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Current Opinion in Immunology Jun 2022The meninges encase the brain and spinal cord and house a variety of immune cells, including developing and mature B cells, and antibody-secreting plasma cells. In... (Review)
Review
The meninges encase the brain and spinal cord and house a variety of immune cells, including developing and mature B cells, and antibody-secreting plasma cells. In homeostasis, these cells localize around the dural venous sinuses, providing a defense 'zone' to protect the brain and spinal cord from blood-borne pathogens. Dural plasma cells predominantly secrete IgA antibodies, and some originate from the gastrointestinal tract, with the number and antibody isotype shaped by the gut microbiome. For developing B cells arriving from the adjacent bone marrow, the dura provides a site to tolerize against central nervous system antigens. In this review, we will discuss our current understanding of meningeal humoral immunity in homeostasis.
Topics: Brain; Dura Mater; Homeostasis; Humans; Immunity, Humoral; Meninges
PubMed: 35569417
DOI: 10.1016/j.coi.2022.102188 -
Acta Neurochirurgica Jun 2024The discovery of the glymphatic system has fundamentally altered our comprehension of cerebrospinal fluid transport and the removal of waste from brain metabolism. In... (Review)
Review
The discovery of the glymphatic system has fundamentally altered our comprehension of cerebrospinal fluid transport and the removal of waste from brain metabolism. In the past decade, since its initial characterization, research on the glymphatic system has surged exponentially. Its potential implications for central nervous system disorders have sparked significant interest in the field of neurosurgery. Nonetheless, ongoing discussions and debates persist regarding the concept of the glymphatic system, and our current understanding largely relies on findings from experimental animal studies. This review aims to address several key inquiries: What methodologies exist for evaluating glymphatic function in humans today? What is the current evidence supporting the existence of a human glymphatic system? Can the glymphatic system be considered distinct from the meningeal-lymphatic system? What is the human evidence for glymphatic-meningeal lymphatic system failure in neurosurgical diseases? Existing literature indicates a paucity of techniques available for assessing glymphatic function in humans. Thus far, intrathecal contrast-enhanced magnetic resonance imaging (MRI) has shown the most promising results and have provided evidence for the presence of a glymphatic system in humans, albeit with limitations. It is, however, essential to recognize the interconnection between the glymphatic and meningeal lymphatic systems, as they operate in tandem. There are some human studies demonstrating deteriorations in glymphatic function associated with neurosurgical disorders, enriching our understanding of their pathophysiology. However, the translation of this knowledge into clinical practice is hindered by the constraints of current glymphatic imaging modalities.
Topics: Humans; Glymphatic System; Neurosurgical Procedures; Meninges; Animals; Magnetic Resonance Imaging
PubMed: 38904802
DOI: 10.1007/s00701-024-06161-4 -
Immunity Jun 2017The central nervous system (CNS) and its meningeal coverings accommodate a diverse myeloid compartment that includes parenchymal microglia and perivascular macrophages,... (Review)
Review
The central nervous system (CNS) and its meningeal coverings accommodate a diverse myeloid compartment that includes parenchymal microglia and perivascular macrophages, as well as choroid plexus and meningeal macrophages, dendritic cells, and granulocytes. These myeloid populations enjoy an intimate relationship with the CNS, where they play an essential role in both health and disease. Although the importance of these cells is clearly recognized, their exact function in the CNS continues to be explored. Here, we review the subsets of myeloid cells that inhabit the parenchyma, meninges, and choroid plexus and discuss their roles in CNS homeostasis. We also discuss the role of these cells in various neurological pathologies, such as autoimmunity, mechanical injury, neurodegeneration, and infection. We highlight the neuroprotective nature of certain myeloid cells by emphasizing their therapeutic potential for the treatment of neurological conditions.
Topics: Animals; Autoimmune Diseases; Central Nervous System; Choroid Plexus; Humans; Infections; Meninges; Myeloid Cells; Neurodegenerative Diseases; Neuroimmunomodulation; Neuroprotection; Wounds and Injuries
PubMed: 28636961
DOI: 10.1016/j.immuni.2017.06.007 -
Current Opinion in Neurobiology Apr 2023The spatial and temporal development of the brain, overlying meninges (fibroblasts, vasculature and immune cells) and calvarium are highly coordinated. In particular,... (Review)
Review
The spatial and temporal development of the brain, overlying meninges (fibroblasts, vasculature and immune cells) and calvarium are highly coordinated. In particular, the timing of meningeal fibroblasts into molecularly distinct pia, arachnoid and dura subtypes coincides with key developmental events in the brain and calvarium. Further, the meninges are positioned to influence development of adjacent structures and do so via depositing basement membrane and producing molecular cues to regulate brain and calvarial development. Here, we review the current knowledge of how meninges development aligns with events in the brain and calvarium and meningeal fibroblast "crosstalk" with these structures. We summarize outstanding questions and how the use of non-mammalian models to study the meninges will substantially advance the field of meninges biology.
Topics: Meninges; Dura Mater; Arachnoid; Brain
PubMed: 36773497
DOI: 10.1016/j.conb.2023.102676 -
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 -
Trends in Immunology Apr 2023The emphasis on mechanisms driving multiple sclerosis (MS) symptomatic worsening suggests that we move beyond categorical clinical classifiers such as... (Review)
Review
The emphasis on mechanisms driving multiple sclerosis (MS) symptomatic worsening suggests that we move beyond categorical clinical classifiers such as relapsing-remitting MS (RR-MS) and progressive MS (P-MS). Here, we focus on the clinical phenomenon progression independent of relapse activity (PIRA), which begins early in the disease course. PIRA occurs throughout MS, becoming more phenotypically evident as patients age. The underlying mechanisms for PIRA include chronic-active demyelinating lesions (CALs), subpial cortical demyelination, and nerve fiber injury following demyelination. We propose that much of the tissue injury associated with PIRA is driven by autonomous meningeal lymphoid aggregates, present before disease onset and unresponsive to current therapeutics. Recently, specialized magnetic resonance imaging (MRI) has identified and characterized CALs as paramagnetic rim lesions in humans, enabling novel radiographic-biomarker-clinical correlations to further understand and treat PIRA.
Topics: Humans; Multiple Sclerosis; Meninges; Disease Progression; Multiple Sclerosis, Relapsing-Remitting
PubMed: 36868982
DOI: 10.1016/j.it.2023.02.002 -
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 -
Handbook of Clinical Neurology 2020The dura mater is the major gateway for accessing most extra-axial lesions and all intra-axial lesions of the central nervous system. It provides a protective barrier...
The dura mater is the major gateway for accessing most extra-axial lesions and all intra-axial lesions of the central nervous system. It provides a protective barrier against external trauma, infections, and the spread of malignant cells. Knowledge of the anatomical details of dural reflections around various corners of the skull bases provides the neurosurgeon with confidence during transdural approaches. Such knowledge is indispensable for protection of neurovascular structures in the vicinity of these dural reflections. The same concept is applicable to arachnoid folds and reflections during intradural excursions to expose intra- and extra-axial lesions of the brain. Without a detailed understanding of arachnoid membranes and cisterns, the neurosurgeon cannot confidently navigate the deep corridors of the skull base while safely protecting neurovascular structures. This chapter covers the surgical anatomy of dural and arachnoid reflections applicable to microneurosurgical approaches to various regions of the skull base.
Topics: Arachnoid; Cadaver; Dura Mater; Humans; Meninges; Skull Base
PubMed: 32553288
DOI: 10.1016/B978-0-12-804280-9.00002-0 -
Child's Nervous System : ChNS :... Jul 2015Hypertrophic pachymeningitis (HP) is a rare clinical entity characterized by diffuse or localized fibrous thickening of the dura mater. It is well known but rare...
BACKGROUND
Hypertrophic pachymeningitis (HP) is a rare clinical entity characterized by diffuse or localized fibrous thickening of the dura mater. It is well known but rare especially in pediatric population disease of differing origins. The primary (idiopathic) form is diagnosed after excluding other possible etiologies. Similar results from magnetic resonance imaging (MRI) for patients with hypertrophic pachymeningitis and meningiomas may make the diagnosis confusing. Additionally, making a proper diagnosis without histological sampling can be difficult in some cases.
CASE DESCRIPTION
We present a case of an 18-year-old boy diagnosed with hypertrophic pachymeningitis in the area of the hypoglossal canal. The diagnosis was made after a 2-month history of hypoglossal nerve palsy and dysphagia preceded by a middle ear infection. The patient was treated surgically with suspicion of meningioma, but no evidence of a tumor was found during the operation. The postoperative period was uneventful. At the latest check-up, MRI revealed regression of all previously observed pathological changes.
Topics: Adolescent; Dura Mater; Humans; Hypertrophy; Magnetic Resonance Imaging; Male; Meningitis
PubMed: 25771924
DOI: 10.1007/s00381-015-2680-z -
Neurology India 2022Hypertrophic pachymeningitis (HPM) is a unique disorder characterized by thickening and fibrosis of the dura mater. Clinically it presents with headache, cranial nerve... (Observational Study)
Observational Study
BACKGROUND
Hypertrophic pachymeningitis (HPM) is a unique disorder characterized by thickening and fibrosis of the dura mater. Clinically it presents with headache, cranial nerve palsies, and other focal neurological deficits. Two forms exist, one is primary, where all other causes have been excluded and the other is secondary where an identifiable cause exists. It is important to recognize these secondary causes as treatment depends on the etiology.
OBJECTIVE
To elucidate the various characteristics of HPM. To delineate clinical-radiological features that help differentiate secondary from primary causes and to understand treatment response and disease outcomes of HPM.
METHODS
This retrospective observational study included 33 patients who presented with radiological diagnosis of HPM from January 2014 to July 2019. Spontaneous intracranial hypotension patients were excluded. All patients were extensively evaluated for secondary causes and treatment outcomes were analyzed on follow-up.
RESULTS AND CONCLUSIONS
Secondary causes of HPM were present in 48% cases. The clue for primary causes is an associated Tolosa-Hunt syndrome. Secondary causes in our series are immunological, infection, and malignancy. Clues to differentiate primary from these secondary causes are clinical like myelopathy, seizures, poor response to immunosuppression; radiological like hypertrophic cranial nerves, infarcts, bony erosion, and leptomeningeal involvement. There are case reports in literature but large Indian studies are lacking. This manuscript presents a large cohort of cases with HPM, which helps differentiate primary from secondary causes, as management and prognosis depend on etiology. An algorithm depicting the approach to the management of HPM has been presented.
Topics: Humans; Magnetic Resonance Imaging; Meningitis; Cranial Nerve Diseases; Headache; Treatment Outcome; Hypertrophy; Dura Mater
PubMed: 36537427
DOI: 10.4103/0028-3886.364052