Disruptions of the Human Connectome Associated With Hemispatial Neglect

Background and ObjectivesHemispatial neglect is a heterogeneous and complex disorder that can be classified by frame of reference for “left” vs “right,” including viewer-centered neglect (VCN, affecting the contralesional side of the view), stimulus-centered neglect (SCN, affecting the contralesional side of the stimulus, irrespective of its location with respect to the viewer), or both. We investigated the effect of acute stroke lesions on the connectivity of neural networks that underlie VCN or SCN.MethodsA total of 174 patients within 48 hours of acute right hemispheric infarct underwent a detailed hemispatial neglect assessment that included oral reading, scene copy, line cancellation, gap detection, horizontal line bisection tests, and MRI. Each patient's connectivity map was generated. We performed a linear association analysis between network connectivity strength and continuous measures of neglect to identify lesion-induced disconnections associated with the presence or severity of VCN and SCN. Results were corrected for multiple comparisons.ResultsAbout 42% of the participants with right hemisphere stroke had at least one type of neglect. The presence of any type of neglect was associated with lesions to tracts connecting the right inferior parietal cortex, orbitofrontal cortex, and right thalamus to other right-hemispheric structures. VCN only was strongly associated with tracts connecting the right putamen to other brain regions and tracts connecting right frontal regions with other brain regions. The presence of both types of neglect was most strongly associated with tracts connecting the right inferior and superior parietal cortex to other brain regions and those connecting left or right mesial temporal cortex to other brain regions.DiscussionOur study provides new evidence for the specific white matter tracts where disruption can cause hemispatial neglect in a relatively large number of participants and homogeneous time after onset. We obtained MRI and behavioral testing acutely, before the opportunity for rehabilitation or substantial recovery.Classification of EvidenceThis study provides Class II evidence that damage to specific white matter tracts identified on MRI are associated with the presence of neglect following right hemispheric stroke.

Taking phenomenology beyond the first-person perspective: conceptual grounding in the collection and analysis of observational evidence

Phenomenology has been adapted for use in qualitative health research, where it’s often used as a method for conducting interviews and analyzing interview data. But how can phenomenologists study subjects who cannot accurately reflect upon or report their own experiences, for instance, because of a psychiatric or neurological disorder? For conditions like these, qualitative researchers may gain more insight by conducting observational studies in lieu of, or in conjunction with, interviews. In this article, we introduce a phenomenological approach to conducting this kind of observational research. The approach relies on conceptual grounding to focus a study on specific aspects of the participants’ experiences. Moreover, the approach maintains the openness to novel discoveries that qualitative research requires while also providing a structured framework for data collection and analysis. To illustrate its practical application, we use examples of hemispatial neglect—a neurologic disorder in which patients characteristically lack awareness of their own illness and bodily capacities. However, the approach that we describe can be applied more broadly to the study of complex illness experiences and other experiential alterations.

The Company Prosodic Deficits Keep Following Right Hemisphere Stroke: A Systematic Review

Objectives: The aim of this systematic review was to identify the presence and nature of relationships between specific forms of aprosodia (i.e., expressive and receptive emotional and linguistic prosodic deficits) and other cognitive-communication deficits and disorders in individuals with right hemisphere damage (RHD) due to stroke. Methods: One hundred and ninety articles from 1970 to February 2020 investigating receptive and expressive prosody in patients with relatively focal right hemisphere brain damage were identified via database searches. Results: Fourteen articles were identified that met inclusion criteria, passed quality reviews, and included sufficient information about prosody and potential co-occurring deficits. Twelve articles investigated receptive emotional aprosodia, and two articles investigated receptive linguistic aprosodia. Across the included studies, receptive emotional prosody was not systematically associated with hemispatial neglect, but did co-occur with deficits in emotional facial recognition, interpersonal interactions, or emotional semantics. Receptive linguistic processing was reported to co-occur with amusia and hemispatial neglect. No studies were found that investigated the co-occurrence of expressive emotional or linguistic prosodic deficits with other cognitive-communication impairments. Conclusions: This systematic review revealed significant gaps in the research literature regarding the co-occurrence of common right hemisphere disorders with prosodic deficits. More rigorous empirical inquiry is required to identify specific patient profiles based on clusters of deficits associated with right hemisphere stroke. Future research may determine whether the co-occurrences identified are due to shared cognitive-linguistic processes, and may inform the development of evidence-based assessment and treatment recommendations for individuals with cognitive-communication deficits subsequent to RHD.

Disruption of large-scale electrophysiological networks in stroke patients with visuospatial neglect

Stroke frequently produces attentional dysfunctions including symptoms of hemispatial neglect, which is characterized by a breakdown of awareness for the contralesional hemispace. Recent studies with functional MRI (fMRI) suggest that hemineglect patients display abnormal intra- and interhemispheric functional connectivity. However, since stroke is a vascular disorder and fMRI signals remain sensitive to nonneuronal (i.e., vascular) coupling, more direct demonstrations of neural network dysfunction in hemispatial neglect are warranted. Here, we utilize electroencephalogram (EEG) source imaging to uncover differences in resting-state network organization between patients with right hemispheric stroke (N = 15) and age-matched, healthy controls (N = 27), and determine the relationship between hemineglect symptoms and brain network organization. We estimated intra- and interregional differences in cortical communication by calculating the spectral power and amplitude envelope correlations of narrow-band EEG oscillations. We first observed focal frequency-slowing within the right posterior cortical regions, reflected in relative delta/theta power increases and alpha/beta/gamma decreases. Secondly, nodes within the right temporal and parietal cortex consistently displayed anomalous intra- and interhemispheric coupling, stronger in delta and gamma bands, and weaker in theta, alpha, and beta bands. Finally, a significant association was observed between the severity of left-hemispace search deficits (e.g., cancellation test omissions) and reduced functional connectivity within the alpha and beta bands. In sum, our novel results validate the hypothesis of large-scale cortical network disruption following stroke and reinforce the proposal that abnormal brain oscillations may be intimately involved in the pathophysiology of visuospatial neglect.

Case Report: Visual Deprivation in Pusher Syndrome Complicated by Hemispatial Neglect After Basal Ganglia Stroke

We aimed to explore whether motor function and activities of daily life (ADL) could be improved with the application of visual deprivation in two patients with Pusher syndrome complicated by hemispatial neglect after right basal ganglia stroke. We assessed two stroke patients suffering from severe motor disturbances, both tilting heavily to the left, with diagnoses of Pusher syndrome and left hemispatial neglect. Vision in the left eye was deprived using patches during clinical rehabilitation. Motor function promotion was confirmed using the Burke Lateropulsion Scale (BLS), Fugl–Meyer Balance Scale (FMBS), and Holden grade (HG), while the Barthel index (BI) assessed ADL immediately and 1 week after intervention. Both patients regained standing balance immediately using visual deprivation, as well as walking ability, although both scored 0 on the FMBS and HG. After 1 week of treatment, one patient increased to 11 and 3 on the FMBS and HG, respectively, while the BLS score decreased from 12 to 2, and the ADL increased from 23 to 70. The other patient demonstrated increases to 10 and 3 on the FMBS and HG, respectively, with the BLS decreasing from 13 to 3, and the ADL increasing from 25 to 60. Therefore, in the rehabilitation treatment of Pusher syndrome complicated by hemispatial neglect due to basal ganglia stroke, visual deprivation can significantly improve motor function and shorten the treatment course.

FOPR test: a virtual reality-based technique to assess field of perception and field of regard in hemispatial neglect

Background We previously proposed a novel virtual reality-based method to assess human field of perception (FOP) and field of regard (FOR), termed the FOPR test. This study assessed the diagnostic validity of the FOPR test for hemispatial neglect (HSN). Methods We included 19 stroke patients with a lesion in the right hemisphere and with HSN (HSN+SS), 22 stroke patients with a lesion in the right hemisphere and without HSN (HSN−SS), and 22 healthy controls aged 19–65 years. The success rate (SR) and response time (RT) in the FOPR test for both FOP and FOR were assessed (FOP-SR, FOR-SR, FOP-RT, and FOR-RT, respectively). Using a Bland–Altman plot, agreements between the FOPR test and conventional tests were confirmed, and the FOPR test accuracy was verified using the support vector machine (SVM). Measured values were analysed using ANOVA and Kruskall–Wallis tests for group comparison. Results The Bland–Altman plot showed good agreement between FOPR test and conventional tests; individuals within 95% agreement limits were within the range of 94.8–100.0%. The SVM classification accuracy, using FOP and FOR variables from the left hemispace, ranged from 83.3 to 100.0% in a binary classification (HSN vs non-HSN). The FOPR test demonstrated differences in SR and RT for both FOP and FOR across the groups. Conclusion The FOPR test was valid for the HSN diagnosis and provided quantitative and intuitive information regarding visuospatial function. Furthermore, it might enhance our understanding of visuospatial function including HSN by applying the time relative component and concepts of perception and exploration, FOP and FOR. Trial registration: NCT03463122. Registered 13 March 2018, retrospectively registered.

Efficacy of repetitive transcranial magnetic stimulation combined with visual scanning treatment on cognitive and behavioral symptoms of left hemispatial neglect in right hemispheric stroke patients: study protocol for a randomized controlled trial

Background Left hemispatial neglect (LHN) is a neuropsychological syndrome often associated with right hemispheric stroke. Patients with LHN have difficulties in attending, responding, and consciously representing the right side of space. Various rehabilitation protocols have been proposed to reduce clinical symptoms related to LHN, using cognitive treatments, or on non-invasive brain stimulation. However, evidence of their benefit is still lacking; in particular, only a few studies focused on the efficacy of combining different approaches in the same patient. Methods In the present study, we present the SMART ATLAS trial (Stimolazione MAgnetica Ripetitiva Transcranica nell’ATtenzione LAteralizzata dopo Stroke), a multicenter, randomized, controlled trial with pre-test (baseline), post-test, and 12 weeks follow-up assessments based on a novel rehabilitation protocol based on the combination of brain stimulation and standard cognitive treatment. In particular, we will compare the efficacy of inhibitory repetitive-transcranial magnetic stimulation (r-TMS), applied over the left intact parietal cortex of LHN patients, followed by visual scanning treatment, in comparison with a placebo stimulation (SHAM control) followed by the same visual scanning treatment, on visuospatial symptoms and neurophysiological parameters of LHN in a population of stroke patients. Discussion Our trial results may provide scientific evidence of a new, relatively low-cost rehabilitation protocol for the treatment of LHN. Trial registration ClinicalTrials.gov NCT04080999. Registered on September 2019.

Ruptured hidden intracranial aneurysm during mechanical thrombectomy: A case report

Background: Acute ischemic stroke (AIS) patients have a higher prevalence of cerebral aneurysm than a healthy reference population. However, it was recently reported that cases of an unknown hidden aneurysm in AIS patients with large-vessel occlusion are rare. We report a rare case of subarachnoid hemorrhage (SAH) during mechanical thrombectomy (MT) using a stent retriever for AIS. Case Description: A 46-year-old patient with the right internal carotid artery terminal occlusion presented with the left-sided hemiparesis, hemispatial neglect, and dysarthria and underwent MT. Initial thrombectomy using a stent retriever and reperfusion catheter was unsuccessful. Angiography just before the second attempt showed SAH. Fortunately, we achieved recanalization of the thrombolysis in cerebral infarction 2b and hemostasis by lowering the blood pressure followed by coil embolization of the ruptured aneurysm. Only a few cases of ruptured aneurysms have been reported during MT using a stent retriever. Stent withdrawal is suspected to cause aneurysm rupture in cases with an unknown hidden middle cerebral artery bifurcation aneurysm. Conclusion: Preinterventional detection of a hidden aneurysm is difficult. Therefore, surgeons must always consider the possibility of a hidden aneurysm rupture in vessels distal to the occlusion site and make adequate preparations for the prompt treatment of ruptured aneurysms after MT.