Pathophysiologic mechanisms, neuroimaging and treatment in wake-up stroke

Exploring the role of CT scouts in expediting MRI in acute stroke

PURPOSE

For acute stroke patients requiring MR examination and unable to provide a reliable history, screening for potentially MRI-incompatible objects (PMIOs) typically necessitates the use of plain-film radiographs (PFRs). However, using a whole body CT scout at the time of non-contrast head CT scans can preclude critical delays. Here, we aim to compare the effectiveness of PFRs and CT scouts in detecting PMIOs.

METHODS

A case-control study was conducted at a tertiary care institution, involving 408 imaging studies from 200 patients, half of which contained PMIOs. The diagnostic performances of CT scouts and PFRs were evaluated by six blinded readers, including two board-certified neuroradiologists, one neuroradiology fellow, and three radiology residents.

RESULTS

2448 interpretations from the 6 readers were analyzed. The diagnostic performance of combined CT scout images (full-body and regional) was not significantly different from that of PFRs for all six readers (p = 0.06). However, PFRs outperformed full-body CT scouts in PMIO detection (p = 0.01), with no significant differences observed between PFRs and regional CT scouts (p = 0.4). Notably, the diagnostic accuracy of the radiology residents was found to be equivalent to radiologists across all imaging techniques.

CONCLUSION

Integrating CT scouts in acute stroke protocols may help expedite MRI screening. The scouts should include the head, neck, chest, upper arms, abdomen, pelvis, and thighs. Including radiology residents in the screening process for PMIOs may be an avenue for resource optimization in acute care settings.

Dual antiplatelet therapy versus intravenous tissue plasminogen activator with acute minor ischemic stroke: A systematic review and meta-analysis of safety and efficacy

OBJECTIVES

To compare the safety and efficacy of Dual Antiplatelet Therapy (DAPT) and Intravenous (IV) Tissue Plasminogen Activator (t-PA) in minor Acute Ischemic Stroke (AIS).

MATERIALS AND METHODS

Following Cochrane and PRISMA guidelines, we analyzed observational studies and clinical trials comparing DAPT and IV t-PA in patients with minor AIS. Databases included PubMed, Scopus, and Web of Science. Data extraction included study characteristics, patient demographics, and analyzed outcomes. RevMan 5.3 and OpenMetaAnalyst 2021 were used to analyze the data and assess heterogeneity, respectively. The risk of bias was determined using RoB 2.0 and the Newcastle-Ottawa scale.

RESULTS

This meta-analysis included five studies with 3,978 DAPT-treated patients and 2,224 IV t-PA-treated patients. We found no significant differences in achieving modified Rankin scale (mRS) scores of 0-1 (OR 1.11, 95 % CI: 0.79, 1.55, p = 0.56) and 0-2 (OR 0.90, 95 % CI: 0.61, 1.31, p = 0.57), as well as combined mRS scores (OR 1.05, 95 % CI: 0.82, 1.34, p = 0.72). Similarly, there were no significant disparities between the two treatment groups in NIHSS score change from baseline (MD 0.32, 95 % CI: -0.35, 0.98, p = 0.35) and in mortality rates (OR 0.87, 95 % CI: 0.26, 2.93, p = 0.83). Notably, in comparison to the IV t-PA group, the DAPT group exhibited a significantly lower incidence of bleeding (OR 0.31, 95 % CI: 0.14, 0.69, p = 0.004) and symptomatic intracranial hemorrhage (sICH) (OR 0.10, 95 % CI: 0.04, 0.26, p < 0.00001).

CONCLUSIONS

Our meta-analysis found no significant differences in efficacy between DAPT and IV t-PA. However, DAPT demonstrated a significantly lower risk of sICH and bleeding compared with IV t-PA.

Stroke in Parkinson's disease: a review of epidemiological studies and potential pathophysiological mechanisms

Parkinson's disease (PD) is the fastest growing neurological disorder and one of the leading neurological causes of disability worldwide following stroke. An overall aging global population, as well as general changes in lifestyle associated with mass industrialization in the last century, may be linked to both increased incidence rates of PD and an increase in cumulative cardiovascular risk. Recent epidemiological studies show an increased risk of stroke, post-stroke complications, and subclinical ischemic insults in PD. PD patients have a host of characteristics that might contribute to increasing the risk of developing ischemic stroke including motor impairment, dysautonomia, and sleep disorders. This increases the urgency to study the interplay between PD and other neurological disorders, and their combined effect on mortality, morbidity, and quality of life. In this review, we provide a comprehensive overview of the studied etiological factors and pathological processes involved in PD, specifically with regard to their relationship to stroke. We hope that this review offers an insight into the relationship between PD and ischemic stroke and motivates further studies in this regard.

Identifying patients with acute ischemic stroke within a 6-h window for the treatment of endovascular thrombectomy using deep learning and perfusion imaging

Introduction

It is critical to identify the stroke onset time of patients with acute ischemic stroke (AIS) for the treatment of endovascular thrombectomy (EVT). However, it is challenging to accurately ascertain this time for patients with wake-up stroke (WUS). The current study aimed to construct a deep learning approach based on computed tomography perfusion (CTP) or perfusion weighted imaging (PWI) to identify a 6-h window for patients with AIS for the treatment of EVT.

Methods

We collected data from 377 patients with AIS, who were examined by CTP or PWI before making a treatment decision. Cerebral blood flow (CBF), time to maximum peak (Tmax), and a region of interest (ROI) mask were preprocessed from the CTP and PWI. We constructed the classifier based on a convolutional neural network (CNN), which was trained by CBF, Tmax, and ROI masks to identify patients with AIS within a 6-h window for the treatment of EVT. We compared the classification performance among a CNN, support vector machine (SVM), and random forest (RF) when trained by five different types of ROI masks. To assess the adaptability of the classifier of CNN for CTP and PWI, which were processed respectively from CTP and PWI groups.

Results

Our results showed that the CNN classifier had a higher performance with an area under the curve (AUC) of 0.935, which was significantly higher than that of support vector machine (SVM) and random forest (RF) (p = 0.001 and p = 0.001, respectively). For the CNN classifier trained by different ROI masks, the best performance was trained by CBF, Tmax, and ROI masks of Tmax > 6 s. No significant difference was detected in the classification performance of the CNN between CTP and PWI (0.902 vs. 0.928; p = 0.557).

Discussion

The CNN classifier trained by CBF, Tmax, and ROI masks of Tmax > 6 s had good performance in identifying patients with AIS within a 6-h window for the treatment of EVT. The current study indicates that the CNN model has potential to be used to accurately estimate the stroke onset time of patients with WUS.

Ambient fine particulate pollution hysteresis triggers wake-up stroke and rapidly triggers non-wake-up stroke: a case-crossover study

Atmospheric pollutants increase the risk of acute ischemic stroke (AIS) which has been widely reported. However, little is known about the relationships between air pollution and specific subsets of AIS, such as wake-up stroke (WUS) and non-wake-up stroke (non-WUS). This study aimed to explore the relationship between WUS and non-WUS and atmospheric pollutants. A total of 1432 patients (331 WUS patients and 1101 non-WUS patients) were admitted to a tertiary hospital from 2016 to 2019. A time-stratified case-crossover design and a conditional logistic regression model to study the associations of change in pollutant concentration with WUS and non-WUS events were constructed. Data analysis revealed that WUS-related risks increased 48 to 72 h after the increase in the PM_2.5 concentration (each 10 μg/m³ increase, lag 0-72 h) [threshold OR (95% CI):18 μg/m³ 1.03 (0.94-1.11), 35 μg/m³ 1.01 (0.92-1.12), 50 μg/m³ 1.04 (0.91-1.19)]; the non-WUS-related risk increased 1 to 6 h after the increase in the PM_2.5 concentration (each 10 μg/m³ increase, lag 0-1 h) [threshold OR (95% CI):18 μg/m³ 1.01 (0.98-1.03), 35 μg/m³ 1.00 (0.97-1.04), 50 μg/m³ 1.01 (0.96-1.05)] (lag 0-6 h) [threshold OR (95% CI): 18 μg/m³ 1.00 (0.97-1.03), 35 μg/m³ 1.00 (0.97-1.04), 50 μg/m³ 1.01 (0.97-1.06)]; O₃ exposure was related to WUS events, and its impact on WUS events was stronger and longer-lasting (1-96 h) than its impact on non-WUS events (1-6 h). Greater than or equal to 65 years of age, overweight (BMI ≥ 25), and diabetes had a significantly greater risk of WUS associated with increased PM_2.5 concentration in the previous 12-96 h than patients without these conditions. Patients with hypertension and smoking had a significant risk of non-WUS associated with increased PM_2.5 concentration in the previous 1-6 h. The increase in PM_2.5 concentration in the cold season increased the risk of both WUS and non-WUS events. Ambient air pollution hysteresis triggers WUS and rapidly triggers non-WUS, even if the degree of pollutant is relatively low. Patients with elderly, overweight, and diabetes appeared particularly susceptible to WUS, and patients with hypertension and smoking history were susceptible to non-WUS. We need to expand the sample for further investigation into mechanisms by which environmental pollutants trigger WUS or non-WUS.

Stroke: What's Sleep Got to Do With It?

SUMMARY

Ischemic strokes most often occur between 6 am and 12 am after awakening from sleep but up to 30% occur during sleep. Wake-up strokes (WUS) are new focal neurological deficit(s) persisting for ≥ 24 hours attributable to an ischemic event present on patient awakening. Obstructive sleep apnea (OSA) is a major risk factor for WUS because it compounds the instability of the morning environment and increases the likelihood of cardiovascular events, including hypertension, atrial fibrillation, right-to-left shunts, and stroke. Circadian-driven alterations in structural, homeostatic, and serological factors also predispose to WUS. Also, WUS patients are often not considered candidates for time-dependent intravenous thrombolysis therapy because of an uncertain onset time. However, using the tissue clock (positive diffusion weighted imaging-negative fluid-attenuated inversion recovery mismatch) dates the WUS as 3 to 4.5 hours old and permits consideration for intravenous thrombolysis and if needed mechanical thrombectomy. Given the high prevalence of moderate/severe OSA in stroke patients and its impact on stroke outcomes, screening with overnight pulse oximetry and home sleep apnea test is needed. Treating OSA poststroke remains challenging. Polysomnographic changes in sleep architecture following acute/subacute stroke may also impact upon stroke outcome.

Efficacy and safety of rt-PA intravenous thrombolysis in patients with wake-up stroke: A meta-analysis

BACKGROUND

: Recombinant tissue plasminogen activator (rt-PA) is one of the most effective therapies for patients with acute ischemic stroke. However, wake-up stroke (WUS) is typically excluded from intravenous thrombolytic therapy because of the unclear time of symptom onset. Therefore, we aimed to assess the efficacy and safety of rt-PA intravenous thrombolysis in patients with WUS by meta-analysis.

METHODS

: We completed a systematic literature search of PubMed, Embase, the Cochrane Library, and SinoMed and included relevant studies of WUS patients covering rt-PA thrombolysis and nonthrombolysis (published from January 1, 2000, to February 28, 2021, with no language restrictions). The primary outcomes included safety outcomes and functional outcomes. Safety outcomes were measured according to the incidence of symptomatic intracranial hemorrhage and mortality within 90 days. The efficacy outcomes were measured based on 90-day modified Rankin Scale scores. We assessed pooled data using either a random-effects model (when P < .10, I2 > 50%) or a fixed-effects model (when P > .10, I2 < 50%).

RESULTS

: A total of 913 patients from 9 studies were included in the meta-analysis. All patients had ischemic stroke confirmed by computed tomography or magnetic resonance imaging. The incidence of modified Rankin Scale 0 to 2 was significantly higher in the rt-PA thrombolysis group compared with the nonthrombolysis group. And rt-PA thrombolytic WUS patients did not differ significantly from nonthrombolytic WUS patients in terms of 90-day mortality. However, the incidence of Symptomatic intracranial hemorrhage was also significantly higher in the rt-PA thrombolysis group than that in the nonthrombolysis group.

CONCLUSIONS

: Patients with WUS who received rt-PA thrombolysis had a significant positive effect within 90 days. In addition, although there was no significant increase in mortality, we need to be aware of the risk of intracranial hemorrhage transformation associated with rt-PA thrombolysis despite no obvious increase in mortality. The safety of rt-PA intravenous thrombolysis should be closely monitored in patients with WUS.

Nanomedicines, an emerging therapeutic regimen for treatment of ischemic cerebral stroke: A review

Owing to its intricate pathophysiology, cerebral stroke is a serious medical condition caused by interruption or obstruction of blood supply (blockage of vasculature) to the brain tissues which results in diminished supply of essential nutrients and oxygen (hypoxia) and ultimate necrosis of neuronal tissues. A prompt risks assessment and immediate rational therapeutic plan with proficient neuroprotection play critically important role in the effective management of this neuronal emergency. Various conventional medications are being used for treatment of acute ischemic cerebral stroke but fibrinolytic agents, alone or in combination with other agents are considered the mainstay. These clot-busting agents effectively restore blood supply (reperfusion) to ischemic regions of the brain; however, their clinical significance is hampered due to various factors such as short plasma half-life, limited distribution to brain tissues due to the presence of highly efficient physiological barrier, blood brain barrier (BBB), and lacking of target-specific delivery to the ischemic brain regions. To alleviate these issues, various types of nanomedicines such as polymeric nanoparticles (NPs), liposomes, nanoemulsion, micelles and dendrimers have been designed and evaluated. The implication of these newer therapies (nanomedicines) have revolutionized the therapeutic outcomes by improving the plasma half-life, permeation across BBB, efficient distribution to ischemic cerebral tissues and neuroprotection. Furthermore, the adaptation of some diverse techniques including PEGylation, tethering of targeting ligands on the surfaces of nanomedicines, and pH responsive features have also been pondered. The implication of these emerging adaptations have shown remarkable potential in maximizing the targeting efficiency of drugs to ischemic brain tissues, simultaneous delivery of drugs and imaging agents (for early prognosis as well as monitoring of therapy), and therapeutic outcomes such as long-term neuroprotection.

Accuracy of Brain MRI Interpretation of Emergency Medicine Specialists Versus Radiologist and Neurologist in Suspected Acute Ischemic Stroke Patients; a Diagnostic Accuracy Study

Background: Despite numerous brain magnetic resonance imaging (MRI) utilization in the emergency department (ED), certainly, imaging alone is not enough, and it is necessary to have a correct interpretation by a physician who has sufficient skills in this regard. Objectives: Here, we decided to investigate the accuracy of interpreting brain MRI of suspected acute ischemic stroke (AIS) patients conducted by emergency medicine physicians (EMPs) in comparison with a radiologist and a neurologist. Methods: This diagnostic accuracy study was conducted from April to November 2019 in Tehran, Iran. All attending EMPs of one major educational, medical center, a radiologist, and a neurologist also participated. A set of brain MRI stereotypes related to patients suspected of having a AIS was randomly selected. By reviewing the brain MRI interpretation of EMPs, once in comparison with the radiologist and once in comparison with the neurologist, misinterpretations (presence or absence of findings compatible with the diagnosis of AIS) were extracted. Results: Brain MRI stereotypes of 287 suspected AIS patients were interpreted of these patients, 160 cases (55.7%) were male. The mean age of the study patients was 65.0 ± 14.1 (range of 18 to 98) years. The value of the agreement for diagnosis between EMPs and neurologists was 0.684 (95% CI: 0.580 to 0.787). Considering the neurologist as the gold standard, the accuracy of AIS diagnosis by the EMPs was 0.85% (95% CI: 79.3 to 89.6). The agreement value for diagnosis between EMPs and radiologist was 0.673 (95% CI: 0.553 to 0.794). Considering the radiologist as the gold standard, the accuracy of AIS diagnosis by the EMPs was 86.3% (95% CI: 79.8 to 91.3). The agreement value for diagnosis in these two groups was 0.752 (95% CI: 0.627 to 0.877). Conclusions: The findings of the current study revealed that the accuracy of brain MRI interpretation performed by the EMPs, compared with both neurologist and radiologist was proper.

Safety and efficacy of intravenous thrombolytic treatment in wake-up stroke: Experiences from a single center

OBJECTIVES

Wake-up stroke is an important clinical problem that may account for a quarter of all ischemic strokes. This study aimed to establish the safety and efficacy of intravenous thrombolytic treatment of wake-up strokes by comparing it to the standard thrombolysis treatment in strokes with clear onsets and wake-up strokes that did not receive reperfusion therapy.

METHODS

This retrospective study enrolled 95 patients with ischemic strokes who underwent thrombolytic treatment with alteplase, including nine patients with wake-up strokes. The safety profile (mortality and intracranial bleeding) and efficacy (clinical and functional outcomes on admission, discharge, and 90 days after stroke onset) were evaluated.

RESULTS

When assessed using the modified Rankin scale (mRs), the patients with wake-up strokes had significantly more favorable functional outcomes on discharge when compared to those who received standard thrombolysis (p = .0289). No significant differences were noted when the favorable outcome rate (mRs score = 0-2) at three months post-thrombolysis (Odds ratio [OR] = 2.07; 95% confidence interval [CI] = 0.41-10.6; p = .3807) and safety outcomes (death during hospitalization: OR = 0.49; 95% CI = 0.03-9.11; p = .6295 and intracranial bleeding 24 hr after treatment: OR = 0.43; 95% CI = 0.02-7.58; p = .5707) were compared between the two groups. The Cochran-Mantel-Haenchel shift analysis showed a significantly more favorable distribution of the mRs scores at three months after the stroke onset in the patients with wake-up strokes who were treated with alteplase compared to those who did not receive thrombolysis (OR = 1.42; 95% CI = 1.01-1.82; p = .0426).

CONCLUSIONS

Our study demonstrated that in patients who awaken with stroke symptoms, intravenous thrombolytic treatment is a safe procedure that may lead to favorable outcomes. Further studies should be performed to increase the size of the group of patients with wake-up strokes who can be treated with reperfusion therapy.

Emerging paradigms in treating cerebral infarction with nanotheranostics: opportunities and clinical challenges

Interest is increasing in the use of nanotheranostics as diagnosis, imaging and therapeutic tools for stroke management, but movement to the clinic remains challenging.