Cerebral haemodynamics with head position changes post-ischaemic stroke: A systematic review and meta-analysis

Cerebral hemodynamic response to upright position in acute ischemic stroke

Introduction

Concerns exist that a potential mechanism for harm from upright activity (sitting, standing, and walking) early after an acute ischaemic stroke could be the reduction of cerebral perfusion during this critical phase. We aimed to estimate the effects of upright positions (sitting and standing) on cerebral hemodynamics within 48 h and later, 3-7 days post-stroke, in patients with strokes with and without occlusive disease and in controls.

Methods

We investigated MCAv using transcranial Doppler in 0° head position, then at 30°, 70°, 90° sitting, and 90° standing, at <48 h post-stroke, and later at 3-7 days post-stroke. Mixed-effect linear regression modeling was used to estimate differences in MCAv between the 0° and other positions and to compare MCAv changes across groups.

Results

A total of 42 stroke participants (anterior and posterior circulation) (13 with occlusive disease, 29 without) and 22 controls were recruited. Affected hemisphere MCAv decreased in strokes with occlusive disease (<48 h post-stroke): from 0° to 90° sitting (-9.9 cm/s, 95% CI[-16.4, -3.4]) and from 0° to 90° standing (-7.1 cm/s, 95%CI[-14.3, -0.01]). Affected hemisphere MCAv also decreased in strokes without occlusive disease: from 0° to 90° sitting (-3.3 cm/s, 95%CI[-5.6, -1.1]) and from 0° to 90° standing (-3.6 cm/s, 95%CI [-5.9, -1.3]) (p-value interaction stroke with vs. without occlusive disease = 0.07). A decrease in MCAv when upright was also observed in controls: from 0° to 90° sitting (-3.8 cm/s, 95%CI[-6.0, -1.63]) and from 0° to 90° standing (-3 cm/s, 95%CI[-5.2, -0.81]) (p-value interaction stroke vs. controls = 0.85). Subgroup analysis of anterior circulation stroke showed similar patterns of change in MCAv in the affected hemisphere, with a significant interaction between those with occlusive disease (n = 11) and those without (n = 26) (p = 0.02). Changes in MCAv from 0° to upright at <48 h post-stroke were similar to 3-7 days. No association between changes in MCAv at <48 h and the 30-day modified Rankin Scale was found.

Discussion

Moving to more upright positions <2 days post-stroke does reduce MCAv in the affected hemisphere; however, these changes were not significantly different for stroke participants (anterior and posterior circulation) with and without occlusive disease, nor for controls. The decrease in MCAv in anterior circulation stroke with occlusive disease significantly differed from without occlusive disease. However, the sample size was small, and more research is warranted to confirm these findings.

Acute recanalization treatments in postnatal paediatric ischaemic arterial stroke. Paediatric stroke code

In children, arterial ischemic stroke is a much less understood disease compared to in adults due to its lower frequency and different aetiology. However, it is also a serious disease, with a high incidence of severe and permanent sequelae that exceeds 50% of total cases. The acute management of postnatal arterial ischaemic stroke (MNAIS) has changed drastically in recent years, chiefly on account of recanalization treatments (thrombolysis and endovascular therapies). These treatments, which used to not be recommended in childhood, are increasingly implemented in everyday clinical practice. Although the evidence from studies carried out in children is not of high quality due to their retrospective design and the small number of reported cases, they support the hypothesis that these treatments are as safe and effective as they are in adults as long as appropriate eligibility criteria are applied and they are used within a certain time from the onset of symptoms (therapeutic window). This article reviews the acute management of postnatal paediatric arterial ischemic stroke based on the current scientific evidence. Since the efficacy of these treatments is highly dependent on their early initiation, a paediatric stroke code needs to be in place as an extension of the stroke code applied to adults. It has started to be introduced in Spain since 2019, although there are still large areas of the country where it has yet to be applied.

A randomized trial of Trendelenburg position for acute moderate ischemic stroke

We aim to explore the effect of head-down position (HDP), initiated within 24 hours of onset, in moderate anterior circulation stroke patients with probable large artery atherosclerosis (LAA) etiology. This investigator-initiated, multi-center trial prospective, randomized, open-label, blinded-endpoint, multi-center and phase-2 trial was conducted in China and completed in 2021. Eligible patients were randomly assigned (1:1) into the HDP group receiving -20° Trendelenburg, or control group receiving standard care according to national guideline. The primary endpoint was proportion of modified Rankin Scale (mRS) of 0 to 2 at 90 days, which is a scale for measuring the degree of disability after stroke. 90-day mRS was assessed by a certified staff member who was blinded to group assignment. A total of 96 patients were randomized (47 in HDP group and 49 in control group) and 94 (97.9%) patients were included in the final analysis: 46 in HDP group and 48 in control group. The proportion of favorable outcome was 65.2% (30/46) in the HDP group versus 50.0% (24/48) in the control group (unadjusted: OR 2.05 [95%CI 0.87-4.82], P = 0.099). No severe adverse event was attributed to HDP procedures. This work suggests that the head-down position seems safe and feasible, but does not improve favorable functional outcome in acute moderate stroke patients with LAA. This trial was registered with ClinicalTrials.gov, NCT03744533.

Cerebral blood flow velocity progressively decreases with increasing levels of verticalization in healthy adults. A cross-sectional study with an observational design

Background

Autoregulation of the cerebral vasculature keeps brain perfusion stable over a range of systemic mean arterial pressures to ensure brain functioning, e.g., in different body positions. Verticalization, i.e., transfer from lying (0°) to upright (70°), which causes systemic blood pressure drop, would otherwise dramatically lower cerebral perfusion pressure inducing fainting. Understanding cerebral autoregulation is therefore a prerequisite to safe mobilization of patients in therapy.

Aim

We measured the impact of verticalization on cerebral blood flow velocity (CBFV) and systemic blood pressure (BP), heart rate (HR) and oxygen saturation in healthy individuals.

Methods

We measured CBFV in the middle cerebral artery (MCA) of the dominant hemisphere in 20 subjects using continuous transcranial doppler ultrasound (TCD). Subjects were verticalized at 0°, -5°, 15°, 30°, 45° and 70° for 3-5 min each, using a standardized Sara Combilizer chair. In addition, blood pressure, heart rate and oxygen saturation were continuously monitored.

Results

We show that CBFV progressively decreases in the MCA with increasing degrees of verticalization. Systolic and diastolic BP, as well as HR, show a compensatory increase during verticalization.

Conclusion

In healthy adults CBFV changes rapidly with changing levels of verticalization. The changes in the circulatory parameters are similar to results regarding classic orthostasis.

Registration

ClinicalTrials.gov, identifier: NCT04573114.

Pre-stroke Physical Activity and Cerebral Collateral Circulation in Ischemic Stroke: A Potential Therapeutic Relationship?

Favorable cerebral collateral circulation contributes to hindering penumbral tissue from progressing to infarction and is associated with positive clinical outcomes after stroke. Given its clinical importance, improving cerebral collateral circulation is considered a therapeutic target to reduce burden after stroke. We provide a hypothesis-generating discussion on the potential association between pre-stroke physical activity and cerebral collateral circulation in ischemic stroke. The recruitment of cerebral collaterals in acute ischemic stroke may depend on anatomical variations, capacity of collateral vessels to vasodilate, and individual risk factors. Physical activity is associated with improved cerebral endothelial and vascular function related to vasodilation and angiogenic adaptations, and risk reduction in individual risk factors. More research is needed to understand association between cerebral collateral circulation and physical activity. A presentation of different methodological considerations for measuring cerebral collateral circulation and pre-stroke physical activity in the context of acute ischemic stroke is included. Opportunities for future research into cerebral collateral circulation, physical activity, and stroke recovery is presented.

Verticalization for Refractory Intracranial Hypertension: A Case Series

BACKGROUND

Severe intracranial hypertension is strongly associated with mortality. Guidelines recommend medical management involving sedation, hyperosmotic agents, barbiturates, hypothermia, and surgical intervention. When these interventions are maximized or are contraindicated, refractory intracranial hypertension poses risk for herniation and death. We describe a novel intervention of verticalization for treating intracranial hypertension refractory to aggressive medical treatment.

METHODS

This study was a single-center retrospective review of six cases of refractory intracranial hypertension in a tertiary care center. All patients were treated with a standard-of-care algorithm for lowering intracranial pressure (ICP) yet maintained an ICP greater than 20 mmHg. They were then treated with verticalization for at least 24 h. We compared the median ICP, the number of ICP spikes greater than 20 mmHg, and the percentage of ICP values greater than 20 mmHg in the 24 h before verticalization vs. after verticalization. We assessed the use of hyperosmotic therapies and any changes in the mean arterial pressure and cerebral perfusion pressure related with the intervention.

RESULTS

Five patients were admitted with subarachnoid hemorrhage and one with intracerebral hemorrhage. All patients had ICP monitoring by external ventricular drain. The median opening pressure was 30 mmHg (25th-75th interquartile range 22.5-30 mmHg). All patients demonstrated a reduction in ICP after verticalization, with a significant decrease in the median ICP (12 vs. 8 mmHg; p < 0.001), the number of ICP spikes (12 vs. 2; p < 0.01), and the percentage of ICP values greater than 20 mmHg (50% vs. 8.3%; p < 0.01). There was a decrease in total medical interventions after verticalization (79 vs. 41; p = 0.05) and a lower total therapy intensity level score after verticalization. The most common adverse effects included asymptomatic bradycardia (n = 3) and pressure wounds (n = 4).

CONCLUSIONS

Verticalization is an effective noninvasive intervention for lowering ICP in intracranial hypertension that is refractory to aggressive standard management and warrants further study.

Early physical rehabilitation therapy between 24 and 48 h following acute ischemic stroke onset: a randomized controlled trial

PURPOSE

Early mobilization is believed to be helpful for patients with acute ischemic stroke. This study aimed to compare the difference between starting rehabilitation between 24 and 48 h and 72 and 96 h following the onset of ischemic stroke.

MATERIALS AND METHODS

This was a single-center, single-blind, randomized controlled trial. The early rehabilitation (ER) group started exercising between 24 and 48 h after stroke onset, which the standard rehabilitation (SR) group started exercising between 72 and 96 h. The two groups received sitting, standing, and repetitive body strength training respectively.

RESULTS

In this study, 110 patients were analyzed. Patients in the early rehabilitation group had more favorable outcomes (The modified Rankin scale score 0-2, ER group = 32 versus SR group = 20, adjusted odds ratio 2.27, 95% CI 1.05-4.87; p = 0.036) at 3-month follow-up. The simplified Fugl-Meyer assessment (FMA) scores for the lower extremity were influenced by the interaction effect (F = 7.24, p = 0.01). The post-hoc analysis revealed a difference in the lower extremity FMA score at one week after stroke (difference 2.30 (95% CI 0.65-3.96); p = 0.007).

CONCLUSIONS

Early physical rehabilitation training between 24 and 48 h may be beneficial and improve patients' lower extremity function within the first week.

CLINICAL TRIAL REGISTRATION UNIQUE IDENTIFIER

NCT02718534Implications for rehabilitationAcute ischemic stroke has a variety of symptoms, and acroparalysis is a major concern.Starting physical rehabilitation early can improve the prognosis of patients with ischemic stroke.Early rehabilitation is more conducive to the recovery of lower extremity motor function, but in the subsequent rehabilitation process, the upper extremity function should be paid more attention.

Fatal and Nonfatal Events Within 14 days After Early, Intensive Mobilization Poststroke

OBJECTIVE

This tertiary analysis from A Very Early Rehabilitation Trial (AVERT) examined fatal and nonfatal serious adverse events (SAEs) at 14 days.

METHOD

AVERT was a prospective, parallel group, assessor blinded, randomized international clinical trial comparing mobility training commenced <24 hours poststroke, termed very early mobilization (VEM), to usual care (UC). Primary outcome was assessed at 3 months. Patients with ischemic or hemorrhagic stroke within 24 hours of onset were included. Treatment with thrombolytics was allowed. Patients with severe premorbid disability or comorbidities were excluded. Interventions continued for 14 days or hospital discharge if less. The primary early safety outcome was fatal SAEs within 14 days. Secondary outcomes were nonfatal SAEs classified as neurologic, immobility-related, and other. Mortality influences were assessed using binary logistic regression adjusted for baseline stroke severity (NIH Stroke Scale [NIHSS] score) and age.

RESULTS

A total of 2,104 participants were randomized to VEM (n = 1,054) or UC (n = 1,050) with a median age of 72 years (interquartile range [IQR] 63-80) and NIHSS 7 (IQR 4-12). By 14 days, 48 had died in VEM, 32 in UC, age and stroke severity adjusted odds ratio of 1.76 (95% confidence interval 1.06-2.92, p = 0.029). Stroke progression was more common in VEM. Exploratory subgroup analyses showed higher odds of death in intracerebral hemorrhage and >80 years subgroups, but there was no significant treatment by subgroup interaction. No difference in nonfatal SAEs was found.

CONCLUSION

While the overall case fatality at 14 days poststroke was only 3.8%, mortality adjusted for age and stroke severity was increased with high dose and intensive training compared to usual care. Stroke progression was more common in VEM.

REGISTRATION

Australian New Zealand Clinical Trials Registry, ACTRN12606000185561.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that very early mobilization increases mortality at 14 days poststroke.

Occlusive Disease and Upright Activity in Acute Ischemic Stroke

The impact of out-of-bed upright activity on outcomes in ischemic stroke patients with severe extra- and intracranial stenosis or occlusion is unknown. Using ultrasound findings from a cohort recruited to A Very Early Rehabilitation Trial (AVERT) which compared higher dose very early mobilisation (VEM) to usual care (UC), we aimed to explore the association between occlusive disease and 3-month outcomes and occlusive disease-by-mobilisation treatment interactions. Participants with ischemic stroke, with carotid and transcranial Doppler ultrasounds performed ≤1 week after admission, were included in this single centre substudy in Melbourne, Australia. Reports were retrospectively reviewed to determine the degree of stenosis or presence of occlusion in the relevant arterial territory. Stenosis ≥70% extracranial or ≥50% intracranial were classified as severe or occlusion. Overall, 19% (n = 36/191) had occlusive disease in the affected circulation. About 40% (n = 14/36) with occlusive disease and 51% (n = 79/155) without had a 3-month favourable outcome (mRS 0-2) (adjusted OR0.53, CI0.17-1.67). Fourteen percent (n = 5) with occlusive disease and 4% (n = 6) without died by 3 months (adjusted OR2.52, CI0.6-10.7). Fifty percent (n = 11/22) of UC (adjusted OR0.86, CI0.23-3.2) and 21% (n = 3/14) of VEM participants (adjusted OR0.16, CI0.01-2.7) with occlusive disease had a favourable outcome. Almost 30% (n = 4) VEM participants with occlusive disease died (adjusted OR3.99, CI0.69-22.9) compared to 5% (n = 1) UC participants with occlusive disease (adjusted OR0.45, CI0.02-8.6), however numbers were small. No stenosis-by-treatment interactions were found. High quality prospective studies are needed to help guide decision making about when patients with occlusive disease should commence upright activity in acute stroke.