Impact of Cognitive Neuroscience on Stroke Rehabilitation

Outcome of severe COVID-19: spotlight on fatigue, fatigability, multidomain complaints and pattern of cognitive deficits in a case series without prior brain dysfunction and without COVID-19-related stroke and/or cardiac arrest

BACKGROUND

Population-wide surveys and large-scale investigations highlighted the presence of cognitive deficits in the acute and postacute stages of severe COVID-19; a few studies documented their occurrence in cases without prior or COVID-19-related brain damage. The evolution of cognitive deficits in the latter population and their relationship to the post-COVID-19 fatigue syndrome are poorly understood.

CASE PRESENTATION

We report the outcome at 12 months after severe COVID-19 involving an intensive care unit stay and mechanical ventilation in six (five Caucasian and one Asian) patients (age range: 53-71 years, mean age 61.7 ± 6.5 years) without history of prior brain dysfunction and without stroke and/or cardiac arrest during or after COVID-19. All patients reported pervading mental and physical fatigue as well as numerous multidomain complaints, which impacted everyday life. Individual patients described mental fatigability, apathy, and/or anxiety. Standardized neuropsychological tests revealed isolated symptoms of cognitive dysfunction or performance at the lower limit of the norm in the attentional, executive, and/or working memory domains in four of the six patients. Somatic scales documented dyspnoea, muscle weakness, olfactory disorder, and/or minor sleep problems in some, but not all, patients.

CONCLUSION

Fatigue, fatigability, multidomain complaints, cognitive difficulties, or dysfunction, as well as isolated neurobehavioral and/or psychiatric and/or somatic symptoms, tend to occur in the aftermath of severe COVID-19 and persist at 12 months, even in the absence of prior and/or COVID-19-related brain damage. This clinical situation, which impacts everyday life, calls for a detailed investigation of patients' complaints, its neural underpinning, and an elaboration of specific rehabilitation programs.

Global synergistic actions to improve brain health for human development

The global burden of neurological disorders is substantial and increasing, especially in low-resource settings. The current increased global interest in brain health and its impact on population wellbeing and economic growth, highlighted in the World Health Organization's new Intersectoral Global Action Plan on Epilepsy and other Neurological Disorders 2022-2031, presents an opportunity to rethink the delivery of neurological services. In this Perspective, we highlight the global burden of neurological disorders and propose pragmatic solutions to enhance neurological health, with an emphasis on building global synergies and fostering a 'neurological revolution' across four key pillars - surveillance, prevention, acute care and rehabilitation - termed the neurological quadrangle. Innovative strategies for achieving this transformation include the recognition and promotion of holistic, spiritual and planetary health. These strategies can be deployed through co-design and co-implementation to create equitable and inclusive access to services for the promotion, protection and recovery of neurological health in all human populations across the life course.

Choosing Sides: Impact of Prismatic Adaptation on the Lateralization of the Attentional System

Seminal studies revealed differences between the effect of adaptation to left- vs. right-deviating prisms (L-PA, R-PA) in normal subjects. Whereas L-PA leads to neglect-like shift in attention, demonstrated in numerous visuo-spatial and cognitive tasks, R-PA has only minor effects in specific aspects of a few tasks. The paucity of R-PA effects in normal subjects contrasts with the striking alleviation of neglect symptoms in patients with right hemispheric lesions. Current evidence from activation studies in normal subjects highlights the contribution of regions involved in visuo-motor control during prism exposure and a reorganization of spatial representations within the ventral attentional network (VAN) after the adaptation. The latter depends on the orientation of prisms used. R-PA leads to enhancement of the ipsilateral visual and auditory space within the left inferior parietal lobule (IPL), switching thus the dominance of VAN from the right to the left hemisphere. L-PA leads to enhancement of the ipsilateral space in right IPL, emphasizing thus the right hemispheric dominance of VAN. Similar reshaping has been demonstrated in patients. We propose here a model, which offers a parsimonious explanation of the effect of L-PA and R-PA both in normal subjects and in patients with hemispheric lesions. The model posits that prismatic adaptation induces instability in the synaptic organization of the visuo-motor system, which spreads to the VAN. The effect is lateralized, depending on the side of prism deviation. Successful pointing with prisms implies reaching into the space contralateral, and not ipsilateral, to the direction of prism deviation. Thus, in the hemisphere contralateral to prism deviation, reach-related neural activity decreases, leading to instability of the synaptic organization, which induces a reshuffling of spatial representations in IPL. Although reshuffled spatial representations in IPL may be functionally relevant, they are most likely less efficient than regular representations and may thus cause partial dysfunction. The former explains, e.g., the alleviation of neglect symptoms after R-PA in patients with right hemispheric lesions, the latter the occurrence of neglect-like symptoms in normal subjects after L-PA. Thus, opting for R- vs. L-PA means choosing the side of major IPL reshuffling, which leads to its partial dysfunction in normal subjects and to recruitment of alternative or enhanced spatial representations in patients with hemispheric lesions.

Occupational therapy for cognitive impairment in stroke patients

BACKGROUND

Cognitive impairment is a frequent consequence of stroke and can impact on a person's ability to perform everyday activities. Occupational therapists use a range of interventions when working with people who have cognitive impairment poststroke. This is an update of a Cochrane Review published in 2010.

OBJECTIVES

To assess the impact of occupational therapy on activities of daily living (ADL), both basic and instrumental, global cognitive function, and specific cognitive abilities in people who have cognitive impairment following a stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE, Embase, four other databases (all last searched September 2020), trial registries, and reference lists.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials that evaluated an intervention for adults with clinically defined stroke and confirmed cognitive impairment. The intervention needed either to be provided by an occupational therapist or considered within the scope of occupational therapy practice as defined in the review. We excluded studies focusing on apraxia or perceptual impairments or virtual reality interventions as these are covered by other Cochrane Reviews. The primary outcome was basic activities of daily living (BADL) such as dressing, feeding, and bathing. Secondary outcomes were instrumental ADL (IADL) (e.g. shopping and meal preparation), community integration and participation, global cognitive function and specific cognitive abilities (including attention, memory, executive function, or a combination of these), and subdomains of these abilities. We included both observed and self-reported outcome measures.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies that met the inclusion criteria, extracted data, and assessed the certainty of the evidence. A third review author moderated disagreements if consensus was not reached. We contacted trial authors for additional information and data, where available. We assessed the certainty of key outcomes using GRADE.  MAIN RESULTS: We included 24 trials from 11 countries involving 1142 (analysed) participants (two weeks to eight years since stroke onset). This update includes 23 new trials in addition to the one study included in the previous version. Most were parallel randomised controlled trials except for one cross-over trial and one with a two-by-two factorial design. Most studies had sample sizes under 50 participants. Twenty studies involved a remediation approach to cognitive rehabilitation, particularly using computer-based interventions. The other four involved a compensatory and adaptive approach. The length of interventions ranged from 10 days to 18 weeks, with a mean total length of 19 hours. Control groups mostly received usual rehabilitation or occupational therapy care, with a few receiving an attention control that was comparable to usual care; two had no intervention (i.e. a waiting list). Apart from high risk of performance bias for all but one of the studies, the risk of bias for other aspects was mostly low or unclear.  For the primary outcome of BADL, meta-analysis found a small effect on completion of the intervention with a mean difference (MD) of 2.26 on the Functional Independence Measure (FIM) (95% confidence interval (CI) 0.17 to 4.22; P = 0.03, I2 = 0%; 6 studies, 336 participants; low-certainty evidence). Therefore, on average, BADL improved by 2.26 points on the FIM that ranges from 18 (total assist) to 126 (complete independence). On follow-up, there was insufficient evidence of an effect at three months (MD 10.00, 95% CI -0.54 to 20.55; P = 0.06, I2 = 53%; 2 studies, 73 participants; low-certainty evidence), but evidence of an effect at six months (MD 11.38, 95% CI 1.62 to 21.14, I2 = 12%; 2 studies, 73 participants; low-certainty evidence). These differences are below 22 points which is the established minimal clinically important difference (MCID) for the FIM for people with stroke. For IADL, the evidence is very uncertain about an effect (standardised mean difference (SMD) 0.94, 95% CI 0.41 to 1.47; P = 0.0005, I2 = 98%; 2 studies, 88 participants). For community integration, we found insufficient evidence of an effect (SMD 0.09, 95% CI -0.35 to 0.54; P = 0.68, I2 = 0%; 2 studies, 78 participants). There was an improvement of clinical importance in global cognitive functional performance after the intervention (SMD 0.35, 95% CI 0.16 to 0.54; P = 0.0004, I2 = 0%; 9 studies, 432 participants; low-certainty evidence), equating to 1.63 points on the Montreal Cognitive Assessment (MoCA) (95% CI 0.75 to 2.52), which exceeds the anchor-based MCID of the MoCA for stroke rehabilitation patients of 1.22. We found some effect for attention overall (SMD -0.31, 95% CI -0.47 to -0.15; P = 0.0002, I2 = 20%; 13 studies, 620 participants; low-certainty evidence), equating to a difference of 17.31 seconds (95% CI 8.38 to 26.24), and for executive functional performance overall (SMD 0.49, 95% CI 0.31 to 0.66; P < 0.00001, I2 = 74%; 11 studies, 550 participants; very low-certainty evidence), equating to 1.41 points on the Frontal Assessment Battery (range: 0-18). Of the cognitive subdomains, we found evidence of effect of possible clinical importance, immediately after intervention, for sustained visual attention (moderate certainty) equating to 15.63 seconds, for working memory (low certainty) equating to 59.9 seconds, and thinking flexibly (low certainty), compared to control.

AUTHORS' CONCLUSIONS

The effectiveness of occupational therapy for cognitive impairment poststroke remains unclear. Occupational therapy may result in little to no clinical difference in BADL immediately after intervention and at three and six months' follow-up. Occupational therapy may slightly improve global cognitive performance of a clinically important difference immediately after intervention, likely improves sustained visual attention slightly, and may slightly increase working memory and flexible thinking after intervention. There is evidence of low or very low certainty or insufficient evidence for effect on other cognitive domains, IADL, and community integration and participation.  Given the low certainty of much of the evidence in our review, more research is needed to support or refute the effectiveness of occupational therapy for cognitive impairment after stroke. Future trials need improved methodology to address issues including risk of bias and to better report the outcome measures and interventions used.

Somatosensory Plasticity in Pediatric Cerebral Palsy following Constraint-Induced Movement Therapy

Cerebral palsy (CP) is predominantly a disorder of movement, with evidence of sensory-motor dysfunction. CIMT¹ is a widely used treatment for hemiplegic CP. However, effects of CIMT on somatosensory processing remain unclear. To examine potential CIMT-induced changes in cortical tactile processing, we designed a prospective study, during which 10 children with hemiplegic CP (5 to 8 years old) underwent an intensive one-week-long nonremovable hard-constraint CIMT. Before and directly after the treatment, we recorded their cortical event-related potential (ERP) responses to calibrated light touch (versus a control stimulus) at the more and less affected hand. To provide insights into the core neurophysiological deficits in light touch processing in CP as well as into the plasticity of this function following CIMT, we analyzed the ERPs within an electrical neuroimaging framework. After CIMT, brain areas governing the more affected hand responded to touch in configurations similar to those activated by the hemisphere controlling the less affected hand before CIMT. This was in contrast to the affected hand where configurations resembled those of the more affected hand before CIMT. Furthermore, dysfunctional patterns of brain activity, identified using hierarchical ERP cluster analyses, appeared reduced after CIMT in proportion with changes in sensory-motor measures (grip or pinch movements). These novel results suggest recovery of functional sensory activation as one possible mechanism underlying the effectiveness of intensive constraint-based therapy on motor functions in the more affected upper extremity in CP. However, maladaptive effects on the less affected constrained extremity may also have occurred. Our findings also highlight the use of electrical neuroimaging as feasible methodology to measure changes in tactile function after treatment even in young children, as it does not require active participation.

A Role for New Brain Magnetic Resonance Imaging Modalities in Daily Clinical Practice: Protocol of the Prediction of Cognitive Recovery After Stroke (PROCRAS) Study

Background

Cognitive impairment is common after acute ischemic stroke, affecting up to 75% of the patients. About half of the patients will show recovery, whereas the others will remain cognitively impaired or deteriorate. It is difficult to predict these different cognitive outcomes.

Objective

The objective of this study is to investigate whether diffusion tensor imaging–based measures of brain connectivity predict cognitive recovery after 1 year, in addition to patient characteristics and stroke severity. A specific premise of the Prediction of Cognitive Recovery After Stroke (PROCRAS) study is that it is conducted in a daily practice setting.

Methods

The PROCRAS study is a prospective, mono-center cohort study conducted in a large teaching hospital in the Netherlands. A total of 350 patients suffering from an ischemic stroke who screen positive for cognitive impairment on the Montreal Cognitive Assessment (MoCA<26) in the acute stage will undergo a 3Tesla-Magnetic Resonance Imaging (3T-MRI) with a diffusion-weighted sequence and a neuropsychological assessment. Patients will be classified as being unimpaired, as having a mild vascular cognitive disorder, or as having a major vascular cognitive disorder. One year after stroke, patients will undergo follow-up neuropsychological assessment. The primary endpoint is recovery of cognitive function 1 year after stroke in patients with a confirmed poststroke cognitive disorder. The secondary endpoint is deterioration of cognitive function in the first year after stroke.

Results

The study is already ongoing for 1.5 years, and thus far, 252 patients have provided written informed consent. Final results are expected in June 2019.

Conclusions

The PROCRAS study will show the additional predictive value of diffusion tensor imaging-based measures of brain connectivity for cognitive outcome at 1 year in patients with a poststroke cognitive disorder in a daily clinical practice setting.

Registered Report Identifier

RR1-10.2196/9431