Right Hemisphere Stroke Survivors Research Articles

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.

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.

How is carer strain related to the recovery of stroke survivors with right hemisphere dysfunction? Implications for practice

Aim Right hemisphere strokes are associated with neuro-behavioural impairments including hemi-inattention, impulsiveness and anosognosia, which can impede stroke recovery and adversely affect carer health. This study explored the impact of associated impairments on carer strain and depression through a mixed methods approach. Method Fifty-one carer-survivor dyads were recruited from inpatient rehabilitation units and followed-up for 6 months. Validated measures assessed survivors’ physical and cognitive function and carers’ strain and depression levels. Survey methods captured qualitative experiences of the caring role. Data collection occurred at baseline, discharge, 6 weeks post-discharge and 6 months. Multilevel-modelling and thematic data analysis, were employed. Results Carer strain median scores were within normal ranges of the Caregiver Strain Index scale. Carer strain was positively linked to carer depression, number of carers’ concerns reported and survivors’ anosognosia levels. Carer strain was negatively linked to the survivors’ functional and cognitive abilities. Carers’ experiences differed qualitatively with caring concerns increasing over time. Conclusion Carer strain worsens with increases in significant concerns about the rehabilitation process and poor survivor functioning skills, which potentially increase risk of depression in carers. Consequently, improving right-hemisphere stroke survivors’ recovery and nurturing the carer-survivor relationship are likely to enhance overall outcomes and caring experiences. IMPLICATIONS FOR REHABILITATION In the context of right hemisphere stroke: Carer assessment should be comprehensive and include a measure of perceived ability to care. Less strained carers tend to report fewer caring concerns and have lower depression levels. Education, training and practical support should be tailored to carer identified needs, abilities and the caring context.

Which perseverative behaviors are symptoms of spatial neglect?

Spatial neglect is a characterized by a failure to attend or make movements towards left-sided stimuli. Common paper-and-pencil tasks to diagnose spatial neglect are sensitive to perseverative errors, including additional marks over already cancelled targets and “scribbling” out a target. Here, we examine whether functionally distinct perseverative behaviors are related to spatial neglect. Line cancellation tasks of 45 healthy controls and 220 right-hemisphere stroke survivors were examined for recurrent marks (RM) and continuous marks (CM) perseverations. We found that RM perseveration correlated with neglect severity, while CM perseveration did not. Examination of lesion profiles for the two groups indicated distinct anatomical correlates, with RM lesions overlapping regions implicated in spatial neglect including the rolandic operculum, superior temporal gyrus, and inferior parietal lobule.

The Role of Social Support in the Familyand Community Integration of Right-Hemisphere Stroke Survivors

The goal of this project was to understand better the communicative processes by which social support can assist right-hemisphere stroke survivors in the process of community integration. Open-ended interviews were conducted with 12 right-hemisphere stroke survivors and their family caregivers. The transcribed interviews revealed 7 challenges (physical, cognitive–perceptual, emotional, relationship, employment, financial, and challenges to activities of daily living) and three types of resources (formal external, informal external, and internal). Stroke survivors' internal resources were shown to be essential for facilitating community integration. Implications for researchers and health care providers are discussed within the framework of Hobfoll's (1988) conservation of resources theory.

Rasch Modeling of Revised Token Test Performance: Validity and Sensitivity to Change

The purpose of this research was to examine the validity of the 55-item Revised Token Test (RTT) and to compare traditional and Rasch-based scores in their ability to detect group differences and change over time. The 55-item RTT was administered to 108 left- and right-hemisphere stroke survivors, and the data were submitted to Rasch analysis. Traditional and Rasch-based scores for a subsample of 60 stroke survivors were submitted to analyses of variance with group (left hemisphere with aphasia vs. right hemisphere) and time post onset (3 vs. 6 months post onset) as factors. The 2 scoring methods were compared using an index of relative precision. Forty-eight items demonstrated acceptable model fit. Misfitting items came primarily from Subtest IX. The Rasch model accounted for 71% of the variance in the responses to the remaining items. Intersubtest patterns of item difficulty were well predicted by item content, but unexpected within-subtest differences were found. Both traditional and Rasch person scores demonstrated significant group differences, but only the latter demonstrated statistically significant change over time. Analysis of relative precision, however, failed to confirm a significant difference between the 2 methods. The findings generally support the RTT's validity, but a minority of items appears to respond to a different construct. Also, within-subtest differences in item difficulty suggest the need for further examination of variability in impaired language performance. Finally, the results suggest an equivocal advantage for Rasch scores in detecting change over time.

Oestrogen replacement after oophorectomy: Authors' reply

<h3>Abstract</h3> Stroke is the largest cause of complex disability in adults. Approximately half of right-hemisphere stroke survivors suffer spatial neglect–an inability to voluntarily orient to people or objects in contralesional space. Neglect is a significant impediment to successful community reintegration. Prism adaptation (PA) is a promising behavioural intervention that can alleviate symptoms of spatial neglect. PA induces a leftward pointing bias–the prism after-effect (AE). In neglect, the prism AE generalises to improve other sensory, motor, and cognitive domains. Although the formation of an AE is a key index in neglect, we do not yet know where it is formed in the brain. Here, we used a novel computational fMRI-based approach to study, for the first time, the brain circuits that mediate the formation of PA in stroke survivors and age matched controls. Healthy individuals (<i>n</i> = 17) and stroke patients (<i>n</i> = 11) performed prism adaptation during fMRI. Temporal signatures of memory formation were extracted from the behavioural data using a state-space model and regressed against the fMRI data. This revealed that, in both groups, fMRI signal in left sensorimotor cortex correlated with the gradual formation of the prism after-effect during adaptation. This indicates that the sensorimotor cortex may be a useful target for neuromodulation that aims to improve the persistence of therapeutic prism after effects.