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.

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.

An analysis of verbal fluency task performance profiles in patients with vascular brain pathology

Aim: Considering the data on the important role of verbal fluency tasks in neuropsychological diagnosis and the models of hemispherically specialised modulation of processes essential for different types of verbal fluency, we made an attempt to identify differences in correct and incorrect performance of 5 verbal fluency tasks between patients with vascular cerebral pathology, including hypertension, and healthy individuals. We also analysed task performance profiles within the groups. Materials and methods: The study included healthy volunteers (n = 36), hypertensive individuals (n = 33), and patients after left (n = 15) or right hemisphere stroke (n = 30) – 114 subjects in total. We used the Frenchay Aphasia Screening Test (FAST) to exclude patients with significant language difficulties/aphasia. We used 5 verbal fluency tasks: semantic (Animals), phonemic (“k”), verb fluency and two emotional tasks: Joy and Fear. We used general linear models for repeated measures for the analysis of correctly and incorrectly performed tasks. Results: The profiles of correct responses for all 5 tasks were similar in all groups, with quantitative intergroup differences. The highest number of correct responses appeared in the semantic, phonemic and verb fluency tasks, whereas the lowest number in the emotional tasks. Hypertensive individuals scored statistically insignificantly lower than healthy individuals, whereas patients after right/left hemisphere stroke scored significantly lower compared to both these groups. Despite a large number of errors, healthy individuals had the highest scores. Patients after right hemisphere stroke showed little differentiation in the number of correct responses in subsequent tasks. There were no intergroup differences in the level of performance of emotional tasks with different valences (positive and negative). Healthy and hypertensive individuals were characterised by a distinct heterogeneity of correct and incorrect responses in various tasks. Patients with brain pathology, regardless of its lateralisation, performed these tasks at a similar level, with left hemisphere damage resulting in the highest number of errors, mainly in semantic and phonemic tasks, and with right hemisphere pathology associated with errors in all types of tasks. The difficulties in patients with left hemisphere damage may result from weaker phonological and lexical processes, including access to semantic features of a word, while the low scores of patients with right hemisphere damage may be a consequence of impaired attention and executive processes. Conclusions: Patients with vascular pathology of the brain hemispheres achieved significantly lower scores in all types of fluency, while hypertensive individuals scored insignificantly lower than healthy subjects. This means that the method can be useful in differentiating between healthy individuals and patients with central nervous system damage, as well as those at risk. Future research should focus on a detailed analysis of the types of errors made by patients with hemispheric damage in various types of verbal fluency tasks. An analysis of the location of the pathology in the anterior-posterior dimension of each hemisphere could reveal specific features of verbal fluency.

Is Lateropulsion Really Related with a Specific Lesion of the Brain?

Lateropulsion (pusher syndrome) is an important barrier to standing and gait after stroke. Although several studies have attempted to elucidate the relationship between brain lesions and lateropulsion, the effects of specific brain lesions on the development of lateropulsion remain unclear. Thus, the present study investigated the effects of stroke lesion location and size on lateropulsion in right hemisphere stroke patients. The present retrospective cross-sectional observational study assessed 50 right hemisphere stroke patients. Lateropulsion was diagnosed and evaluated using the Scale for Contraversive Pushing (SCP). Voxel-based lesion symptom mapping (VLSM) analysis with 3T-MRI was used to identify the culprit lesion for SCP. We also performed VLSM controlling for lesion volume as a nuisance covariate, in a multivariate model that also controlled for other factors contributing to pusher behavior. VLSM, combined with statistical non-parametric mapping (SnPM), identified the specific region with SCP. Lesion size was associated with lateropulsion. The precentral gyrus, postcentral gyrus, inferior frontal gyrus, insula and subgyral parietal lobe of the right hemisphere seemed to be associated with the lateropulsion; however, after adjusting for lesion volume as a nuisance covariate, no lesion areas were associated with the SCP scores. The size of the right hemisphere lesion was the only factor most strongly associated with lateropulsion in patients with stroke. These results may be useful for planning rehabilitation strategies of restoring vertical posture and understanding the pathophysiology of lateropulsion in stroke patients.

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.