card Sorting Test (WCST), the Trail Making Test (TMT part A, TMT part B), and the letter test and category test with the Verbal Fluency Test (VFT). The tests were carried out twice: the first time before the start of rehabilitation and 5 weeks later after its completion. Although patients with right-hemispheric stroke showed better improvement in executive functions, stroke location did not prove to have significant impact on how effective the rehabilitation was. Right hemisphere stroke patients showed greater improvement in restoring executive functions after rehabilitation compared to left hemisphere stroke patients. The location of the stroke did not significantly correlate with the efficiency of the rehabilitation setting. Int J Occup Med Environ Health. 2024;37(4):452-67.

Neck muscle vibration and prism adaptation fail to improve balance disturbances after stroke: A multicentre randomised controlled study

BackgroundPilot studies suggest potential effects of neck muscle vibration (NMV) and prism adaptation (PA) on postural balance disturbances related to spatial cognition. ObjectivesTo evaluate the effect of 10 sessions of NMV and/or PA on ML deviation. We used the mediolateral centre of pressure position (ML deviation) as a biomarker for spatial cognition perturbation, hypothesising that PA and NMV would improve ML deviation, with a potential synergistic impact when used together. MethodsWe conducted a multicentre, single-blind, randomised controlled study. Participants within 9 months of a right-hemisphere supratentorial stroke and with less than 40% body weight supported on the paretic side in standing were randomised into 4 groups (PA, NMV, PA+NMV, or control). Primary outcomeML deviation at Day 14. Secondary outcomes: force platform data, balance abilities, autonomy, and ML deviation, measured just after the first session (Day 1), at Day 90, and Day 180. A generalised linear mixed model (GLMM) assessed intervention effects on these outcomes, adjusting for initial ML deviation and incorporating other relevant factors. Results89 participants were randomised and data from 80 participants, mean (SD) age 59.2 (10.2) years, mean time since stroke 94 (61) days were analysed. At Day 14, a weak time x group interaction (P = .001, omega-squared = 0.08) was found, with no significant between-group differences in ML deviation (P = .12) or in secondary outcomes (P = .08). Between-group differences were found on Day 1 (P = .03), Day 90 (P = .001) and Day 180 (P < .0001) regardless of age and stroke-related data. On Day 1, ML deviation improved in both the PA and NMV groups (P = .03 and P = .01). In contrast, ML deviation deteriorated in the NMV+PA group on Day 90 and Day 180 (P = .01 and P = .01). ConclusionsThe study found no evidence of any beneficial effects of repeated unimodal or combined sessions of NMV and/or PA on ML deviation after stroke. Trial registrationClinicalTrials.gov identifier NCT01677091

The engagement of temporal attention in left spatial neglect

Previous literature showed how left spatial neglect arises from an asymmetrical distribution of spatial attention. However, it was also suggested that left spatial neglect might be partially caused or at least worsened by non-spatial attention disorders of the right-lateralized stimulus-driven attentional fronto-parietal network. Here, we psychophysically tested the efficiency of temporal attentional engagement of foveal perception through meta-contrast (Experiment 1) and “attentional” masking (Experiment 2) tasks in patients with right-hemisphere stroke with left neglect (N+), without left neglect (N-) and matched healthy controls (C). In both experiments, N+ patients showed higher thresholds, not only than Cs, but also than N- patients. Temporal engagement was clinically impaired in all N+ patients and highly correlated with their typical inability to direct spatial attention towards stimuli on the left side. Our findings suggest that a temporal impairment of attentional engagement is a relevant deficit of left spatial neglect.

A simple psychophysical procedure separates representational and noise components in impairments of speech prosody perception after right-hemisphere stroke

After a right hemisphere stroke, more than half of the patients are impaired in their capacity to produce or comprehend speech prosody. Yet, and despite its social-cognitive consequences for patients, aprosodia following stroke has received scant attention. In this report, we introduce a novel, simple psychophysical procedure which, by combining systematic digital manipulations of speech stimuli and reverse-correlation analysis, allows estimating the internal sensory representations that subtend how individual patients perceive speech prosody, and the level of internal noise that govern behavioral variability in how patients apply these representations. Tested on a sample of N = 22 right-hemisphere stroke survivors and N = 21 age-matched controls, the representation + noise model provides a promising alternative to the clinical gold standard for evaluating aprosodia (MEC): both parameters strongly associate with receptive, and not expressive, aprosodia measured by MEC within the patient group; they have better sensitivity than MEC for separating high-functioning patients from controls; and have good specificity with respect to non-prosody-related impairments of auditory attention and processing. Taken together, individual differences in either internal representation, internal noise, or both, paint a potent portrait of the variety of sensory/cognitive mechanisms that can explain impairments of prosody processing after stroke.

Severity-Dependent Interhemispheric White Matter Connectivity Predicts Poststroke Neglect Recovery.

Left-sided spatial neglect is a very common and challenging issue after right-hemispheric stroke, which strongly and negatively affects daily living behavior and recovery of stroke survivors. The mechanisms underlying recovery of spatial neglect remain controversial, particularly regarding the involvement of the intact, contralesional hemisphere, with potential contributions ranging from maladaptive to compensatory. In the present prospective, observational study, we assessed neglect severity in 54 right-hemispheric stroke patients (32 male; 22 female) at admission to and discharge from inpatient neurorehabilitation. We demonstrate that the interaction of initial neglect severity and spared white matter (dis)connectivity resulting from individual lesions (as assessed by diffusion tensor imaging, DTI) explains a significant portion of the variability of poststroke neglect recovery. In mildly impaired patients, spared structural connectivity within the lesioned hemisphere is sufficient to attain good recovery. Conversely, in patients with severe impairment, successful recovery critically depends on structural connectivity within the intact hemisphere and between hemispheres. These distinct patterns, mediated by their respective white matter connections, may help to reconcile the dichotomous perspectives regarding the role of the contralesional hemisphere as exclusively compensatory or not. Instead, they suggest a unified viewpoint wherein the contralesional hemisphere can - but must not necessarily - assume a compensatory role. This would depend on initial impairment severity and on the available, spared structural connectivity. In the future, our findings could serve as a prognostic biomarker for neglect recovery and guide patient-tailored therapeutic approaches.

Abstract 123: Emotional Prosody and Facial Expressions Differentially Augment Comprehension of Discourse for Left and Right Hemisphere Stroke Survivors

Deficits in spoken discourse comprehension are common after left hemisphere (LH) and right hemisphere (RH) stroke. Thus, it is important to identify factors that facilitate comprehension and enhance communication between stroke survivors and their care partners. Emotional prosody and facial expression cues can facilitate comprehension, but this may depend on an intact RH. To determine if such cues are facilitatory to LH and RH stroke survivors, we compared discourse comprehension between the groups across 3 conditions. We hypothesized that RH participants would not benefit as much from these cues as LH participants due to concomitant impairments in recognition of prosody and facial expression. We assessed 72 stroke survivors within 3 months of unilateral ischemic stroke, including 40 LH (15 female; aged 62±13 yrs) and 32 RH (17 female; aged 68±10 yrs), and 29 healthy controls (19 female; aged 72±15 yrs). Participants listened to a series of recorded spoken descriptions of scenarios and selected 1 picture from 4 to match each scenario. Targets and foils were balanced across spatial positions. Each description was presented in 3 conditions: read with neutral prosody (Trial 1), read with emotional prosody (Trial 2), and read with emotional prosody + facial expressions (Trial 3, audio + video). If 100% accuracy was achieved on a trial, the next trial was not presented. We used a Kruskal-Wallace test and paired samples t -tests for analyses and corrected for multiple comparisons. Accuracy differed significantly between groups on Trial 1, H (2) = 26.68, p &lt; .001. Controls achieved higher accuracy than LH ( p &lt; .01) and RH participants ( p &lt; .01). LH and RH participants did not differ, p = .51. LH participants achieved significant gains in accuracy from Trial 1 to 2 ( t (32) = 4.16, p = .001) and from Trial 1 to 3 ( t (32) = 5.49, p &lt; .001), but not from Trial 2 to 3 ( t (32) = 1.79, p = .08). RH participants did not achieve significant gains in accuracy from Trial 1 to 2 ( t (23) = 1.59, p = .13), Trial 2 to 3 ( t (23) = 0, p = 1.0), or Trial 1 to 3 ( t (23) = 1.21, p = .24). To conclude, emotional prosody and facial expressions significantly improved discourse comprehension for LH but not for RH stroke survivors. Different/additional strategies to improve discourse comprehension after RH stroke are needed.

Targeted non-invasive brain stimulation boosts attention and modulates contralesional brain networks following right hemisphere stroke

Right hemisphere stroke patients frequently present with a combination of lateralised and non-lateralised attentional deficits characteristic of the neglect syndrome. Attentional deficits are associated with poor functional outcome and are challenging to treat, with non-lateralised deficits often persisting into the chronic stage and representing a common complaint among patients and families.In this study, we investigated the effects of non-invasive brain stimulation on non-lateralised attentional deficits in right-hemispheric stroke. In a randomised double-blind sham-controlled crossover study, twenty-two patients received real and sham transcranial Direct Current Stimulation (tDCS) whilst performing a non-lateralised attentional task. A high definition tDCS montage guided by stimulation modelling was employed to maximise current delivery over the right dorsolateral prefrontal cortex, a key node in the vigilance network. In a parallel study, we examined brain network response to this tDCS montage by carrying out concurrent fMRI during stimulation in healthy participants and patients.At the group level, stimulation improved target detection in patients, reducing overall error rate when compared with sham stimulation. TDCS boosted performance throughout the duration of the task, with its effects briefly outlasting stimulation cessation. Exploratory lesion analysis indicated that response to stimulation was related to lesion location rather than volume. In particular, reduced stimulation response was associated with damage to the thalamus and postcentral gyrus. Concurrent stimulation-fMRI revealed that tDCS did not affect local connectivity but influenced functional connectivity within large-scale networks in the contralesional hemisphere.This combined behavioural and functional imaging approach shows that brain stimulation targeted to surviving tissue in the ipsilesional hemisphere improves non-lateralised attentional deficits following stroke. This effect may be exerted via contralesional network effects.

Neurophysiological features in patients with psychopathological disorders in the right hemisphere stroke

Neurophysiological changes and functional activity of the brain on the electroencephalogram after a cerebral infarction reflect the direct electromagnetic activity of neurons that can be measured in the affected areas of the brain. EEG signals provide a non-invasive and sensitive indicator of brain function during mental processes. Its main use is in the assessment of cerebral function, and not in the detection of structural abnormalities. There is a lot of evidence that the analysis of the electrical fields of the brain can detect changes in the behavior of brain signals in neurological patients. The aim of the study was to establish correlational relationships between the development of psychopathological disorders and neurophysiological changes using EEG in right hemisphere stroke. The subject of the study was neglect and its relationship with neurophysiological changes and functional activity of the brain. Twenty-three patients with a right-hemisphere stroke who were undergoing inpatient treatment in the medical and diagnostic department No. 1 of the LORITOM PE. The correlation of the reduced α-index in patients with manifestations of unilateral neglect on the background curve was determined in the cohort of subjects. Moderate irritation phenomena was noted closer to the center in the parietal and to the right in the temporal and parietal leads in patients with neglect syndrome. While without manifestations of hemineglect, moderate phenomena of irritation was noted mainly parasagittal and on the left. A trend of slow-wave activity in the frontal areas in patients with neglect syndrome has been demonstrated. The prospect of further research in the field of psychopathological disorders is shown which will significantly increase the efficiency of diagnosis and treatment and as a result increase the degree of restoration of impaired functions of post-stroke patients, the level of their social and everyday adaptation and accordingly the quality of life. Keywords: electroencephalography, unilateral neglect, hemineglect.

Examining the role of self-reported somatosensory sensations in body (dis)ownership: A scoping review and empirical study of patients with a disturbed sense of limb ownership

Patients with a disturbed sense of limb ownership (DSO) offer a unique window of insight into the multisensory processes contributing to the sense of body ownership. A limited amount of past research has examined the role of sensory deficits in DSO, and even less is known regarding the role of patient self-reported somatosensory sensations in the pathogenesis of DSO. To address this lack of knowledge we first conducted a systematic scoping review following PRISMA-SR guidelines, examining current research into somatosensory deficits and patient self-reported somatosensory sensations in patients with DSO. Eighty studies, including 277 DSO patients, were identified. The assessment of sensory deficits was generally limited in scope and quality, and deficits in tactile sensitivity and proprioception were most frequently found. The reporting of somatosensory sensations was even less frequent, with instances of paraesthesia (pins-and-needles), stiffness/rigidity, numbness and warmth, coldness and heaviness amongst the deficits recorded. In a second part of the study, we sought to directly address the lack of evidence concerning the impact of patient self-reported somatosensory sensations in DSO by measuring DSO and self-reported somatosensory sensations in a large (n = 121) sample of right-hemisphere stroke patients including N = 65 with DSO and N = 56 hemiplegic controls. Results show that feelings of coldness and stiffness modulate DSO symptoms. Sense of heaviness and numbness are more frequent in patients with DSO but do not have a clear impact on disownership symptomology. Although preliminary, these results suggest a role of subjective sensations about the felt body in the sense of limb ownership.

The Application of Immersive Virtual Reality and Machine Learning for the Assessment of Unilateral Spatial Neglect

Abstract Even subtle forms of hemispatial neglect after stroke negatively affect the performance of daily life tasks, increase the risk of injury, and are associated with poor rehabilitation outcomes. Conventional paper-and-pencil tests, however, often underestimate the symptoms. We aimed to identify relevant neglect-specific measures and clinical decision rules based on machine learning techniques on behavioral data generated in a new Virtual Reality (VR) application, the immersive virtual road-crossing task. In total, 59 participants were included in our study: two right-hemispheric stroke groups with left neglect (N = 20) or no neglect (N = 19), classified based on conventional tests and medical diagnosis, and healthy controls (N = 20). A neuropsychological test battery and the VR task were administered to all participants. We applied decision trees and random forest models to predict the respective groups based on the results of the VR task. Our feature selection procedure yielded six features as suitable predictors, most of which involved lateral time-related measures, particularly reaction times, and head movements. Our model achieved a high training accuracy of 96.6% and estimated test accuracy of 76.8%. These results confirm previous reports that temporal behavioral patterns are key to detecting subtle neglect in patients with chronic stroke. Our results indicate that VR combined with machine learning has the potential to achieve higher test accuracies while being highly applicable to clinical practice.

Comparison of uni- and multimodal motion stimulation on visual neglect: A proof-of-concept study

Spatial neglect is characterized by the failure to attend stimuli presented in the contralesional space. Typically, the visual modality is more severely impaired than the auditory one. This dissociation offers the possibility of cross-modal interactions, whereby auditory stimuli may have beneficial effects on the visual modality. A new auditory motion stimulation method with music dynamically moving from the right to the left hemispace has recently been shown to improve visual neglect. The aim of the present study was twofold: a) to compare the effects of unimodal auditory against visual motion stimulation, i.e., smooth pursuit training, which is an established therapeutical approach in neglect therapy and b) to explore whether a combination of auditory + visual motion stimulation, i.e., multimodal motion stimulation, would be more effective than unimodal auditory or visual motion stimulation. 28 patients with left-sided neglect due to a first-ever, right-hemispheric subacute stroke were included. Patients either received auditory, visual, or multimodal motion stimulation. The between-group effect of each motion stimulation condition as well as a control group without motion stimulation was investigated by means of a one-way ANOVA with the patient’s visual exploration behaviour as an outcome variable. Our results showed that unimodal auditory motion stimulation is equally effective as unimodal visual motion stimulation: both interventions significantly improved neglect compared to the control group. Multimodal motion stimulation also significantly improved neglect, however, did not show greater improvement than unimodal auditory or visual motion stimulation alone. Besides the established visual motion stimulation, this proof-of-concept study suggests that auditory motion stimulation seems to be an alternative promising therapeutic approach to improve visual attention in neglect patients. Multimodal motion stimulation does not lead to any additional therapeutic gain. In neurorehabilitation, the implementation of either auditory or visual motion stimulation seems therefore reasonable.

Monocular eye patching modulates ipsilesional reactive saccades and smooth pursuit in patients with left hemispatial neglect

Patients with hemispatial neglect show multiple oculomotor deficits like delayed contralesional saccade latencies, hypometric saccade amplitudes, and impaired smooth pursuit. We aimed to investigate whether modulation of superior colliculus (SC) activity via monocular eye patching improves neglect patients’ eye movements to the contralesional side of space. Thirteen neglect patients with left-hemispheric (LH) stroke, 22 neglect patients with right-hemispheric (RH) stroke, and 24 healthy controls completed a video-oculographic examination of horizontal smooth pursuit and reactive saccades twice, while the left or right eye was covered with an eye patch. Independent of the eye patch position, LH and RH patients showed enlarged saccade latencies toward contralesional stimuli. In addition, both during smooth pursuit and reactive saccades, RH patients made significantly fewer rightward saccades when the right than when the left eye was patched. Moreover, during reactive saccades, RH patients made significantly fewer right than left saccades, but only when the right eye was patched. These findings suggest that the ipsilesional eye patch modulated ipsilesional ocular performance in the RH group, presumably resulting from differences in SC activity. Yet, ipsilesional eye patching did not improve eye movements to the contralesional side of space, possibly due to the incomplete contralateral retinocollicular projection in humans.

Clinical and paraclinical features of psychopathological disorders in right hemisphere stroke

Aims: To investigate correlations between psychopathological disorders, clinical-neurological changes, and stroke severity in right-hemispheric ischemic stroke, considering age and gender influences. Study design: A descriptive cross-sectional approach was used. Place and Duration of Study: A group of 171 patients who suffered from right-hemisphere strokes were included in the study. These patients received treatment at the medical and diagnostic department No. 1 of the private company "LORITOM". Methodology: A pre-tested questionnaire was utilised to gather information from patients who were receiving treatment for right-hemispheric strokes at Treatment and Diagnostic Department No. 1 of the private enterprise "LORITOM." The National Institutes of Health Stroke Scale (NIHSS) was created to assess the seriousness of stroke symptoms. A scale ranging from 0 to 5 was employed to evaluate Muscle Strength, with plegia being a separate category. Results: Gender distribution among stroke patients was balanced (48% males, 52% females), highlighting equal susceptibility. The age analysis revealed a mean of 70.79 years, with significant differences across the age groups. Prevalence was notably high in the over 70s (χ2=57.0877, p&lt;0.0001) and 60-69 age group (Z=5.3, p&lt;0.0001). Gender differences exist in certain age categories. The stroke severity is associated with patient characteristics but not gender. The muscle strength correlates with the stroke severity (Z=9.93, p&lt;0.05). The neglect is prevalent (61.91%) and linked to the stroke severity. Right-hemispheric stroke is associated with higher anxiety than depression, with a weakening correlation at severe levels (R=0.782, p=0.00000). Conclusion: The comprehensive analysis of stroke patient data underscored the need for gender-specific healthcare strategies, highlighted the age-related prevalence patterns, and emphasised the significance of assessing psychomotional well-being, particularly in individuals with right-hemispheric stroke.

Clinimetric properties of relevant criteria for assessing writing and drawing orientation after right hemisphere stroke

BackgroundWriting and drawing orientation is rarely assessed in clinical routine, although it might have a potential value in detecting impaired verticality perception after right hemispheric stroke (RHS). Assessment tools and criteria must be conceived and validated. We therefore explored the clinimetric properties of a set of quantitative writing and drawing orientation criteria, their ranges of normality, and their tilt prevalence in RHS individuals. New methodsWe asked 69 individuals with subacute RHS and 64 matched healthy controls to write three lines and to copy the Gainotti Figure (house and trees). We determined six criteria referring to the orientation of writing and drawing main axes: for writing, the line and margin orientations, and for drawing, the tree, groundline, wall, and roofline orientations. Orientations were measured by using an electronic protractor from specific landmarks positioned by independent evaluators. ResultsThe set of criteria fulfilling all clinimetric properties (feasibility, measurability, reliability) comprised the line orientation of the writing and the wall and roofline orientations of the drawing. Writing and drawing tilts were frequent after RHS (about 30% by criterion). Comparison with existing methodsSo far, graphomotor orientation was mostly tested qualitatively and could not be objectively appreciated in absence of validated tools and criteria, and without ranges of normality. Writing and drawing tilts may now be assessed both in routine clinical practice and research. ConclusionsOur study paves the way for investigating the clinical determinants of graphomotor tilts, including impaired verticality perception, to better understand their underlying mechanisms.

EEG Microstates as a Signature of Hemispheric Lateralization in Stroke

Stroke recovery trajectories vary substantially. The need for tracking and prognostic biomarkers in stroke is utmost for prognostic and rehabilitative goals: electroencephalography (EEG) advanced signal analysis may provide useful tools toward this aim. EEG microstates quantify changes in configuration of neuronal generators of short-lasting periods of coordinated synchronized communication within large-scale brain networks: this feature is expected to be impaired in stroke. To characterize the spatio-temporal signatures of EEG microstates in stroke survivors in the acute/subacute phase, EEG microstate analysis was performed in 51 first-ever ischemic stroke survivors [(28–82) years, 24 with right hemisphere (RH) lesion] who underwent a resting-state EEG recording in the acute and subacute phase (from 48 h up to 42 days after the event). Microstates were characterized based on 4 parameters: global explained variance (GEV), mean duration, occurrences per second, and percentage of coverage. Wilcoxon Rank Sum tests were performed to compare features of each microstate across the two groups [i.e., left hemisphere (LH) and right hemisphere (RH) stroke survivors]. The canonical microstate map D, characterized by a mostly frontal topography, displayed greater GEV, occurrence per second, and percentage of coverage in LH than in RH stroke survivors (p < 0.05). The EEG microstate map B, with a left-frontal to right-posterior topography, and F, with an occipital-to-frontal topography, exhibited a greater GEV in RH than in LH stroke survivors (p = 0.015). EEG microstates identified specific topographic maps which characterize stroke survivors’ lesioned hemisphere in the acute and early subacute phase. Microstate features offer an additional tool to identify different neural reorganization.

Dynamic brain states in spatial neglect after stroke.

Previous studies indicated that spatial neglect is characterized by widespread alteration of resting-state functional connectivity and changes in the functional topology of large-scale brain systems. However, whether such network modulations exhibit temporal fluctuations related to spatial neglect is still largely unknown. This study investigated the association between brain states and spatial neglect after the onset of focal brain lesions. A cohort of right-hemisphere stroke patients (n = 20) underwent neuropsychological assessment of neglect as well as structural and resting-state functional MRI sessions within 2 weeks from stroke onset. Brain states were identified using dynamic functional connectivity as estimated by the sliding window approach followed by clustering of seven resting state networks. The networks included visual, dorsal attention, sensorimotor, cingulo-opercular, language, fronto-parietal, and default mode networks. The analyses on the whole cohort of patients, i.e., with and without neglect, identified two distinct brain states characterized by different degrees of brain modularity and system segregation. Compared to non-neglect patients, neglect subjects spent more time in less modular and segregated state characterized by weak intra-network coupling and sparse inter-network interactions. By contrast, patients without neglect dwelt mainly in more modular and segregated states, which displayed robust intra-network connectivity and anti-correlations among task-positive and task-negative systems. Notably, correlational analyses indicated that patients exhibiting more severe neglect spent more time and dwelt more often in the state featuring low brain modularity and system segregation and vice versa. Furthermore, separate analyses on neglect vs. non-neglect patients yielded two distinct brain states for each sub-cohort. A state featuring widespread strong connections within and between networks and low modularity and system segregation was detected only in the neglect group. Such a connectivity profile blurred the distinction among functional systems. Finally, a state exhibiting a clear separation among modules with strong positive intra-network and negative inter-network connectivity was found only in the non-neglect group. Overall, our results indicate that stroke yielding spatial attention deficits affects the time-varying properties of functional interactions among large-scale networks. These findings provide further insights into the pathophysiology of spatial neglect and its treatment.

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

Delirium, an acute and fluctuating decline in cognitive functioning, increases mortality and length of hospital stays (LOS) and adversely affects functional outcomes. Previous studies suggested that the incidence of delirium may be increased in right-hemisphere strokes. Similarly, spatial neglect, a disabling deficit in unilateral spatial processing, is more common and more severe following a right-sided stroke. Spatial neglect has been established as a risk factor for delirium. It was hypothesized that functionally relevant spatial neglect and delirium are associated in patients with right-hemisphere stroke during acute inpatient rehabilitation. Data were examined from consecutive unilateral stroke patients evaluated with the 3-minute diagnostic interview for confusion assessment method (3D-CAM) and the Catherine Bergego Scale (CBS) via the Kessler Foundation Neglect Assessment Process (KF-NAP). A retrospective, cohort study. Data collected in an acute inpatient rehabilitation facility. Six hundred twenty six patients with stroke were included. The measures were the relative risk of patients with right-hemisphere stroke having delirium when also positive for spatial neglect compared to patients with right-hemisphere stroke without spatial neglect, the incidence of 3D-CAM positive results by stroke hemisphere, and the effect of spatial neglect and delirium on functional outcomes for patients with right-brain stroke patients. There was a significantly higher risk of delirium in patients with right-hemisphere stroke with spatial neglect compared to patients with right-hemisphere stroke without spatial neglect. The rates of 3D-CAM positive results were not statistically different for left- compared to right-hemisphere strokes. Both delirium and spatial neglect had significant adverse effects on right-hemisphere stroke patients' functional independence. The results demonstrate an association between spatial neglect and delirium in patients with right hemisphere stroke in the acute inpatient rehabilitation setting. Because of the negative effect of these impairments on functional outcomes after stroke, prevention, early detection, and targeted treatments should be prioritized for these patients.

The Effect of Mirror Visual Feedback on Spatial Neglect for Patients after Stroke: A Preliminary Randomized Controlled Trial.

We investigated the effects of mirror visual feedback (MVF), with reference to using a glass wall or a covered mirror, on the reduction of spatial neglect for patients with stroke. A total of 21 subacute patients with left spatial neglect after right-hemispheric stroke were randomly assigned to 3 groups: MVF, sham 1 (viewing the hemiparetic arm through the transparent glass during bilateral arm movement) and sham 2 (using a covered mirror). The 3-week treatment program for all groups consisted of 12 sessions of movement tasks for the hemiparetic arm graded according to the severity of arm impairments. Blinded assessments were administered at pre/post and a three-week follow-up. The results showed that there was no significant advantage for MVF than sham 1; however, MVF was more beneficial than sham 2, as shown by the line crossing (p = 0.022). Improvement in discriminating the left-gap figures on the left and right side of the page in the Gap Detection Test was greater in MVF than using the covered mirror (p = 0.013; p = 0.010), showing a slight advantage of MVF in alleviating allocentric symptoms. Our study confirms that MVF was superior to using a covered mirror as a method for reducing spatial neglect and in alleviating its allocentric symptoms, but no significant advantage over bilateral arm movement through transparent glass was found. Further research in comparing their therapeutic effects is warranted.