Occipital Sinus-Sparing Linear Paramedian Dural Incision: A Technical Note and Case Series for Median Suboccipital Approach.

BACKGROUND: Durotomies, traditionally used during the midline suboccipital approach, involve sacrificing the occipital sinus (OS) with consequent shrinking of the dura, risk of venous complications, difficulty performing watertight closure, and a higher rate of postoperative cerebrospinal fluid (CSF) leaks. The present technical note describes the OS-sparing linear paramedian dural incision, which leads to a decrease in the risk of complications during the median suboccipital approach in our case series. METHODS: The OS-sparing linear incision technique involves a dural incision placed 1 cm lateral to the OS. The angle of view of the microscope is frequently changed to overcome the narrowed exposure of the linear durotomy. Copious irrigation with saline prevents drying of the dura. A running watertight closure of the dura is performed. The overall results of 5 cases are reviewed. RESULTS: The cases were 3 tumors and 2 cavernomas. The OS was preserved in all 5, and no duraplasty was needed. The average dura closure time was 16.8 minutes. No CSF leak occurred, and no wound complications were observed. A gross total resection of the lesion was achieved in all the patients. The mean follow-up was 10.2 months, and there were no late complications related to the dura closure. CONCLUSIONS: In comparison to the types of durotomies conventionally used for the midline suboccipital approach, the OS-sparing linear paramedian dural incision entails lower risks of bleeding, venous complications, CSF leaks, and infections by avoiding duraplasty. Validation of this technical note on a larger patient cohort is needed.

A Subdural Dissection of Cerebrospinal Fluid Causing Cauda Equina Centralization After Durotomy: A Case Report.

CASE: A 61-year-old woman with recurrent left L5 radiculopathy underwent revision L4-5 decompression complicated by incidental durotomy requiring primary repair. Postoperative course was complicated by wound drainage and headache. Repeat magnetic resonance imaging demonstrated cerebrospinal fluid dissecting a plane deep to the dura mater but superficial to the arachnoid, with the collection compressing the cauda equina in an atypical horizontal and linear fashion. Nonoperative treatment was ineffective, and she required revision decompression and dural repair. CONCLUSION: Spine surgeons should recognize this finding on postoperative imaging as a potential sign of an incomplete dural repair necessitating return to the operating room.

Clinical Observation of Various Types of Idiopathic Hypertrophic Cranial Pachymeningitis.

BACKGROUND: To assist doctors in making better treatment decisions and improve patient prognosis, it is important to determine which therapy modalities are suitable for various forms of idiopathic hypertrophic cranial pachymeningitis (IHCP). METHODS: All cases were received from the hospital medical record system, and some follow-up information was gathered through telephone follow-up. RESULTS: A total of 26 patients, 14 men and 12 women, with ages ranging from 20 to 73 years and a mean of 47.42 years, were included in the research. Regular types were less likely to recur than irregular and nodular types, focal types were less likely to recur than diffuse types, and corticosteroid-refractory types were more likely to recur than corticosteroid-sensitive types. CONCLUSIONS: The extent and shape of the lesion and susceptibility to corticosteroids are potential factors that could influence recurrence. Futhermore, this paper also proposes the fibroblasts as a new therapeutic target which may improve the quality of prognostic survival of patients.

Peptidomics insights: neutrophil extracellular traps (NETs) related to the chronic subdural hemorrhage.

Chronic subdural hemorrhage (CSDH) refers to a hematoma with an envelope between the dura mater and the arachnoid membrane and is more common among the elderly. It was reported that the dura mater, which is highly vascularized with capillary beds, precapillary arterioles and postcapillary venules play an important role in the protection of the central nervous system (CNS). Numerous evidences suggests that peptides play an important role in neuroprotection of CNS. However, whether dura mater derived endogenous peptides participate in the pathogenesis of CSDH remains undetermined. In the current study, the peptidomic profiles were performed in human dura of CSDH (three patients) and the relative control group (three non-CSDH samples) by LC-MS (liquid chromatography-mass spectrometry). The results suggested that a total of 569 peptides were differentially expressed in the dura matter of CSDH compared with relative controls, including 217 up-regulated peptides and 352 down-regulated peptides. Gene Ontology (GO) analysis demonstrated that the precursor proteins of those differentially expressed peptides were involved in the various biological processes. Interestingly, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis suggested that NETs participated in the pathogenies of CSDH. Further investigate showed that H3Cit was significantly elevated in the dural and hematoma membranes of patients with CSDH compared to patients without CSDH. Taken together, our results showed the differentially expressed peptides in human dura mater of CSDH and demonstrated that NETs formation in the dural and hematoma membranes might be involved in the pathogenesis of CSDH. It is worth noting that pharmacological inhibition of NETs may have potential therapeutic implications for CSDH.

A selected case series of idiopathic hypertrophic pachymeningitis in a single center: Pathological characteristics and case-oriented review.

Hypertrophic pachymeningitis (HP) is a relatively rare disease of the central nervous system characterized by local or diffuse fibrous thickening of the dura mater. At present, there is still insufficient research on the pathogenesis and treatment strategies of this disease. We reported a continuous case series of seven patients with idiopathic HP (IHP), and also details one case of immunoglobulin G4-related HP requiring surgical intervention. Early diagnosis and appropriate surgical intervention for IHP could prevent the progression of permanent neurological damage and spinal cord paraplegia.

The role of the dura mater in cerebral metastases.

OBJECTIVE: The objective of this review was to describe the immunological changes that take place in the dura mater in response to metastatic disease that seeds the CNS. The authors hypothesized that the dura's anatomy and resident immune cell population play a role in enabling metastasis to the brain and leptomeninges. METHODS: An extensive literature search was conducted to identify evidence that supports the dura's participation in metastasis to the CNS. The authors' hypothesis was informed by a recent upsurge in studies that have investigated the dura's role in metastatic development, CNS infections, and autoimmunity. They reviewed this literature as well as the use of immunotherapy in treating brain metastases and how these therapies change the meningeal immune landscape to overcome and reverse tumor-promoting immunosuppression. RESULTS: Evidence suggests that the unique architecture and immune cell profile of the dura, compared with other immune compartments within the CNS, facilitate entry of metastatic tumor cells into the brain. Once these tumor cells penetrate the dural barrier, they propagate an immunosuppressive tumor microenvironment. Therefore, immunotherapy may serve to overcome this immunosuppressive environment and liberate proinflammatory immune cells in an effort to combat metastatic disease. CONCLUSIONS: Within the next few years, the authors expect the addition of several more scientific studies into the literature that further underscore the dura as a chief participant and neuroanatomical barrier in neuro-oncology.

Catastrophic Outcome Following Apparently Trivial Nondominant Transverse Sinus Injury During Resection of a Tentorial Meningioma: Case Report.

A 52-year-old man was admitted to our hospital with symptoms of raised intracranial pressure and cerebellar dysfunction caused by a medium-sized (4 cm in diameter) tentorial meningioma with an infratentorial extension. Preoperative magnetic resonance imaging showed that the tumor indented and possibly partially invaded the adjacent junction of the nondominant transverse and sigmoid sinuses. The contralateral dominant transverse sinus was fully patent. Total surgical removal of the lesion was done through the left retrosigmoid approach. During dissection of the meningioma, some bleeding from the venous sinus was noted, which was easily controlled by packing with hemostatic materials. The initial postoperative period was unremarkable, but approximately 48 h after surgery, acute clinical deterioration caused by hemorrhagic venous infarction of the left cerebellar hemisphere and brain stem developed and necessitated urgent reoperation for the evacuation of hematoma and brain decompression. Thereafter, the patient remained in a prolonged coma with a severe neurological deficit. After several years of extensive neurorehabilitation, he was able to walk with support but had a tracheostomy, required a feeding tube, and voided with a urinary catheter. Such a catastrophic outcome after an apparently trivial nondominant transverse sinus injury during resection of a tentorial meningioma raises the question whether reconstruction of the sinus wall with preservation of its patency might have prevented this complication in our patient.

Photosealing of dural defects using a biocompatible patch.

PURPOSE: Photosealing of many biological tissues can be achieved using a biocompatible material in combination with a dye that is activated by visible light to chemically bond over the tissue defect via protein cross-linking reactions. The aim of this study was to test the efficacy of photosealing using a commercially available biomembrane (AmnioExcel Plus) to securely close dural defects in comparison to another sutureless method (fibrin glue) in terms of repair strength. METHODS: Two-millimeter diameter holes were created in dura harvested from New Zealand white rabbits and repaired ex vivo using one of two methods: (1) in n = 10 samples, photosealing was used to bond a 6-mm-diameter AmnioExcel Plus patch over the dural defect, and (2) in n = 10 samples, fibrin glue was used to attach the same patch over the dural defect. Repaired dura samples were then subjected to burst pressure testing. Histological analysis was also performed of photosealed dura. RESULTS: The mean burst pressures of rabbit dura repaired with photosealing and fibrin glue were 302 ± 149 mmHg and 26 ± 24 mmHg, respectively. The increased repair strength using photosealing was statistically significant and considerably higher than the normal intracranial pressure of ~ 20 mmHg. Histology demonstrated a tight union at the interface between the dura surface and patch with no disruption of the dura structure. CONCLUSION: The results of this study suggest that photosealing performs better than fibrin glue for the fixation of a patch for ex vivo repair of small dural defects. Photosealing is worthy of testing in pre-clinical models for the repair of dural defects.

Simplified anterior transpetrosal approach without superior petrosal sinus and tentorial incision for lesions centered in Meckel's cave.

OBJECTIVE: The anterior transpetrosal approach (ATPA) is an effective method to reach lesions in the petroclival region. This approach involves many steps, including superior petrosal sinus (SPS) ligation and tentorial cutting. It is sometimes unnecessary to perform all procedures in the ATPA for certain lesions, especially those centered in the Meckel's cave. Here, we present a simplified anterior transpetrosal approach (SATPA) without superior petrosal sinus and tentorial incision for lesions centered in the Meckel's cave as a modified ATPA. METHODS: This study included 13 patients treated with SATPA. The initial steps of SATPA are similar to ATPA, excluding a middle cranial fossa dural incision, SPS dissection, or tentorial incision. Histological examination was performed to understand the membrane structure of the trigeminal nerve, which runs through the Meckel's cave. RESULTS: Pathology revealed trigeminal schwannoma (n=11), extraventricular central neurocytoma (n=1), and a metastatic tumor (n=1). The average tumor size was 2.4 cm. The total removal rate was 76.9% (10/13). Permanent complications included trigeminal neuropathy in four cases and cerebrospinal fluid leakage in one case. Histological examination revealed the trigeminal nerve traverses the subarachnoid space from the posterior fossa subdural space to the Meckel's cave and is covered with the epineurium in the inner reticular layer. CONCLUSIONS: We used SATPA for lesions located in the Meckel's cave identified using histological examination. This approach may be considered for small- to medium-sized lesions centered in the Meckel space. CLINICAL TRIAL REGISTRATION NUMBER: None.

Human parasagittal dura is a potential neuroimmune interface.

Parasagittal dura (PSD) is located on both sides of the superior sagittal sinus and harbours arachnoid granulations and lymphatic vessels. Efflux of cerebrospinal fluid (CSF) to human PSD has recently been shown in vivo. Here we obtain PSD volumes from magnetic resonance images in 76 patients under evaluation for CSF disorders and correlate them to age, sex, intracranial volumes, disease category, sleep quality, and intracranial pressure. In two subgroups, we also analyze tracer dynamics and time to peak tracer level in PSD and blood. PSD volume is not explained by any single assessed variable, but tracer level in PSD is strongly associated with tracer in CSF and brain. Furthermore, peak tracer in PSD occurs far later than peak tracer in blood, implying that PSD is no major efflux route for CSF. These observations may indicate that PSD is more relevant as a neuroimmune interface than as a CSF efflux route.

Immunohistochemical visualization of lymphatic vessels in human dura mater: methodological perspectives.

BACKGROUND: Despite greatly renewed interest concerning meningeal lymphatic function over recent years, the lymphatic structures of human dura mater have been less characterized. The available information derives exclusively from autopsy specimens. This study addressed methodological aspects of immunohistochemistry for visualization and characterization of lymphatic vessels in the dura of patients. METHODS: Dura biopsies were obtained from the right frontal region of the patients with idiopathic normal pressure hydrocephalus (iNPH) who underwent shunt surgery as part of treatment. The dura specimens were prepared using three different methods: Paraformaldehyde (PFA) 4% (Method #1), paraformaldehyde (PFA) 0.5% (Method #2), and freeze-fixation (Method #3). They were further examined with immunohistochemistry using the lymphatic cell marker lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), and as validation marker we used podoplanin (PDPN). RESULTS: The study included 30 iNPH patients who underwent shunt surgery. The dura specimens were obtained average 16.1 ± 4.5 mm lateral to the superior sagittal sinus in the right frontal region (about 12 cm posterior to glabella). While lymphatic structures were seen in 0/7 patients using Method #1, it was found in 4/6 subjects (67%) with Method #2, while in 16/17 subjects (94%) using Method #3. To this end, we characterized three types of meningeal lymphatic vessels: (1) Lymphatic vessels in intimate contact with blood vessels. (2) Lymphatic vessels without nearby blood vessels. (3) Clusters of LYVE-1-expressing cells interspersed with blood vessels. In general, highest density of lymphatic vessels were observed towards the arachnoid membrane rather than towards the skull. CONCLUSIONS: The visualization of meningeal lymphatic vessels in humans seems to be highly sensitive to the tissue processing method. Our observations disclosed most abundant lymphatic vessels towards the arachnoid membrane, and were seen either in close association with blood vessels or remote from blood vessels.

Effectiveness of C1 Laminectomy for Chiari Malformation Type 1: Posterior Fossa Volume Expansion and Syrinx-Volume Decrease Rate.

PURPOSE: This study aimed to analyze the effect of foramen magnum decompression with C1 laminectomy (C1L) for Chiari malformation type 1 (CM-1) in terms of improving clinical symptoms, expanding posterior fossa volume, and decreasing syrinx volume. MATERIALS AND METHODS: Between January 2007 and June 2019, 107 patients with CM-1 were included. The median patient age was 13±13 years (range: 9 months-60 years), female-to-male ratio was 1:1, and average length of tonsil herniation was 13±5 mm (range: 5-24 mm). Surgical techniques were divided into four groups based on duraplasty or C1L usage. Among the study subjects, 38 patients underwent duraplasty and had their syrinx volumes measured separately on serial magnetic resonance imaging. A three-dimensional visualization software was used to evaluate the syrinx-volume decrease rate. RESULTS: Bony decompression exhibited a mere 20% volume expansion of the lower-half posterior fossa. C1L offered a 3% additional volume expansion, which rose to 5% when duraplasty was added (p=0.029). There were no significant differences in complication rate when C1L was combined with duraplasty (p=0.526). Syrinx volumes were analyzed in 38 patients who had undergone duraplasty. Among them, 28 patients who had undergone duraplasty without C1L demonstrated a 5.9% monthly decrease in syrinx volume, which was 7.5% in the remaining 10 patients with C1L (p=0.040). CONCLUSION: C1L was effective in increasing posterior fossa volume expansion, both with and without duraplasty. A more rapid decrease in syrinx volume occurred when C1L was combined with duraplasty.

Spontaneous intracerebral haemorrhage associated with early-onset cerebral amyloid angiopathy and Alzheimer's disease neuropathological changes five decades after cadaveric dura mater graft.

Cerebral amyloid angiopathy (CAA) is a small vessel disease, causing spontaneous intracerebral hemorrhage (ICH) in the elderly. It is strongly associated with Alzheimer disease (AD), as most CAA patients show deposition of Aß-i.e. the basic component of parenchymal Alzheimer amyloid deposits-in the cerebral vessels. Iatrogenic early-onset CAA has been recently identified in patients with a history of traumatic brain injury or other cerebral as well as extra-cerebral lesions that led to neurosurgery or other medical procedures as intravascular embolization by cadaveric dura mater extracts many years before the first ICH event. In those patients, a transmission of Aß seeds from neurosurgical instruments or from cadaveric dura mater exposure was suggested. We report a 51-year-old woman with unremarkable family history who presented abruptly with aphasia and right hemiparesis. A cerebral left lobar haemorrhagic stroke was documented by neuroimaging. Accurate anamnesis revealed a neurosurgical procedure with cadaveric dura mater graft at the age of 2 years for an arachnoid cyst. The neuropathological examination of the cerebral parietal biopsy showed severe amyloid angiopathy in many leptomeningeal and cortical vessels, as well as abundant parenchymal Aß deposits, neurofibrillary tangles and neuropil threads. The mechanism involved in the human-to-human transmission of the Aß proteinopathy remains to be clarified. In our patient the cadaver derived dura used for grafting is a very strong candidate as the source of the transmission. A systematic monitoring of individuals who have had neurosurgical procedures in early life, especially those involving cadaveric dural grafts, is required to determine the ratio of those affected by CAA many years later and unaffected. Moreover, our report confirms that in addition to vascular and parenchymal Aß pathology, neurofibrillary changes indistinguishable from AD may develop in specific conditions with long latency period from the neurosurgical or embolization procedure.

Comparison of supratentorial meningioma resection outcomes by dural reconstruction technique.

OBJECTIVE: Excision of intracranial meningiomas often requires resection or coagulation of the dura mater. The choice of dural closure technique is individualized and based on surgeon preference. The objective of this study was to determine outcomes following various dural closure techniques for supratentorial meningiomas. METHODS: A retrospective, single-center cohort study was performed for patients who underwent excision of supratentorial meningiomas from 2000 to 2019. Outcomes including operative time, postoperative in-hospital complications, readmission, causes of readmission including surgical site infection, pseudomeningocele, need for shunt surgery, and imaging appearance of pseudomeningocele on long-term follow-up imaging were compared. Univariate and multivariable analyses were conducted. RESULTS: A total of 353 patients who had complete clinical and operative data available for review were included. Of these patients, 227 (64.3%) had nonsutured dural graft reconstruction and 126 (35.7%) had sutured dural repair, including primary closure, artificial dura, or pericranial graft. There was significant variability in using nonsutured dural reconstruction compared with sutured dural repair technique among surgeons (p < 0.001). Tumors with sagittal sinus involvement were more likely to undergo nonsutured closure (n = 79, 34.8%) than dural repair (n = 26, 20.6%) (p = 0.003). There were no other differences in preoperative imaging findings or WHO grade. Frequency of surgical site infection and pseudomeningocele, need for shunt surgery, and recurrence were similar between those undergoing nonsutured and those undergoing sutured dural repair. The mean operative time for the study cohort was 234.9 (SD 106.6) minutes. The nonsutured dural reconstruction group had a significantly shorter mean operative time (223.9 [SD 99.7] minutes) than the sutured dural repair group (254.5 [SD 115.8] minutes) (p = 0.015). In a multivariable linear regression analysis, after controlling for tumor size and sinus involvement, nonsutured dural graft reconstruction was associated with a 36.8-minute reduction (95% CI -60.3 to -13.2 minutes; p = 0.002) in operative time. CONCLUSIONS: Dural reconstruction using a nonsutured graft and sutured dural repair exhibit similar postoperative outcomes for patients undergoing resection for supratentorial meningiomas. Although sutured grafts may sometimes be necessary, nonsutured graft reconstruction for most supratentorial meningioma resections may suffice. The decreased operative time associated with nonsutured grafts may ultimately result in cost savings. These findings should be taken into consideration when selecting a dural reconstruction technique for supratentorial meningioma.

Comparison of Clinical and Radiologic Outcomes between Dural Splitting and Duraplasty for Adult Patients with Chiari Type I Malformation.

BACKGROUND: The most used surgical procedure in the treatment of patients with Chiari type I malformation (CIM) is posterior fossa decompression. However, no consensus has been reached regarding the superiority of either dural splitting or duraplasty. Thus, the aim of this study was to compare clinical and radiologic outcomes between the two techniques used in consecutive patients. METHODS: We retrospectively reviewed 74 adult patients with CIM who were diagnosed and treated surgically between 2015 and 2020 at our neurosurgery department. The patients were divided into two groups: dural splitting in group 1 and duraplasty in group 2. Clinical outcomes based on Chicago Chiari Outcome Scale (CCOS) scores at the last control visits were compared between the groups. Radiologic outcomes were compared in terms of tonsillar regression rate based on 12-postoperative-month magnetic resonance images. RESULTS: Overall improved, unchanged, and worsened neurologic statuses were observed in 75.6% (n = 56), 17.5% (n = 13), and 6.7% (n = 5) of our patients, respectively. The mean last visit CCOS scores in groups 1 and 2 were 12.3 ± 2.1 and 13.5 ± 1.7, respectively. The difference between the groups was statistically significant (p < 0.01). The mean tonsillar regression rates were 34.7 ± 17.0% and 52.1 ± 15.3% in groups 1 and 2, respectively, with a statistically significant difference (p < 0.001). CONCLUSION: Adult patients undergoing duraplasty had better clinical and radiologic outcomes than those treated with dural splitting. Therefore, we recommend decompression with duraplasty for adult CIM patients.

Stage M Infantile Neuroblastoma With Involvement of Falx Cerebri: Case Report and Literature Review.

Neuroblastoma is the most common extracranial solid tumor in children. When metastasis to the falx cerebri is present, it is classified as stage M; however, its behavior has not been well characterized. Here we present a case of stage M infantile neuroblastoma (NB) with involvement of the falx cerebri, and also summarize the clinical profiles of previously reported cases. Notably, all of the tumors resolved with low-dose chemotherapy alone. Although further study is needed to distinguish NBs presenting at these different intracranial locations, NB with metastasis to the falx cerebri may be categorized as MS when diagnosed at less than 18 months of age.