Plasticity of Adult Sensorimotor System in Severe Brain Infarcts: Challenges and Opportunities

Functional reorganization forms the critical mechanism for the recovery of function after brain damage. These processes are driven by inherent changes within the central nervous system (CNS) triggered by the insult and further depend on the neural input the recovering system is processing. Therefore these processes interact with not only the interventions a patient receives, but also the activities and behaviors a patient engages in. In recent years, a wide range of research programs has addressed the association between functional reorganization and the spontaneous and treatment-induced recovery. The bulk of this work has focused on upper-limb and hand function, and today there are new treatments available that capitalize on the neuroplasticity of the brain. However, this is only true for patients with mild to moderated impairments; for those with very limited hand function, the basic understanding is much poorer and directly translates into limited treatment opportunities for these patients. The present paper aims to highlight the knowledge gap on severe stroke with a brief summary of the literature followed by a discussion of the challenges involved in the study and treatment of severe stroke and poor long-term outcome

Rate of complications due to carotid angioplasty in a tertiary university hospital

Introduction: Stenoses greater than 50% in the cervical internal carotid artery cause up to 8% of all ischemic strokes. Carotid artery stenting (CAS) is an effective alternative to prevent cerebrovascular events to occur. According to recommendations from the American Heart Association/American Stroke Association, CAS is indicated for symptomatic patients with internal carotid stenosis greater than 70% (measured by non-invasive methods), as long as the risk for periprocedural stroke or death is less than 6%. There is few information about complication rates of CAS in developing countries. Objectives: The primary goal of this study was to evaluate the frequency of any stroke or death until hospital discharge after CAS in symptomatic patients with carotid stenosis in a tertiary university hospital. Other complication rates were also assessed as secondary aims. Methods: A single-center retrospective study based on the analysis of charts from patients submitted to CAS between April 2011 and March 2016. Inclusion criteria were: age ≥ 18 years old, admission and follow-up by neurologists from the Neurology Ward, performance of CAS according to the hospital´s protocol (carotid stenosis ≥70%, patients with transient ischemic attack (TIA), amaurosis fugax or minor stroke in the last 180 days, and life expectancy greater than a year). Patients not followed by neurologists after CAS were excluded. Results: A total of 65 patients were included: 3 (4.6%) suffered stroke or death after CAS. Two of these patients presented ischemic strokes and one, an hemorrhagic stroke that lead to death. Myocardial infarctions were not identified, as well as carotid ruptures or dissections, hyperperfusion syndrome, artery perforations, stent thrombosis or encephalopathy. Minor complication rates were: 12.3% for hypotension, 9.2% for bradycardia, 1.5% for TIA, 3.1% for carotid vasospasm and 6.2% for acute kidney injury. The total rate of minor complications was 23.1%, and none of then led to permanent harm. Conclusions: The rate of stroke or death in a reference tertiary service in a developing country was in line with international recommendations

Rate of complications due to carotid angioplasty in a tertiary university hospital

Introduction: Stenoses greater than 50% in the cervical internal carotid artery cause up to 8% of all ischemic strokes. Carotid artery stenting (CAS) is an effective alternative to prevent cerebrovascular events to occur. According to recommendations from the American Heart Association/American Stroke Association, CAS is indicated for symptomatic patients with internal carotid stenosis greater than 70% (measured by non-invasive methods), as long as the risk for periprocedural stroke or death is less than 6%. There is few information about complication rates of CAS in developing countries. Objectives: The primary goal of this study was to evaluate the frequency of any stroke or death until hospital discharge after CAS in symptomatic patients with carotid stenosis in a tertiary university hospital. Other complication rates were also assessed as secondary aims. Methods: A single-center retrospective study based on the analysis of charts from patients submitted to CAS between April 2011 and March 2016. Inclusion criteria were: age ≥ 18 years old, admission and follow-up by neurologists from the Neurology Ward, performance of CAS according to the hospital´s protocol (carotid stenosis ≥70%, patients with transient ischemic attack (TIA), amaurosis fugax or minor stroke in the last 180 days, and life expectancy greater than a year). Patients not followed by neurologists after CAS were excluded. Results: A total of 65 patients were included: 3 (4.6%) suffered stroke or death after CAS. Two of these patients presented ischemic strokes and one, an hemorrhagic stroke that lead to death. Myocardial infarctions were not identified, as well as carotid ruptures or dissections, hyperperfusion syndrome, artery perforations, stent thrombosis or encephalopathy. Minor complication rates were: 12.3% for hypotension, 9.2% for bradycardia, 1.5% for TIA, 3.1% for carotid vasospasm and 6.2% for acute kidney injury. The total rate of minor complications was 23.1%, and none of then led to permanent harm. Conclusions: The rate of stroke or death in a reference tertiary service in a developing country was in line with international recommendations

Effects of Somatosensory Stimulation on the Excitability of the Unaffected Hemisphere in Chronic Stroke Patients

INTRODUCTION: Somatosensory stimulation of the paretic upper limb enhances motor performance and excitability in the affected hemisphere, and increases activity in the unaffected hemisphere, in chronic stroke patients. We tested the hypothesis that somatosensory stimulation of the paretic hand would lead to changes in excitability of the unaffected hemisphere in these patients, and we investigated the relation between motor function of the paretic hand and excitability of the unaffected hemisphere. METHODS: Transcranial magnetic stimulation was administered to the unaffected hemisphere of nine chronic stroke patients. Patients were submitted to 2-h somatosensory stimulation in the form of median nerve stimulation and control stimulation using a cross-over design. Baseline Jebsen-Taylor test scores were evaluated. Resting motor threshold, intracortical facilitation, short-interval intracortical inhibition, and visual analog scores for attention, fatigue and drowsiness were measured across conditions. RESULTS: Better pre-stimulation baseline motor function was correlated with deeper SICI in the unaffected hemisphere. We found no overt changes in any physiological marker after somatosensory stimulation. There was increased drowsiness in the control session, which may have led to changes in intracortical facilitation. CONCLUSIONS: Our results do not support an overt effect of a single session of somatosensory stimulation of the paretic hand on motor cortical excitability of the unaffected hemisphere as measured by motor threshold, short-interval intracortical inhibition or intracortical facilitation. It remains to be determined if other markers of cortical excitability are modulated by somatosensory stimulation, and whether repeated sessions or lesion location may lead to different effects

Diffusion Tensor Imaging Biomarkers to Predict Motor Outcomes in Stroke: A Narrative Review

Stroke is a leading cause of disability worldwide. Motor impairments occur in most of the patients with stroke in the acute phase and contribute substantially to disability. Diffusion tensor imaging (DTI) biomarkers such as fractional anisotropy (FA) measured at an early phase after stroke have emerged as potential predictors of motor recovery. In this narrative review, we: (1) review key concepts of diffusion MRI (dMRI); (2) present an overview of state-of-art methodological aspects of data collection, analysis and reporting; and (3) critically review challenges of DTI in stroke as well as results of studies that investigated the correlation between DTI metrics within the corticospinal tract and motor outcomes at different stages after stroke. We reviewed studies published between January, 2008 and December, 2018, that reported correlations between DTI metrics collected within the first 24 h (hyperacute), 2–7 days (acute), and >7–90 days (early subacute) after stroke. Nineteen studies were included. Our review shows that there is no consensus about gold standards for DTI data collection or processing. We found great methodological differences across studies that evaluated DTI metrics within the corticospinal tract. Despite heterogeneity in stroke lesions and analysis approaches, the majority of studies reported significant correlations between DTI biomarkers and motor impairments. It remains to be determined whether DTI results could enhance the predictive value of motor disability models based on clinical and neurophysiological variables

Abnormal sensory integration affects balance control in hemiparetic patients within the first year after stroke

OBJECTIVE: Impairments in balance can be a consequence of changes in the motor, sensory, and integrative aspects of motor control. Abnormal sensory reweighting, i.e., the ability to select the most appropriate sensory information to achieve postural stability, may contribute to balance impairment. The Sensory Organization Test is a component of Computerized Dynamic Posturography that evaluates the impact of visual, vestibular, and somatosensory inputs, as well as sensory reweighting, under conditions of sensory conflict. The aim of this study is to compare balance control in hemiparetic patients during the first year post-stroke and in age-matched neurologically normal subjects using the Berg Balance Scale and Computerized Dynamic Posturography. METHODS: We compared the Berg Balance Scale and Sensory Organization Test scores in 21 patients with hemiparesis after first-ever ischemic stroke and in 21 age-matched, neurologically normal subjects. An equilibrium score was defined for each Sensory Organization Test condition. RESULTS: Berg Balance Scale scores were significantly lower in the patients than in the neurologically normal subjects. Equilibrium scores were significantly lower in the patients than in the neurologically normal subjects for those Sensory Organization Test conditions that did not provide appropriate somatosensory information and under conditions of sensory conflict. A history of falls was more frequent in patients with lower equilibrium scores. CONCLUSION: During the first year after a stroke, defective sensory reweighting significantly impacts balance control in hemiparetic patients. These results are important for the planning of effective rehabilitation interventions