Arachnoid Membrane Research Articles

Long-term outcomes following surgical treatment of spinal arachnoid cysts: a population-based consecutive cohort study

BACKGROUND CONTEXTSpinal arachnoid cysts (SACs) are rare, cerebrospinal fluid-filled sacs lined by an arachnoid membrane in the spinal canal. Symptoms can develop due to pressure on the spinal cord or adjacent spinal nerves by the cyst itself or by interrupted flow of cerebrospinal fluid. If noninvasive management fails or neurological deterioration occurs, surgical treatment is recommended. However, data is lacking on long-term outcomes after surgery. PURPOSETo determine long-term outcomes in patients surgically treated for SACs. STUDY DESIGNPopulation-based cohort-study. PATIENT SAMPLEAll consecutive patients treated for either intra- or extradural SACs with surgery between 2005 and 2020 at the author's institution were included. OUTCOME MEASURESAmerican Spinal Injury Association Impairment Scale (AIS) and modified Japanese Orthopedic Association score (mJOA). METHODSData was primarily extracted from electronic patient medical notes. Telephone interviews were performed to assess long-term postoperative outcomes. All analyses were conducted using the statistical software program R version 4.0.5. Statistical significance was set at p<.05. RESULTSThirty-four patients were included. Cyst excision was performed in 11 (32%) cases, and fenestration in the remaining 23 (68%). The median follow-up time was 8.0 years. Surgery resulted in a significant long-term improvement in both AIS (p=.012) and mJOA (p=.005). Sensory deficit was the symptom that most often improved (81%), followed by pain (74%) and motor function (64%). AIS deteriorated in two patients, of which one case was attributed to a surgical complication. Local cyst recurrence requiring reoperation was seen in 4 (12%) cases, all of them following cyst fenestration. One patient (3%) required reoperation for progression of the cyst progression at a different level. CONCLUSIONThis study reports outcomes of surgically treated SACs with the longest follow-up time to date. Microsurgical cyst excision or fenestration were safe treatment options, and the neurological improvements seen in the immediate postoperative phase were maintained at long-term follow-up.

Clinicoradiologic Risk Stratification and Outcome Assessment in Symptomatic Intracranial Arachnoid Cyst Managed Over Fifteen Years

Arachnoid cysts (ACs) are developmental anomalies formed by splitting the arachnoid membrane's layers. ACs contribute around 2% of all intracranial space-occupying lesions. ACs are more prevalent in children. Because of varied clinical presentation, there has been a constant need for clinicoradiologic risk stratification with a possible role in outcome prediction. The present study describes the management strategies and outcomes in symptomatic intracranial ACs. All biopsy-proven symptomatic patients who underwent surgical management over last 15 years were included in this study (January 2008-December 2022), while those with non-conclusive biopsies were excluded. Patients presenting with acute deterioration were managed in the emergency department with or without cerebrospinal fluid diversion and decompression of the AC. The microsurgical or endoscopic approach was the preferred surgical modality. Postoperative clinicoradiologic improvement was evaluated at 3 months follow-up visit. A total of 108 patients were analyzed in this retrospective observational study. The median age of the patients was 27.5 years (range, 1 to 76 years). Headache was the most typical clinical presentation. Supratentorial ACs (n= 59, 54.6%) were higher than the infratentorial ACs (n= 49, 45.4%). Forty-seven patients belonged to the pediatric age group (<18 years), and seizure was their presenting complaint. In this observational study, there was no statistical difference in operative duration between microsurgical technique versus endoscopic decompression (P= 0.23). ACs are uncommon brain lesions having a broad spectrum of symptoms. The location and clinical presentation of ACs decide the preferred surgical approach. Individuals in high-risk groups must be treated on priority to achieve long-term relief of symptoms.

MicroRNAs miR-16 and miR-519 control meningioma cell proliferation via overlapping transcriptomic programs shared with the RNA-binding protein HuR.

Meningiomas are the most common type of primary central nervous system tumors. In about 80% cases, these tumors are benign and grow very slowly, but the remainder 20% can unlock higher proliferation rates and become malignant. In this study we examined two miRs, miR-16 and miR-519, and evaluated their role in tumorigenesis and cell growth in human meningioma. A cohort of 60 intracranial grade 1 and grade 2 human meningioma plus 20 healthy meningeal tissues was used to quantify miR-16 and miR-519 expressions. Cell growth and dose-response assays were performed in two human meningioma cell lines, Ben-Men-1 (benign) and IOMM-Lee (aggressive). Transcriptomes of IOMM-lee cells were measured after both miR-mimics transfection, followed by integrative bioinformatics to expand on available data. In tumoral tissues, we detected decreased levels of miR-16 and miR-519 when compared with arachnoid cells of healthy patients (miR-16: P=8.7e-04; miR-519: P=3.5e-07). When individually overexpressing these miRs in Ben-Men-1 and IOMM-Lee, we observed that each showed reduced growth (P<0.001). In IOMM-Lee cell transcriptomes, downregulated genes, among which ELAVL1/HuR (miR-16: P=6.1e-06; miR-519:P=9.38e-03), were linked to biological processes such as mitotic cell cycle regulation, pre-replicative complex, and brain development (FDR<1e-05). Additionally, we uncovered a specific transcriptomic signature of miR-16/miR-519-dysregulated genes which was highly enriched in HuR targets (>6-fold; 79.6% of target genes). These results were confirmed on several public transcriptomic and microRNA datasets of human meningiomas, hinting that the putative tumor suppressor effect of these miRs is mediated, at least in part, via HuR direct or indirect inhibition.

Hyaluronan hydrates and compartmentalises the CNS/PNS extracellular matrix and provides niche environments conducive to the optimisation of neuronal activity.

The central nervous system/peripheral nervous system (CNS/PNS) extracellular matrix is a dynamic and highly interactive space-filling, cell-supportive, matrix-stabilising, hydrating entity that creates and maintains tissue compartments to facilitate regional ionic micro-environments and micro-gradients that promote optimal neural cellular activity. The CNS/PNS does not contain large supportive collagenous and elastic fibrillar networks but is dominated by a high glycosaminoglycan content, predominantly hyaluronan (HA) and collagen is restricted to the brain microvasculature, blood-brain barrier, neuromuscular junction and meninges dura, arachnoid and pia mater. Chondroitin sulphate-rich proteoglycans (lecticans) interactive with HA have stabilising roles in perineuronal nets and contribute to neural plasticity, memory and cognitive processes. Hyaluronan also interacts with sialoproteoglycan associated with cones and rods (SPACRCAN) to stabilise the interphotoreceptor matrix and has protective properties that ensure photoreceptor viability and function is maintained. HA also regulates myelination/re-myelination in neural networks. HA fragmentation has been observed in white matter injury, multiple sclerosis, and traumatic brain injury. HA fragments (2 × 105 Da) regulate oligodendrocyte precursor cell maturation, myelination/remyelination, and interact with TLR4 to initiate signalling cascades that mediate myelin basic protein transcription. HA and its fragments have regulatory roles over myelination which ensure high axonal neurotransduction rates are maintained in neural networks. Glioma is a particularly invasive brain tumour with extremely high mortality rates. HA, CD44 and RHAMM (receptor for HA-mediated motility) HA receptors are highly expressed in this tumour. Conventional anti-glioma drug treatments have been largely ineffective and surgical removal is normally not an option. CD44 and RHAMM glioma HA receptors can potentially be used to target gliomas with PEP-1, a cell-penetrating HA-binding peptide. PEP-1 can be conjugated to a therapeutic drug; such drug conjugates have successfully treated dense non-operative tumours in other tissues, therefore similar applications warrant exploration as potential anti-glioma treatments.

P.128 Recurrent subarachnoid hemorrhage secondary to Chiari 1 malformation

Background: We describe a patient with recurrent subarachnoid hemorrhage (SAH) secondary to Chiari 1 malformation. Methods: A retrospective review of the clinical chart was performed. Results: A previously healthy female in her 70’s presented with worst headache of life. CT demonstrated 4th ventricular hemorrhage with SAH extending into the bilateral cerebellomedullary fissures. CTA did not show a vascular etiology and patient was discharged home. Incidental note was made of a right persistent trigeminal artery. The patient then represented 2 weeks later with worst headache of life and decreased level of consciousness. CT demonstrated extensive SAH extending into the 3rd and 4th ventricles. CTA and diagnostic cerebral angiogram did not show a vascular etiology. MRI brain/C-spine revealed Chiari 1 malformation. An external ventricular drain was placed but could not be weaned. She underwent suboccipital craniectomy with C1 laminectomy. Intraoperatively, there was a prominent dorsal spinal vein that appeared under tension as it pierced the arachnoid membrane and subsequently entering the dura as a rudimentary occipital sinus. This vein was coagulated and divided. The patient recovered well and was at neurological baseline at 6 month follow-up. Conclusions: This is the first reported case of recurrent SAH secondary to Chiari 1 malformation.

A synthetic model simulator for intracranial aneurysm clipping: validation of the UpSurgeOn AneurysmBox.

In recent decades, the rise of endovascular management of aneurysms has led to a significant decline in operative training for surgical aneurysm clipping. Simulation has the potential to bridge this gap and benchtop synthetic simulators aim to combine the best of both anatomical realism and haptic feedback. The aim of this study was to validate a synthetic benchtop simulator for aneurysm clipping (AneurysmBox, UpSurgeOn). Expert and novice surgeons from multiple neurosurgical centres were asked to clip a terminal internal carotid artery aneurysm using the AneurysmBox. Face and content validity were evaluated using Likert scales by asking experts to complete a post-task questionnaire. Construct validity was evaluated by comparing expert and novice performance using the modified Objective Structured Assessment of Technical Skills (mOSATS), developing a curriculum-derived assessment of Specific Technical Skills (STS), and measuring the forces exerted using a force-sensitive glove. Ten experts and eighteen novices completed the task. Most experts agreed that the brain looked realistic (8/10), but far fewer agreed that the brain felt realistic (2/10). Half the expert participants (5/10) agreed that the aneurysm clip application task was realistic. When compared to novices, experts had a significantly higher median mOSATS (27 vs. 14.5; p < 0.01) and STS score (18 vs. 9; p < 0.01); the STS score was strongly correlated with the previously validated mOSATS score (p < 0.01). Overall, there was a trend towards experts exerting a lower median force than novices, however, these differences were not statistically significant (3.8 N vs. 4.0 N; p = 0.77). Suggested improvements for the model included reduced stiffness and the addition of cerebrospinal fluid (CSF) and arachnoid mater. At present, the AneurysmBox has equivocal face and content validity, and future versions may benefit from materials that allow for improved haptic feedback. Nonetheless, it has good construct validity, suggesting it is a promising adjunct to training.

궁륭부 수막종으로 오인된 원발성 중추신경계 림프종

We are reporting the case of a 56-year-old female patient who presented with headache, nausea, and vomiting. Magnetic resonance imaging (MRI) revealed a homogeneous enhancing mass on the left frontal lobe. Based on the impression of a convexity meningioma, surgical treatment was planned, and intravenous (IV) steroids were administered to alleviate brain edema. Additional brain MRI was performed just before surgery for intraoperative navigation, which showed a significant reduction in tumor size. Due to the good response to IV steroids, we suspected that the tumor might be a differ-ent lesion rather than a meningioma, and thus, we proceeded with surgery for histologic diagnosis. Intraoperative findings revealed a whitish-gray, rubbery tumor adhering to the dura and arachnoid membrane, which was removed, and intraoperative frozen biopsy reported lymphoma. Finally, the patient was diagnosed with diffuse large B-cell lymphoma. This case report highlights the impor-tance of considering lesions that may be responsive to steroids and the imaging characteristics of lymphoma, which can be distinguished from other lesions.

Hyperplasia of Arachnoid Trabecular Cells: A Hitherto Undescribed Lesion Observed in the Setting of Neurofibromatosis Type 1.

Central nervous system manifestations, a variety of benign and malignant tumors as well as non-neoplastic abnormalities, are found in over 70% of neurofibromatosis type 1 (NF1) patients. Herein, we report hitherto undescribed space-occupying lesions in the setting of NF1. We aimed to clarify their characteristics, especially whether they represent neoplastic or non-neoplastic (hyperplastic) lesions. All 3 cases were preoperatively assessed as non-neoplastic; 2 and 1 cases were suspected to be arachnoid cysts and dilation of subarachnoid space, respectively. However, all lesions were revealed to be whitish jelly-like masses by operation, and the histology composed of spindle cells resembling arachnoid trabecular cells with moderate cellularity and cellular uniformity gave an impression that these lesions may be neoplastic. In contrast, electron microscopic analysis showed that the characteristics of these cells were compatible with those of normal arachnoid trabecular cells. Furthermore, whole-exome sequencing and array comparative genomic hybridization did not show any obvious alterations suggestive of their neoplastic nature. DNA methylation analysis demonstrated that these lesions were epigenetically distinct not only from meningiomas but also from normal healthy meninges. In conclusion, considering the clinicopathologic aspects of the present lesions and the results of the molecular analysis that failed to suggest their neoplastic nature, they may represent previously unrecognized rare hyperplasia of arachnoid trabecular cells, which may be associated with NF1.

DNA methylation profile of human dura and leptomeninges.

Healthy meninges are used as control tissue in meningioma studies usually without specification of the exact meningeal layer or macroanatomical origin but the DNA methylation profile of human meninges has not been investigated on a macroanatomical level. We undertook a proof-of-principle analysis to determine whether (1) meningeal tissues show sufficiently homogenous DNA methylation profiles to function as normal control tissue without further specification and (2) if previously described location-specific molecular signatures of meningiomas correspond to region-specific DNA methylation patterns. Dura mater and arachnoid membrane specimens were dissected from 5 anatomical locations in 2 fresh human cadavers and analyzed with the Illumina Infinium MethylationEPIC array. Dura and leptomeninges showed marked differences in global DNA methylation patterns and between rostral and caudal anatomical locations. These differences did not reflect known anatomical predilection of meningioma molecular signatures. The highest numbers of differentially methylated probes were annotated to DIPC2 and FOXP1. Samples from foramen magnum showed hypomethylation of TFAP2B compared to those from remaining locations. Thus, the DNA methylation profiles of human meninges are heterogenous in terms of meningeal layer and anatomical location. The potential variability of DNA methylation data from meningiomas should be considered in studies using meningeal controls.

Interhemispheric arachnoid cysts: case series

Objective: Interhemispheric arachnoid cysts (IHACs) are a rare congenital malformation arising from the duplication of the arachnoid membrane of the cerebral meninges associated with malformations of the corpus callosum. The scope of this study is to describe a series of cases of IHACs treated via neuroendoscopy in a reference center. Method: description of a case series of children diagnosed with IHAC undergoing neuroendoscopic treatment (cystoventriculostomy) between 2015 and 2022, describing the main clinical manifestations, the surgical indication, and the neuroendoscopic technique performed. Results: Four children diagnosed with IHACs, with a predominance of males (3:1), were included in the study. Considering the Mori and Barkovich classification systems, magnetic resonance imaging of the brain showed multiseptate extra-axial interhemispheric cysts without communication with the ventricular system in all cases. Macrocrania and bulging fontanel were the clinical manifestations that indicated urgent hospitalization for the proposed neurosurgical treatment. Conclusion: Signs of increased intracranial pressure were observed in all cases of IHACs in the first months of life. Endoscopic cystoventriculostomy was performed in all cases with satisfactory results, showing that this is an option to be evaluated for the treatment of IHACs classified as multiseptate extra-axial and without communication with the ventricular system or brain cisterns, according to Mori and Barkovich classification systems.

Microsurgical anatomy and pathoanatomy of the outer arachnoid membranes in the cerebellopontine angle: cadaveric and intraoperative observations.

The cerebellopontine angle (CPA) is a frequent region of skull base pathologies and therefore a target for neurosurgical operations. The outer arachnoid is the key structure to approach the here located lesions. The goal of our study was to describe the microsurgical anatomy of the outer arachnoid of the CPA and its pathoanatomy in case of space-occupying lesions. Our examinations were performed on 35 fresh human cadaveric specimens. Macroscopic dissections and microsurgical and endoscopic examinations were performed. Retrospective analysis of the video documentations of 35 CPA operations was performed to describe the pathoanatomical behavior of the outer arachnoid. The outer arachnoid cover is loosely attached to the inner surface of the dura of the CPA. At the petrosal surface of the cerebellum the pia mater is strongly adhered to the outer arachnoid. At the level of the dural penetration of the cranial nerves, the outer arachnoid forms sheath-like structures around the nerves. In the midline, the outer arachnoid became detached from the pial surface and forms the base of the posterior fossa cisterns. In pathological cases, the outer arachnoid became displaced. The way of displacement depends on the origin of the lesion. The most characteristic patterns of changes of the outer arachnoid were described in case of meningiomas, vestibular schwannomas, and epidermoid cysts of the CPA. The knowledge of the anatomy of the outer arachnoid of the cerebellopontine region is essential to safely perform microsurgical approaches as well as of dissections during resection of pathological lesions.

The Microcisternal Drainage Technique

Microsurgical dissection of arachnoid cisterns requires a combination of anatomic knowledge and microsurgical skill. The latter relies on experience and microsurgical dexterity, which depend on visual identification of cisternal microvasculature. We describe a novel standardized operative sequence to allow for bloodless arachnoid dissection when cisternal anatomy is challenging. We used the reported technique in 1928 cases over the past 5 years (2018-2022). The outer arachnoid was incised to enter the cisternal space. A cotton pledget was placed in contact with an inner membrane and gently pushed laterally and superficially with the suction cannula at medium suction power. When the arachnoid membranes dried, arachnoid trabeculae were cut and microvasculature were released at the convexity of their loops and gently transposed off the dissection trajectory. The same principle was used to release parent and perforating arteries from the aneurysm dome. The microcisternal drainage technique enabled safe and efficient access through adhered arachnoid in all cases. A complex anterior communicating artery aneurysm in a 52-year-old lady demonstrated the use of the microcisternal drainage technique during access through the pericallosal cistern. This technique was used in all cases where cisternal dissection was needed. The microcisternal drainage technique uses deliberate and strategic suction, dynamic retraction, and nuanced scissor cuts to enable precise and bloodless microdissection of adherent arachnoid cisterns. This technique combines common neurosurgical maneuvers in a novel standardized sequence to improve efficiency and safety during arachnoid dissection.

Endoscopic Fenestration of an Intra-ventricular Arachnoid Cyst in a Young Male – A Rare Entity

Introduction: Among intracranial space-occupying lesions, arachnoid cysts compromise 1% only. Abnormal collection of cerebrospinal fluid occurs in these types of cysts leading to pressure symptoms. Developmental abnormalities of cerebrospinal structures in early fetal life lead to the primary type of arachnoid cysts, while the second type of arachnoid cyst is formed after some neurological insult like head injury, tumor, meningitis, or brain surgery. In 60 – 90% of cases, the primary type predominates and presents with pressure symptoms before the age of 20 years. The adjudged incidence is 1.4% in adults, the least frequent being intraventricular location. Clinical Case: A 23-year-old male presented with a long-standing left-sided cranial vault headache, right-sided focal seizures, and progressive right- hemiparesis. Neurological evaluation revealed upper motor neuron signs on the right side of the body. A computerized axial tomography raised the suspicion of an arachnoid cyst for which magnetic resonance imaging was done which revealed a large intraventricular cyst of lateral ventricles causing mass effect over the ipsilateral hemisphere and mild obstructive hydrocephalous. Surgical intervention was required as per symptomology (intractable headache, seizures, and hemiparesis) and large cyst size. Conclusion: Cerebrospinal fluid accumulation in the brain's arachnoid layer causes non-cancerous arachnoid cysts. Larger cysts may push on brain tissue and cause neurological difficulties. MRI may diagnose arachnoid cysts, and treatment options include cystoperitoneal shunt, craniotomy, and neuro-endoscopic fenestration, the least invasive. Cyst size and location determine therapy. In this example, endoscopic treatment reduced symptoms and consequences.

877 EZH2 Inhibition Decreases SMARCB1 and NF2 Mutant Meningioma Cell Viability

INTRODUCTION: The majority of sporadic and familial forms of meningiomas bear mutations in NF2. A subset of NF2 mutant meningiomas are co-mutant for SMARCB1, which encodes the SWI/SNF complex core subunit BAF47, grow in the midline/parafalcine region, and confer risk for atypia. SMARCB1/NF2 meningiomas and WHO Grade II NF2 meningiomas have demonstrated PRC2/EZH2 hyperactivity by ChIPseq analysis, providing a rationale for EZH2 inhibition for these aggressive tumors. METHODS: Pharmacologic growth inhibition experiments were conducted in a SMARCB1/NF2 co-mutant meningioma cell line (BEN-MEN-1), an NF2 mutant/SMARCB1 wildtype meningioma cell line (MN1-LF), and a control wildtype arachnoid cell line (A2). Tazemetostat was administered in triplicate at 9 dosages (ranging from 1.5 uM to 10 mM) over 14 days. Cell viability was calculated via luminescent-based assay and normalized to DMSO-treated cells. RESULTS: After 14 days of tazemetostat treatment, SMARCB1/NF2 mutant cells showed a significantly decreased viability compared to control arachnoid cells (26.87% viability for SMARCB1 mutant vs 87.80% viability for arachnoid cells; p = 0.0047). NF2 mutant meningioma cells also had significantly decreased viability (48.84% vs 87.80%, p = 0.0102). The calculated IC50 for tazemetostat is 3.098 mM for SMARCB1/NF2 mutant cells, 6.263 mM for NF2 mutant cells, and was estimated to be 43.98 mM in control arachnoid cells using nonlinear regression. CONCLUSIONS: Tazemetostat decreases viability for both SMARCB1/NF2 and NF2 mutant meningioma cells. This represents a novel pharmacologic target for the majority of meningiomas, and may obviate the need for repeat surgery for recurrent tumors or serve as a suppressant agent for patients with neurofibromatosis type II.

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

BackgroundDespite 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.MethodsDura 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).ResultsThe 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.ConclusionsThe 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.

Symptomatic arachnoiditis ossificans associated with syringomyelia: a clinical case and a brief literature review

Objective. To present a clinical case of arachnoiditis ossificans associated with syringomyelia and a brief literature review with an emphasis on its etiology, pathogenesis and methods of diagnosis and treatment.Material and Methods. A clinical case of a 68-year-old patient with symptomatic arachnoiditis ossificans is described. The diagnosis was established on the basis of the results of intraoperative biopsy, histological examination of the resected fragment and confirmed in the postoperative period using CT of the spinal cord, multislice CT myelography, etc. Analysis of the course of the pathology raised the following questions: diagnostic criteria and optimal tactics for treating this disease. A brief review of cases of arachnoiditis ossificans described in the literature for the period from 1982 to the present is given.Results. A review of cases of ossifying arachnoiditis described in the literature showed that today there is no single tactic for diagnosing and treating this disease. In most cases, the diagnosis is established intraoperatively (65 % of analyzed cases). At the preoperative stage, CT provides reliable visualization of ossification. When choosing therapy, it is necessary to be based on the severity of the clinical picture, the degree of ossification of the arachnoid membrane and the presence of concomitant pathology of the affected spinal cord department (such as syringomyelia).Conclusion. The presence of a growing neurological deficit should be considered an indication for surgical treatment of patients with arachnoiditis ossificans. The goals of surgery should include decompression of neural structures and restoration of normal cerebrospinal fluid circulation.

Large-scale morphometry of the subarachnoid space of the optic nerve

BackgroundThe meninges, formed by dura, arachnoid and pia mater, cover the central nervous system and provide important barrier functions. Located between arachnoid and pia mater, the cerebrospinal fluid (CSF)-filled subarachnoid space (SAS) features a variety of trabeculae, septae and pillars. Like the arachnoid and the pia mater, these structures are covered with leptomeningeal or meningothelial cells (MECs) that form a barrier between CSF and the parenchyma of the optic nerve (ON). MECs contribute to the CSF proteome through extensive protein secretion. In vitro, they were shown to phagocytose potentially toxic proteins, such as α-synuclein and amyloid beta, as well as apoptotic cell bodies. They therefore may contribute to CSF homeostasis in the SAS as a functional exchange surface. Determining the total area of the SAS covered by these cells that are in direct contact with CSF is thus important for estimating their potential contribution to CSF homeostasis.MethodsUsing synchrotron radiation-based micro-computed tomography (SRµCT), two 0.75 mm-thick sections of a human optic nerve were acquired at a resolution of 0.325 µm/pixel, producing images of multiple terabytes capturing the geometrical details of the CSF space. Special-purpose supercomputing techniques were employed to obtain a pixel-accurate morphometric description of the trabeculae and estimate internal volume and surface area of the ON SAS.ResultsIn the bulbar segment, the ON SAS microstructure is shown to amplify the MECs surface area up to 4.85-fold compared to an “empty” ON SAS, while just occupying 35% of the volume. In the intraorbital segment, the microstructure occupies 35% of the volume and amplifies the ON SAS area 3.24-fold.ConclusionsWe provided for the first time an estimation of the interface area between CSF and MECs. This area is of importance for estimating a potential contribution of MECs on CSF homeostasis.

Diagnosis and treatment of spinal extradural arachnoid cysts: A chronic traumatic case report with review of the literature

Arachnoid cysts are formed by duplication of the arachnoid membrane between the arachnoid and the pia mater. Although it is very common in intracranial localization, those with spinal location are rare. Extradural arachnoid cysts of the spinal canal are extremely rare pathologies regarded as either congenital or acquired. These cysts, which can develop idiopathic, post-traumatic, and after arachnoiditis, are often detected incidentally. They present with weakness in the extremities, neuropathic pain, paresthesia, or myelopathy. Here we describe the case of a 17-year-old male patient with a history of chronic spinal trauma who attended our clinic with severe low back pain for 7 months.

A Classification Proposal for Spinal Vascular Lesions.

A Classification Proposal for Spinal Vascular Lesions.

Cavernous Malformations: What They Have Taught Us.

Cavernous Malformations: What They Have Taught Us.