Cognitive rehabilitation for unilateral neglect: Review

Foraging and inertia: Understanding the developmental dynamics of overt visual attention

During early life, we develop the ability to choose what we focus on and what we ignore, allowing us to regulate perception and action in complex environments. But how does this change influence how we spontaneously allocate attention to real-world objects during free behaviour? Here, in this narrative review, we examine this question by considering the time dynamics of spontaneous overt visual attention, and how these develop through early life. Even in early childhood, visual attention shifts occur both periodically and aperiodically. These reorientations become more internally controlled as development progresses. Increasingly with age, attention states also develop self-sustaining attractor dynamics, known as attention inertia, in which the longer an attention episode lasts, the more the likelihood increases of its continuing. These self-sustaining dynamics are driven by amplificatory interactions between engagement, comprehension, and distractibility. We consider why experimental measures show decline in sustained attention over time, while real-world visual attention often demonstrates the opposite pattern. Finally, we discuss multi-stable attention states, where both hypo-arousal (mind-wandering) and hyper-arousal (fragmentary attention) may also show self-sustaining attractor dynamics driven by moment-by-moment amplificatory child-environment interactions; and we consider possible applications of this work, and future directions.

The Effect of Cognitive Style on Individual Differences in Prismatic Adaptation: A Pilot Study

Prism adaptation (PA) is a well-known and widely used technique for rehabilitating unilateral spatial neglect and studying sensory-motor plasticity. However, there is conflicting evidence in the literature regarding its effectiveness which may arise from differences in the type of prisms used, clinical characteristics of the patients, and the procedure used in training. Individual differences may play a role in PA effectiveness in rehabilitating neglect, affecting both its development and its effects. Field-dependent/independent cognitive style is a pervasive characteristic of individual functioning, affecting how environmental information is processed. Here, we tested the hypothesis that cognitive style plays a role in PA efficacy by submitting to a protocol of prism adaptation to 38 health participants, who were classified as field-dependent (FD, N = 19) or field-independent (FI, N = 19), by using the Embedded Figure Test. Results show that during the exposure phase, FI individuals needed a lesser number of pointing movements to reduce the deviation error than FD individuals. However, there are no differences in the extinction of sensory-motor and cognitive after-effects. These results suggest that prismatic adaptation is affected by individuals' cognitive style since FI individuals will need fewer trials to reach adaptation and this could explain why using this rehabilitation technique with a unique, standard protocol is not always effective.

Using non-invasive transcranial direct current stimulation for neglect and associated attentional deficits following stroke

Neglect is a disabling neuropsychological syndrome that is frequently observed following right-hemispheric stroke. Affected individuals often present with multiple attentional deficits, ranging from reduced orienting towards contralesional space to a generalized impairment in maintaining attention over time. Although a degree of spontaneous recovery occurs in most patients, in some individuals this condition can be treatment-resistant with prominent ongoing non-spatial deficits. Further, there is a large inter-individual variability in response to different therapeutic approaches. Given its potential to alter neuronal excitability and affect neuroplasticity, non-invasive brain stimulation is a promising tool that could potentially be utilized to facilitate recovery. However, there are many outstanding questions regarding its implementation in this heterogeneous patient group. Here we provide a critical overview of the available evidence on the use of non-invasive electrical brain stimulation, focussing on transcranial direct current stimulation (tDCS), to improve neglect and associated attentional deficits after right-hemispheric stroke. At present, there is insufficient robust evidence supporting the clinical use of tDCS to alleviate symptoms of neglect. Future research would benefit from careful study design, enhanced precision of electrical montages, multi-modal approaches exploring predictors of response, tailored dose-control applications and increased efforts to evaluate standalone tDCS versus its incorporation into combination therapy.

Dissociable effects of attention vs working memory training on cognitive performance and everyday functioning following fronto-parietal strokes

Difficulties with attention are common following stroke, particularly in patients with frontal and parietal damage, and are associated with poor outcome. Home-based online cognitive training may have the potential to provide an efficient and effective way to improve attentional functions in such patients. Little work has been carried out to assess the efficacy of this approach in stroke patients, and the lack of studies with active control conditions and rigorous evaluations of cognitive functioning pre and post-training means understanding is limited as to whether and how such interventions may be effective. Here, in a feasibility pilot study, we compare the effects of 20 days of cognitive training using either novel Selective Attention Training (SAT) or commercial Working Memory Training (WMT) programme, versus a waitlist control on a range of attentional and working memory tasks. We demonstrate separable effects of each training condition, with SAT leading to improvements in spatial and non-spatial aspects of attention and WMT leading to improvements on closely related working memory tasks. In addition, both training groups reported improvements in everyday functioning, which were associated with improvements in attention, suggesting that improving attention may be of particular importance in maximising functional improvements in this patient group.

Occurrence and Recovery of Different Neglect-Related Symptoms in Right Hemisphere Infarct Patients during a 1-Year Follow-Up

OBJECTIVES

To examine the occurrence of and recovery from visual neglect-related symptoms with the focus on neglect laterality, ipsilateral orienting bias, and slowed processing speed in right hemisphere (RH) infarct patients during a 1-year follow-up. Furthermore, to propose guidelines for assessing processing speed alongside the Behavioural Inattention Test (BIT).

METHODS

We studied three RH patient groups: neglect (N+), mild left inattention (MLI+), and non-neglect (N-) patients, and healthy controls. The BIT with some additional analyses was conducted at the acute phase and at 6 and 12 months.

RESULTS

The N+ group's BIT score increased and originally lateralized omissions became more evenly distributed during the follow-up. The N+ and MLI+ groups' starting points were more rightward located than the healthy group's at the acute phase and at 6, and partly at 12 months. Patient groups were slower than the controls in performing cancellation tests at the acute phase. The N+ and MLI+ groups remained slower than the controls throughout the follow-up.

CONCLUSIONS

During the first year after RH infarct, originally left-sided manifestation of neglect shifted toward milder non-lateralized attentional deficit. Ipsilateral orienting bias and slowed processing speed appeared to be rather persistent neglect-related symptoms both in neglect patients and patients with initially milder inattention. We propose some effortless, tentative ways of examining processing speed and ipsilateral orienting bias alongside the BIT to better recognize these neglect-related symptoms, and highlight the need to assess and treat patients with initially milder inattention, who have been under-recognized and under-treated in clinical work. (JINS, 2018, 24, 617-628).

The effect of voluntary trunk rotation and half-field eye-patching for patients with unilateral neglect in stroke: a randomized controlled trial

Objective : To investigate the effectiveness of voluntary trunk rotation and half-field eye-patching to treat patients with unilateral neglect in stroke.

Design : Pre—post, day 60 follow-up, single-blinded randomized controlled trial.

Setting : Single-centre inpatient rehabilitation hospital.

Subjects : Sixty subacute patients with right hemisphere stroke having unilateral neglect within eight weeks post stroke consented to participate between November 2003 and July 2005. They were randomly assigned to three comparison groups.

Interventions : Nineteen patients received daily experimental training in voluntary trunk rotation (TR) for 1 hour five times a week for 30 days. Twenty patients received the same kind of treatment together with half-field eye-patching

(TR + EP). Fifteen patients in the control group received conventional training with the same contact time.

Main outcome measures : Patients were assessed on days 0, 30 and 60 using the Behavioural Inattention Test, the Clock Drawing Test, and the Functional Independence Measure.

Results : No significant differences between voluntary trunk rotation (TR), voluntary trunk rotation and half-field eye-patching (TR + EP) and controls were found in functional performance and neglect measures at day 30 (P = 0.042—0.994) and follow-up (P = 0.052—0.911) at P = 0.005 using Bonferroni correction.

Conclusions : The results of this study do not support the use of voluntary trunk rotation alone or with half-field eye-patching to improve functional performance or reduce unilateral neglect in subacute patients with stroke.

Adding transcutaneous electrical nerve stimulation to visual scanning training does not enhance treatment effect on hemispatial neglect: a randomized, controlled, double-blind study

BACKGROUND

Left-sided transcutaneous electrical nerve stimulation (TENS) increases right hemispheric activity, which may improve the rehabilitative outcome of hemispatial neglect.

OBJECTIVE

To examine the behavioral effect of electrical stimulation of the nerve afferents of the left hand during early neuropsychological rehabilitation of post-stroke patients with hemispatial neglect.

METHODS

This randomized, controlled, double-blind study included 29 patients (enrolled in the experimental or control group) with left hemispatial neglect after right hemispheric stroke. For 3 weeks, patients received 15 therapeutic sessions involving TENS (active or sham) with a mesh glove applied on the entire left hand during the first 30 minutes of a 45-minute conventional visual scanning training (VST). Signs of hemispatial neglect were assessed using a psychometric test before and after treatment.

RESULTS

Univariate analysis of covariance revealed that differences between the control and experimental groups were not significant after treatment (F(1, 22) = 0.294, P = 0.593) when adjusted for pre-treatment scores and time since stroke onset. This suggested that electrical stimulation failed to mitigate the severity of hemispatial neglect symptoms.

CONCLUSION

Our study did not provide evidence of the effectiveness of TENS when added to VST during early rehabilitation for patients with post-stroke hemispatial neglect. Other techniques (applied alone or together) should be sought to improve recovery in this population.

Treatment of Visual Perceptual Disorders Post Stroke

Visual perceptual disorders are a common clinical consequence of stroke. They include unilateral neglect, which has a major impact on rehabilitation outcome. The nature of the behavioral deficits associated with neglect has suggested that behavioral modification strategies may improve performance. This article presents a critical review and synthesis of published research evidence for the effectiveness of treatments for visual perceptual disorders after stroke. The strongest evidence for rehabilitation effectiveness was for the following: (a) specific treatment for perceptual disorders; and (b) specific training for neglect (including visual scanning). Findings also suggest that more research is needed into how the assessment of specific features of visual perceptual disorders might lead to improved methods for rehabilitation, including the use of assistive devices for mobility and activities of daily living.

Awakening is not a metaphor: the effects of Buddhist meditation practices on basic wakefulness

Buddhist meditation practices have become a topic of widespread interest in both science and medicine. Traditional Buddhist formulations describe meditation as a state of relaxed alertness that must guard against both excessive hyperarousal (restlessness) and excessive hypoarousal (drowsiness, sleep). Modern applications of meditation have emphasized the hypoarousing and relaxing effects without as much emphasis on the arousing or alertness-promoting effects. In an attempt to counterbalance the plethora of data demonstrating the relaxing and hypoarousing effects of Buddhist meditation, this interdisciplinary review aims to provide evidence of meditation's arousing or wake-promoting effects by drawing both from Buddhist textual sources and from scientific studies, including subjective, behavioral, and neuroimaging studies during wakefulness, meditation, and sleep. Factors that may influence whether meditation increases or decreases arousal are discussed, with particular emphasis on dose, expertise, and contemplative trajectory. The course of meditative progress suggests a nonlinear multiphasic trajectory, such that early phases that are more effortful may produce more fatigue and sleep propensity, while later stages produce greater wakefulness as a result of neuroplastic changes and more efficient processing.

Visual processing asymmetries in change detection

Change detection is critically dependent on attentional mechanisms. However, the relation between an asymmetrical distribution of visuo-spatial attention and the detection of changes in visual scenes is not clear. Spatial tasks are known to induce a stronger activation of the right hemisphere. The effects of such visual processing asymmetries induced by a spatial task on change detection were investigated. When required to detect changes in the left and in the right visual fields, participants were significantly faster in detecting changes on the left than on the right. Importantly, this left-side superiority in change detection is not influenced by inspection time, suggesting a critical role of visual processing benefit for the left visual field.

Prism adaptation does not change the rightward spatial preference bias found with ambiguous stimuli in unilateral neglect

Previous research has shown that prism adaptation (prism adaptation) can ameliorate several symptoms of spatial neglect after right-hemisphere damage. But the mechanisms behind this remain unclear. Recently we reported that prisms may increase leftward awareness for neglect in a task using chimeric visual objects, despite apparently not affecting awareness in a task using chimeric emotional faces (Sarri et al., 2006). Here we explored potential reasons for this apparent discrepancy in outcome, by testing further whether the lack of a prism effect on the chimeric face task task could be explained by: i) the specific category of stimuli used (faces as opposed to objects); ii) the affective nature of the stimuli; and/or iii) the particular task implemented, with the chimeric face task requiring forced-choice judgements of lateral 'preference' between pairs of identical, but left/right mirror-reversed chimeric face tasks (as opposed to identification for the chimeric object task). We replicated our previous pattern of no impact of prisms on the emotional chimeric face task here in a new series of patients, while also similarly finding no beneficial impact on another lateral 'preference' measure that used non-face non-emotional stimuli, namely greyscale gradients. By contrast, we found the usual beneficial impact of prism adaptation (prism adaptation) on some conventional measures of neglect, and improvements for at least some patients in a different face task, requiring explicit discrimination of the chimeric or non-chimeric nature of face stimuli. The new findings indicate that prism therapy does not alter spatial biases in neglect as revealed by 'lateral preference tasks' that have no right or wrong answer (requiring forced-choice judgements on left/right mirror-reversed stimuli), regardless of whether these employ face or non-face stimuli. But our data also show that prism therapy can beneficially modulate some aspects of visual awareness in spatial neglect not only for objects, but also for face stimuli, in some cases.

Recovery from hemiparesis and unilateral spatial neglect after neonatal stroke. Case report and rehabilitation of an infant

PRIMARY OBJECTIVE

To report rehabilitation of neglect in a child through task contexts.

METHODS AND PROCEDURES

A 7-month-old boy with hemiparesis and neglect following neonatal stroke was evaluated with standard assessments during the first year of intervention. The intervention included timely training of each upper limb's movement (reaching, grasping, lifting, rotating, releasing, etc.), balance training and Constraint-Induced Movement Therapy (CIMT). We promoted the storing of spatial representation through enriched environment by meaningful sensory inputs engaging spatial localization/orientation and eye movements.

MAIN OUTCOMES

During intervention the child developed reaching and grasping and other new motor behaviours (holding, releasing, lifting, rotating, transferring, pulling, manipulating objects, gesturing, self-feeding, walking). In parallel he also exhibited a decrease of neglect.

CONCLUSION

Infants with stroke should be routinely checked for neglect. Especially those with hemiparesis and neglect challenge the rehabilitation team for the complexity of the treatment directly focused on addressing integration at more conscious levels of upper limb paresis and neglect.

Chronic unilateral neglect from focal meningoencephalitis lesions in an immune-compromised hemodialysis patient

Unilateral neglect (UN) is a disorder associated primarily with right-brain damage; it causes individuals to behave as if the contralesional half of their world has become unimportant or has simply ceased to exist. This is the first known case study to describe and measure UN caused by an infectious process, meningoencephalitis. The patient was immune compromised as a result of antirejection drugs following a kidney and pancreas transplant, as well as from a baseline vulnerability common to patients with hemodialysis. She was reassessed serially during hemodialysis treatments over 12 months and demonstrated improvement in some measures of UN but not in others. UN is a recognized nursing diagnosis and can be assessed, treated, and researched by nurses. Neuroscience nurses need to better understand and investigate UN to improve their own practice and the practice of other specialties.

Validation of the Behavioural Inattention Test (BIT) in patients with acquired brain injury in Turkey

The aim of this descriptive study was to evaluate the construct validity and reliability of the Behavioural Inattention Test (BIT) in patients with acquired brain injury in Turkey. One hundred and eighteen acquired brain injury patients undergoing rehabilitation were assessed by the BIT. Internal construct validity was tested by Rasch analysis; reliability by internal consistency and the Person Separation Index; and external construct validity by associations with physical and cognitive disability. Analysis of the data revealed that some subtests deviated from Rasch model expectation and the conventional subscale of the BIT had an unsatisfactory reliability for individual use. Consequently, a common 10-item scale (BIT-10) was derived from both the behavioural and conventional subscales of the BIT. Reliability of .87 met expectation for individual use. The BIT-10 correlated at .52 with cognitive disability upon admission. As a conclusion the original BIT adapted for use in Turkey was shown to lack reliability and internal construct validity. A revised 10-item new version, BIT-10, gave a valid unidimensional summed score, with high sensitivity and specificity to the original cut points. Reliability of the BIT-10 was high and external construct validity was as expected.

Perspectives on treatment for communication deficits associated with right hemisphere brain damage

PURPOSE

To describe the current treatment research for communication (prosodic, discourse, and pragmatic) deficits associated with right hemisphere brain damage and to provide suggestions for treatment selection given the paucity of evidence specifically for this population.

METHOD

The discussion covers (a) clinical decision processes and evidence-based practice; (b) a review of right hemisphere communication deficits and existing treatment studies; (c) accounts of right hemisphere function, right hemisphere deficits, and theoretically motivated treatments; and (d) a guide for exploring and selecting treatments based on deficits rather than etiology.

CONCLUSIONS

Controlled treatment studies for communication deficits specifically for adults with right hemisphere brain damage are limited to aprosodia. For other communication deficits, clinicians may select treatments based on current theories of right hemisphere function and right hemisphere deficits, and/or treatments developed for other etiologies for which deficits are similar to those associated with right hemisphere damage.

Action errors and dressing disability after stroke: An ecological approach to neuropsychological assessment and intervention

A combination of detailed observation of dressing behaviour and neuropsychological assessment was used to identify the cognitive barriers to independent dressing in a series of eight stroke patients. For those with right hemisphere damage, dressing was disrupted by visuospatial problems or poor sustained attention. Those with left hemisphere damage and ideomotor apraxia were unable to learn the correct procedure to compensate for hemiparesis when dressing. The value of a therapeutic approach based on these observations was assessed in a single-blind randomised multiple-baseline experiment. A baseline phase of conventional dressing therapy which takes no account of individual patterns of cognitive impairment was contrasted with an approach which was formulated for each case. A permutation test demonstrated that there was a significant treatment effect for the right hemisphere cases but there was no therapy-related improvement for those with left or bilateral damage and apraxia. Observation of a naturalistic but controlled task (dressing with a standard item of clothing) appears to allow greater insight into the impact of specific neuropsychological deficits than has been found for more complex naturalistic tasks. The benefits of this ecological approach over conventional approaches to dressing therapy need to be evaluated further in a randomised clinical trial.

Pseudoneglect: Evidence for both perceptual and attentional factors

When neurologically normal individuals bisect a horizontal line as accurately as possible, they reliably show a slight leftward error. This leftward inaccuracy is called pseudoneglect because errors made by neurologically normal individuals are directionally opposite to those made by persons with visuospatial neglect (Jewell & McCourt, 2000). In the current study, normal right-handed observers bisected horizontal lines that were altered to bias line length judgments either toward the right or the left side of the line. Non-target dots were placed on or near the line stimuli using principles derived from a theory of visual illusions of length called centroid extraction (Morgan, Hole, & Glennerster, 1990). This theory argues that the position of a visual target is calculated as the mean position of all stimuli in close proximity to the target stimulus. We predicted that perceptual alterations that shifted the direction of centroid extraction would also shift the direction of line bisection errors. Our findings confirmed this prediction and support the idea that both perceptual and attentional factors contribute to the pseudoneglect effect.

Developing functional outcome measures for unilateral neglect: A pilot study

Stroke patients may develop personal neglect, peripersonal neglect or both. Four new measures were tested in a sample of 42 right-handed inpatients (25 male; 17 female, median age 72 years). Participants removed keys from a rack, identified grocery items, washed their face, and cleaned a tray. Prior to this, they were classified as: no neglect (15), personal neglect (8), peripersonal neglect (7), and both personal and peripersonal neglect (12). The sensitivity and specificity of each new measure was determined by agreement with the classification. Test-retest reliability was determined using weighted kappa statistics or limits of agreement. Four occupational therapists (OTs) rated videos of the face and tray measures, and software was developed to measure objectively time spent and area covered on Face and Tray. Keys and Grocery had high specificity, good reliability but poor sensitivity. For the OTs' video ratings, there was good and moderate inter-rater reliability on Tray and Face respectively for area covered, but not time spent. Intra-rater reliability was also better for area than time on Tray. However, the validity of Face and Tray themselves is currently inadequate. A longitudinal study is proposed to modify the measures, increase their sensitivity and evaluate their ability to monitor change over time.

The use of Optokinetic Stimulation in Rehabilitation of the Hemineglect Disorder

The aim of this study was to investigate whether it is possible to strengthen the rehabilitation of spatial hemineglect by combining standard training for spatial scanning with optokinetic stimulation. A simple randomized design was used: one group of neglect patients was treated with a combination of the two techniques, and a second group received only the standard treatment. Both treatments were given for six consecutive weeks and produced significant improvements. However, addition of the optokinetic stimulation did not improve the patients' performance. Also, none of the independent variables (i.e., presence/absence of hemianopia) predicted the positive effect occasionally observed in individual patients.