Disruption of the ascending arousal system and cortical attention networks in post-stroke delirium and spatial neglect

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

BACKGROUND

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.

OBJECTIVE

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).

DESIGN

A retrospective, cohort study.

SETTING

Data collected in an acute inpatient rehabilitation facility.

PARTICIPANTS

Six hundred twenty six patients with stroke were included.

MAIN OUTCOME MEASURES

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.

RESULTS

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.

CONCLUSIONS

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.

Recent advances in treatment of spatial neglect: networks and neuropsychology

INTRODUCTION

Spatial neglect remains an underdiagnosed and undertreated consequence of stroke that imposes significant disability. A growing appreciation of brain networks involved in spatial cognition is helping us to develop a mechanistic understanding of different therapies under development.

AREAS COVERED

This review focuses on neuromodulation of brain networks for the treatment of spatial neglect after stroke, using evidence-based approaches including 1) Cognitive strategies that are more likely to impact frontal lobe executive function networks; 2) Visuomotor adaptation, which may depend on the integrity of parietal and parieto- and subcortical-frontal connections and the presence of a particular subtype of neglect labeled Aiming neglect; 3) Non-invasive brain stimulation that may modulate relative levels of activity of the two hemispheres and depend on corpus callosum connectivity; and 4) Pharmacological modulation that may exert its effect primarily via right-lateralized networks more closely involved in arousal.

EXPERT OPINION

Despite promising results from individual studies, significant methodological heterogeneity between trials weakened conclusions drawn from meta-analyses. Improved classification of spatial neglect subtypes will benefit research and clinical care. Understanding the brain network mechanisms of different treatments and different types of spatial neglect will make possible a precision medicine treatment approach.

EEG complexity correlates with residual consciousness level of disorders of consciousness

BACKGROUND AND OBJECTIVE

Electroencephalography (EEG) and neuroimaging measurements have been highly encouraged to be applied in clinics of disorders of consciousness (DOC) to improve consciousness detection. We tested the relationships between neural complexity measured on EEG and residual consciousness levels in DOC patients.

METHODS

Resting-state EEG was recorded from twenty-five patients with DOC. Lempel-Ziv complexity (LZC) and permutation Lempel-Ziv complexity (PLZC) were measured on the EEG, and their relationships were analyzed with the consciousness levels of the patients.

RESULTS

PLZC and LZC values significantly distinguished patients with a minimally conscious state (MCS), vegetative state/unresponsive wakefulness syndrome (VS/UWS), and healthy controls. PLZC was significantly correlated with the Coma Recovery Scale-Revised (CRS-R) scores of DOC patients in the global brain, particularly in electrodes locating in the anterior and posterior brain regions. Patients with higher CRS-R scores showed higher PLZC values. The significant difference in PLZC values between MCS and VS/UWS was mainly located in the bilateral frontal and right hemisphere regions.

CONCLUSION

Neural complexity measured on EEG correlates with residual consciousness levels of DOC patients. PLZC showed higher sensitivity than LZC in the classification of consciousness levels.

Cortical reactivity to transcranial magnetic stimulation predicts risk of post-stroke delirium

OBJECTIVE

Post-stroke delirium (PSD) is a frequent and with regard to outcome unfavorable complication in acute stroke. The neurobiological mechanisms predisposing to PSD remain poorly understood, and biomarkers predicting its risk have not been established. We tested the hypothesis that hypoexcitable or disconnected brain networks predispose to PSD by measuring brain reactivity to transcranial magnetic stimulation with electroencephalography (TMS-EEG).

METHODS

We conducted a cross-sectional study in 33 acute stroke patients within 48 hours of stroke onset. Brain reactivity to single-pulse TMS of dorsolateral prefrontal cortex, primary motor cortex and superior parietal lobule of the right hemisphere was quantified by response intensity, effective connectivity, perturbational complexity index (PCI^ST), and natural frequency of the TMS-EEG response. PSD development was clinically tracked every 8 hours before and for 7 days following TMS-EEG.

RESULTS

Fourteen patients developed PSD while 19 patients did not. The PSD group showed lower excitability, effective connectivity, PCI^ST and natural frequency compared to the non-PSD group. The maximum PCI^ST over all three TMS sites demonstrated largest classification accuracy with a ROC-AUC of 0.943. This effect was independent of lesion size, affected hemisphere and stroke severity. Maximum PCI^ST and maximum natural frequency correlated inversely with delirium duration.

CONCLUSIONS

Brain reactivity to TMS-EEG can unravel brain network states of reduced excitability, effective connectivity, perturbational complexity and natural frequency that identify acute stroke patients at high risk for development of delirium.

SIGNIFICANCE

Findings provide novel insight into the pathophysiology of pre-delirium brain states and may promote effective delirium prevention strategies in those patients at high risk.

Benzodiazepines Remain Important Therapeutic Options in Psychiatric Practice

Benzodiazepines and medications acting on benzodiazepine receptors that do not have a benzodiazepine structure (z-drugs) have been viewed by some experts and regulatory bodies as having limited benefit and significant risks. Data presented in this article support the use of these medications as treatments of choice for acute situational anxiety, chronic anxiety disorders, insomnia, alcohol withdrawal syndromes, and catatonia. They may also be useful adjuncts in the treatment of anxious depression and mania, and for medically ill patients. Tolerance develops to sedation and possibly psychomotor impairment, but not to the anxiolytic effect of benzodiazepines. Sedation can impair cognitive function in some patients, but assertions that benzodiazepines increase the risk of dementia are not supported by recent data. Contrary to popular opinion, benzodiazepines are not frequently misused or conduits to misuse of other substances in patients without substance use disorders who are prescribed these medications for appropriate indications; most benzodiazepine misuse involves medications that are obtained from other people. Benzodiazepines are usually not lethal in overdose except when ingested with other substances, especially alcohol and opioids. Benzodiazepines comprise one of the few classes of psychotropic medication the mechanisms of action of which are clearly delineated, allowing for greater precision in their clinical use. These medications, therefore, belong in the therapeutic armamentarium of the knowledgeable clinician.

Brain Network Dysfunction in Poststroke Delirium and Spatial Neglect: An fMRI Study

BACKGROUND AND PURPOSE

Delirium, an acute reduction in cognitive functioning, hinders stroke recovery and contributes to cognitive decline. Right-hemisphere stroke is linked with higher delirium incidence, likely, due to the prevalence of spatial neglect (SN), a right-brain disorder of spatial processing. This study tested if symptoms of delirium and SN after right-hemisphere stroke are associated with abnormal function of the right-dominant neural networks specialized for maintaining attention, orientation, and arousal.

METHODS

Twenty-nine participants with right-hemisphere ischemic stroke undergoing acute rehabilitation completed delirium and SN assessments and functional neuroimaging scans. Whole-brain functional connectivity of 4 right-hemisphere seed regions in the cortical-subcortical arousal and attention networks was assessed for its relationship to validated SN and delirium severity measures.

RESULTS

Of 29 patients, 6 (21%) met the diagnostic criteria for delirium and 16 (55%) for SN. Decreased connectivity of the right basal forebrain to brain stem and basal ganglia predicted more severe SN. Increased connectivity of the arousal and attention network regions with the parietal, frontal, and temporal structures in the unaffected hemisphere was also found in more severe delirium and SN.

CONCLUSIONS

Delirium and SN are associated with decreased arousal network activity and an imbalance of cortico-subcortical hemispheric connectivity. Better understanding of neural correlates of poststroke delirium and SN will lead to improved neuroscience-based treatment development for these disorders. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03349411.

DelIrium VULnerability in GEriatrics (DIVULGE) study: a protocol for a prospective observational study of electroencephalogram associations with incident postoperative delirium

INTRODUCTION

Delirium is a neurocognitive disorder common in older adults in acute care settings. Those who develop delirium are at an increased risk of dementia, cognitive decline and death. Electroencephalography (EEG) during delirium in older adults is characterised by slowing and reduced functional connectivity, but markers of vulnerability are poorly described. We aim to identify EEG spectral power and event-related potential (ERP) markers of incident delirium in older adults to understand neural mechanisms of delirium vulnerability. Characterising delirium vulnerability will provide substantial theoretical advances and outcomes have the potential to be translated into delirium risk assessment tools.

METHODS AND ANALYSIS

We will record EEG in 90 participants over 65 years of age prior to elective coronary artery bypass grafting (CABG) or transcatheter aortic valve implantation (TAVI). We will record 4-minutes of resting state (eyes open and eyes closed) and a 5-minute frequency auditory oddball paradigm. Outcome measures will include frequency band power, 1/f offset and slope, and ERP amplitude measures. Participants will undergo cognitive and EEG testing before their elective procedures and daily postoperative delirium assessments. Group allocation will be done retrospectively by linking preoperative EEG data according to postoperative delirium status (presence, severity, duration and subtype).

ETHICS AND DISSEMINATION

This study is approved by the Human Research Ethics Committee of the Royal Adelaide Hospital, Central Adelaide Local Health Network and the University of South Australia Human Ethics Committee. Findings will be disseminated through peer-reviewed journal articles and presentations at national and international conferences.

TRIAL REGISTRATION NUMBER

ACTRN12618001114235 and ACTRN12618000799257.

Spatial Neglect and Anosognosia After Right Brain Stroke

PURPOSE OF REVIEW

Up to 80% of survivors of right brain stroke leave acute care without being diagnosed with a major invisible disability. Studies indicate that a generic cognitive neurologic evaluation does not reliably detect spatial neglect, nor does it identify unawareness of deficit after right brain stroke; this article reviews the symptoms, clinical presentation, and management of these two cognitive disorders occurring after right brain stroke.

RECENT FINDINGS

Stroke and occupational therapy practice guidelines stress a quality standard for spatial neglect assessment and treatment to reduce adverse outcomes for patients, their families, and society. Neurologists may attribute poor outcomes associated with spatial neglect to stroke severity. However, people with spatial neglect are half as likely to return to home and community, have one-third the community mobility, and require 3 times as much caregiver supervision compared with similar stroke survivors. Multiple randomized trials support a feasible first-line rehabilitation approach for spatial neglect: prism adaptation therapy; more than 20 studies reported that this treatment improves daily life independence. Evidence-based treatment of anosognosia is not as developed; however, treatment for this problem is also available.

SUMMARY

This article guides neurologists' assessment of right brain cognitive disorders and describes how to efficiently assemble and direct a treatment team to address spatial neglect and unawareness of deficit.

Are We Right about the Right TPJ? A Review of Brain Stimulation and Social Cognition in the Right Temporal Parietal Junction

In the past decade, the functional role of the TPJ (Temporal Parietal Junction) has become more evident in terms of its contribution to social cognition. Studies have revealed the TPJ as a ‘distinguisher’ of self and other with research focused on non-clinical populations as well as in individuals with Autism and Type I Schizophrenia. Further research has focused on the integration of self-other distinctions with proprioception. Much of what we now know about the causal role of the right TPJ derives from TMS (Transcranial Magnetic Stimulation), rTMS repetitive Transcranial Magnetic Stimulation), and tDCS (transcranial Direct Cortical Stimulation). In this review, we focus on the role of the right TPJ as a moderator of self, which is integrated and distinct from ‘other’ and how brain stimulation has established the causal relationship between the underlying cortex and agency.

Barriers and Facilitators to Rehabilitation Care of Individuals With Spatial Neglect: A Qualitative Study of Professional Views

Objective

To identify barriers and facilitators to achieving optimal inpatient rehabilitation outcome among individuals with spatial neglect (SN).

Design

Cross-sectional, semistructured focus group discussions.

Setting

Rehabilitation hospitals.

Participants

A total of 15 occupational therapists and 14 physical therapists treating patients with SN on 3 campuses of a rehabilitation hospital system (N=29). Six focus group sessions were conducted and audio-recorded for transcription.

Interventions

Not applicable.

Main Outcome Measures

Not applicable.

Results

Participants identified several patient-related characteristics that posed barriers to treatment, including the symptoms of SN itself, cognitive issues, physical weakness, comorbidities, and reduced therapy engagement. Supportive family members were considered a key facilitator, but lack of preparedness to assume caregiving roles, poor understanding of SN and rehabilitation goals, and inadequate levels of involvement were family-related barriers to successful treatment. Participants expressed that having resources and technologies available at their center to support SN treatment facilitated positive outcomes and perceived limited staff knowledge and skills and poor interclinician communication as barriers to treatment. At the health care system level, barriers included a lack of responsive measures of SN progress and insurer-related issues. Strong continuity of care between transitions was considered an important factor for enabling effective treatment.

Conclusions

Barriers and facilitators to the current practice of SN care were identified from occupational and physical therapists’ point of view. Opportunities exist to promote identified facilitators and minimize barriers to improve SN rehabilitation. The present study makes a unique contribution in identifying specific needs for innovative interventions that involve family support and training, promotion of interdisciplinary collaboration, development of interprofessional vocabulary, and continuous treatment and follow-up assessment for SN through care transitions.

Current clinical practice in the screening and diagnosis of spatial neglect post-stroke: Findings from a multidisciplinary international survey

Spatial neglect has profound implications for quality of life after stroke, yet we lack consensus for screening/diagnosing this heterogeneous syndrome. Our first step in a multi-stage research programme aimed to determine which neglect tests are used (within four categories: cognitive, functional, neurological and neuroimaging/neuromodulation), by which stroke clinicians, in which countries, and whether choice is by professional autonomy or institutional policy. 454 clinicians responded to an online survey: 12 professions (e.g., 39% were occupational therapists) from 33 countries (e.g., 38% from the UK). Multifactorial logistic regression suggested inter-professional differences but fewer differences between countries (Italy was an outlier). Cognitive tests were used by 82% (particularly by psychologists, cancellation and drawing were most popular); 80% used functional assessments (physiotherapists were most likely). 20% (mainly physicians, from Italy) used neuroimaging/ neuromodulation. Professionals largely reported clinical autonomy in their choices. Respondents agreed on the need for a combined approach to screening and further training. This study raises awareness of the translation gap between theory and practice. These findings lay an important foundation to subsequent collaborative action between clinicians, researchers and stroke survivors to reach consensus on screening and diagnostic measures. The immediate next step is a review of the measures' psychometric properties.

Predictors of Arm Nonuse in Chronic Stroke: A Preliminary Investigation

Background. Nonuse (NU) after stroke is characterized by failure to use the contralesional arm despite adequate capacity. It has been suggested that NU is a consequence of the greater effort and/or attention required to use the affected limb, but such accounts have not been directly tested, and we have poor understanding of the predictors of NU. Objective. We aimed to provide preliminary evidence regarding demographic, neuropsychological (ie, apraxia, attention/arousal, neglect), and psychological (ie, self-efficacy) factors that may influence NU in chronic stroke. Methods. Twenty chronic stroke survivors with mild to moderate sensory-motor impairment characterized by the Upper-Extremity Fugl-Meyer (UEFM) were assessed for NU with a modified version of the Actual Amount of Use Test (AAUT), which measures the disparity between amount of use in spontaneous versus forced conditions. Participants were also assessed with measures of limb apraxia, spatial neglect, attention/arousal, and self-efficacy. Using stepwise multiple regression, we determined which variables predicted AAUT NU scores. Results. Scores on the UEFM as well as attention/arousal predicted the degree of NU (P < .05). Attention/arousal predicted NU above and beyond UEFM (P < .05). Conclusions. The results are consistent with the importance of attention and engagement necessary to fully incorporate the paretic limb into daily activities. Larger-scale studies that include additional behavioral (eg, sensation, proprioception, spasticity, pain, mental health, motivation) and neuroanatomical measures (eg, lesion volume and white matter connectivity) will be important for future investigations.

Visuospatial Neglect - a Theory-Informed Overview of Current and Emerging Strategies and a Systematic Review on the Therapeutic Use of Non-invasive Brain Stimulation

Visuospatial neglect constitutes a supramodal cognitive deficit characterized by reduction or loss of spatial awareness for the contralesional space. It occurs in over 40% of right- and 20% of left-brain-lesioned stroke patients with lesions located mostly in parietal, frontal and subcortical brain areas. Visuospatial neglect is a multifaceted syndrome - symptoms can be divided into sensory, motor and representational neglect - and therefore requires an individually adapted diagnostic and therapeutic approach. Several models try to explain the origins of visuospatial neglect, of which the "interhemispheric rivalry model" is strongly supported by animal and human research. This model proposes that allocation of spatial attention is balanced by transcallosal inhibition and both hemispheres compete to direct attention to the contralateral hemi-space. Accordingly, a brain lesion causes an interhemispheric imbalance, which may be re-installed by activation of lesioned, or deactivation of unlesioned (over-activated) brain areas through noninvasive brain stimulation. Research in larger patient samples is needed to confirm whether noninvasive brain stimulation can improve long-term outcomes and whether these also affect activities of daily living and discharge destination.

Delirium Screening and Management in Inpatient Rehabilitation Facilities

Delirium is an acute and fluctuating disturbance in cognition attention and awareness that is often a reflection of abnormal physiological condition of an individual. Delirium is highly prevalent among an older population and is associated with high mortality, poor medical and functional outcomes, and high healthcare cost. Delirium often has iatrogenic triggers, and it has been recognized as a quality indicator of healthcare organizations. Despite its high prevalence and significance, more than 50% of the delirium cases are underrecognized by healthcare professionals and remained untreated. Most patients in inpatient rehabilitation facilities are older adults with multiple risk factors for delirium including operation, intensive care stay, multiple co-morbidities, and impaired mobility. Early detection, intervention, and primary prevention of delirium will allow patients to avoid additional morbidities and reach their maximum functional potential during their rehabilitation stay. After the systematic implementation of delirium screening in our inpatient rehabilitation facility, we found that 10.3% of patients were screened positive for delirium at admission. This review discusses the systematic implementation of screening and intervention for delirium as well as the epidemiology of delirium to increase the awareness and guide clinical practice for clinicians in inpatient rehabilitation facilities.

Ventral attention and motor network connectivity is relevant to functional impairment in spatial neglect after right brain stroke

Emerging research suggests spatial neglect after right stroke is linked to dysfunctional attention and motor networks. Advanced functional connectivity analysis clarified brain network recovery, however we need to know how networks participate in adaptive motor performance. We need to verify network changes associated with validated functional measures and spatial-motor performance in spatial neglect, especially in patients with large brain lesions and significant disability. This study tested whether disability-relevant spatial neglect associates with different patterns of resting state functional connectivity between motor, dorsal and ventral attention networks (MN, DAN and VAN). Right stroke patients had spatial neglect (n = 8) or not (n = 10) on the Behavioural Inattention Test-conventional. Spatial neglect patients had weaker intranetwork VAN connectivity, and reduced internetwork connectivity between VAN and left frontal eye field (DAN), and between VAN and the left primary motor area (MN). These network impairments might explain the co-occurrence of attention and motor deficits in spatial neglect, and open a path to assessing functional connectivity in clinical trials of combined spatial retraining and motor rehabilitation after stroke.

Clinical Predictors of Engagement in Inpatient Rehabilitation Among Stroke Survivors With Cognitive Deficits: An Exploratory Study

OBJECTIVES

The purpose of this exploratory study was to identify clinical predictors that could distinguish clients' level of engagement in inpatient rehabilitation following stroke.

METHODS

This is a secondary analysis of pooled data from three randomized controlled trials that examined the effects of a behavioral intervention. The sample (n=208) consisted of clients with stroke who had cognitive deficits (Quick-EXIT≥3) and were admitted to inpatient rehabilitation facilities associated with a university medical center. Individuals with pre-morbid dementia, aphasia and mood disorders were excluded. The Pittsburgh Rehabilitation Participation Scale was used to measure engagement. Clinical predictors were measured using the Functional Independence Measure, National Institutes of Health Stroke Scale, Repeatable Battery for the Assessment of Neuropsychological Status, selected subtests of the Delis-Kaplan Executive Function System, Patient Health Questionnaire-9, and Chedoke McMaster Stroke Assessment. Simple logistic regression identified individual clinical predictors associated with engagement. Hierarchical logistic regression identified the strongest predictors of engagement.

RESULTS

Impairments in executive functions [mean D-KEFS, odds ratio (OR)=4.062; 95% confidence interval (CI)=.866, 19.051], impairments in visuospatial skills (RBANS Visuospatial Index Score, OR=3.940; 95% CI=1.317, 11.785), impairments in mood (Patient Health Questionnaire-9, OR=2.059, 95% CI=.953, 4.449), and male gender (OR=2.474; 95% CI=1.145, 5.374) predicted levels of engagement in inpatient rehabilitation after controlling for study intervention group, baseline stroke severity, and baseline disability.

CONCLUSIONS

Executive functions, visuospatial skills, mood, and gender distinguished individuals with high or low engagement in inpatient rehabilitation following stroke. Further studies should examine additional factors that may influence engagement (therapist-client relationship, treatment expectancy). (JINS, 2018, 24, 572-583).