Mechanism of Action and Translational Potential of (S)-Meclizine in Preemptive Prophylaxis Against Stroke.

BACKGROUND: Mild chemical inhibition of mitochondrial respiration can confer resilience against a subsequent stroke or myocardial infarction, also known as preconditioning. However, the lack of chemicals that can safely inhibit mitochondrial respiration has impeded the clinical translation of the preconditioning concept. We previously showed that meclizine, an over-the-counter antivertigo drug, can toggle metabolism from mitochondrial respiration toward glycolysis and protect against ischemia-reperfusion injury in the brain, heart, and kidney. Here, we examine the mechanism of action of meclizine and report the efficacy and improved safety of the (S) enantiomer. METHODS: We determined the anoxic depolarization latency, tissue and neurological outcomes, and glucose uptake using micro-positron emission tomography after transient middle cerebral artery occlusion in mice pretreated (-17 and -3 hours) with either vehicle or meclizine. To exclude a direct effect on tissue excitability, we also examined spreading depression susceptibility. Furthermore, we accomplished the chiral synthesis of (R)- and (S)-meclizine and compared their effects on oxygen consumption and histamine H1 receptor binding along with their brain concentrations. RESULTS: Micro-positron emission tomography showed meclizine increases glucose uptake in the ischemic penumbra, providing the first in vivo evidence that the neuroprotective effect of meclizine indeed stems from its ability to toggle metabolism toward glycolysis. Consistent with reduced reliance on oxidative phosphorylation to sustain the metabolism, meclizine delayed anoxic depolarization onset after middle cerebral artery occlusion. Moreover, the (S) enantiomer showed reduced H1 receptor binding, a dose-limiting side effect for the racemate, but retained its effect on mitochondrial respiration. (S)-meclizine was at least as efficacious as the racemate in delaying anoxic depolarization onset and decreasing infarct volumes after middle cerebral artery occlusion. CONCLUSIONS: Our data identify (S)-meclizine as a promising new drug candidate with high translational potential as a chemical preconditioning agent for preemptive prophylaxis in patients with high imminent stroke or myocardial infarction risk.

The effect of comorbidity on early clinical decision making in acute mesenteric ischemia.

INTRODUCTION: Acute mesenteric ischemia (AMI) is a surgical emergency with a high mortality and morbidity rate. Prompt diagnosis and early surgical management are the cornerstones of management. In certain patients, however, treatment is futile and early palliative care, lessens patient, and family distress. The aim of this study was to investigate factors, focusing on patient comorbidity, that may predict futility of treatment and hence, guide clinicians in their decision making. PATIENTS AND METHODS: Consecutive adult patients with AMI diagnosed on imaging were reviewed for demographics, comorbidity, imaging, and biochemical results. RESULTS: Seventy patients were identified with average age of 67 (range 33 - 94). Overall hospital mortality was 72%. Patients were divided into three distinct groups, patients who recovered (27%), patients deceased despite surgical treatment (18%), and patients palliated on presentation (54%). Age was comparable between groups (61 vs. 69 vs. 69; p=.2). Length of stay was highest in the recovered group (41.6 vs. 12.3 vs. 2.8 d). Biochemically, only lactate level differed (3.1 vs. 2.3 vs. 5.3 mmol/L, p=.03). Both deceased and palliative group scored similarly but significantly higher than the recovered group in both the Charlson comorbidity index (CCI) (4.2 and 5.6 vs. 3.4, p=.02) and age-adjusted CCI (ACCI) (6.7 and 8.2 vs. 5; p<.01). Other co-morbidities of atrial fibrillation (AF) and hypertension were comparable. CONCLUSIONS: Raised ACCI confers poor outcomes in AMI despite surgical management. ACCI may be used to aid early decision making in AMI, predicting futility of treatment, and altering management goals to palliative comfort care.

Reversible Cerebral Vasoconstriction Syndrome in Patients with Coronavirus Disease: A Multicenter Case Series.

BACKGROUND AND OBJECTIVES: RCVS (Reversible Cerebral Vasoconstrictive Syndrome) is a condition associated with vasoactive agents that alter endothelial function. There is growing evidence that endothelial inflammation contributes to cerebrovascular disease in patients with coronavirus disease 2019 (COVID-19). In our study, we describe the clinical features, risk factors, and outcomes of RCVS in a multicenter case series of patients with COVID-19. MATERIALS AND METHODS: Multicenter retrospective case series. We collected clinical characteristics, imaging, and outcomes of patients with RCVS and COVID-19 identified at each participating site. RESULTS: Ten patients were identified, 7 women, ages 21 - 62 years. Risk factors included use of vasoconstrictive agents in 7 and history of migraine in 2. Presenting symptoms included thunderclap headache in 5 patients with recurrent headaches in 4. Eight were hypertensive on arrival to the hospital. Symptoms of COVID-19 included fever in 2, respiratory symptoms in 8, and gastrointestinal symptoms in 1. One patient did not have systemic COVID-19 symptoms. MRI showed subarachnoid hemorrhage in 3 cases, intraparenchymal hemorrhage in 2, acute ischemic stroke in 4, FLAIR hyperintensities in 2, and no abnormalities in 1 case. Neurovascular imaging showed focal segment irregularity and narrowing concerning for vasospasm of the left MCA in 4 cases and diffuse, multifocal narrowing of the intracranial vasculature in 6 cases. Outcomes varied, with 2 deaths, 2 remaining in the ICU, and 6 surviving to discharge with modified Rankin scale (mRS) scores of 0 (n=3), 2 (n=2), and 3 (n=1). CONCLUSIONS: Our series suggests that patients with COVID-19 may be at risk for RCVS, particularly in the setting of additional risk factors such as exposure to vasoactive agents. There was variability in the symptoms and severity of COVID-19, clinical characteristics, abnormalities on imaging, and mRS scores. However, a larger study is needed to validate a causal relationship between RCVS and COVID-19.

Seizure as the presenting symptom of COVID-19: A retrospective case series.

BACKGROUND: Coronavirus Disease 2019 (COVID-19) has rapidly become a global pandemic, with over 1.8 million confirmed cases worldwide to date. Preliminary reports suggest that the disease may present in diverse ways, including with neurological symptoms, but few published reports in the literature describe seizures in patients with COVID-19. OBJECTIVE: The objective of the study was to characterize the risk factors, clinical features, and outcomes of seizures in patients with COVID-19. METHODS: This is a retrospective case series. Cases were identified through a review of admissions and consultations to the neurology and neurocritical care services between April 1, 2020 and May 15, 2020. SETTING: The study setting was in a tertiary care, safety-net hospital in Boston, MA. PARTICIPANTS: Patients presenting with seizures and COVID-19 during the study period were included in the study. RESULTS: Seven patients met inclusion criteria (5 females, 71%). Patients ranged in age from 37 to 88 years (median: 75 years). Three patients had a prior history of well-controlled epilepsy (43%), while 4 patients had new-onset seizures, including 2 patients with prior history of remote stroke. Three patients had no preceding symptoms of COVID-19 prior to presentation (57%), and in all cases, seizures were the symptom that prompted presentation to the emergency department, regardless of prior symptoms of COVID-19. CONCLUSIONS: Provoking factors for seizures in patients with COVID-19 may include metabolic factors, systemic illness, and possibly direct effects of the virus. In endemic areas with community spread of COVID-19, clinicians should be vigilant for the infection in patients who present with seizures, which may precede respiratory symptoms or prompt presentation to medical care. Early testing, isolation, and contact tracking of these patients can prevent further transmission of the virus.

CT-Negative Subarachnoid Hemorrhage in the First Six Hours.

BACKGROUND: There are no reported cases of negative CT head in the first six hours after a thunderclap headache in a patient found to have an aneurysmal subarachnoid hemorrhage (SAH). METHODS: We present a case of an anemic patient who experienced aneurysmal SAH with a negative head CT within the first 6 h following thunderclap headache. RESULTS: A 47-year-old woman presented with a thunderclap headache and examination showed somnolence and marked meningismus. After a negative CT head was obtained within the first 6 hours of symptom onset, a non-traumatic lumbar puncture (LP) showed consistently bloody collection tubes, prompting repeat imaging that demonstrated a tiny amount of intraventricular hemorrhage. CT angiography revealed an intradural carotid artery aneurysm, and pipeline embolization was successfully performed. CONCLUSION: Non-contrast head CT may be falsely negative within the first 6 hours of aneurysmal SAH in the setting of anemia. In our case, the cause may not have been determined if an LP had not been performed. LP still has a role in diagnosing SAH, particularly in the setting of significant anemia, despite the high sensitivity of non-contrast head CT.

Cerebral Venous Sinus Thromboses in Patients with SARS-CoV-2 Infection: Three Cases and a Review of the Literature.

INTRODUCTION: Early studies suggest that acute cerebrovascular events may be common in patients with coronavirus disease 2019 (COVID-19) and may be associated with a high mortality rate. Most cerebrovascular events described have been ischemic strokes, but both intracerebral hemorrhage and rarely cerebral venous sinus thrombosis (CVST) have also been reported. The diagnosis of CVST can be elusive, with wide-ranging and nonspecific presenting symptoms that can include headache or altered sensorium alone. OBJECTIVE: To describe the presentation, barriers to diagnosis, treatment, and outcome of CVST in patients with COVID-19. METHODS: We abstracted data on all patients diagnosed with CVST and COVID-19 from March 1 to August 9, 2020 at Boston Medical Center. Subsequently, we reviewed the literature and extracted all published cases of CVST in patients with COVID-19 from January 1, 2020 through August 9, 2020 and included all studies with case descriptions. RESULTS: We describe the clinical features and management of CVST in 3 women with COVID-19 who developed CVST days to months after initial COVID-19 symptoms. Two patients presented with encephalopathy and without focal neurologic deficits, while one presented with visual symptoms. All patients were treated with intravenous hydration and anticoagulation. None suffered hemorrhagic complications, and all were discharged home. We identified 12 other patients with CVST in the setting of COVID-19 via literature search. There was a female predominance (54.5%), most patients presented with altered sensorium (54.5%), and there was a high mortality rate (36.4%). CONCLUSIONS: During this pandemic, clinicians should maintain a high index of suspicion for CVST in patients with a recent history of COVID-19 presenting with non-specific neurological symptoms such as headache to provide expedient management and prevent complications. The limited data suggests that CVST in COVID-19 is more prevalent in females and may be associated with high mortality.

Intravenous tPA for Acute Ischemic Stroke in Patients with COVID-19.

BACKGROUND/PURPOSE: Coronavirus disease 2019 (COVID-19) is associated with increased risk of acute ischemic stroke (AIS), however, there is a paucity of data regarding outcomes after administration of intravenous tissue plasminogen activator (IV tPA) for stroke in patients with COVID-19. METHODS: We present a multicenter case series from 9 centers in the United States of patients with acute neurological deficits consistent with AIS and COVID-19 who were treated with IV tPA. RESULTS: We identified 13 patients (mean age 62 (±9.8) years, 9 (69.2%) male). All received IV tPA and 3 cases also underwent mechanical thrombectomy. All patients had systemic symptoms consistent with COVID-19 at the time of admission: fever (5 patients), cough (7 patients), and dyspnea (8 patients). The median admission NIH stroke scale (NIHSS) score was 14.5 (range 3-26) and most patients (61.5%) improved at follow up (median NIHSS score 7.5, range 0-25). No systemic or symptomatic intracranial hemorrhages were seen. Stroke mechanisms included cardioembolic (3 patients), large artery atherosclerosis (2 patients), small vessel disease (1 patient), embolic stroke of undetermined source (3 patients), and cryptogenic with incomplete investigation (1 patient). Three patients were determined to have transient ischemic attacks or aborted strokes. Two out of 12 (16.6%) patients had elevated fibrinogen levels on admission (mean 262.2 ± 87.5 mg/dl), and 7 out of 11 (63.6%) patients had an elevated D-dimer level (mean 4284.6 ±3368.9 ng/ml). CONCLUSIONS: IV tPA may be safe and efficacious in COVID-19, but larger studies are needed to validate these results.

Subarachnoid hemorrhage guidance in the era of the COVID-19 pandemic - An opinion to mitigate exposure and conserve personal protective equipment.

Aneurysmal subarachnoid hemorrhage (SAH) patients require frequent neurological examinations, neuroradiographic diagnostic testing and lengthy intensive care unit stay. Previously established SAH treatment protocols are impractical to impossible to adhere to in the current COVID-19 crisis due to the need for infection containment and shortage of critical care resources, including personal protective equipment (PPE). Centers need to adopt modified protocols to optimize SAH care and outcomes during this crisis. In this opinion piece, we assembled a multidisciplinary, multicenter team to develop and propose a modified guidance algorithm that optimizes SAH care and workflow in the era of the COVID-19 pandemic. This guidance is to be adapted to the available resources of a local institution and does not replace clinical judgment when faced with an individual patient.

Plastic in the Brain: Delayed Recognition of Progressive Unilateral Hemispheric Lesions.

BACKGROUND: Flow diverters are increasingly used to treat complex ruptured intracranial aneurysms. Most complications are ischemic and seen early after placement. METHODS: We present a patient with 3 year duration of neurologic symptoms and seizures as a result of lesions associated with a inflammatory response to embolized polymer coating. RESULTS: Over a period of 3 years MRI abnormalities were noted with substantial gadolinium enhancement of the stent but with resolution after corticosteroids. CONCLUSION: Polymer embolization associated with a flow diverter may cause fluctuating unilateral hemisheric lesions and become symptomatic. Inflammatory response to a foreign body (polymer strands) can be succesfully treated with corticosteroids.

VEGF Requires the Receptor NRP-1 To Inhibit Lipopolysaccharide-Dependent Dendritic Cell Maturation.

To stimulate a productive T cell response, dendritic cells (DC) must undergo maturation characterized by heightened cell surface expression of MHC and costimulatory molecules as well as cytokine production. Conversely, the inhibition of DC maturation is a central mechanism of immune tolerance. The control of the DC maturation process relies on the integration of several cellular stimulatory or inhibitory signals. The soluble factors and their receptors controlling this central aspect of DC biology are incompletely characterized. We show that murine bone marrow-derived DC (BMDC) maturation induced by LPS, as opposed to polyinosinic:polycytidylic acid or cytosine-phosphate-guanine, is robustly inhibited by vascular endothelial growth factor (VEGF), a previously identified immunosuppressive cytokine. Using BMDC from wild type and conditional knockout mice, we show that neuropilin-1 (NRP-1), a known receptor of VEGF, is necessary to suppress LPS-dependent BMDC maturation. The absence of NRP-1 had no ostensible effects on the biology of BMDC in the absence of VEGF. However, NRP-1-deficient BMDC remained completely insensitive to the VEGF-dependent inhibition of BMDC maturation in culture. In the presence of VEGF, NRP-1 directly interacted with the LPS receptor TLR4 and suppressed downstream signaling through ERK and NF-κß, resulting in a sharp inhibition of MHC class II and costimulatory molecules (CD40, CD86) expression as well as proinflammatory cytokine production. Consequently, we identify NRP-1 as a target to optimize DC maturation within environments that are rich in VEGF, such as tumors.

First-in-man experience of self-expanding nitinol stents combined with drug-coated balloon in the treatment of femoropopliteal occlusive disease.

Purpose The present study aimed to determine the safety and efficacy of a drug-coated balloon inflated within a thin-strut self-expanding bare-metal stent in patients with severe and complex femoropopliteal occlusive disease. Methods This prospective study used the Pulsar-self-expanding stent and Passeo-18 Lux drug-coated balloon in patients with severe and complex femoropopliteal occlusive disease. The primary endpoint was the 12-month primary patency, and the secondary endpoints included 24-month primary patency, assisted primary patency, secondary patency, and clinically associated target lesion revascularisation. Results The study included 44 patients (51 limbs). The mean age of the patients was 67.6 ± 10.2 years, with 73% men. Chronic limb severity was classified as Rutherford Category III in 41% of the patients, stage IV in 31%, and stage V in 27%. Lesions were predominantly Trans-Atlantic Inter-Society Consensus (TASC 2007) D (51%) and C (45%), with 32 (63%) chronic total occlusions. Procedural success was obtained in all cases. The mean lesion length was 200 ± 74.55 mm (95% CI = 167.09-208.01) with a mean number of stents per limb used of 1.57 ± 0.70 (95% CI = 1.37-1.76). Distal embolisation occurred in two patients. The primary patency rates at the 12- and 24-month follow-up were 94% (95% CI = 82.9-98.1) and 88% (95% CI = 75.7-94.5), respectively. The assisted primary was 94% (95% CI = 82.9-98.1) and secondary patency was 96% (95% CI = 85.2-99.0) at 24-month follow-up. The cumulative stent fracture rate at the 24-month follow-up was 10%. Freedom from clinically driven target lesion revascularisation was 94% (95% CI = 83-98%) at 12-month follow-up and 88% (95% CI = 76-94%) at 24-month follow-up, with two patients requiring a bypass graft. Conclusion Our novel approach involving the combination of a thin-strut bare-metal stent and a drug-coated balloon may be safe and effective, with sustainable and promising clinical outcomes up to 24 months after treatment.

Aag-initiated base excision repair promotes ischemia reperfusion injury in liver, brain, and kidney.

Inflammation is accompanied by the release of highly reactive oxygen and nitrogen species (RONS) that damage DNA, among other cellular molecules. Base excision repair (BER) is initiated by DNA glycosylases and is crucial in repairing RONS-induced DNA damage; the alkyladenine DNA glycosylase (Aag/Mpg) excises several DNA base lesions induced by the inflammation-associated RONS release that accompanies ischemia reperfusion (I/R). Using mouse I/R models we demonstrate that Aag(-/-) mice are significantly protected against, rather than sensitized to, I/R injury, and that such protection is observed across three different organs. Following I/R in liver, kidney, and brain, Aag(-/-) mice display decreased hepatocyte death, cerebral infarction, and renal injury relative to wild-type. We infer that in wild-type mice, Aag excises damaged DNA bases to generate potentially toxic abasic sites that in turn generate highly toxic DNA strand breaks that trigger poly(ADP-ribose) polymerase (Parp) hyperactivation, cellular bioenergetics failure, and necrosis; indeed, steady-state levels of abasic sites and nuclear PAR polymers were significantly more elevated in wild-type vs. Aag(-/-) liver after I/R. This increase in PAR polymers was accompanied by depletion of intracellular NAD and ATP levels plus the translocation and extracellular release of the high-mobility group box 1 (Hmgb1) nuclear protein, activating the sterile inflammatory response. We thus demonstrate the detrimental effects of Aag-initiated BER during I/R and sterile inflammation, and present a novel target for controlling I/R-induced injury.

Durability of the balloon-expandable covered versus bare-metal stents in the Covered versus Balloon Expandable Stent Trial (COBEST) for the treatment of aortoiliac occlusive disease.

OBJECTIVE: The Covered vs Balloon Expandable Stent Trial (COBEST) is the first multicenter trial to investigate the patency of covered stents (CSs) and bare-metal stents (BMSs) in the treatment of aortoiliac arterial disease. The short-term results demonstrated that CSs were superior to BMSs in maintaining patency for TransAtlantic Inter-Society Consensus (TASC) C and D lesions at 18 months and were equivalent to BMSs for TASC B lesions. The current study was conducted to determine if the initial patency advantage of CSs over BMSs was sustained at the 5-year follow-up. METHODS: A retrospective post hoc analysis of COBEST was performed. Originally, 125 patients with 168 iliac arteries were prospectively enrolled and randomly assigned to receive a CS or BMS. In this study, 77 of the 125 patients (61.6%; 119 limbs) were assessed at 60 months for the primary and secondary end points, with particular attention paid to the outcomes stratified according to TASC lesion severity. The primary end point was the rate of binary stenosis or freedom from stent occlusion of the treated area, as determined by ultrasound imaging or quantitative visual angiography. RESULTS: The 5-year results of the COBEST showed that the CS had a significantly higher patency rate than the BMS at 18, 24, 48, and 60 months (95.1%, 82.1%, 79.9%, 74.7% for CS vs 73.9%, 70.9%, 63% and 62.5% for BMS; log-rank test, P = .01). On multivariate analysis, the type of stent used (hazard ratio [HR], 2.797; 95% confidence interval [CI], 1.471-5.318; P = .002) and the Rutherford classification (HR, 2.019; 95% CI, 1.278-3.191; P = .026) significantly affected the adjusted primary patency. On subgroup analysis, the CS showed significantly higher patency and a survival benefit compared with the BMS in TASC C and D lesions (HR, 8.639; 95% CI, 54.253-75.753; P = .003). Moreover, fewer patients received target limb revascularization in the CS group than in the BMS group (odds ratio, 2.32; 95% CI, 1.47-3.36; P = .02); however, there was no statistically significant difference in the rate of amputations between the groups. CONCLUSIONS: The 5-year results of the COBEST demonstrated that the CS has an enduring patency advantage over the BMS in both the short and long terms. Furthermore, the CS showed acceptable patency rates for the treatment of more severe TASC C and D lesions, and patients who received a CS required fewer revascularization procedures. However, the choice of stent did not affect the rate of major limb amputations.

Migraine prophylaxis, ischemic depolarizations, and stroke outcomes in mice.

BACKGROUND AND PURPOSE: Migraine with aura is an established stroke risk factor, and excitatory mechanisms such as spreading depression (SD) are implicated in the pathogenesis of both migraine and stroke. Spontaneous SD waves originate within the peri-infarct tissue and exacerbate the metabolic mismatch during focal cerebral ischemia. Genetically enhanced SD susceptibility facilitates anoxic depolarizations and peri-infarct SDs and accelerates infarct growth, suggesting that susceptibility to SD is a critical determinant of vulnerability to ischemic injury. Because chronic treatment with migraine prophylactic drugs suppresses SD susceptibility, we tested whether migraine prophylaxis can also suppress ischemic depolarizations and improve stroke outcome. METHODS: We measured the cortical susceptibility to SD and ischemic depolarizations, and determined tissue and neurological outcomes after middle cerebral artery occlusion in wild-type and familial hemiplegic migraine type 1 knock-in mice treated with vehicle, topiramate or lamotrigine daily for 7 weeks or as a single dose shortly before testing. RESULTS: Chronic treatment with topiramate or lamotrigine reduced the susceptibility to KCl-induced or electric stimulation-induced SDs as well as ischemic depolarizations in both wild-type and familial hemiplegic migraine type 1 mutant mice. Consequently, both tissue and neurological outcomes were improved. Notably, treatment with a single dose of either drug was ineffective. CONCLUSIONS: These data underscore the importance of hyperexcitability as a mechanism for increased stroke risk in migraineurs, and suggest that migraine prophylaxis may not only prevent migraine attacks but also protect migraineurs against ischemic injury.

Candida Dublinensis Meningitis in an Immunocompetent Host: A Case Report and Review of the Literature.

Objectives: This study presents a case of Candida dubliniensis meningitis in an immunocompetent injection drug user and provides a literature review of CNS infections related to C dubliniensis. Methods: A 32-year-old man with a history of opioid use disorder presented with seizures and underwent extensive diagnostic evaluations, including imaging, lumbar puncture, and tissue biopsies. Treatment consisted of antifungal therapy and placement of ventriculoperitoneal shunt (VPS). Results: C dublinensis meningitis was identified on culture from a posterior fossa arachnoid sample. The patient demonstrated leptomeningeal enhancement on imaging, which resolved following 20 weeks of fluconazole. The development of hydrocephalus necessitated placement of VPS. Additional published cases of C dublinensis meningitis revealed varying presentations, diagnostic methods, and treatment regimens. Discussion: C dublinensis meningitis is a rare condition affecting both immunocompromised and immunocompetent individuals, particularly those with intravenous drug use. The diagnosis can be challenging, often requiring repeat lumbar punctures, extensive CSF sampling, or meningeal biopsy. Treatment involves a combination of antifungal agents, such as amphotericin B and fluconazole. Intracranial hypertension and hydrocephalus may necessitate surgical intervention. In conclusion, C dublinensis meningitis should be considered as a potential etiology of meningitis, particularly in those with a history of injection drug use.