Normal pio-dural arterial connections

Dural arteriovenous fistulas in the falx cerebri: case series and literature review

Dural arteriovenous fistulas (DAVFs) within the falx cerebri are infrequently documented and may be linked with the falcine sinus/venous plexus. The falcine sinus/venous plexus, often regarded as a normal venous structure, can exhibit pathological characteristics, differing from the persistent fetal falcine sinus. A retrospective analysis was conducted at a single center to identify all cases of DAVFs within the falx cerebri spanning from 2002 to 2022. Demographic data, fistula features, treatment modalities, clinical outcomes, and fistula closure were collected and analyzed. Additionally, relevant literature on DAVFs in this location was reviewed. Ten cases were identified at our center, supplemented by 13 cases reported in the literature. In our cohort, patients had an average age of 49.4 ± 8.1 years, with a male predominance of 90%. Trans-arterial embolization (TAE) alone achieved immediate complete occlusion in eight cases, while conservative treatment was pursued in two cases. No treatment-related complications or fistula recurrences were observed. In the literature, seven patients underwent direct surgery, three underwent TAE, and one underwent both direct surgery and radiosurgery for complete fistula closure. No instances of fistula recurrence or treatment complications were reported. Dural arteriovenous fistulas within the falx cerebri are rare, with limited literature available. They typically present as aggressive lesions. Treatment options include direct surgery or TAE. However, due to a lack of long-term DSA follow-up, the cure and recurrence rates are unknown for endovasdcular therapy. Further investigation is warranted to elucidate the involvement of the falcine sinus/venous plexus in falx cerebri DAVFs.

In vitro comparison of middle meningeal artery embolization with Squid liquid embolic agent and Contour polyvinyl alcohol particles

BACKGROUND

Liquid embolic agents and polyvinyl alcohol (PVA) particles have been used for the embolization of the middle meningeal artery (MMA) for the treatment of chronic subdural hematomas. However, the vascular penetration and distribution of these embolic agents have not yet been compared. The current study compares distribution of a liquid embolic agent (Squid) to PVA particles (Contour) in an in vitro model of the MMA.

METHODS

MMA models were embolized with Contour PVA particles 45-150 µm, Contour PVA particles 150-250 µm, and Squid-18 liquid embolic agent (n=5 each). The models were scanned and every vascular segment with embolic agent was manually marked on the images. Embolized vascular length as a percentage of control, average embolized vascular diameter, and embolization time were compared between the groups.

RESULTS

The 150-250 µm Contour particles primarily accumulated close to the microcatheter tip, yielding proximal branch occlusions. The 45-150 µm Contour particles achieved a more distal distribution, but in a patchy segmental pattern. However, the models embolized with Squid-18 had a consistently distal, near-complete and homogenous distribution. Embolized vascular length was significantly higher (76±13% vs 5±3%, P=0.0007) and average embolized vessel diameter was significantly smaller (405±25 µm vs 775±225 µm, P=0.0006) with Squid than with Contour. Embolization time with Squid was also lower (2.8±2.4 min vs 6.4±2.7 min, P=0.09).

CONCLUSIONS

Squid-18 liquid results in a considerably more consistent, distal and homogeneous pattern of embolysate distribution than Contour PVA particles in an anatomical model of the MMA tree.

Posterior inferior cerebellar artery originating from the posterior meningeal artery mimicking dural arteriovenous fistula

PURPOSE

Many variations in the origin of the posterior inferior cerebellar artery (PICA) have been reported. To our knowledge, only one case of a PICA originating from the posterior meningeal artery (PMA) has been reported.

METHODS

We describe a case with a PICA that was supplied retrograde from the distal segment of the PMA, mimicking a dural arteriovenous fistula on magnetic resonance angiography (MRA).

RESULTS

A 31-year-old man was admitted to our hospital with a sudden occipital headache and nausea. MRA showed a hyperplastic left PMA, continuing to an abnormal vessel that was suspicious for venous drainage. Digital subtraction angiography revealed the left PMA originated from the extradural segment of the vertebral artery and then connected to the left PICA near the torcula. The cortical segment of the PICA flowed retrograde, which appeared as venous reflux on MRA. A second PICA originated from the extradural segment of the left vertebral artery and perfused the tonsillomedullary and televelotonsillar segment of the left PICA territory.

CONCLUSION

We present an anatomical variant of the PICA mimicking a dural arteriovenous fistula. Digital subtraction angiography is useful for diagnosis of the cortical segment of the PICA flowing retrograde from the distal segment of the PMA because signal intensity in MRA of retrograde flow tends to decrease and diagnosis may be difficult. During endovascular treatment and open surgery, we should note that ischemic complications may occur due to the potential anastomosing channels between cerebral and dural arteries.

Analysis of the Pial Arterial Supply as a Cause of Intraprocedural Hemorrhage During Transarterial Liquid Embolization of Tentorial Dural Arteriovenous Fistulas

OBJECTIVE

Tentorial dural arteriovenous fistulas (AVFs) are bridging vein shunts, and are therefore sometimes supplied by the pial artery as well as the dural artery. Recently, intraprocedural hemorrhage from the pial artery was reported, and we experienced 2 tentorial dural AVFs with the same complication. Pure pial artery has a glomus-like structure and forms direct shunts along the draining vein, and is likely to bleed after restriction of the draining vein caused by the transarterial embolization. This study investigated the characteristics of the pial arterial supply as a cause of hemorrhage.

METHODS

Twenty-six tentorial dural AVFs in 25 patients treated in our institute were retrospectively investigated and the characteristics of the pial feeders responsible for bleeding were analyzed.

RESULTS

Thirteen pial arterial feeders (pure pial feeder in 7, dilated dural branch of the pial artery in 4, and undefined in 2) were identified in 10 of the 26 tentorial dural AVFs. Pure pial feeders were responsible for bleeding in 2 tentorial dural AVFs.

CONCLUSIONS

To prevent intraprocedural hemorrhage, differentiation of the pure pial supply from the dural branch of the pial artery is important. The infratentorial artery will supply supratentorial fistula as the dural branch after passing through the tentorium. In contrast, the supratentorial artery can supply supratentorial fistula not only as a dural branch but also as a pure pial feeder. Therefore, attribution of the fistula and the pial supply, supratentorial or infratentorial, is useful in identifying pure pial supply.

Mixed Pial-Dural Arteriovenous Malformation in the Anterior Cranial Fossa Mimicking Dural Arteriovenous Fistula

Mixed pial-dural arteriovenous malformation (MpdAVM) and dural arteriovenous fistula (dAVF) are rare entities in the anterior cranial fossa (ACF). As dural-pial vascular anastomosis can exist near the cribriform plate, MpdAVM with a small nidus, which cannot be apparently identified, can be logically indistinguishable from dAVF in ACF. A 71-year-old man was referred for evaluation of possible intracranial vascular malformation. Cerebral angiography revealed an arteriovenous shunt in the ACF. The lesion was fed by the bilateral ethmoidal arteries and right orbitofrontal artery, draining through the bilateral cortical veins to the superior sagittal sinus. As a nidus was not detected, dAVF was suspected. Venous interruption was planned with direct surgery. Intraoperatively, an arterial aggregation was observed in the right frontal lobe. The arterial aggregation seemed to be connected to the interrupted drainer in the right ACF. The arterial aggregation was removed and pathologically diagnosed as arteriovenous malformation. Postoperatively, intracerebral hemorrhage was confirmed, and postoperative cerebral angiography confirmed the resolved arteriovenous shunt. The intracranial hemorrhage was possibly due to the timing gap between drainer interruption and removal of the nidus. MpdAVM with a small nidus in the ACF can mimic dAVF. Clinicians must be aware that an unremoved nidus of MpdAVM may postoperatively result in fatal intracranial hemorrhage.

Vermian subtentorial arteriovenous malformation supplied by the artery of Wollschlaeger and Wollschlaeger

BACKGROUND

The artery of Wollschlaeger and Wollschlaeger is a tentorial branch of the superior cerebellar artery: due to its small diameter, it is not usually seen in normal angiograms except when enlarged in the setting of a dural AVF or tentorial meningioma. Its presence has been rarely described in the Literature.

CASE REPORT

herein we describe the first ever reported case of a vermian subtentorial arteriovenous malformation supplied by the artery of Wollschlaeger and Wollschlaeger in 70 year old female patient.

CONCLUSION

vermian subtentorial AVMs supplied by the artery of Wollschlaeger and Wollschlaeger are extremely rare vascular malformations. The presence of the artery of Wollschlaeger and Wollschlaeger must be carefully evaluated during preoperative surgical planning due to its key role in the supply of vascular malformation and to decrease the risk of intra operative bleeding during surgery.

Neuroanatomy of cranial dural vessels: implications for subdural hematoma embolization

Adoption of middle meningeal artery embolization in the management of chronic subdural hematomas has led to a renewed interest in dural vascular anatomy. The readily identifiable major dural arteries and potential hazards associated with their embolization are well described. Less emphasized are several levels of intrinsic dural angioarchitecture, despite their more direct relationship to dural based diseases, such as subdural hematoma and dural fistula. Fortunately, microvascular aspects of dural anatomy, previously limited to ex vivo investigations, are becoming increasingly accessible to in vivo visualization, setting the stage for synthesis of the old and the new, and providing a rationale for the endovascular approach to subdural collections in particular. In contrast with traditional anatomical didactics, where descriptions advance from larger trunks to smaller pedicles, we present a strategic approach that proceeds from a fundamental understanding of the dural microvasculature and its relationship to larger vessels.

Microsurgical Findings of Pial Arterial Feeders in Intracranial Dural Arteriovenous Fistulae: A Case Series

BACKGROUND

Pial arterial feeders in an intracranial dural arteriovenous fistula (dAVF) are risk factors for both ischemic and hemorrhagic complications during endovascular embolization. Microsurgery in dAVF with pial arterial feeders has rarely been reported.

OBJECTIVE

To assess our original experience with microsurgery for dAVF with pial arterial feeders by investigating surgical findings and outcomes.

METHODS

In 40 patients with intracranial dAVF who underwent microsurgery, we found 8 patients who had pial arterial feeders. A retrospective review was conducted.

RESULTS

The locations of the dAVFs were as follows: tentorium, 2 patients; Galenic system, 1; straight sinus, 1; torcula, 1; transverse sinus, 1; ethmoid, 1; and convexity, 1. Preoperative angiography revealed that the pial arterial feeders originated from the middle cerebral artery in 2 patients, the anterior cerebral artery in 1, the posterior cerebral artery in 2, and the posterior medial choroidal artery in 1. Of note, in 2 patients (6.7%), feeders from the superior cerebellar artery were determined to be angiographically occult during preoperative examination and were detected through careful intraoperative observation and arachnoid dissection. In 5 cases, the additional obliteration of the pial arterial feeders and/or more distal cortical venous drainers after the simple disconnection of proximal cortical drainers was necessary to cure the dAVF. Finally, all shunts were cured with only 1 minor complication.

CONCLUSION

Although microsurgical results were acceptable, the surgeon should be aware of the presence of pial arterial feeders even after the simple disconnection of cortical venous drainage. Angiographically occult feeders may also exist.

Clinical, angiographic, and treatment characteristics of cranial dural arteriovenous fistulas with pial arterial supply

BACKGROUND

The prevalence of pial arterial supply to cranial dural arteriovenous fistulas (dAVF) and its implication in the management of these fistulas is not well characterized. We performed a retrospective study to characterize pial arterial supply to dural arteriovenous fistulas and the implications for treatment.

METHODS

Consecutive patients evaluated over a 12-year period were retrospectively reviewed. Angiograms were reviewed to characterize dAVF angioarchitecture and the presence of pial artery supply. Pial artery supply was categorized as dilated pre-existing dural branches and pure pial supply. We then studied the association between pial artery supply and clinical, angiographic, and treatment features.

RESULTS

A total of 201 patients were included of which 27 (13.4%) had pial artery supply. Of these, 11 had supply from dilated pre-existing dural branches, nine had pure pial supply,and seven had both. There was a higher rate of dAVF rupture in the pial supply group (30.8% vs 9.8%, P=0.003) and these fistulas had a higher rate of Borden 2 and 3 (88.9% vs 38.4%, P<0.0001). Fistulas with pial artery supply had similar rates of endovascular and gamma knife treatment, but were more likely to undergo surgery than those without pial supply (25.9% vs 10.4%, P=0.03). Major complication rates were similar between groups (0% vs 1.1%, P=0.55).

CONCLUSIONS

More than 10% of dAVFs also have pial supply but this is not a contraindication to embolization. In our study pure pial supply was associated with a more aggressive fistula and was most common in tentorial dAVFs.

The anatomy and immunology of vasculature in the central nervous system

Barriers between circulation and the central nervous system (CNS) play a key role in the development and modulation of CNS immune responses. Structural variations in the vasculature traversing different anatomical regions within the CNS strongly influence where and how CNS immune responses first develop. Here, we provide an overview of cerebrovascular anatomy, focusing on the blood-CNS interface and how anatomical variations influence steady-state immunology in the compartment. We then discuss how CNS vasculature is affected by and influences the development of different pathophysiological states, such as CNS autoimmune disease, cerebrovascular injury, cerebral ischemia, and infection.

Microsurgical Anatomy of the Meningeal Branch of the Dorsolateral Medullary Plexus

BACKGROUND

Meningeal branches originating from intradural arteries may be involved in several diseases such as meningeal tumors and arteriovenous lesions. These "pial-dural" arterial connections have been described for anterior cerebral, posterior cerebral, and cerebellar arteries. However, to the best of our knowledge, meningeal supply originating from the arterial plexus over the dorsolateral aspect of the medulla oblongata (dorsolateral medullary plexus [DLMP]) has not been described.

OBJECTIVE

To define the microsurgical anatomy of the meningeal branch of DLMP.

METHODS

A total of 20 cadaver heads (40 sides) underwent far-lateral craniotomy and the cerebellomedullary cisterns were explored to find the DLMP and any meningeal branches. Additionally, de-identified intraoperative images of 85 patients with vertebral artery (VA)/posterior inferior cerebellar artery aneurysms who had undergone far-lateral craniotomy were studied to find any meningeal branches of DLMP.

RESULTS

The meningeal branches of DLMP were identified in 4 cadavers/sides. These branches reached the region of jugular tubercle (JT) after crossing the accessory nerve. In 3 specimens, these branches were joined by a small twig from V4-VA before penetrating the dura. DLMP meningeal branches were found in 12 patients of the studied cohort (14%) with similar anatomical features as those found in the cadaveric study.

CONCLUSION

DLMP may give rise to meningeal branches to the adjacent dura of JT. The actual prevalence of this anatomic variation is difficult to estimate using our data. However, when present, these branches may have important clinical implications, ie, diseases such as dural arteriovenous fistulas, pial arteriovenous malformations (AVMs), and meningeal-based tumors.

Intracranial Dural Arteriovenous Fistulas with Pial Arterial Supply

BACKGROUND

Pial arterial supplies are sometimes found in patients with dural arteriovenous fistulas (DAVFs), though their characteristics have rarely been clarified.

OBJECTIVE

To investigate the characteristics of pial arterial supplies in DAVFs and to discuss their pathophysiology and treatment.

METHODS

Two hundred four consecutive patients with intracranial DAVFs over 11 yr were retrospectively reviewed. Clinical factors and radiological findings, including the presence of pial arterial supplies, were evaluated. Supply from a pial artery was classified into 2 categories: dilated pre-existing dural branches of pial arteries, and a "pure" pial supply.

RESULTS

Twenty-three of 204 patients (11.3%) showed an additional pial arterial supply. Multivariate analysis identified 3 independent predictors of a pial arterial supply: younger age (P < .0005), DAVF within the tentorium (P = .0162), and presence of venous dilatation (P = .0001). A dilated pre-existing dural branch of a pial artery was identified in 17 patients, while 8 had a pure pial supply. Of these 23 patients, 17 underwent interventional therapy. No postoperative intracranial hemorrhage or infarction occurred in patients with pial arterial supplies.

CONCLUSION

An additional pial supply is not uncommon in DAVFs and may be explained by a rich physiological pial arterial supply to the dura mater from the posterior circulation, while potential angiogenesis due to venous hypertension remains speculative. Prior to interventional treatment for DAVFs, recognition of a pial arterial supply to the DAVF might influence the treatment strategy and could help avoid inadvertent retrograde embolization of brain supplying vessels through the pial network.

Medullary Hemorrhage Caused by Foramen Magnum Dural Arteriovenous Fistula Successfully Obliterated using Combination of Endovascular and Surgical Treatments: A Case Report and Literature Review

The authors describe an extremely rare case of foramen magnum dural arteriovenous fistula (DAVF), Cognard type V, presented with medullary hemorrhage caused by venous varix on the lateral medullary draining vein embedded into the medulla oblongata. Following mild myelopathy for 3 days, a 20-year-old male developed dyspnea, generalized seizures, loss of consciousness, and finally cardiac arrest. After successful resuscitation, computed tomography scan (CT) of the brain was obtained and showed acute medullary hemorrhage. Subsequent magnetic resonance imaging of the brain revealed diffuse venous congestion or edema of the medulla with multiple dilated flow voids surrounding the medulla, more prominent on the left side, with venous varix embedded into the left-sided of the lower medulla. He was sent to the emergency department of the local hospital and intubated promptly. A few minutes later, the patient had a cardiac arrest. Digital subtraction angiography (DSA) demonstrated DAVF of the foramen magnum supplied mainly by dural branches of bilateral hypertrophic posterior inferior cerebellar arteries (PICAs), slightly by the posterior meningeal branch of the left vertebral artery, and the jugular branch of the left ascending pharyngeal artery (APA) originating from the occipital artery. Transarterial embolization through the bilateral dural branches of the PICAs was successfully performed using N-butyl-2-cyanoacrylate (NBCA), resulting in complete obliteration. The patient had excellence recovery and lost to annual follow-up. Seven years later, he had a recurrent of the fistula presented with occipital headache. DSA with angiographic CT in three-dimensional reconstruction and maximum intensity projection reformatted images clearly demonstrated the exact location of the DAVFs at the posterior rim of the foramen magnum, mainly recruited by the hypertrophic jugular branch of the APA originating from the occipital artery. The fistula was successfully treated surgically following transarterial embolization through the jugular branch of the APA using NBCA. Follow-up DSA confirmed complete obliteration of the DAVF. The patient has remained clinically asymptomatic 2 years after the operation.

Sumo-Associated Traumatic Vertebral Artery Dissection Precipitating Subarachnoid Hemorrhage in Association with Bifid Origins of the Posterior Inferior Cerebellar Artery

BACKGROUND

Traumatic vertebral artery dissection (tVAD) is frequently accompanied by cerebellar infarction, but subarachnoid hemorrhage (SAH) is rare.

CASE DESCRIPTION

We report a unique case of tVAD precipitating SAH, from which the patient fully recovered, most likely because of the protective effects of an anomalously duplicated posterior inferior cerebellar artery (PICA) origin. A 17-year-old Sumo wrestler experienced a brief loss of consciousness after an attack by an opponent to his neck. Head computed tomography imaging demonstrated diffuse posterior fossa SAH; cerebral angiography demonstrated left vertebral artery (VA) occlusion, which was thought to be most likely attributable to tVAD. Angiography revealed distal PICA reconstitution, supplied by collateral arterial flow from the meningeal branch of the proximal ipsilateral VA. An external ventricular drain was placed acutely for treatment of SAH-induced hydrocephalus; however, the patient had an otherwise uneventful course, and remained without clinical evidence of ischemic infarct. A repeat imaging confirming a probable duplicated PICA origin from the VA, distal to the tVAD-associated thrombosis.

CONCLUSIONS

Of particular interest, the patient's abnormal anatomy may have been a mixed blessing, with a more fragile bifid PICA potentially underlying the unexpected development of SAH, whereas the sister branch simultaneously spared him a potentially catastrophic infarction via arterial collateralization.

Thrombosis of the straight sinus and microbleedings due to deep seated arteriovenous fistula - Hemodynamic changes, cognitive impairment and improvement after microsurgery. A technical report

Dural arteriovenous fistulas (dAVF) are rare vascular malformations accounting for only 10-15% that may lead to life threatening deficits due to hemodynamic changes in blood supply and pressure conditions. We present a 64-year old patient who was admitted with disorientation and aphasia. Following images confirmed an infratentorial dural fistula draining into the straight sinus. Additional findings were progressive thrombosis of the straight sinus, microbleedings and bithalamic edema due changes in hemodynamic conditions and venous congestion. Microsurgery was performed. After treatment improvement in clinical condition was observed and the venous congestion was regressive. Hemodynamic changes due to infratentorial dAVFs may lead to bleedings in deep regions and worsening of clinical condition fastly. Treatment requires carefully planning and visualization of angioarchitecture. Symptoms and hemodynamic changes are reversible after treatment, which are essential for treatment decisions.

The meninges as barriers and facilitators for the movement of fluid, cells and pathogens related to the rodent and human CNS

Meninges that surround the CNS consist of an outer fibrous sheet of dura mater (pachymeninx) that is also the inner periosteum of the skull. Underlying the dura are the arachnoid and pia mater (leptomeninges) that form the boundaries of the subarachnoid space. In this review we (1) examine the development of leptomeninges and their role as barriers and facilitators in the foetal CNS. There are two separate CSF systems during early foetal life, inner CSF in the ventricles and outer CSF in the subarachnoid space. As the foramina of Magendi and Luschka develop, one continuous CSF system evolves. Due to the lack of arachnoid granulations during foetal life, it is most likely that CSF is eliminated by lymphatic drainage pathways passing through the cribriform plate and nasal submucosa. (2) We then review the fine structure of the adult human and rodent leptomeninges to establish their roles as barriers and facilitators for the movement of fluid, cells and pathogens. Leptomeningeal cells line CSF spaces, including arachnoid granulations and lymphatic drainage pathways, and separate elements of extracellular matrix from the CSF. The leptomeningeal lining facilitates the traffic of inflammatory cells within CSF but also allows attachment of bacteria such as Neisseria meningitidis and of tumour cells as CSF metastases. Single layers of leptomeningeal cells extend into the brain closely associated with the walls of arteries so that there are no perivascular spaces around arteries in the cerebral cortex. Perivascular spaces surrounding arteries in the white matter and basal ganglia relate to their two encompassing layers of leptomeninges. (3) Finally we examine the roles of ligands expressed by leptomeningeal cells for the attachment of inflammatory cells, bacteria and tumour cells as understanding these roles may aid the design of therapeutic strategies to manage developmental, autoimmune, infectious and neoplastic diseases relating to the CSF, the leptomeninges and the associated CNS.