Cerebral venous thrombosis and Escherichia coli infection in neonates

The coming of age of neutrophil extracellular traps in thrombosis: Where are we now and where are we headed?

Thrombosis remains a major problem in our society, manifesting across multiple demographic groups and with high associated morbidity and mortality. Thrombus development is the result of a complex mechanism in which multiple cell types and soluble factors play a crucial role. One cell that has gained the most attention in recent years is the neutrophil. This key member of the innate immune system can form neutrophil extracellular traps (NETs) in response to activating stimuli in circulation. NETs form a scaffold for thrombus formation, both initiating the process and stabilizing the final product. As the first responders of the host immune system, neutrophils have the flexibility to recognize a variety of molecules and can quickly interact with a range of different cell types. This trait makes them sensitive to exogenous stimuli. NET formation in response to pathogens is well established, leading to immune-mediated thrombus formation or immunothrombosis. NETs can also be formed during sterile inflammation through the activation of neutrophils by fellow immune cells including platelets, or activated endothelium. In chronic inflammatory settings, NETs can ultimately promote the development of tissue fibrosis, with organ failure as an end-stage outcome. In this review, we discuss the different pathways through which neutrophils can be activated toward NET formation and how these processes can result in a shared outcome: thrombus formation. Finally, we evaluate these different interactions and mechanisms for their potential as therapeutic targets, with neutrophil-targeted therapies providing a future approach to treating thrombosis. In contrast to current practices, such treatment could result in reduced pathogenic blood clot formation without increasing the risk of bleeding.

Cerebral venous thrombosis in COVID-19

BACKGROUND AND AIMS

Initially, novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) was considered primarily a respiratory pathogen. However, with time it has behaved as a virus with the potential to cause multi-system involvement, including neurological manifestations. Cerebral venous sinus thrombosis (CVT) has increasingly been reported in association with coronavirus infectious disease of 2019 (COVID-19). Here, we have shed light upon CVT and its possible mechanisms in the backdrop of the ongoing COVID-19 pandemic.

METHODS

In this review, data were collected from PubMed, EMBASE and Web of Science, until March 30, 2021, using pre-specified searching strategies. The search strategy consisted of a variation of keywords of relevant medical subject headings and keywords, including "COVID-19", "SARS-CoV-2", "coronavirus", and "cerebral venous sinus thrombosis".

RESULTS

COVID-19 has a causal association with a plethora of neurological, neuropsychiatric and psychological effects. CVT has gained particular importance in this regard. The known hypercoagulable state in SARS-CoV-2 infection is thought to be the main mechanism in COVID-19 related CVT. Other plausible mechanisms may include vascular endothelial dysfunction and altered flow dynamics.

CONCLUSIONS

Although there are no specific clinical characteristics, insidious or acute onset headache, seizures, stroke-like, or encephalopathy symptoms in a patient with, or who has suffered COVID-19, should prompt the attending physician to investigate for CVT. The treatment of COVID-19 associated CVT does not differ radically from the therapy of CVT without the infection, i.e. urgent initiation of parenteral unfractionated heparin or low molecular weight heparin followed by conventional or mostly newer oral anticoagulants.

Cerebral venous sinus thrombosis secondary to typhoid fever: a case report and brief summary of the literature

BACKGROUND

There have been few reports of typhoid fever (or salmonellosis) presenting with cerebral venous sinus thrombosis. We present such a case to highlight the importance of recognizing an etiology for cerebral sinus thrombosis and to discuss the role of salmonella in thrombogenesis.

PATIENT

A 19-year-old man with a history of migraine presented with headache, nausea, vomiting, and fever, and was found to have a cerebral venous sinus thrombosis on magnetic resonance venography. He later developed profuse watery diarrhea and cultures grew salmonella species, consistent with typhoid fever.

RESULTS

Treatment with antibiotics and oral anticoagulation led to resolution of his symptoms within 2 days and recanalization of the thrombosis was proven on magnetic resonance venography 6 months later.

CONCLUSIONS

The development of profuse diarrhea after thrombosis suggests a direct thrombogenic effect of salmonella independent of dehydration. Systemic infections should be considered in all patients with thrombosis to identify treatable causes.

Magnetic resonance imaging evaluation of possible neonatal sinovenous thrombosis

There are few data on magnetic resonance imaging findings in newborns for whom there is a concern for cerebral sinovenous thrombosis. The study objective was to document findings on magnetic resonance imaging or magnetic resonance venography in cases of suspected neonatal sinovenous thrombosis. A retrospective search of the institutional database was performed to find neonates whose cranial computed tomography raised the suspicion for thrombus. Documented abnormalities were detected on magnetic resonance venography, diffusion-weighted imaging, and T(2)-weighted imaging. Of 15 neonates with suspicious computed tomography studies, 2 had a definite intraluminal clot in the deep venous system; the remainder showed decreased flow-related enhancement within the dural venous sinuses. In all these cases, the sinus was compressed by adjacent subdural hematoma or sutural diastasis. Of the 15 patients, 5 had parenchymal abnormalities (2 of these had definite intraluminal clot). Parenchymal abnormalities were classified as hemorrhage (3/5), cytotoxic edema (3/5), or vasogenic edema (1/5). Intraluminal clot in the newborn is more often identified in the deep than in the superficial venous system. With evidence of venous injury in the absence of identified thrombus, it is possible that either clots dissolve quickly, escaping detection, or that the superficial venous system is vulnerable to mechanical forces during delivery.

Can thromboembolism be the result, rather than the inciting cause, of acute vascular events such as stroke, pulmonary embolism, mesenteric ischemia, and venous thrombosis?: a maladaptation of the prehistoric trauma response

Thromboembolism is considered the inciting cause of many vascular disorders including acute coronary syndrome (ACS), ischemic stroke, pulmonary embolism (PE), deep vein thrombosis (DVT), and mesenteric ischemia. Adrenergia and inflammation are known to accompany these conditions, particularly among arterial thromboembolic disorders, but the teleologic basis of these associations remains poorly understood. We argue that thromboembolism may sometimes be the result, rather than the cause, of acute vascular events, and may be precipitated by underlying adrenergia. Thromboembolic events are most prone to occur during parts of the circadian, seasonal, lifespan, and reproductive cycles with sympathetic dominance, as well as during behavioral, exertional, physiologic, and iatrogenic activation of sympathetic stress. Molecular evidence suggests that adrenergia and inflammation can promote coagulation and lead to co-activation of the pathways. Acute vascular events that occur without angiographic evidence of occlusion suggest that some infarcts may be attributable to adrenergia alone. "Embolic" disorders may represent asynchronous systemic phenomena rather than clot migration. During acute thromboembolism, downstream tissue hypoxia can activate maladaptive self-propelling cycles of sympathetic bias, inflammation, and coagulation. The counterproductive co-activation of these pathways may reflect a maladaptive interlink forged during the primordial evolution of trauma physiology. Their rapid co-mobilization enables rapid control of hemorrhage, microbial defense, and perfusion maintenance during trauma, but the pathways may behave maladaptively in the setting of modern diseases where endothelial injury may be more often precipitated by smoking, diabetes, dyslipidemia, or hypertension. Sympathetic blockade is already employed in ACS, and beta-blockers are used as antihypertensives to prevent stroke. Our hypothesis suggests that the benefits of beta-blockers in stroke may be independent of antihypertensive effects, and that adrenergia may represent a target for managing all thromboembolic disorders, independent of anti-coagulative and thrombolytic therapies. Perhaps reducing adrenergia, rather than maintaining high cerebral perfusion pressure, may represent a counterintuitive strategy for treating stroke and for reducing reperfusion injury. Plausible mechanisms by which autonomic dysfunction may induce venous thrombosis are discussed, especially in those with baroreceptor dysfunction, immobilization, or dehydration. Unexplained hypercoagulability of cancer may also operate through tumor-induced adrenergia and inflammation.