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The endothelial-lined dural venous sinuses collect blood from the brain, meninges, and calvaria and drain it to the internal jugular veins. The adult drainage pathway of the venous sinuses confluent is commonly via the transverse and sigmoid sinuses to the jugular bulb. The occipital (OS) and marginal (MS) sinuses are well-represented before birth, in most cases. During a retrospective study of the computed tomography angiograms of a 64 y.o. female was found a rare combination of variants of the posterior fossa sinuses. The confluence of the dural venous sinuses was rhomboidal and drained superiorly the superior sagittal sinus, and inferiorly a well-represented occipital sinus (OS). The transverse sinuses were aplastic, on the right side, and hypoplastic on the opposite side. The OS further drained into the MS which, on each side, emptied into the respective jugular bulb. On each side a condylar vein left the junction of the sigmoid sinus and jugular bulb. Such posterior fossa drainage, exclusively on the OS-MS pathway, should be kept in mind when transections of the venous sinuses are intended during neurosurgical approaches of the foramen magnum. The OS-MS drainage is rather a persisting fetal pattern. The bilateral anatomical exclusion of the transverse sinuses is an added condition to spare the OS and MS.

Background The coexistence of falcine and occipital sinuses is rare and its natural course has not been reported. Case reports Two patients with persistent falcine and occipital sinuses are described. Both patients had straight sinuses. In one, both the transverse and sigmoid sinuses were hypoplastic and the patient had an acquired Chiari I malformation. The other patient had no other venous anomalies and had a normal posterior cranial fossa. Conclusion The coexistence of falcine and occipital sinuses can lead to an acquired Chiari I malformation. These cases suggest the importance of checking other venous and brain anomalies in this situation.

Introduction: A patent persistent occipital sinus (OS) can be seen in 10% of adults. The presence of such a dominant draining OS can present as a challenge for posterior fossa surgeries. Occlusion or division of the sinus can cause venous hypertension, causing a cerebellar bulge or increased intra-op bleeding. Case report: A 3-and-a-half-year-old female child presented with a vermian medulloblastoma with hydrocephalus. MR venography (MRV) revealed a large patent OS draining from the torcula to the right sigmoid sinus. She underwent a left Frazier’s point VP shunt followed by a midline suboccipital craniotomy for the lesion. The OS was divided during a “Y”-shaped durotomy. Following the sinus ligation, there was a significant cerebellar bulge and excessive bleeding from the lesion. We released cisternal CSF and punctured the tumor cysts to allow the brain bulge to settle. Hemostasis was secured, and surgery was deferred, an augmented duroplasty was done, and bone flap was removed to allow for intracranial pressure decompression. The patient was electively ventilated for 24 h and weaned off gradually. A repeat MRV at 7 days showed the reorganization of the venous outflow at the torcula. Reexploration with tumor resection was done on post-op day 10. The patient recovered well from the surgery and was referred for adjuvant therapy. Conclusion: Surgeons should carefully analyze venous anatomy before posterior fossa surgeries. The persistent dominant OS, when present, should be taken care of while planning the durotomy. A hypoplastic but persistent transverse sinus allowed us to ligate and divide the OS. By doing a staged division of the sinus, reorganization of the venous outflow from the torcula can be allowed to occur, and the lesion can be resected.

BACKGROUND AND PURPOSE: The role of the dural venous sinus system in cerebrovascular pathology and the understanding of normal developmental patterns and sizes of the dural venous sinus system continue to expand. The purpose of this study was to review MR venograms to elucidate developmental patterns and diameters of the major dural venous sinuses from 0 to 20 years of age. MATERIALS AND METHODS: All available MR venograms of patients 0–20 years of age who presented to our institution were retrospectively reviewed. Patient age at the time of image acquisition was noted, and measurements were taken of the diameters of the major dural venous sinuses. The presence of embryonic sinuses including the persistent falcine sinus and the occipital sinus was noted. Dominance patterns of the transverse sinus system were determined. Mean diameters of each sinus were plotted as a function of age. The prevalence of persistent prenatal sinuses and transverse sinus–dominance patterns was compared across ages. RESULTS: A total of 429 MR venograms from 429 patients were reviewed. All dural venous sinuses demonstrated a maximal growth rate from 0 to 7 years of age and reached maximal diameters around 5–10 years of age. The prevalence of falcine sinuses and occipital sinuses trended downward across increasing age categories (P = .09 and

A 47-year-old live kidney-donor woman presented with headaches and blurred vision. Neuro-ophthalmological examination demonstrated papilledema and right eye inferior nasal defect. Brain MRV showed no sinus thrombosis but solitary right venous sinus draining the torcular Herophili to right jugular bulb. Lumbar puncture revealed elevated CSF opening pressure of 40 cm H2O with normal composition. She was diagnosed with idiopathic intracranial hypertension (IIH). She did not tolerate medical management and declined CSF diversion surgery. Cerebral angiography and venography showed venous outflow drainage from torcular Herophili through a solitary occipital sinus which has distal severe stenosis and pressure gradient of 10 mmHg. Balloon angioplasty and stenting of the occipital sinus were performed. Post-stenting, the stenosis and pressure gradient resolved. At 3-months follow-up, her symptoms and papilledema had resolved and CSF opening pressure was normal at 15 cm H2O. Aberrant cerebral venous anatomy may cause IIH and can be treatable with neuroendovascular techniques.

Background: Variations of the dural venous sinuses may result in inaccurate imaging interpretation or complications during surgical approaches. One of these variations reported infrequently is the occipital sinus with an overall incidence of under 10%.When present, it may get thrombosed or become source of intracranial bleeds or pose difficulty during occipital craniotomies. Our review suggests that the thrombosis of this unique venous sinus variant is a rare condition as there are very few case reports of the same. Herein, we present a case series of persistent occipital sinus and the unusual combination of a persistent occipital sinus and its thrombosis. Subjects and Methods: The study included 4 paediatric cases that presented with neonatal seizuressecondary to different underlying aetiologies and in retrospect had either persistent andpatent occipital sinus or a thrombosed occipital sinus. A descriptive study of the aforementioned cases was carried out. MRI scanner PHILIPS Achieva 1.5 Tesla was used for diagnosis. Results: One case had thrombosis of bilateral persistent occipital sinuses and superficial cortical veins with minimal intraventricular haemorrhage in bilateral lateral ventricles.Second case had persistent and thrombosed right occipital sinus; while two other cases had persistent but patent occipital sinuses. Conclusion: A comprehensive knowledge of cerebral venous anatomy and meticulous recognition of venous variations essentially helps when dealing with a pathology, which presents along with a particular venous variation, no matter how rare this combination is.

The torcular Herophili is formed by the joining of the major dural venous sinuses including the superior sagittal sinus, transverse sinuses, straight sinuses, and the occipital sinus. Surgically, knowledge of the position of the torcular Herophili is vitally important to avoid catastrophic hemorrhage. Here, we present a case report of an elevated torcularia found on radiological imaging. Such an anatomical variation should be kept in mind by clinicians and anatomists alike.

Conventional fluoroscopic guidance can provide enough information to precisely insert an occipital screw in ordinary cases. However, the occipital screw creates a potential risk of dural venous sinus injury or thrombosis. In some cases, with dural sinus variation, surgeons must especially be cautious to avoid its injury. We present a rare case of proper occipital screw placement using a navigation system for a pathological odontoid fracture with a high risk of dural venous sinus injury because of anatomical variations in the transverse and occipital sinuses. A 60-year-old man who underwent thyroidectomy at the age of 37 years for thyroid carcinoma developed acute neck pain and quadriparesis due to falling out of bed. He urgently underwent closed reduction and temporary immobilization with a halo-vest for a pathological odontoid fracture and atlantoaxial dislocation. Preoperative contrast-enhanced CT showed an absent right transverse sinus and a prominent occipital sinus as variations of the dural venous sinuses. Occipito-C7 fusion surgery was performed without intraoperative active venous bleeding or postoperative brain disorder by using a navigation system for the occipital screw placement to avoid injury to the dural sinus. Postoperative computed tomography showed bi-cortical occipital screw placement avoiding the prominent occipital sinus. The patient's postoperative course was uneventful. In this case, although rigid occipito-cervical fixation using bi-cortical occipital screws was needed for the pathological odontoid fracture, the variation of the occipital sinus created a high risk of injury during occipital screw placement with conventional fluoroscopic guidance. There is an anatomical variation of the dural venous sinuses between individuals. Prominent occipital sinus injury may notably cause fatal complications such as massive bleeding or occlusion. Thus, we safely inserted the occipital screws using a navigation system that enabled us to avoid occipital venous sinus injury. Occipital screw placement with a navigation system can be a better option to prevent dural venous sinus injury in cases where there is variation in the dural venous sinuses, such as with a prominent occipital venous sinus.

Dural arteriovenous fistulas (DAVFs) are benign but may present with life-threatening hemorrhage or symptoms of venous hypertension (eg, progressive myelopathy).1-3 DAVFs follow well-described anatomic patterns.4 The marginal sinus is located between the layers of the dura, circumferentially around the foramen magnum. It communicates with the basal venous plexus of the clivus anteriorly and the occipital sinus posteriorly.5,6 Arterial supply to the dura in this region that fistulizes into the sinus arises from meningeal branches from the V3 or V4 segments. A man in his early 70s presented with chronic neck pain and new onset of left arm and face paresthesias. He had brisk patellar reflexes bilaterally and a marginal sinus DAVF, with numerous dilated veins around the cisterna magna, causing dorsal cervicomedullary compression. Angiography confirmed the diagnosis of DAVF rather than arteriovenous malformation. Endovascular embolization was considered, but surgery was preferable because of poor transarterial access. The patient underwent left far lateral craniotomy and C1 laminectomy with exposure of the condylar fossa. The dura was carefully elevated laterally, revealing a network of dilated tortuous veins, with multiple points of fistulous connection within the dura emanating in a large venous varix. Indocyanine green videoangiography showed the aberrant flow dynamics. The fistulous point was occluded with aneurysm clips on the venous side, then cauterized and interrupted. The patient was discharged within 3 d of surgery and had full resolution of symptoms at 6 wk. Angiography confirmed complete obliteration of the DAVF. The patient provided written informed consent for treatment. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

The retrosigmoid craniotomy is the standard approach to resect pathologies in the cerebellopontine angle (CPA). Following the craniotomy, the dura mater is opened in the inferolateral direction and the basal cistern arachnoid is dissected in order to release pressure by the outflow of cerebrospinal fluid (CSF) from the foramen magnum, so that the CPA compartment can be approached with minimal retraction of the cerebellum. We report two patients, both with vestibular schwannoma, in whom preoperative magnetic resonance imaging (MRI) revealed unusual large oblique occipital sinus (OOS) draining laterally into the sigmoid sinus - jugular bulb junction. The sinuses were preserved intact while dura mater was opened for CSF release. Careful preoperative imaging is essential prior to posterior fossa lesions approaches in order to evaluate the persistency of an OOS, especially in a retrosigmoid approach. Inadvertent OOS damage might result in, not only significant bleeding during dural opening, but also air embolism or venous hypertension, if the contralateral sigmoid sinus is small or absent.

The sinus pericranii refers to a set of clinical presentations that share a pathological communication between the scalp veins and the underlying cranial venous sinus. The nature of this connection ranges from the simple dilatation of the emissary veins, to wide connections through a calvarial bone loss leaving almost the cranial venous sinus in direct contact with the subcutaneous tissue. The authors present the case of an occipital pericranii sinus of intraoperative discovery. Congenital, post-traumatic or spontaneous, this anomaly is most often frontal and located on or close to the midline. The usual clinical presentation is that of a soft mass that empties to the pressure while standing, while it fills in all situations that increase the intracranial pressure (Valsalva maneuver …). The diagnosis is not always easy to establish, and relies on a bundle of clinical and radiological arguments. Through a review of the literature we propose to focus on the clinical features, diagnostic means and therapeutic options of this rare entity.

Introduction: In this study, we aimed to analyze the dural venous system variations in Turkey by magnetic resonance imaging examinations. Material and Methods: Images of a total of 200 patients (65 males, 135 females M/F: 0.48) who underwent a magnetic resonance venography examination were retrospectively screened. Results: Variation was detected in 101 patients (53.85% of males [35/65] and 48.89% of females [66/135]). In 16.5% of the patients, only one variation of dural venous system was detected, while the most common variation was left transverse hypoplasia in this group. Twenty-six percent of the patients had two variations of the dural venous system since the most common dual variations were left transverse hypoplasia + left sigmoid hypoplasia in this group. In 8% of the patients, three or more variations of the dural venous system were observed as the most common variations were right transverse hypoplasia + right sigmoid hypoplasia + presence of occipital sinus in this group. Discussion and Conclusion: It is essential to know the anatomical variations of the dural venous system for the discrimination between pathological processes such as thrombosis and physiologic conditions. Furthermore, the association of these variations with each other must be kept in mind for the explanation of the presence of multiple variations in the same individuals.

Purpose Human falx cerebelli is an important anatomical structure in regard to its relations with venous structures during infratentorial approach to reach cerebellar tumors, vascular malformations, traumatic hemorrhage and Chiari malformations. The present study aim to describe the different types of variations of the falx cerebelli, its morphological features and its association with occipital venous sinuses. Method In this study 49 dura mater was obtained from the Institution of Forensic Medicine. The length, width and the depth of the falx cerebelli were measured using a digital compass. The data obtained were statistically analyzed in relation to age and gender. The relations of the falx cerebelli with the occipital sinus was documented. Histological sections from the falx cerebelli were stained with Hematoxylin Eosin to evaluate the fine structure. Results Among the 49 falx cerebelli examined 36 (73.5%) were classified as normal. The average length, width and depth of the normal falx cerebelli was 3.7, 1.0 and 0.4 cm respectively. Of the 49 falx cerebelli in 1 (2%) case it was absent, in 5 cases (10.2%) duplicate, in 5 cases (10.2%) triplicate, in 1 (2%) case quadruplets and in 1 case (2%) it was five-folded. The proximal and the distal attachments of the falx cerebelli showed 3 types of variations; both attachments triangular, the proximal attachments triangular and the distal ramified and distal attachments triangular and the proximal attachments ramified. The drainage of the occipital sinus of falx cerebelli with variations were evaluated. The increased number of falx cerebelli highly corresponded with the increased number of occipital sinus. Conclusions The dural-venous variation in the posterior cranial fossa can be problematic in various diagnostic and operative procedures of this region. Neurosurgeons should be aware of such variations, as these could be potential sources of haemorrhage during the midline suboccipital and infratentorial approaches.

Background Dural venous sinus stenting (VSS) is an effective treatment for idiopathic intracranial hypertension (IIH) in adult patients. There are no published series to date evaluating safety and efficacy of VSS in pediatric patients. Objective To report on procedural device selection and technique as well as safety and efficacy of VSS for pediatric patients with medically refractory IIH due to underlying venous sinus stenosis. Methods A multi-institutional retrospective case series identified patients with medically refractory IIH aged less than 18 years who underwent VSS. Results 14 patients were identified at four participating centers. Patient ages ranged from 10 to 17 years, and 10 patients (71.4%) were female. Mean body mass index was 25.7 kg/m2 (range 15.8–34.6 kg/m2). Stenting was performed under general endotracheal anesthesia in all except two patients. The average trans-stenotic gradient during diagnostic venography was 10.6 mm Hg. Patients had stents placed in the superior sagittal sinus, transverse sinus, sigmoid sinus, occipital sinus, and a combination. Average follow-up was 1.7 years after stenting. Six patients out of 10 (60%) had reduced medication dosing, 12 of 14 patients (85.7%) had improvements in headaches, two patients (100%) with pre-stent tinnitus had resolution of symptoms, and four (80%) of five patients with papilledema had improvement on follow-up ophthalmological examinations. Two patients (14.3%) developed postprocedural groin hematomas, one patient (7.1%) developed a groin pseudoaneurysm, and one patient (7.1%) had postprocedural groin bleeding. No other procedural complications occurred. Four patients (28.6%) required further surgical treatment (cerebrospinal shunting and/or stenting) after their first stenting procedure. Conclusions This series suggests that VSS is feasible in a pediatric population with IIH and has a low complication rate and good clinical outcomes.

Background and importance Although foramen magnum decompression (FMD) with expansive duraplasty is a popular procedure for treating chiari malformation (CM), the common Y-shaped dural incision can lead to a life-threatening cerebral venous circulation disturbance in patients with a developed occipital sinus. Here, we describe the effectiveness of intraoperative indocyanine green video angiography (ICG-VA) for a CM type 1 (CM1) patient with a highly developed unilateral occipital sinus. Clinical presentation A 40-yr-old woman presented with sensory disturbance on the left side of the body. Magnetic resonance imaging (MRI) revealed cerebellar tonsil herniation into the foramen magnum with cervical syringomyelia, and computed tomography additionally revealed skull anomalies: fontanel closure insufficiencies, cranial dysraphism, thin cranial bone, and dentition abnormalities. We diagnosed as symptomatic CM1 with syringomyelia associated with cleidocranial dysplasia, which is a dominantly inherited autosomal bone disease. Cerebral angiography revealed a developed right occipital sinus and hypoplasia of the bilateral transverse sinus. We performed FMD, paying special attention to the developed occipital sinus using ICG-VA to ensure a safe duraplasty. The angiography clearly highlighted a right-sided occipital sinus with a high contrast ratio, and no left-sided occipital sinus was visible. After a dural incision in a unilateral curvilinear fashion was safely completed, expansive duraplasty was performed. The sensory disorders experienced by the patient disappeared postoperatively. Postoperative MRI revealed elevation of the cerebellar tonsil and decreasing of the syringomyelia. Conclusion Additional assessment using intraoperative ICG-VA provides useful information for a safe FMD, particularly in patients with complicated cerebral venous circulation anomalies.

Among the dural venous sinuses, the occipital sinus is one of those studied least. One reason for this might be its absence in a significant number of people with no clinical sequelae; another reason may be the high degree of variation that it exhibits, which is discussed later. This chapter details the anatomy, variations, and clinical significance of this intradural venous sinus.

The torcular Herophili (confluence of sinuses) is a highly variable structure that constitutes a vital part of the network of dural venous sinuses. The torcular Herophili is defined historically as the intersection of the superior sagittal sinus, the straight sinus, the occipital sinus, and the two transverse sinuses. Its size varies and it is located inferior to the occipital lobes and posterosuperiomedially to the cerebellum. This chapter outlines the anatomy and clinical implications of this sinus.

The primitive tentorial, occipital, and falcine sinuses are thought to attain the adult pattern or regress between the fetal stage and adulthood. The anatomy of these three primitive dural sinuses has seldom been studied in the infant population, and it remains unclear when these dural sinuses reach the adult condition. Using computed tomography digital subtraction venography (CT-DSV), we analyzed the anatomy of these embryonic dural sinuses in infants. We included 13 infants who underwent CT-DSV prior to neurosurgery and 35 cases with unruptured cerebral aneurysms as normal adult controls. Three embryonic dural sinuses, i.e., the primitive tentorial, occipital, and falcine sinuses, were retrospectively analyzed in CT-DSV images of infants and adults. We also analyzed the drainage patterns of the superficial middle cerebral vein (SMCV), determined by the connection between the primitive tentorial sinus and the cavernous sinus. The primitive tentorial, occipital, and falcine sinuses were present in 15.4%, 46.2%, and none of the infants, respectively, and in 10.0, 8.6, and 2.9% of the adults, respectively. The difference in SMCV draining pattern between infants and adults was insignificant. The incidence of the occipital sinus was significantly higher in infants than in adults. The connection between the primitive tentorial sinus and the cavernous sinus appears to be established before birth. The occipital sinus is formed at the embryonic stage and mostly regresses after infancy. The falcine sinus is usually obliterated prenatally. Our findings form the basis for interventions by pediatric interventional neuroradiologists and neurosurgeons.

The occipital sinus may occasionally remain patent, but the incidence is extremely low and observed in less than 10% of cases. A persistent patent occipital sinus (POS) may be associated with other venous sinus abnormality. The absence of transverse sinus in association with POS is an extremely rare condition and not reported yet. The neuroradiologist, neurosurgeons, otolaryngologist, and neurologist must be aware of the possible existence of POS and other associated venous sinus anomaly, as its warrants very crucial modification of surgical planning, selection of appropriate approaches, and, additionally, may also critically limit the extent of surgical exposure of target, and may hinder intended extent of surgical excision of tumor and associated possibility of injury to POS, which may produce catastrophic hemorrhage, brain swelling, and neurosurgical morbidity. The authors report a 35-year-old male who underwent suboccipital craniotomy for right-side giant acoustic schwannoma. Following the raising bone flap, a markedly prominent, turgid, occipital sinus was observed, not placed exactly in the midline but deviated to the right side, causing further restraining of dural opening. Surgical nuances and intraoperative difficulty encountered along with pertinent literature is reviewed briefly.

BACKGROUND: It is essential to identify and be aware of the anatomy of the posterior condylar emissary vein (PCEV) for achieving an adequate operative field for the transcondylar fossa approach (TCFA). OBJECTIVE: To describe the variations in the drainage patterns of PCEVs and the technical issues encountered in such cases. METHODS: This was a retrospective analysis of the anatomy of PCEVs in 104 sides in 52 cases treated by the TCFA. Preoperative findings of multidetector-row computed tomography (CT) and CT venography (CTV) were compared with the intraoperative findings. The drainage patterns were classified as 5 types: the sigmoid sinus (SS), jugular bulb (JB), occipital sinus (OS), anterior condylar emissary vein (ACEV), and marginal sinus (MS). RESULTS: The SS, JB, ACEV, and OS types were observed in 33 (31.7%), 42 (40.3%), 8 (7.7%), and 1 (1.0%) side(s), respectively. One side (1.0%) each had combined drainage from MS and JB, and ACEV and JB, respectively. In 17 sides (16.3%), the PCEVs and posterior condylar canals could not be identified on CT and CTV. CONCLUSIONS: Preoperative CT and CTV findings correlated well with the intraoperative findings. To make a sufficient operative field for TCFA, PCEVs should be appropriately dealt with based on the preoperative knowledge of their running course, pattern, and origin.

Background Descriptions of intracranial extensions of vertebral venous plexuses are lacking. Objective To identify vertebral venous plexuses at the craniocervical junction in cadavers and describe them. Methods The authors dissected 15 ink-injected, formalin-fixed, adult cadaveric heads and measured cranial extensions of the spinal venous plexuses. Results All specimens had vertebral venous plexuses at the craniocervical junction composed of multiple interwoven vessels concentrated anteriorly (anterior vertebral plexuses), posteriorly (posterior vertebral venous plexuses), and laterally (lateral vertebral venous plexuses). Veins making up the plexus tended to be largest for the anterior internal vertebral venous plexus. On 33%, a previously unnamed lateral internal vertebral venous plexus was identified that connected to the lateral marginal sinus. The anterior external vertebral venous plexus connected to the basilar venous plexus via transclival emissary veins in 13%; remaining veins connected either intracranially via small perforating branches through the anterior atlanto-occipital membrane (33%) or had no direct gross connections inside the cranium (53%). The anterior internal vertebral plexus, which traveled between layers of the posterior longitudinal ligament, connected to the anterior half of the marginal sinus in 33% and anterolateral parts of the marginal sinus in 20%. The posterior internal venous plexus connected to the posterior aspect of the marginal sinus on 80% and into the occipital sinus in 13.3%. The posterior external venous plexus connected to veins of the hypoglossal canal in 20% and into the posterior aspect of the marginal sinus in 13.3%. Conclusion Knowledge of these connections is useful to neurosurgeons and interventional radiologists.

Background It is essential to identify and be aware of the anatomy of the posterior condylar emissary vein (PCEV) for achieving an adequate operative field for the transcondylar fossa approach (TCFA). Objective To describe the variations in the drainage patterns of PCEVs and the technical issues encountered in such cases. Methods This was a retrospective analysis of the anatomy of PCEVs in 104 sides in 52 cases treated by the TCFA. Preoperative findings of multidetector-row computed tomography (CT) and CT venography (CTV) were compared with the intraoperative findings. The drainage patterns were classified as 5 types: the sigmoid sinus (SS), jugular bulb (JB), occipital sinus (OS), anterior condylar emissary vein (ACEV), and marginal sinus (MS). Results The SS, JB, ACEV, and OS types were observed in 33 (31.7%), 42 (40.3%), 8 (7.7%), and 1 (1.0%) side(s), respectively. One side (1.0%) each had combined drainage from MS and JB, and ACEV and JB, respectively. In 17 sides (16.3%), the PCEVs and posterior condylar canals could not be identified on CT and CTV. Conclusions Preoperative CT and CTV findings correlated well with the intraoperative findings. To make a sufficient operative field for TCFA, PCEVs should be appropriately dealt with based on the preoperative knowledge of their running course, pattern, and origin.

Background Occipital sinus (OS) dural arteriovenous fistula (DAVF) is extremely rare, and we are aware of no case accompanied by cerebral hemorrhage. We present a case of OS DAVF presenting with cerebellar hemorrhage, treated successfully by transvenous embolization. Case Description A 62-year-old female presented with headache and nausea of recent onset. Computed tomography revealed left cerebellar hemorrhage with perihematomal edema. Angiography showed OS DAVF fed by bilateral occipital and posterior meningeal arteries, with drainage into the left inferior hemispheric vein and right transverse sinus receiving the shunt flow from OS. The caudal side of the OS was occluded. The inferior hemispheric vein was dilated with 2 varices, and the junction between the OS and right transverse sinus was narrowed. Because the OS was not involved in normal cerebellar drainage, transvenous embolization of the OS was performed. The microcatheter was advanced to the OS from the transverse sinus during balloon occlusion at the confluence of sinuses. Coils were placed in the OS from the caudal to cranial side, and complete occlusion of the shunt was obtained. Conclusions This is the first report of OS DAVF presenting with cerebellar hemorrhage. Transvenous embolization of the affected OS appears ideal when transvenous access is feasible, and the OS is not involved in normal venous drainage of the cerebellum.

The fetal and postnatal development patterns of dural venous sinuses are not fully understood. In their article, published in the American Journal of Neuroradiology in October 2020, Larson et al[1][1] examined the development of dural venous sinuses using MR venography in more than 400 patients.