Classical monocyte ontogeny dictates their functions and fates as tissue macrophages.

Classical monocytes (CMs) are ephemeral myeloid immune cells that circulate in the blood. Emerging evidence suggests that CMs can have distinct ontogeny and originate from either granulocyte-monocyte- or monocyte-dendritic-cell progenitors (GMPs or MDPs). Here, we report surface markers that allowed segregation of murine GMP- and MDP-derived CMs, i.e., GMP-Mo and MDP-Mo, as well as their functional characterization, including fate definition following adoptive cell transfer. GMP-Mo and MDP-Mo yielded an equal increase in homeostatic CM progeny, such as blood-resident non-classical monocytes and gut macrophages; however, these cells differentially seeded various other selected tissues, including the dura mater and lung. Specifically, GMP-Mo and MDP-Mo differentiated into distinct interstitial lung macrophages, linking CM dichotomy to previously reported pulmonary macrophage heterogeneity. Collectively, we provide evidence for the existence of two functionally distinct CM subsets in the mouse that differentially contribute to peripheral tissue macrophage populations in homeostasis and following challenge.

Neonatal IL-4 Over-Exposure is Accompanied by Macrophage Accumulation in Dura Mater After Instant Anti-inflammatory Cytokine Response in CSF.

Multiple studies have shown that clinical events resulting into neonatal IL-4 over-exposure, such as asthma in early life and food allergy, were associated with brain damage and that the neuroinflammation induced by them might lead to cognitive impairments, anxiety-/depressive-like behaviors. IL-4 is the most major elevated cytokine in periphery when these clinical events occur and peripheral IL-4 level positively correlates with the severity of those events. Our previous studies have verified that neonatal IL-4 over-exposure induced a delayed neuroinflammatory damage in rodents, which might have adverse implications for brain development and cognition. Neuroinflammation in brain parenchyma is often accompanied by changes in CSF cytokines levels. However, whether the cytokines levels in CSF change after neonatal IL-4 over-exposure is unknown. Here, we found a delayed pro-inflammatory cytokines response (higher IL-6, IL-1ß and, TNF levels) in both hippocampus and CSF after an instant anti-inflammatory cytokine response in IL-4 over-exposed rats. Moreover, the pro-inflammatory cytokines response appeared earlier in CSF than in hippocampus. The level of each of the pro-inflammatory cytokines in CSF positively correlated with that in hippocampus at the age of postnatal day 42. More microglia numbers/activation and higher M-CSF level in the hippocampus in IL-4 over-exposed rats were also observed. Furthermore, there were more macrophages with inflammatory activation in dural mater of IL-4 over-exposed rats. In sum, neonatal IL-4 over-exposure in rats induces delayed inflammation in CSF, suggesting CSF examination may serve as a potential method in predicting delayed neuroinflammation in brain following neonatal IL-4 over-exposure.

Iatrogenic cerebral amyloid angiopathy in older adults.

BACKGROUND AND PURPOSE: An increasing number of cases of iatrogenic cerebral amyloid angiopathy (CAA) have now been reported worldwide. Proposed diagnostic criteria require a history of medical intervention with potential for amyloid-ß transmission, for example those using cadaveric dura mater or requiring instrumentation of the brain or spinal cord. Clinical presentation occurs after an appropriate latency (usually three or four decades); to date, most patients with iatrogenic CAA have had 'early-onset' disease (compared to sporadic, age-related, CAA), as a consequence of childhood procedures. RESULTS: We describe five cases of possible iatrogenic CAA in adults presenting in later life (aged 65 years and older); all had prior neurosurgical interventions and presented after a latency suggestive of iatrogenic disease (range 30-39 years). Use of cadaveric dura mater was confirmed in one case, and highly likely in the remainder. CONCLUSION: The presentation of iatrogenic CAA in older adults widens the known potential spectrum of this disease and highlights the difficulties of making the diagnosis in this age group, and particularly in differentiating iatrogenic from sporadic CAA. Increased vigilance for cases presenting at an older age is essential for furthering our understanding of the clinical phenotype and broader implications of iatrogenic CAA.

"The novel dura substitute: a revolutionary advancement in neurosurgery".

This Article provides a concise summary of the comprehensive exploration into the dura mater, dural tears, and the groundbreaking medical device, ArtiFascia® Dura Substitute. The neuroanatomy of the dura mater is elucidated, emphasizing its resilience and susceptibility to tears during spinal surgery. Dural repair methods are scrutinized, with research findings revealing the efficacy of primary closure with or without a patch.The introduction of ArtiFascia®, a nanofiber-based resorbable dural repair graft, represents a pivotal moment in neurosurgery. Obtaining 510(k) clearance from the FDA, ArtiFascia® demonstrates exceptional biological benefits, including enhanced cellular adhesion and tissue regeneration. The device's safety is affirmed through chemical analysis and toxicological risk assessment.The NEOART study, a randomized clinical trial involving 85 subjects across prominent European medical centers, validates ArtiFascia®'s superiority over existing dural substitutes. Noteworthy findings include exceptional graft strength, durability, and its ability to withstand physiological pressures.In conclusion, ArtiFascia® marks a revolutionary era in neurosurgery, promising safer and more effective solutions. This innovative device has the potential to elevate standards of care, offering both patients and surgeons an improved experience in navigating the complexities of neurosurgical procedures. The abstract encapsulates the key elements of the research, emphasizing the transformative impact of ArtiFascia® in the field.

Magnetic resonance imaging-based classification of the myodural bridge complex and its influencing factors.

Cerebrospinal fluid (CSF) circulation is considered the third circulation of the human body. Recently, some scholars have proposed the myodural bridge (MDB) as a novel power source for CSF flow. Moreover, the suboccipital muscles can exert a driving force on the CSF via the MDB. This hypothesis is directly supported by head rotation and nodding movements, which can affect CSF circulation. The MDB has been validated as a normal structure in humans and mammals. In addition, the fusion of MDB fibers of different origins that act in concert with each other forms the MDB complex (MDBC). The MDBC may be associated with several CSF disorder-related neurological disorders in clinical practice. Therefore, the morphology of the MDBC and its influencing factors must be determined. In this study, T2-weighted imaging sagittal images of the cervical region were analyzed retrospectively in 1085 patients, and magnetic resonance imaging (MRI) typing of the MDBC was performed according to the imaging features of the MDBC in the posterior atlanto-occipital interspace (PAOiS) and posterior atlanto-axial interspace (PAAiS). The effects of age and age-related degenerative changes in the cervical spine on MRI staging of the MDBC were also determined. The results revealed four MRI types of the MDBC: type A (no MDBC hyposignal shadow connected to the dura mater in either the PAOiS or PAAiS), type B (MDBC hyposignal shadow connected to the dura mater in the PAOiS only), type C (MDBC hyposignal shadow connected to the dura mater in the PAAiS only), and type D (MDBC hyposignal shadow connected to the dura mater in both the PAOiS and PAAiS). The influencing factors for the MDBC typing were age (group), degree of intervertebral space stenosis, dorsal osteophytosis, and degenerative changes in the cervical spine (P < 0.05). With increasing age (10-year interval), the incidence of type B MDBC markedly decreased, whereas that of type A MDBC increased considerably. With the deepening of the degree of intervertebral space stenosis, the incidence of type C MDBC increased significantly, whereas that of type A MDBC decreased. In the presence of dorsal osteophytosis, the incidence of type C and D MDBCs significantly decreased, whereas that of type A increased. In the presence of protrusion of the intervertebral disc, the incidence of type B, C, and D MDBCs increased markedly, whereas that of type A MDBC decreased considerably, with cervical degenerative changes combined with spinal canal stenosis. Moreover, the incidence of both type C and D MDBCs increased, whereas that of type A MDBC decreased. Based on the MRI signal characteristics of the dural side of the MDBC, four types of the MDBC were identified. MDBC typing varies dynamically according to population distribution, depending on age and cervical degeneration (degree of intervertebral space stenosis, vertebral dorsal osteophytosis formation, simple protrusion of intervertebral disc, and cervical degeneration changes combined with spinal canal stenosis, except for the degree of protrusion of the intervertebral disc and the degree of spinal canal stenosis); however, it is not influenced by sex.

Dura mater and survival time determination in individuals who died after traumatic brain injury: a preliminary study.

BACKGROUND: Traumatic brain injury (TBI) is one of the major causes of morbidity and mortality among young people and is a matter of concern for forensic pathologists. Many authors have tried to estimate a person's survival time (ST) after TBI using different approaches. OBJECTIVE: The present study aimed to present an innovative workflow to estimate the ST after TBI by observing the inflammatory reaction of the dura mater (DM). METHODS: The authors collected DM samples from 36 cadavers (20 with TBI and 16 with no history or signs of TBI). Each sample was labelled via immunohistochemistry with three different primary antibodies, CD15, CD68, and CD3, yielding 108 slides in total. The slides were digitalized and analysed using QuPath software. RESULTS: The DM is involved in the inflammatory response after TBI. CD15 immunoreactivity allowed us to distinguish between subjects who died immediately after TBI and those with an ST of minutes or hours. CD3 immunoreactivity can be used to differentiate subjects with an ST of days from those with other STs. Moreover, the DM samples showed an acceptable diagnostic yield even in samples with signs of putrefaction.

Neural tissue tolerance to synthetic dural mater graft implantation in a rabbit durotomy model.

In neurosurgical interventions, effective closure of the dura mater is essential to prevent cerebrospinal fluid leakage and minimize post-operative complications. Biodegradable synthetic materials have the potential to be used as dura mater grafts owing to their regenerative properties and low immunogenicity. This study evaluated the safety of ArtiFascia, a synthetic dura mater graft composed of poly(l-lactic-co-caprolactone acid) and poly(d-lactic-co-caprolactone acid), in a rabbit durotomy model. Previously, ArtiFascia demonstrated positive local tolerance and biodegradability in a 12-month preclinical trial. Here, specialized stains were used to evaluate potential brain damage associated with ArtiFascia use. Histochemical and immunohistochemical assessments included Luxol Fast Blue, cresyl Violet, Masson's Trichrome, neuronal nuclei,, Glial Fibrillary Acidic Protein, and ionized calcium-binding adaptor molecule 1 stains. The stained slides were graded based on the brain-specific reactions. The results showed no damage to the underlying brain tissue for either the ArtiFascia or control implants. Neither inflammation nor neuronal loss was evident, corroborating the safety of the ArtiFascia. This approach, combined with previous histopathological analyses, strengthens the safety profile of ArtiFascia and sets a benchmark for biodegradable material assessment in dura graft applications. This study aligns with the Food and Drug Administration guidelines and offers a comprehensive evaluation of the potential neural tissue effects of synthetic dura mater grafts.

[The use of the dura mater at the final stage of reconstructive plastic surgical treatment of cicatricial stenosis of the larynx and trachea]. / Ispol'zovanie tverdoi mozgovoi obolochki pri zaklyuchitel'nom etape rekonstruktivno-plasticheskogo operativnogo lecheniya rubtsovogo stenoza gortani i trakhei.

The article presents an analysis of the plastic reconstructive surgery effectiveness for patients with an extended tracheal defect using an allograft based on the dura mater (DM) at the final stage of surgical treatment of laryngeal and tracheal cicatricial stenosis. The study included 20 patients with cicatricial stenosis of the larynx and trachea, who were previously performed plastic reconstructive treatment with scar tissue excision in the lumen of the respiratory tract and restoration of the supporting frame of the larynx and trachea using allografts based on costal allocartilage. The age of the patients ranged from 21 to 54 years, the duration of the disease was from 1 to 5 years. After a standard clinical and laboratory examination, with a mandatory video endoscopic examination of the larynx and trachea, multislice computed tomography of the larynx and trachea, patients underwent plastic closure of the tracheal defect using DM. Dynamic outpatient monitoring was carried out once a week for 1 month, once a month for 3 months, control examination was done 6 months after surgical treatment. The results of the study demonstrated a full-fledged social and labor rehabilitation of all 20 patients after the final stage of surgical treatment using DM, the absence of rejection reaction and migration of allo-implantation material, the preserved lumen of the larynx and trachea with a rigid supporting skeleton and the absence of anterior tracheal wall floatation. The use of DM as an additional strengthening of the anterior tracheal wall for patients with deficiency of muscular aponeurotic tissues and more than 2 cm size tracheal defect is highly effective at the final stage of surgical treatment for plastic closure of the tracheal defect.

Cerebral tumor with hemi-dural enhancement as unique presentation of multiple myeloma: A case report.

Introduction: Intracranial multiple myeloma (MM) is a rare manifestation of MM, a malignant plasma cell disorder that primarily affects bone marrow. Dural involvement in MM is even rarer and can manifest as a dural mass. We present a case of MM presenting as an intracranial dural tumor with primary hemi-dural involvement. Research question: This case report aims to investigate the clinical presentation, diagnostic challenges, and treatment approaches for intracranial multiple myeloma, with a focus on the extensive hemi-dural thickening and enhancement seen in this case. Material and methods: A 73-year-old male presented with progressive dysphasia and weakness. MRI revealed a solid left frontal mass with significant mass-effect. Hemi-dural thickening and enhancement was present along with invasion of the skull. The patient underwent surgical resection of the tumor with dural and bone reconstruction. Results: Histopathological examination confirmed MM diagnosis. Chemotherapy was started. Follow-up MRI showed complete tumor resection, but extensive hemi-dural thickening and enhancement persisted. Postoperative radiation therapy was considered. Discussion and conclusion: MM with primary dural involvement is rare and poses diagnostic challenges. Postoperative treatment involves chemotherapy, the role of surgery and radiotherapy is not established. The extensive hemi-dural thickening and enhancement observed in this case require further investigation, and a wait-and-scan policy was recommended instead of radiotherapy.

The meninges.

The dura was first described in ancient Egypt. Hippocrates insisted that it should be protected and not penetrated. Celsus proposed an association between clinical findings and meningeal damage. Galen proposed that the dura was attached only at the sutures, and he was the first to describe the pia in humans. In the Middle Ages, new interest in the management of meningeal injuries arose, with renewed interest in relating clinical changes to intracranial injuries. These associations were neither consistent nor accurate. The Renaissance brought little change. It was in the 18th century that it became clear that the indication for opening the cranium following trauma was to relieve pressure from hematomas. Moreover, the important clinical findings on which to base an indication for intervention were changes in the level of consciousness.

Bovine Pericardium Treated with Polyethylene Glycol and Ethanol Versus Pericranium for Duraplasty: A Pilot Study in Supratentorial Neurosurgery.

BACKGROUND: Watertight closure of dura mater after intracranial surgery can avoid cerebrospinal fluid leakage and central nervous system infection and herniation. When primary closure is not possible, the pericranium is the preferential choice. When it is not available, a dural substitute becomes necessary. Bovine pericardium treated with polyethylene glycol and ethanol is herein tested as a dural substitute. METHODS: A pilot study comparing bovine pericardium with pericranium in supratentorial neurosurgery was performed. RESULTS: Twenty patients were initially allocated into a bovine pericardium group (group 1) or a pericranium group (group 2). Three patients from group 1 and 2 from group 2 had a loss of follow-up, being excluded. In the remaining 15 patients, epidemiological analysis demonstrated a male:female ratio of 3:4 and 4:4 for groups 1 and 2. Ages varied from 28 to 68 (Mean = 49.6) in group 1 and 40-80 (Mean = 61.2) in group 2, with a mean difference of 11.68 years (P = 0.09). Two cases of surgical site infection and 1 of hydrocephalus were observed. Although the calculated relative risk for complications was higher in group 1 (Relative Risk = 1.08), Fisher exact test demonstrated no statistically significant difference between groups (P = 1.00). Procedure mean time was 23 minutes and 11 seconds in group 1 versus 27 minutes and 55 seconds in group 2 (P = 0.47). Mean graft area was 13.17 and 6.23 cm2 in groups 1 and 2 (P = 0.02). CONCLUSIONS: Bovine pericardium treated with polyethylene glycol and ethanol was comparable to pericranium as a dural substitute. More studies are encouraged to certify our findings.

Biomimetic and Nonbiomimetic Approaches in Dura Substitutes: The Influence of Mechanical Properties.

The dura mater, the furthest and strongest layer of the meninges, is crucial for protecting the brain and spinal cord. Its biomechanical behavior is vital, as any alterations can compromise biological functions. In recent decades, interest in the dura mater has increased due to the need for hermetic closure of dural defects prompting the development of several substitutes. Collagen-based dural substitutes are common commercial options, but they lack the complex biological and structural elements of the native dura mater, impacting regeneration and potentially causing complications like wound/postoperative infection and cerebrospinal fluid (CSF) leakage. To face this issue, recent tissue engineering approaches focus on creating biomimetic dura mater substitutes. The objective of this review is to discuss whether mimicking the mechanical properties of native tissue or ensuring high biocompatibility and bioactivity is more critical in developing effective dural substitutes, or if both aspects should be systematically linked. After a brief description of the properties and architecture of the native cranial dura, we describe the advantages and limitations of biomimetic dura mater substitutes to better understand their relevance. In particular, we consider biomechanical properties' impact on dura repair's effectiveness. Finally, the obstacles and perspectives for developing the ideal dural substitute are explored.

The Impact of VEGF-C-Induced Dural Lymphatic Vessel Growth on Ischemic Stroke Pathology.

Timely relief of edema and clearance of waste products, as well as promotion of anti-inflammatory immune responses, reduce ischemic stroke pathology, and attenuate harmful long-term effects post-stroke. The discovery of an extensive and functional lymphatic vessel system in the outermost meningeal layer, dura mater, has opened up new possibilities to facilitate post-stroke recovery by inducing dural lymphatic vessel (dLV) growth via a single injection of a vector encoding vascular endothelial growth factor C (VEGF-C). In the present study, we aimed to improve post-stroke outcomes by inducing dLV growth in mice. We injected mice with a single intracerebroventricular dose of adeno-associated viral particles encoding VEGF-C before subjecting them to transient middle cerebral artery occlusion (tMCAo). Behavioral testing, Gadolinium (Gd) contrast agent-enhanced magnetic resonance imaging (MRI), and immunohistochemical analysis were performed to define the impact of VEGF-C on the post-stroke outcome. VEGF-C improved stroke-induced behavioral deficits, such as gait disturbances and neurological deficits, ameliorated post-stroke inflammation, and enhanced an alternative glial immune response. Importantly, VEGF-C treatment increased the drainage of brain interstitial fluid (ISF) and cerebrospinal fluid (CSF), as shown by Gd-enhanced MRI. These outcomes were closely associated with an increase in the growth of dLVs around the region where we observed increased vefgc mRNA expression within the brain, including the olfactory bulb, cortex, and cerebellum. Strikingly, VEGF-C-treated ischemic mice exhibited a faster and stronger Gd-signal accumulation in ischemic core area and an enhanced fluid outflow via the cribriform plate. In conclusion, the VEGF-C-induced dLV growth improved the overall outcome post-stroke, indicating that VEGF-C has potential to be included in the treatment strategies of post-ischemic stroke. However, to maximize the therapeutic potential of VEGF-C treatment, further studies on the impact of an enhanced dural lymphatic system at clinically relevant time points are essential.

Investigation of direction- and age-dependent prestretch in mouse cranial dura mater.

Cranial dura mater is a dense interwoven vascularized connective tissue that helps regulate neurocranial remodeling by responding to strains from the growing brain. Previous ex vivo experimentation has failed to account for the role of prestretch in the mechanical behavior of the dura. Here we aim to estimate the prestretch in mouse cranial dura mater and determine its dependency on direction and age. We performed transverse and longitudinal incisions in parietal dura excised from newborn (day ∼ 4) and mature (12 weeks) mice and calculated the ex vivo normalized incision opening (measured width over length). Then, similar incisions were simulated under isotropic stretching within Abaqus/Standard. Finally, prestretch was estimated by comparing the ex vivo and in silico normalized openings. There were no significant differences between the neonatal and adult mice when comparing cuts in the same direction, but adult mice were found to have significantly greater stretch in the anterior-posterior direction than in the medial-lateral direction, while neonatal dura was essentially isotropic. Additionally, our simulations show that increasing curvature impacts the incision opening, indicating that flat in silico models may overestimate prestretch.

Space invaders: Reassessing the histology of hyperostosis frontalis interna.

Hyperostosis frontalis interna (HFI) is a human skeletal lesion characterized by nodules of hyperplastic bone and thickening of the frontal bone's inner surface. Despite its prevalence in the general population and its long history of observation-it is one of the most frequently observed pathologies in gross anatomy laboratories-HFI's etiology and pathogenesis remain poorly understood. This is largely due to the lack of a thorough survey of its histology across the various stages of its development. Our study has three major aims: (1) assess HFI histology from incipient to advanced lesions; (2) elucidate lamellar and trabecular structure in HFI; and (3) clarify impacts/roles of the dura mater in HFI. Sections of nondecalcified bone provide evidence for two different categories of lesions: (1) stratum lesions, characterized by lamellar-based overall thickening of the internal table, and (2) eruptive lesions, characterized by nodular formations of initially lamellar bone that appear to form the bulk of bone mass in advanced stages. Sections of nondecalcified bone also suggest that for both lesion types, HFI growths begin as deposits of lamellar bone, which are later remodeled into woven bone deposits; our data do not support the hypothesis that lesions begin as a "diploization" of cortical bone as suggested by prior studies. Trichrome-stained sections provide evidence that growing lesions erode through and engulf the dura mater, effectively destroying this tissue layer as they grow laterally and inwardly. Our results indicate possible avenues of research to better understand the root causes of this disorder.

Neovascularization in Outer Membrane of Chronic Subdural Hematoma : A Rationale for Middle Meningeal Artery Embolization.

OBJECTIVE: Chronic subdural hematomas (cSDHs) are generally known to result from traumatic tears of bridging veins. However, the causes of repeat spontaneous cSDHs are still unclear. We investigated the changes in vasculature in the human dura mater and outer membrane (OM) of cSDHs to elucidate the cause of their spontaneous repetition. METHODS: The dura mater was obtained from a normal control participant and a patient with repeat spontaneous cSDHs. The pathological samples from the patient included the dura mater and OM tightly adhered to the inner dura. The samples were analyzed with a particular focus on blood and lymphatic vessels by immunohistochemistry, 3-dimensional imaging using a transparent tissue clearing technique, and electron microscopy. RESULTS: The dural border cell (DBC) layer of the dura mater and OM were histologically indistinguishable. There were 5.9 times more blood vessels per unit volume of tissue in the DBC layer and OM in the patient than in the normal control. The DBC layer and OM contained pathological sinusoidal capillaries not observed in the normal tissue; these capillaries were connected to the middle meningeal arteries via penetrating arteries. In addition, marked lymphangiogenesis in the periosteal and meningeal layers was observed in the patient with cSDHs. CONCLUSION: Neovascularization in the OM seemed to originate from the DBC layer; this is a potential cause of repeat spontaneous cSDHs. Embolization of the meningeal arteries to interrupt the blood supply to pathological capillaries via penetrating arteries may be an effective treatment option.

Menthol dural application alters meningeal arteries tone and enhances excitability of trigeminocervical neurons in rats.

Headaches, including migraines, can have a causal relationship to exposure to cold, and this relationship may be both positive and negative, as cold can both provoke and alleviate cephalgia. The role of thermoreceptors responsible for transduction of low temperatures belongs to the transient receptor potential cation channel subfamily melastatin member 8 (TRPM8). These channels mediate normal cooling sensation and have a role in both cold pain and cooling-mediated analgesia; they are seen as a potential target for principally new anti-migraine pharmaceuticals. Using a validated animal migraine models, we evaluated effects of menthol, the TRPM8-agonist, on trigeminovascular nociception. In acute experiments on male rats, effects of applied durally menthol solution in various concentrations on the neurogenic dural vasodilatation (NDV) and firing rate of dura-sensitive neurons of the trigeminocervical complex (TCC) were assessed. Application of menthol solution in concentrations of 5 % and 10 % was associated with NDV suppression, however amplitude reduction of the dilatation response caused not by the vascular dilatation degree decrease, but rather due to the significant increase of the meningeal arterioles' basal tone. In electrophysiological experiments the 1 % and 30 % menthol solutions intensified TCC neuron responses to the dural electrical stimulation while not changing their background activity. Revealed in our study excitatory effects of menthol related to the vascular as well as neuronal branches of the trigeminovascular system indicate pro-cephalalgic effects of TRPM8-activation and suggest feasibility of further search for new anti-migraine substances among TRPM8-antagonists.

Effects of surface profile on porcine dural mechanical properties.

BACKGROUND: Cerebrospinal fluid leakage through the spinal meninges is difficult to diagnose and treat. Moreover, its underlying mechanism remains unknown. Considering that the dura mater is structurally the strongest and outermost membrane among the three-layered meninges, we hypothesized that a dural mechanical tear would trigger spontaneous cerebrospinal fluid leakage, especially when a traumatic loading event is involved. Thus, accurate biomechanical properties of the dura mater are indispensable for improving computational models, which aid in predicting blunt impact injuries and creating artificial substitutes for transplantation and surgical training. METHOD: We characterized the surface profile of the spinal dura and its mechanical properties (Young's moduli) with a distinction of its inherent anatomical sites (i.e., the cervical and lumbar regions as well as the dorsal and ventral sides of the spinal cord). FINDINGS: Although the obtained Young's moduli exhibited no considerable difference between the aforementioned anatomical sites, our results suggested that the wrinkles structurally formed along the longitudinal direction would relieve stress concentration on the dural surface under in vivo and supraphysiological conditions, enabling mechanical protection of the dural tissue from a blunt impact force that was externally applied to the spine. INTERPRETATION: This study provides fundamental data that can be used for accurately predicting cerebrospinal fluid leakage due to blunt impact trauma.

A novel perspective of calvarial development: the cranial morphogenesis and differentiation regulated by dura mater.

There are lasting concerns on calvarial development because cranium not only accommodates the growing brain, but also safeguards it from exogenous strikes. In the past decades, most studies attributed the dynamic expansion and remodeling of cranium to the proliferation of osteoprecursors in cranial primordium, and the proliferation of osteoprogenitors at the osteogenic front of cranial suture mesenchyme. Further investigations identified series genes expressed in suture mesenchymal cells as the markers of the progenitors, precursors and postnatal stem cells in cranium. However, similar to many other organs, it is suggested that the reciprocal interactions among different tissues also play essential roles in calvarial development. Actually, there are increasing evidence indicating that dura mater (DM) is indispensable for the calvarial morphogenesis and osteogenesis by secreting multiple growth factors, cytokines and extracellular matrix (ECM). Thus, in this review, we first briefly introduce the development of cranium, suture and DM, and then, comprehensively summarize the latest studies exploring the involvement of ECM in DM and cranium development. Eventually, we discussed the reciprocal interactions between calvarium and DM in calvarial development. Actually, our review provides a novel perspective for cranium development by integrating previous classical researches with a spotlight on the mutual interplay between the developing DM and cranium.

Clinical, Radiological, and Etiological Aspects of Pachymeningitis: A Study of 24 Cases.

Introduction and importance Hypertrophic pachymeningitis (HP) is an uncommon disorder with varied etiological origins and heterogeneous clinical presentation. Establishing the etiological diagnosis poses a challenge, but prompt identification provides a treatment window, potentially leading to a reversal of symptoms. MRI is the reference examination, allowing not only the early diagnosis of pachymeningitis but also the assessment of its extent and importance, detection of possible complications, and suggestion of etiology. Case presentation We conducted a retrospective study involving 24 patients recruited over 5 years for who brain imaging had revealed the presence of pachymeningitis. The average age of the patients was 40 years, with a male-to-female ratio of 0.6. Clinical discussion Headache was present in 54.17% of patients. All the patients underwent MRI examinations utilizing different sequences, with subsequent Gadolinium injection showing localized and asymmetrical meningeal thickening in 13 cases, and diffuse in the rest. The cerebrospinal fluid study unveiled an inflammatory fluid characterized by a lymphocytic predominance and hyperproteinorrhea, noted in 50% of the patients. The histopathological analysis of a stereotactic biopsy conducted on an individual patient revealed non-diagnostic results. The etiological investigation was dominated by tuberculosis, which was detected in 33.3% of cases. Idiopathic origin was identified in 16.7% of patients. Conclusion Meningeal thickening is rare, and the multitude of potential causes makes the etiological investigation challenging unless they fall within the scope of secondary meningeal disorders; otherwise, a dural biopsy becomes necessary, and the prompt initiation of treatment, along with determining the etiology influences the prognosis.