The pericranium.

The purpose of this chapter is to present how past surgeons have viewed the pericranium and how they have reacted to its appearances. In ancient times, the membrane was considered formed by the dura through the sutures and it retained a relationship with the dura via vessels in the sutures. It was considered advisable to strip it totally from any area to be examined for fissure fractures and also for any area to be trepanned, as pericranial injury was thought to lead to fever and inflammation. In the 18th century, a new idea arose that posttraumatic spontaneous separation of the pericranium from the bone was a reliable indicator of the development of intracranial suppuration. This idea was subsequently refuted. For over two millennia, the pericranium was considered to be an important membrane requiring the close attention of the surgeon. It is no longer required to receive more than minimal attention.

Role of Pericardial Patch in Neurosurgery: Institutional Experience.

INTRODUCTION: Dural closure is an important part of neurosurgery, failure which may lead to wound infection, pseudomeningoceles, meningitis, severe morbidity to a patient, and even mortality. In cases where primary dura closure is not possible, a bovine pericardial patch is a good alternative with the benefits of suturability and the ability to provide watertight closure, hence preventing Cerebrospinal Fluid (CSF) leak. The present study demonstrates the use of the bovine pericardial patch in both cranial and spinal disorders for dural closure as well as for transposition technique in microvascular decompression. OBJECTIVES: The aim of our study is to understand the advantages and feasibility of a bovine pericardial patch in various neurosurgical procedures. MATERIAL METHODS: Fifty-one patients were analyzed prospectively and followed up in which glutaraldehyde-free bovine pericardial patch was used in various cranial and spinal disorders. RESULTS: The most common indications where a bovine pericardial patch was used, in decreasing order of frequency, were meningioma excision surgery (47%), followed by Chiari malformation operated for foramen magnum decompression (17.6%), meningomyelocele (7.8%), spinal dural defects (7.8%), trigeminal neuralgia (5.8%), traumatic decompression with lax duraplasty (4%), glioma (4%), encephalocele (4%), and skull base defects (2%). Two patients had complications, one with CSF leak and the other had superficial wound infection, which were managed appropriately. CONCLUSIONS: The use of a bovine pericardial patch as a dural substitute in various cranial and spinal disorders is feasible with good outcomes, and it can be considered an ideal dural substitute.

Hemopatch® as a primary dural sealant in cranial neurosurgery: Technical note and a retrospective study.

OBJECTIVES: To determine the effectiveness and safety of Hemopatch® as a primary dural sealant in preventing CSF leakage following cranial surgery. Cerebrospinal fluid (CSF) leaks occur in cranial operations and are associated with significant patient burden and expense. The use of Hemopatch® as a dural sealant in cranial neurosurgical procedures is described and analyzed in this study. METHODS: Data were retrospectively collected from all patients who underwent a craniotomy for various neurosurgical indications where Hemopatch® was used as the primary dural sealant between June 2017 and June 2022. Infection and CSF leak were the main indicators evaluated after surgery. RESULTS: A total of 119 consecutive patients met our inclusion criteria. The median was age 41.5 years, and 52.5% were female. The mean follow-up period was 2.3 years (7 months to 6 years). There were 110 (92.44%) supratentorial and 9 (7.56%) infratentorial craniotomies. Postoperative CSF leak was reported in 2 patients (1.68%), one in each cohort. Postoperative infection occurred in one patient (0.84%). CONCLUSION: The results suggest that using Hemopatch® as a dural sealant in cranial surgery is effective and safe. After supra-/infratentorial craniotomies, the rate of postoperative adverse events in our sample was within the range of known surgical revision rates. Future randomized clinical studies are required to confirm our encouraging findings.

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue of the dura mimicking meningioma: a case report and literature review.

MALT lymphoma of the dura is a very rare type of low-grade B-cell lymphoma. Little more than 100 cases have been reported in the literature to date. We report a 43-year-old woman who was referred to hospital because of a series of three tonic-clonic seizures on the day of admission. Neurological examination revealed confusion and aphasia. Magnetic resonance imaging (MRI) showed a contrast-enhanced, broad-based lesion along the dura in the left parieto-occipital area. The suspicion of an en plaque meningioma was raised. The tumour invaded the brain parenchyma with visible extension into the brain sulci. There was a marked brain oedema surrounding the lesion and causing the midline shift 8 mm to the right. After stabilization of neurological condition (intravenous diuretics and steroids), the operation was performed. The diagnosis of dural MALT lymphoma was established. During the pathological examination, it was especially problematic to distinguish MALT lymphoma from follicular lymphoma, but the final diagnosis was MALT lymphoma. Surgical partial removal with additional R-CVP immunochemotherapy (rituximab, cyclophosphamide, vincristine and prednisone) resulted in complete remission. The follow-up period is 1 year. Our presented case of a MALT lymphoma highlights the fact that surgical partial removal with additional immunochemotherapy is an available option in these rare intracranial tumours.

Free temporalis muscle fascia graft in dural reconstruction following surgical resection of intermediate and malignant skull base tumors: A 10-year experience from a single center.

BACKGROUND: Data from patients with post-ablative dural defects reconstructed using a free temporalis muscle fascia graft (FTFG) after resection of anterior or central skull base tumors were retrospectively analyzed. METHODS: The primary predictor and outcome variables were the reconstructive methods for dural repair and postoperative cerebrospinal fluid (CSF) leakage rate, respectively. RESULTS: Eighty patients were included, and 94 postoperative dural reconstructions were performed using FTFG. The postoperative CSF leakage rate was 3.19%. The postoperative CSF leakage rates did not significantly differ between open and endonasal endoscopic surgeries (1.92% vs. 4.88%; p > 0.05). In cases completed using the endonasal endoscopic approach, the postoperative CSF leakage rate was significantly associated with the intraoperative CSF leak flow (p < 0.05). CONCLUSIONS: Post-ablative dural defect reconstruction using FTFG resulted in low postoperative CSF leakage and complication rates comparable to those of free fascia lata graft from available literature.

Bridging anatomical gaps between brain and immune system.

It is increasingly clear that the central nervous system (CNS) relies significantly on both adaptive and innate immune cells for its repair and lifelong maintenance. These interactions hold profound implications for brain aging and neurodegeneration. Recent work by Smyth et al. describes newfound anatomical connections between the brain and dura mater, which they named the arachnoid cuff exit points.

Subarachnoid Hemorrhage Depletes Calcitonin Gene-Related Peptide Levels of Trigeminal Neurons in Rat Dura Mater.

Subarachnoid hemorrhage (SAH) remains a major cause of cerebrovascular morbidity, eliciting severe headaches and vasospasms that have been shown to inversely correlate with vasodilator calcitonin gene-related peptide (CGRP) levels. Although dura mater trigeminal afferents are an important source of intracranial CGRP, little is known about the effects of SAH on these neurons in preclinical models. The present study evaluated changes in CGRP levels and expression in trigeminal primary afferents innervating the dura mater 72 h after experimentally induced SAH in adult rats. SAH, eliciting marked damage revealed by neurological examination, significantly reduced the density of CGRP-immunoreactive nerve fibers both in the dura mater and the trigeminal caudal nucleus in the medulla but did not affect the total dural nerve fiber density. SAH attenuated ex vivo dural CGRP release by ~40% and in the trigeminal ganglion, reduced both CGRP mRNA levels and the number of highly CGRP-immunoreactive cell bodies. In summary, we provide novel complementary evidence that SAH negatively affects the integrity of the CGRP-expressing rat trigeminal neurons. Reduced CGRP levels suggest likely impaired meningeal neurovascular functions contributing to SAH complications. Further studies are to be performed to reveal the importance of impaired CGRP synthesis and its consequences in central sensory processing.

"Curtain-fall" technique for cerebrospinal fluid leak prevention after removal of intradural drainage. Technical note: application in chronic subdural hematoma surgery.

OBJECTIVE: Chronic subdural hematoma (CSDH) is frequently met in neurosurgical practice and often need urgent surgical treatment in case of neurological deterioration. Different surgical approaches to evacuate CSDH are described in the literature. In our experience, an external drainage system is crucial in order to avoid recurrences. We recently encountered a case of subcutaneous CSF collection after drainage removal. Thus, we developed a simple surgical technique to prevent postoperative CSF leak after subdural drainage system removal. METHOD: We have developed a technique in which the periosteum is harvested during the surgery prior to the evacuation of the hemorrhage and fixed with sutures on the uncut dura mater opposite and laterally to the exit of the catheter exiting the dural hole caused by the passage of the Jackson-Pratt subdural drainage system. When the drainage catheter is removed, the flap, partially held by the sutures, falls over the hole avoiding CSF leakage. By using this technique, the small dural hole will be covered with the periosteum allowing for natural closure and wound healing hence preventing CSF leakage. RESULTS: This technique was successfully employed in 21 patients who didn't develop postoperative CSF leakage following CSDH evacuation and removal of subdural drainage system. CONCLUSION: In this technical note, we describe a safe dura closure technique that we developed to help reduce the risk of postoperative CSF leakage following subdural drainage removal, which can, however, also be applied in all surgeries in which a catheter is placed in the subdural space.

Evaluation of Biocompatibility and Healing Properties of Dural Substitutes Produced by Electrospinning Technology.

BACKGROUND/AIM: Dural reconstruction is a critical process after neurosurgical procedures. Improper dural repair leads to serious side-effects, such as cerebrospinal fluid leakage or infection. This is why it is important to properly repair the dura using a dural substitute, and research into dural substitutes is ongoing. The ideal dural substitute should be non-toxic, biocompatible, and capable of maintaining adequate tension and preventing cerebrospinal fluid leakage for extended periods in vivo. This study evaluated the biocompatibility and healing properties of Safe-Seal, poly-L-lactic acid synthetic bioabsorbable dural substitute produced by electrospinning technology. MATERIALS AND METHODS: Safe-Seal, was created by electrospinning, which is a technique for nanofiberizing polymers into three-dimensional structures, and its cytotoxicity was evaluated. The animal study used 30 rats, divided into three groups assessed at two time points (4 and 12 weeks). The study groups were a negative control group with no treatment, an experimental group with Safe-Seal (TDM Co. Ltd., Gwangju, Republic of Korea) implantation, and a positive control group with a commercial product, Redura® (Medprin Biotech, Frankfurt, Germany) implantation. RESULTS: Safe-Seal exhibited no cytotoxic or adverse effects in the in vivo animal study. Histologically, Safe-Seal displayed less inflammatory cell infiltration, less adhesion to brain tissue, and connectivity with the surrounding dura mater as compared to the negative control group and without any significant differences from Redura® in all evaluation criteria. CONCLUSION: Safe-Seal presented adequate biocompatibility in vivo and contributed to the healing of the dura mater at a similar level to that of Redura® when applied to dural defects.

Venous-plexus-associated lymphoid hubs support meningeal humoral immunity.

There is increasing interest in how immune cells in the meninges-the membranes that surround the brain and spinal cord-contribute to homeostasis and disease in the central nervous system1,2. The outer layer of the meninges, the dura mater, has recently been described to contain both innate and adaptive immune cells, and functions as a site for B cell development3-6. Here we identify organized lymphoid structures that protect fenestrated vasculature in the dura mater. The most elaborate of these dural-associated lymphoid tissues (DALT) surrounded the rostral-rhinal confluence of the sinuses and included lymphatic vessels. We termed this structure, which interfaces with the skull bone marrow and a comparable venous plexus at the skull base, the rostral-rhinal venolymphatic hub. Immune aggregates were present in DALT during homeostasis and expanded with age or after challenge with systemic or nasal antigens. DALT contain germinal centre B cells and support the generation of somatically mutated, antibody-producing cells in response to a nasal pathogen challenge. Inhibition of lymphocyte entry into the rostral-rhinal hub at the time of nasal viral challenge abrogated the generation of germinal centre B cells and class-switched plasma cells, as did perturbation of B-T cell interactions. These data demonstrate a lymphoid structure around vasculature in the dura mater that can sample antigens and rapidly support humoral immune responses after local pathogen challenge.

Successful Thrombectomy of the Posterior Cerebral Artery P2 Segment in a 61-Year-Old Man with Acute Ischaemic Stroke: A Case Report.

BACKGROUND Acute ischemic stroke in the posterior cerebral artery (PCA) territory can lead to persistent disabling deficits. The PCA is divided into 4 segments. The P2 segment begins at the posterior communicating artery and curves around the midbrain and above the tentorium cerebelli. This report is of a 61-year-old man with acute ischemic stroke involving the left hippocampus treated with direct thrombectomy of the P2 segment of the PCA. CASE REPORT A 61-year-old white man presented with transient amnesia, aphasia, right-sided hemianopia, dizziness, and persistent acute memory deficits. Magnetic resonance imaging (MRI) showed a left hippocampal acute ischemic stroke with left PCA occlusion in the P2 segment. Despite a low National Institutes of Health Stroke Scale (NIHSS) score and the already-formed lesion in the hippocampus, successful stent retriever thrombectomy was performed due to a considerable perfusion-diffusion mismatch and a persistent potentially disabling neurocognitive deficit. Due to partial thrombus dislocation, occlusion of the common origin of the right posterior inferior cerebellar artery (PICA) and anterior inferior cerebellar artery (AICA) occurred and was immediately treated by thrombectomy to prevent severe cerebellar infarction. His clinical symptoms completely resolved and a neuropsychological exam showed no residual deficits. CONCLUSIONS Thrombectomy of the P2 segment of the PCA is feasible and can be considered to treat patients with acute occlusion at risk for persistent disabling deficits, based on clinical estimation of the impact of such deficits and the presence of potentially salvageable brain tissue. Potential procedural complications should be sought out and immediately treated, if technically feasible.

IgG4-Related Neurological Disease: A Single Center Ambispective Study from South India.

IgG4-related disease (IgG4-RD) is an immune-mediated multi-system disorder. The nervous system (IgG4-RND) is rarely affected. We describe a short case series. We performed an ambispective analysis of IgG4-RND patients admitted at our centre between January 2016 and December 2022. Eight patients (M: F-2:6) were included with a mean age at presentation of 40.63 ± 17.88 years and disease duration of 5.16 ± 4.08 years. The common diseased sites were pachymeninges (7), orbits (4), paranasal sinuses (3), frontal lobe (1), hypophysis (1), leptomeninges (1), and middle ear (1). Common symptoms were headache and cranial neuropathy. The common nerves involved were the optic nerve, followed by the third, fifth, sixth, and seventh. Cerebrospinal fluid showed lymphocytic pleocytosis. Histopathology showed lymphoplasmacytic infiltrate (8), fibrosis (5), >10 IgG4 + cells (7), and IgG4/IgG >40% (6). Six had a relapsing course. The rituximab-based treatment regimen showed a favourable response.

A tough bioadhesive hydrogel supports sutureless sealing of the dural membrane in porcine and ex vivo human tissue.

Complete sequestration of central nervous system tissue and cerebrospinal fluid by the dural membrane is fundamental to maintaining homeostasis and proper organ function, making reconstruction of this layer an essential step during neurosurgery. Primary closure of the dura by suture repair is the current standard, despite facing technical, microenvironmental, and anatomic challenges. Here, we apply a mechanically tough hydrogel paired with a bioadhesive for intraoperative sealing of the dural membrane in rodent, porcine, and human central nervous system tissue. Tensile testing demonstrated that this dural tough adhesive (DTA) exhibited greater toughness with higher maximum stress and stretch compared with commercial sealants in aqueous environments. To evaluate the performance of DTA in the range of intracranial pressure typical of healthy and disease states, ex vivo burst pressure testing was conducted until failure after DTA or commercial sealant application on ex vivo porcine dura with a punch biopsy injury. In contrast to commercial sealants, DTA remained adhered to the porcine dura through increasing pressure up to 300 millimeters of mercury and achieved a greater maximum burst pressure. Feasibility of DTA to repair cerebrospinal fluid leak in a simulated surgical context was evaluated in postmortem human dural tissue. DTA supported effective sutureless repair of the porcine thecal sac in vivo. Biocompatibility and adhesion of DTA was maintained for up to 4 weeks in rodents after implantation. The findings suggest the potential of DTA to augment or perhaps even supplant suture repair and warrant further exploration.

Benefits of Photon-Counting CT Myelography for Localization of Dural Tears in Spontaneous Intracranial Hypotension.

Photon-counting CT is an increasingly used technology with numerous advantages over conventional energy-integrating detector CT. These include superior spatial resolution, high temporal resolution, and inherent spectral imaging capabilities. Recently, photon-counting CT myelography was described as an effective technique for the detection of CSF-venous fistulas, a common cause of spontaneous intracranial hypotension. It is likely that photon-counting CT myelography will also have advantages for the localization of dural tears, a separate type of spontaneous spinal CSF leak that requires different myelographic techniques for accurate localization. To our knowledge, prior studies on photon-counting CT myelography have been limited to techniques for detecting CSF-venous fistulas. In this technical report, we describe our technique and early experience with photon-counting CT myelography for the localization of dural tears.

Identification of direct connections between the dura and the brain.

The arachnoid barrier delineates the border between the central nervous system and dura mater. Although the arachnoid barrier creates a partition, communication between the central nervous system and the dura mater is crucial for waste clearance and immune surveillance1,2. How the arachnoid barrier balances separation and communication is poorly understood. Here, using transcriptomic data, we developed transgenic mice to examine specific anatomical structures that function as routes across the arachnoid barrier. Bridging veins create discontinuities where they cross the arachnoid barrier, forming structures that we termed arachnoid cuff exit (ACE) points. The openings that ACE points create allow the exchange of fluids and molecules between the subarachnoid space and the dura, enabling the drainage of cerebrospinal fluid and limited entry of molecules from the dura to the subarachnoid space. In healthy human volunteers, magnetic resonance imaging tracers transit along bridging veins in a similar manner to access the subarachnoid space. Notably, in neuroinflammatory conditions such as experimental autoimmune encephalomyelitis, ACE points also enable cellular trafficking, representing a route for immune cells to directly enter the subarachnoid space from the dura mater. Collectively, our results indicate that ACE points are a critical part of the anatomy of neuroimmune communication in both mice and humans that link the central nervous system with the dura and its immunological diversity and waste clearance systems.

Granulomatosis With Polyangiitis of Spinal Dura Presenting With "Bottle Brush Sign" on 18 F-FDG PET/CT.

ABSTRACT: A 72-year-old man with fever and weakness in both lower limbs underwent thoracolumbar MRI and 18 F-FDG PET/CT. The PET/CT scan revealed diffused FDG uptake along the spinal dura mater from T7 to S2 level like a "bottle brush." Pathologic examination after biopsy of spinal canal lesions manifested granulomatous inflammation. The blood test showed cytoplasmic antineutrophil cytoplasmic antibody (ANCA) and myeloperoxidase-ANCAs were positive, whereas the perinuclear ANCA was negative. Eventually, he was diagnosed with granulomatosis with polyangiitis.

The Basal or Sphenopetrosal Superficial Middle Cerebral Vein Type.

Background and Objectives: The adult superficial middle cerebral vein (SMCV) commonly drains into the middle cranial fossa. However, different embryonic types persist, in which the SMCV drains into the lateral sinus. The basal type of SMCV coursing on the middle fossa floor is a scarce variant. Materials and Methods: During a retrospective study of archived computed tomography angiography (CTA) and magnetic resonance angiography (MRA) files, three rare adult cases of the basal or sphenopetrosal type of SMCV were found and further documented. Results: In the first case, which was evaluated via CTA, the basal type of SMCV formed a sagittal loop. It continued on the middle fossa floor, over a dehiscent tegmen tympani, to drain into the lateral sinus. In the second case, documented via MRA, the basal type of SMCV's anterior loop was in the coronal plane and closely related to the internal carotid artery and the cavernous sinus. It continued with the basal segment over a dehiscent glenoid fossa of the temporomandibular joint (TMJ). In the third case, documented via CTA, the initial cerebral part of the SMCV had a large fenestration. The middle fossa floor coursed within a well-configured sulcus of the SMCV and received a tributary through the tympanic roof. Its terminal had a tentorial course. Conclusions: Beyond the fact that such rare variants of the SMCV can unexpectedly interfere with specific approaches via the middle fossa, dehiscences of the middle fossa floor beneath such variants can determine otic or TMJ symptoms. Possible loops and fenestrations of the SMCV should be considered and documented preoperatively.

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.

Primary anaplastic large cell lymphoma arising from central nervous system.

A 22-year-old man presented at the emergency department with progressive headache, vomiting and horizontal diplopia over 2-month period. He also developed blurred vision in his left eye. He complained of loss of appetite for the past 2 months, resulting in a 5-kg weight loss. Examination upon arrival revealed papilledema and bilateral abducens nerve palsy. Motor and sensory functions were intact. Magnetic resonance imaging (MRI) of the brain revealed multiple extra-axial nodular enhancing lesions with size of 5-10 mm mainly along with both sides of falx cerebri and vasogenic brain oedema (Fig. 1). Stereotactic brain biopsy was performed to obtain tissue diagnosis. Histologic examination revealed brain infiltration by few atypical cells hidden amongst abundant and mixed population of inflammatory cells including lymphocytes and histiocytes. The atypical cells are large cells with horseshoe nuclei (red arrow; Fig. 2A ×100 and Fig. 2B ×400). Immunohistochemistry showed strong, uniform CD30 expression (Fig. 2C ×400) and cytoplasmic ALK staining (Fig. 2D ×400), as well as for CD3 (Fig. 2E ×400) and CD68 (Fig. 2F ×400). B-cell markers (CD20) were negative (Fig. 2G ×400).

Artificial spinal dura mater made of gelatin microfibers and bioadhesive for preventing cerebrospinal fluid leakage.

Artificial spinal dura mater was designed by combining solution blow-spun gelatin microfibers and dopamine-capped polyurethane bioadhesive. Notably, the gelatin microfibers had a special pore structure, good water adsorption capability, and excellent burst pressure resistance. The bioadhesive layer contributed to the excellent sealing performance in the wet state. This material provides a promising alternative as an artificial spinal dura mater to prevent cerebrospinal fluid leakage.