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Neuroimaging Clinics of North America Feb 2023Neuroimaging provides rapid, noninvasive visualization of central nervous system infections for optimal diagnosis and management. Generalizable and characteristic... (Review)
Review
Neuroimaging provides rapid, noninvasive visualization of central nervous system infections for optimal diagnosis and management. Generalizable and characteristic imaging patterns help radiologists distinguish different types of intracranial infections including meningitis and cerebritis from a variety of bacterial, viral, fungal, and/or parasitic causes. Here, we describe key radiologic patterns of meningeal enhancement and diffusion restriction through profiles of meningitis, cerebritis, abscess, and ventriculitis. We discuss various imaging modalities and recent diagnostic advances such as deep learning through a survey of intracranial pathogens and their radiographic findings. Moreover, we explore critical complications and differential diagnoses of intracranial infections.
Topics: Humans; Neuroimaging; Meningitis; Diagnosis, Differential
PubMed: 36404039
DOI: 10.1016/j.nic.2022.07.001 -
Cells Apr 2021The lymphatic system serves key functions in maintaining fluid homeostasis, the uptake of dietary fats in the small intestine, and the trafficking of immune cells.... (Review)
Review
The lymphatic system serves key functions in maintaining fluid homeostasis, the uptake of dietary fats in the small intestine, and the trafficking of immune cells. Almost all vascularized peripheral tissues and organs contain lymphatic vessels. The brain parenchyma, however, is considered immune privileged and devoid of lymphatic structures. This contrasts with the notion that the brain is metabolically extremely active, produces large amounts of waste and metabolites that need to be cleared, and is especially sensitive to edema formation. Recently, meningeal lymphatic vessels in mammals and zebrafish have been (re-)discovered, but how they contribute to fluid drainage is still not fully understood. Here, we discuss these meningeal vessel systems as well as a newly described cell population in the zebrafish and mouse meninges. These cells, termed brain lymphatic endothelial cells/Fluorescent Granular Perithelial cells/meningeal mural lymphatic endothelial cells in fish, and Leptomeningeal Lymphatic Endothelial Cells in mice, exhibit remarkable features. They have a typical lymphatic endothelial gene expression signature but do not form vessels and rather constitute a meshwork of single cells, covering the brain surface.
Topics: Animals; Brain; Endothelial Cells; Humans; Lymphangiogenesis; Lymphatic System; Macromolecular Substances; Meninges
PubMed: 33918497
DOI: 10.3390/cells10040799 -
Fluids and Barriers of the CNS Dec 2023Traditionally, the meninges are described as 3 distinct layers, dura, arachnoid and pia. Yet, the classification of the connective meningeal membranes surrounding the...
Traditionally, the meninges are described as 3 distinct layers, dura, arachnoid and pia. Yet, the classification of the connective meningeal membranes surrounding the brain is based on postmortem macroscopic examination. Ultrastructural and single cell transcriptome analyses have documented that the 3 meningeal layers can be subdivided into several distinct layers based on cellular characteristics. We here re-examined the existence of a 4 meningeal membrane, Subarachnoid Lymphatic-like Membrane or SLYM in Prox1-eGFP reporter mice. Imaging of freshly resected whole brains showed that SLYM covers the entire brain and brain stem and forms a roof shielding the subarachnoid cerebrospinal fluid (CSF)-filled cisterns and the pia-adjacent vasculature. Thus, SLYM is strategically positioned to facilitate periarterial influx of freshly produced CSF and thereby support unidirectional glymphatic CSF transport. Histological analysis showed that, in spinal cord and parts of dorsal cortex, SLYM fused with the arachnoid barrier layer, while in the basal brain stem typically formed a 1-3 cell layered membrane subdividing the subarachnoid space into two compartments. However, great care should be taken when interpreting the organization of the delicate leptomeningeal membranes in tissue sections. We show that hyperosmotic fixatives dehydrate the tissue with the risk of shrinkage and dislocation of these fragile membranes in postmortem preparations.
Topics: Mice; Animals; Meninges; Dura Mater; Arachnoid; Subarachnoid Space; Cerebral Cortex
PubMed: 38098084
DOI: 10.1186/s12987-023-00500-w -
BMC Veterinary Research May 2021Bovine tuberculosis is a chronic inflammatory disease that causes granuloma formation mainly in retropharyngeal, tracheobronchial, mediastinal lymph nodes and lungs of...
BACKGROUND
Bovine tuberculosis is a chronic inflammatory disease that causes granuloma formation mainly in retropharyngeal, tracheobronchial, mediastinal lymph nodes and lungs of bovines. The presence of these lesions in other tissues such as the eyeball is very rare and difficult to diagnose. This study describes macroscopic and microscopic pathological findings in a calf with ocular and meningeal tuberculosis.
CASE PRESENTATION
March 2019, an eight-month-old Holstein Friesian calf was identified in a dairy farm located in central Mexico with a clinical cough, anorexia, incoordination, corneal opacity and vision loss. At necropsy, pneumonia, lymphadenitis, meningitis, and granulomatous iridocyclitis were observed. The histopathological examination revealed granulomatous lesions in lung tissue, lymph nodes, meninges and eyes with the presence of acid-fast bacilli associated with Mycobacterium spp.
CONCLUSION
To the best of our knowledge, this is the first report that describes macroscopic and microscopic pathological findings of ocular tuberculosis in cattle. This report highlights the importance of considering bovine tuberculosis in the differential diagnosis of corneal opacity and loss of vision in cattle.
Topics: Animals; Cattle; Eye Diseases; Granuloma; Meningitis; Mexico; Mycobacterium; Tuberculosis, Bovine; Tuberculosis, Ocular
PubMed: 33964902
DOI: 10.1186/s12917-021-02893-y -
Immunology Nov 2021Ectopic lymphoid follicles (ELFs), resembling germinal centre-like structures, emerge in a variety of infectious and autoimmune and neoplastic diseases. ELFs can be... (Review)
Review
Ectopic lymphoid follicles (ELFs), resembling germinal centre-like structures, emerge in a variety of infectious and autoimmune and neoplastic diseases. ELFs can be found in the meninges of around 40% of the investigated progressive multiple sclerosis (MS) post-mortem brain tissues and are associated with the severity of cortical degeneration and clinical disease progression. Of predominant importance for progressive neuronal damage during the progressive MS phase appears to be meningeal inflammation, comprising diffuse meningeal infiltrates, B-cell aggregates and compartmentalized ELFs. However, the absence of a uniform definition of ELFs impedes reproducible and comparable neuropathological research in this field. In this review article, we will first highlight historical aspects and milestones around the discovery of ELFs in the meninges of progressive MS patients. In the next step, we discuss how animal models may contribute to an understanding of the mechanisms underlying ELF formation. Finally, we summarize challenges in investigating ELFs and propose potential directions for future research.
Topics: Animals; B-Lymphocytes; Disease Models, Animal; Humans; Meninges; Multiple Sclerosis, Chronic Progressive; Tertiary Lymphoid Structures
PubMed: 34293193
DOI: 10.1111/imm.13395 -
Neuromolecular Medicine Sep 2021Traditionally, the primary role of the meninges is thought to be structural, i.e., to act as a surrounding membrane that contains and cushions the brain with... (Review)
Review
Traditionally, the primary role of the meninges is thought to be structural, i.e., to act as a surrounding membrane that contains and cushions the brain with cerebrospinal fluid. During development, the meninges is formed by both mesenchymal and neural crest cells. There is now emerging evidence that subsets of undifferentiated stem cells might persist in the adult meninges. In this mini-review, we survey representative studies of brain-meningeal interactions and discuss the hypothesis that the meninges are not just protective membranes, but instead contain multiplex stem cell subsets that may contribute to central nervous system (CNS) homeostasis. Further investigations into meningeal multipotent cells may reveal a "hidden" target for promoting neurovascular remodeling and repair after CNS injury and disease.
Topics: Adapalene; Adult Stem Cells; Animals; Brain Ischemia; Central Nervous System; Central Nervous System Diseases; Glymphatic System; Homeostasis; Humans; Male; Meninges; Multipotent Stem Cells; Neural Crest; Neural Stem Cells; Rats; Rats, Sprague-Dawley; Regeneration
PubMed: 33893971
DOI: 10.1007/s12017-021-08663-1 -
Cancer Imaging : the Official... Oct 2009Primary malignant tumours arising from the meninges are distinctly uncommon, and when they occur, they are usually sarcomas. In contrast, metastatic meningeal... (Review)
Review
Primary malignant tumours arising from the meninges are distinctly uncommon, and when they occur, they are usually sarcomas. In contrast, metastatic meningeal involvement is increasingly seen as advances in cancer therapy have changed the natural history of malignant disease and prolonged the life span of cancer patients. The meninges can either be infiltrated by contiguous extension of primary tumours of the central nervous system, paranasal sinuses and skull base origin or can be diffusely infiltrated from haematogenous dissemination from distant primary malignancies. Imaging in these patients provides crucial information in planning management. This article reviews the pertinent anatomy that underlies imaging findings, discusses the mechanism of meningeal metastasis and highlights different imaging patterns of meningeal carcinomatosis and the pitfalls.
Topics: Cerebral Infarction; Contrast Media; Diagnosis, Differential; False Positive Reactions; Humans; Leukemic Infiltration; Magnetic Resonance Imaging; Meningeal Carcinomatosis; Meningeal Neoplasms; Meninges; Sarcoma; Ventriculoperitoneal Shunt
PubMed: 19965290
DOI: 10.1102/1470-7330.2009.9004 -
Glymphatic-lymphatic coupling: assessment of the evidence from magnetic resonance imaging of humans.Cellular and Molecular Life Sciences :... Mar 2024The discoveries that cerebrospinal fluid participates in metabolic perivascular exchange with the brain and further drains solutes to meningeal lymphatic vessels have... (Review)
Review
The discoveries that cerebrospinal fluid participates in metabolic perivascular exchange with the brain and further drains solutes to meningeal lymphatic vessels have sparked a tremendous interest in translating these seminal findings from animals to humans. A potential two-way coupling between the brain extra-vascular compartment and the peripheral immune system has implications that exceed those concerning neurodegenerative diseases, but also imply that the central nervous system has pushed its immunological borders toward the periphery, where cross-talk mediated by cerebrospinal fluid may play a role in a range of neoplastic and immunological diseases. Due to its non-invasive approach, magnetic resonance imaging has typically been the preferred methodology in attempts to image the glymphatic system and meningeal lymphatics in humans. Even if flourishing, the research field is still in its cradle, and interpretations of imaging findings that topographically associate with reports from animals have yet seemed to downplay the presence of previously described anatomical constituents, particularly in the dura. In this brief review, we illuminate these challenges and assess the evidence for a glymphatic-lymphatic coupling. Finally, we provide a new perspective on how human brain and meningeal clearance function may possibly be measured in future.
Topics: Animals; Humans; Lymphatic Vessels; Central Nervous System; Brain; Meninges; Magnetic Resonance Imaging
PubMed: 38472405
DOI: 10.1007/s00018-024-05141-2 -
Cancer Control : Journal of the Moffitt... Jan 2017Neoplastic meningitis is a complication of solid and hematological malignancies. It consists of the spread of malignant cells to the leptomeninges and subarachnoid space... (Review)
Review
BACKGROUND
Neoplastic meningitis is a complication of solid and hematological malignancies. It consists of the spread of malignant cells to the leptomeninges and subarachnoid space and their dissemination within the cerebrospinal fluid.
METHODS
A literature review was conducted to summarize the clinical presentation, differential diagnosis, laboratory values, and imaging findings of neoplastic meningitis.
RESULTS
Neoplastic meningitis is an event in the course of cancer with a variable clinical presentation and a wide differential diagnosis. In general, characteristic findings on gadolinium-enhanced magnetic resonance imaging and the presence of malignant cells in the cerebrospinal fluid remain the cornerstones of diagnosis. However, both modalities do not always confirm the diagnosis of neoplastic meningitis despite a typical clinical picture.
CONCLUSIONS
Clinicians treating patients with cancer should be aware of the possibility of neoplastic meningitis, especially when multilevel neurological symptoms are present. Neoplastic meningitis can be an elusive diagnosis, so clinician awareness is important so that this malignant manifestation is recognized in a timely manner.
Topics: Diagnosis, Differential; Diagnostic Imaging; Humans; Meningeal Neoplasms; Meningitis; Severity of Illness Index
PubMed: 28178708
DOI: 10.1177/107327481702400103 -
World Neurosurgery Oct 2020The extradural neural axis compartment (EDNAC) is an adipovenous zone located between the meningeal and endosteal layers of the dura and has been minimally investigated.... (Review)
Review
OBJECTIVE
The extradural neural axis compartment (EDNAC) is an adipovenous zone located between the meningeal and endosteal layers of the dura and has been minimally investigated. It runs along the neuraxis from the orbits down to the coccyx and contains fat, valveless veins, arteries, and nerves. In the present review, we have outlined the current knowledge regarding the structural and functional significance of the EDNAC.
METHODS
We performed a narrative review of the reported EDNAC data.
RESULTS
The EDNAC can be organized into 4 regional enlargements along its length: the orbital, lateral sellar, clival, and spinal segments, with a lateral sellar orbital junction linking the orbital and lateral sellar segments. The orbital EDNAC facilitates the movement of the eyeball and elsewhere allows limited motility for the meningeal dura. The major nerves and vessels are cushioned and supported by the EDNAC. Increased intra-abdominal pressure will also be conveyed along the spinal EDNAC, causing increased venous pressure in the spine and cranium. From a pathological perspective, the EDNAC functions as a low-resistance, extradural passageway that might facilitate tumor encroachment and expansion.
CONCLUSIONS
Clinicians should be aware of the extent and significance of the EDNAC, which could affect skull base and spine surgery, and have an understanding of the tumor spread pathways and growth patterns. Comparatively little research has focused on the EDNAC since its initial description. Therefore, future investigations are required to provide more information on this underappreciated component of neuraxial anatomy.
Topics: Adipose Tissue; Blood Vessels; Humans; Meninges
PubMed: 32711147
DOI: 10.1016/j.wneu.2020.07.095