Impact of MCA stenosis on the early outcome in acute ischemic stroke patients

High prevalence of intracranial arterial stenosis among acute ischemic stroke patients in a Brazilian center: a transcranial color-coded duplex sonography study

BACKGROUND

 There is limited data available regarding the prevalence of intracranial arterial stenosis (ICAS) among acute ischemic stroke (AIS) patients in Brazil and Latin America.

OBJECTIVE

 The present study sought to investigate the frequency and predictors of ICAS among patients with AIS or transient ischemic attack (TIA) in a Brazilian center, with transcranial color-coded duplex sonography (TCCS) technique.

METHODS

 Consecutive AIS and TIA patients, admitted to an academic public comprehensive stroke center in Brazil from February to December 2014, evaluated by TCCS were prospectively selected. Vascular narrowings > 50% were considered as ICAS, based on ultrasound criteria previously defined in the literature.

RESULTS

 We assessed 170 consecutive patients with AIS or TIA, of whom 27 (15.9%) were excluded due to an inadequate transtemporal acoustic bone window. We confirmed ICAS in 55 patients (38.5%). The most common location was the proximal segment of the middle cerebral artery (28.2%), followed by the vertebral (15.4%), posterior cerebral (13.6%), terminal internal carotid (9.1%) and basilar (8.2%) arteries. On multivariate models adjusting for potential confounders, systolic blood pressure (OR: 1.03, 95%CI: 1.01-1.04; p = 0.008) was independently associated with ICAS.

CONCLUSION

 We found significant ICAS in approximately ⅓ of patients admitted with symptoms of AIS or TIA in a public tertiary academic stroke center in Brazil. The TCCS is an accessible and noninvasive technique that can be used to investigate the presence of moderate and severe ICAS, especially in patients who cannot be exposed to more invasive exams, such as the use of intravenous contrast agents.

Constructing a Transient Ischemia Attack Model Utilizing Flexible Spatial Targeting Photothrombosis with Real-Time Blood Flow Imaging Feedback

Transient ischemic attack (TIA) is an early warning sign of stroke and death, necessitating suitable animal models due to the associated clinical diagnostic challenges. In this study, we developed a TIA model using flexible spatially targeted photothrombosis combined with real-time blood flow imaging feedback. By modulating the excitation light using wavefront technology, we precisely created a square light spot (50 × 250 µm), targeted at the distal middle cerebral artery (dMCA). The use of laser speckle contrast imaging (LSCI) provided real-time feedback on the ischemia, while the excitation light was ceased upon reaching complete occlusion. Our results demonstrated that the photothrombus formed in the dMCA and spontaneously recanalized within 10 min (416.8 ± 96.4 s), with no sensorimotor deficits or infarction 24 h post-TIA. During the acute phase, ischemic spreading depression occurred in the ipsilateral dorsal cortex, leading to more severe ischemia and collateral circulation establishment synchronized with the onset of dMCA narrowing. Post-reperfusion, the thrombi were primarily in the sensorimotor and visual cortex, disappearing within 24 h. The blood flow changes in the dMCA were more indicative of cortical ischemic conditions than diameter changes. Our method successfully establishes a photochemical TIA model based on the dMCA, allowing for the dynamic observation and control of thrombus formation and recanalization and enabling real-time monitoring of the impacts on cerebral blood flow during the acute phase of TIA.

Association between serum transthyretin and intracranial atherosclerosis in patients with acute ischemic stroke

Background

Intracranial atherosclerotic stenosis (ICAS) is a primary cause of ischemic stroke. In addition to dyslipidemia, inflammation has been recognized as a potential pathogenesis of atherosclerosis. It remains unknown whether there is a link between transthyretin and ICAS as an inflammatory index.

Methods

Consecutive patients with acute ischemic stroke admitted to the Second Affiliated Hospital of Wenzhou Medical University between January 2019 and June 2020 were retrospectively analyzed. Blood samples were collected from all patients within 24 h of admission to detect their serum transthyretin levels. ICAS was defined as at least one intracranial artery stenosis on vascular examination with a degree of stenosis ≥50%. Multivariable logistic regression analysis was used to identify independent factors associated with ICAS. Restricted cubic spline models were used to depict patterns in the association between serum transthyretin levels and ICAS.

Results

In total, 637 patients with acute ischemic stroke were included in this study, of whom 267 (41.9%) had ICAS. Compared with the patients without ICAS, serum transthyretin levels in patients with ICAS were significantly lower (226.3 ± 56.5 vs. 251.0 ± 54.9 mg/L; p < 0.001). After adjusting for potential confounders, patients in the lowest tertile showed a significant increase in ICAS compared to those in the highest tertile (odds ratio, 1.85; 95% confidence interval, 1.12–3.05; p = 0.016). This negative linear association is also observed in the restricted cubic spline model. However, this association may only be observed in men. Age, National Institutes of Health Stroke Scale score, hemoglobin A1c level, and low-density lipoprotein cholesterol level were independently associated with ICAS.

Conclusions

Decreased serum transthyretin levels are associated with a more severe ICAS burden in patients with acute ischemic stroke. Our findings suggest that transthyretin may play a role in the pathogenesis of ICAS and provide insight into the control of inflammation for the treatment of ICAS.

Recurrent stroke syndrome without abnormality on magnetic resonance imaging caused by stenosis of middle cerebral artery: A case report

Middle cerebral artery stenosis is the leading and the most frequent cause of stroke due to intracranial stenosis in Asia. Magnetic resonance imaging (MRI) is more sensitive than computed tomography of the head for detecting acute brain ischemia. We are reporting a case of a 28-year-old female with recurrent left hemiparesis. After the last attack, an improvement in motor function was seen in less than 24 hours. Though the restoration of motor functions is not complete yet, an MRI scan that was done two weeks later appeared normal. Ischemic stroke in middle cerebral artery stenosis is associated with hemodynamic stroke due to hypoperfusion or lack of blood flow to brain tissue. Recurrent strokes can be prevented by better medical management in patients through regulation and management of risk factors.

An Optimal Animal Model of Ischemic Stroke Established by Digital Subtraction Angiography-Guided Autologous Thrombi in Cynomolgus Monkeys

Objective

Ischemic stroke seriously threatens human health, characterized by the high rates of incidence, disability, and death. Developing a reliable animal model that mimics most of the features of stroke is critical for pathological studies and clinical research. In this study, we aimed to establish and examine a model of middle cerebral artery occlusion (MCAO) guided by digital subtraction angiography (DSA) in cynomolgus monkeys.

Materials and Methods

In this study, 15 adult male cynomolgus monkeys were enrolled. Under the guidance of DSA, a MCAO model was established by injecting an autologous venous clot into the middle cerebral artery (MCA) via femoral artery catheter. Thrombolytic therapy with alteplase (rt-PA) was given to eight of these monkeys at 3 h after the occlusion. Blood test and imaging examination, such as computed tomography angiography (CTA), CT perfusion (CTP), brain magnetic resonance imaging (MRI), and brain magnetic resonance angiography (MRA), were performed after the operation to identify the post-infarction changes. The behavioral performance of cynomolgus monkeys was continuously observed for 7 days after operation. The animals were eunthanized on the 8th day after operation, and then the brain tissues of monkeys were taken for triphenyltetrazolium chloride (TTC) staining.

Results

Among the 15 cynomolgus monkeys, 12 of them were successfully modeled, as confirmed by the imaging findings and staining assessment. One monkey died of brain hernia resulted from intracranial hemorrhage confirmed by necropsy. DSA, CTA, and MRA indicated the presence of an arterial occlusion. CTP and MRI showed acute focal cerebral ischemia. TTC staining revealed infarct lesions formed in the brain tissues.

Conclusion

Our study may provide an optimal non-human primate model for an in-depth study of the pathogenesis and treatment of focal cerebral ischemia.

Smoking Paradox in Stroke Survivors?: Uncovering the Truth by Interpreting 2 Sets of Data

Background and Purpose- The observation that smokers with stroke could have better outcome than nonsmokers led to the term "smoking paradox." The controversy of such a complex claim has not been fully settled, even though different case mix was noted. Analyses were conducted on 2 independent data sets to evaluate and determine whether such a paradox truly exists. Methods- Taiwan Stroke Registry with 88 925 stroke cases, and MJ cohort with 541 047 adults participating in a medical screening program with 1630 stroke deaths developed during 15 years of follow-up (1994-2008). Primary outcome for stroke registry was functional independence at 3 months by modified Rankin Scale score ≤2, for individuals classified by National Institutes of Health Stroke Scale score at admission. For MJ cohort, mortality risk by smoking status or by stroke history was assessed by hazard ratio. Results- A >11-year age difference in stroke incidence was found between smokers and nonsmokers, with a median age of 60.2 years for current smokers and 71.6 years for nonsmokers. For smokers, favorable outcome in mortality and in functional assessment in 3 months with modified Rankin Scale score ≤2 stratified by the National Institutes of Health Stroke Scale score was present but disappeared when age and sex were matched. Smokers without stroke history had a ≈2-fold increase in stroke deaths (2.05 for ischemic stroke and 1.53 for hemorrhagic stroke) but smokers with stroke history, 7.83-fold increase, overshadowing smoking risk. Quitting smoking at earlier age reversed or improved outcome. Conclusions- "The more you smoke, the earlier you stroke, and the longer sufferings you have to cope." Smokers had 2-fold mortality from stroke but endured stroke disability 11 years longer. Quitting early reduced or reversed the harms.

Lack of association between serum homocysteine level and middle cerebral artery stenosis

OBJECTIVES

Lowering homocysteine (HCY) has beneficial effects on vascular events in primary prevention but not in secondary prevention. Research on serum HCY level and middle cerebral artery (MCA) stenosis is lacking. The purpose of the study was to determine the association between these factors and provide more evidence for the prevention of ischemic stroke.

METHODS

A total of 412 patients (35-93 years old) in the Neurology Department were recruited. Data of clinical and biochemical vascular risk factors were collected. MCA stenosis, including M1, M2, and M3, was determined by brain magnetic resonance angiography (MRA) and classified into stenosis or no stenosis. The differences and associations were analyzed by relevant statistical methods.

RESULTS

There was no significant difference (p = 0.325) in HCY levels between the MCA stenosis and no stenosis groups at baseline. Logistic regression analysis demonstrated that there was no significant association between HCY levels and MCA stenosis (p = 0.447). After the two groups were matched for age and sex, there was still no difference (p = 0.540 for males and 0.061 for females) or association (p = 0.709 for males and 0.098 for females). In addition, we found that ischemic stroke was more prevalent in the MCA stenosis group and uric acid was higher in males with MCA stenosis.

CONCLUSIONS

The study indicates a lack of association between serum HCY level and MCA stenosis, which may partially explain the negative results of secondary prevention clinical trials focused on lowering serum HCY level. Future studies on HCY reduction should focus more on primary prevention of ischemic stroke.

Clinical risk factors predictive of thrombotic stroke with large cerebral infarction

Large cerebral infarctions have high morbidity and mortality. Patients with large cerebral infarctions may have recurrent ischemia as high as 8.1% within 7 days; highest among other types of strokes. Data regarding risk factors for large cerebral infarction in Asian populations are still scant. All adult (age ≥15 years old) patients with the diagnosis of thrombotic ischemic stroke who were treated at Srinagarind Hospital, Khon Kaen University, Thailand from January 2012 to December 2013 were studied. Large cerebral infarctions are defined by clinical criteria of having cerebral cortical impairment, brain stem or cerebellar dysfunction with infarction sizes of more than 1.5 cm. The association of various stroke risk factors and large infarction strokes were calculated using multiple logistic regression analysis. There were 276 thrombotic stroke patients who met the study criteria; classified as large cerebral infarctions in 59 patients (21.38%) and small cerebral infarctions in 217 patients (78.62%). Baseline characteristics and risk factors for stroke were comparable between both groups. The large cerebral infarction group had a significantly larger proportions of right internal carotid artery stenosis, plaques on the left side, left internal carotid artery stenosis, and internal carotid artery stenosis at any side than the small cerebral infarction group. Among various stroke risk factors, only internal carotid artery stenosis at any side was the only significant factor associated with large cerebral infarction with an adjusted odds ratio of 11.14 (95% CI: 3.46, 35.82). In conclusion, significant internal carotid artery stenosis is associated with large cerebral infarction.