Arachnoid granulations

BACKGROUND: The etiology of a non-sinus-type dural arteriovenous fistulas (DAVFs) with shunt points located on the sinus wall, previously described as on-the-wall-type DAVFs, is unknown. CASE DESCRIPTION: Two cases of non-sinus-type transverse sinus DAVF with a shunt point limited to the dural sinus wall, causing cortical venous reflux, were successfully treated with endovascular transarterial Onyx embolization. The Onyx cast showed multiple feeders from the occipital and middle meningeal arteries aggregated in the arachnoid granulation (AG), which dilated the draining vein...

BACKGROUND: Bilateral transverse venous sinus stenosis (TVSS) or stenosis of a dominant venous sinus has been found to be very sensitive radiological findings in patients with intracranial hypertension (IH), yet there is still an ongoing debate whether they constitute reversible or permanent phenomena. Thus, the purpose of this study was to investigate the reversibility of TVSS in patients with IH, including conservatively treated patients with signs of IH as defined by the presence of papilledema...

BACKGROUND: Peri-sinus structures such as arachnoid granulations (AG) and the parasagittal dural (PSD) space have gained much recent attention as sites of cerebral spinal fluid (CSF) egress and neuroimmune surveillance. Neurofluid circulation dysfunction may manifest as morphological changes in these structures, however, automated quantification of these structures is not possible and rather characterization often requires exogenous contrast agents and manual delineation. METHODS: We propose a deep learning architecture to automatically delineate the peri-sinus space (e...

This case report presents a rare anatomical variant of the torcular Herophili, characterized by a circular configuration and the absence of the left transverse sinus. A 12-year-old child presented with intermittent holocranial headaches, and imaging revealed the circular torcular Herophili along with mild ventricular enlargement. The straight sinus drained into the left side of the circular torcular Herophili. Following lumbar puncture and cerebrospinal fluid (CSF) drainage, the child experienced symptom improvement...

Postsurgery intracranial air usually diminishes, presumably merging with cerebrospinal fluid (CSF) and venous circulation. Our study presents two transsphenoidal surgery cases, highlighting potential air absorption by arachnoid granulation (AG)-an underexplored phenomenon. AG has long been deemed pivotal for CSF absorption, but recent perspectives suggest a significant role in waste clearance, neuroinflammation, and neuroimmunity. These cases may stimulate renewed research on the multifaceted role of AG in neurofluid dynamics and potentially elucidate further AG functions...

Xanthogranulomas are considered rare tumors, with their sellar and non-sellar frequency ranging from 1.6 to 7% among intracranial lesions, and described as a separate entity by the World Health Organization in 2000. The diagnosis of sellar xanthogranulomas is challenging, given their uncertain origin and clinical course. In addition, the limited reporting of sellar xanthogranuloma cases and the absence of characteristic images make these entities difficult to distinguish from other cystic lesions of the sellar region, such as adamantinomatous craniopharyngiomas, Rathke's cleft cysts, pituitary tumors, arachnoid cysts, epidermoid cysts, and dermoid cysts...

No abstract text is available yet for this article.

Giant arachnoid granulations (GAGs) are minimally investigated. Here, we systematically review the available data in published reports to better understand their etiologies, nomenclature, and clinical significance. In the literature, 195 GAGs have been documented in 169 persons of varied ages (range, 0.33 to 91 years; mean, 43 ± 20 years; 54% female). Prior reports depict intrasinus (i.e., dural venous sinus, DVS) (84%), extrasinus (i.e., diploic or calvarial) (15%), and mixed (1%) GAG types that exhibit pedunculated, sessile, or vermiform morphologies...

The accumulation of harmful substances has long been recognized as a likely cause of many neurodegenerative diseases. The two classic brain clearance pathways are cerebrospinal fluid (CSF) and vascular circulation systems. Since the discovery of the glymphatic system, research on the CSF pathway has gained momentum, and impaired CSF clearance has been implicated in virtually all neurodegenerative animal models. However, the contribution of the direct participation of vascular transport across the blood-brain barrier in clearing substances is often ignored in glymphatic papers...

Giant arachnoid granulations (GAGs) are poorly investigated. Here, we document clinical findings associated with five new GAGs and illustrate the anatomical composition of these structures as well as diagnostic considerations in three symptomatic adults. The GAGs ranged from 1.1 to 3.6 cm (mean, 2.2 cm) in maximum dimension and manifested in middle-aged individuals who presented with long-standing brain mass and/or chronic headache. On imaging examinations, the tissues appeared as irregular parasagittal and/or perisinus structures that demonstrated heterogeneous internal elements...

A 69-year-old woman suffered attacks of hearing disturbance and vertigo for seven years. Her otologic and ophthalmological examinations did not show any significant findings. Cerebral magnetic resonance imaging revealed a cystic mass in the left cerebellar convexity. Computed tomography demonstrated a contrast defect of the distal left transverse sinus. Magnetic resonance imaging revealed a cyst protruding into the transverse sinus, and enlarging in the supine. Cerebral angiography demonstrated a congestive venous flow in the left transverse sinus, at the upstream of the cyst...

The functions of the glymphatic system include clearance of the metabolic waste and modulation of the water transport in the brain, and it forms a brain-wide fluid network along with cerebrospinal fluid (CSF) and interstitial fluid (ISF). The glymphatic pathway consists of periarterial influx of CSF, astrocyte-mediated interchange between ISF and CSF supported by aquaporin-4 (AQP4) on the endfeet of astrocyte around the periarterioles, and perivenous efflux of CSF. Finally, CSF is absorbed by the arachnoid granules or flows into the cervical lymphatic vessels...

OBJECTIVE: Spontaneous nasal cerebrospinal fluid (CSF) leaks are frequently linked to idiopathic intracranial hypertension (IIH). The objectives of our study were: (1) to determine the rate of transverse venous sinus stenosis (TVSS) in patients with spontaneous nasal CSF leak and in patients with IIH without CSF (controls), and (2) to study the correlation between spontaneous nasal CSF leak and brain imaging features. STUDY DESIGN: A multicenter retrospective case-control study...

OBJECTIVE: Several studies in the literature have used contrast-enhanced magnetic resonance imaging to investigate arachnoid granulations protruding into the cranial dural sinuses. The current study aimed to investigate the protrusion of arachnoid granulations into the superior sagittal sinus, transverse sinus, straight sinus, and confluence of sinuses and determine the frequency of brain herniation into giant arachnoid granulations using contrast-enhanced 3-dimensional T1-weighted magnetic resonance imaging...

No abstract text is available yet for this article.

OBJECTIVES: Idiopathic intracranial hypertension (IIH) is a disease defined by elevated intracranial pressure (ICP) without an established etiology. Arachnoid granulations (AG) are conduits for CSF resorption from the subarachnoid space to the venous system. AG have been implicated to play a central role in maintaining CSF homeostasis. We tested the hypothesis that patients with fewer visible AG on MRI are more likely to present with IIH. METHODS: In this institutional review board (Institutional Review Board)-approved retrospective chart review study, 65 patients with a clinical diagnosis of idiopathic intracranial hypertension were compared to 144 control patients who met inclusion/exclusion criteria...

OBJECTIVE: Many but not all patients with idiopathic intracranial hypertension (IIH) have pulsatile tinnitus (PT). However, little is known about why some patients with IIH develop PT and others do not. The purpose of this study was to determine if any of the classic magnetic resonance imaging (MRI)-detectable markers of IIH differ between patients with and without PT, thereby shedding light on potential pathophysiology. METHODS: A retrospective age-matched cohort study of patients with documented IIH (diagnosed by neuro-ophthalmologist) was performed...

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...

Cerebrospinal fluid (CSF) production and absorption concept significantly changed in the early 2010s from "third circulation theory" and "classical bulk flow theory" to a whole new one as follows: First, CSF is mainly produced from interstitial fluid excreted from the brain parenchyma, and CSF produced from the choroid plexus plays an important role in maintaining brain homeostasis. Second, CSF is not absorbed in the venous sinus via the arachnoid granules, but mainly in the dural lymphatic vessels. Finally, the ventricles and subarachnoid spaces have several compensatory direct CSF pathways at the borders attached to the choroid plexus, e...

Although the microanatomy of Meckel's cave (MC) has been well studied, there are still controversies regarding the meningeal architecture of the space. Moreover, there are only general mentions of the arachnoid granulations near MC in just a few sources. This study is aimed at determining the frequency, location, and anatomical variability of the main clusters of arachnoid granulations around MC. The dissection involved 26 isolated specimens of MC fixed in formalin (neutral buffered, 10%). This number included five freshly harvested specimens examined histologically...