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Background Among the varied causes of pulsatile tinnitus, the condition that can cause severe mortality and morbidity is a cranial dural arteriovenous fistula (cDAVF). This study aimed to assess the diagnostic accuracy of the dilated middle meningeal artery on three-dimensional time-of-flight magnetic resonance angiography in cranial dural arteriovenous fistula and to identify other feeders that can aid in the detection of these lesions. Method Magnetic resonance angiography and digital subtraction angiography data of all patients with cranial dural arteriovenous fistula treated in a single tertiary referral center between 2007–2020 were included. The middle meningeal artery and other feeders recorded from digital subtraction angiography were assessed on magnetic resonance angiography. Results The overall agreement between readers in identifying the dilated middle meningeal artery was substantial (κ = 0.878, 95% confidence interval: 0.775–0.982). The dilated middle meningeal artery indicated the presence of a cranial dural arteriovenous fistula with a sensitivity of 79.49% (95% confidence interval: 66.81–92.16), specificity of 100% (95% confidence interval: 100.00–100.00), and negative predictive value of 94.56% (95% confidence interval: 90.89–98.02). An area under the curve of 0.8341 was observed for the ipsilateral middle meningeal artery, with a sensitivity of 92.2% and a specificity of 75.0% at a cut-off of 0.30 mm for identifying a cranial dural arteriovenous fistula. Of 73 other feeders, the occipital, meningohypophyseal trunk, ascending pharyngeal, and posterior meningeal arteries contributed to a large proportion visualized on magnetic resonance angiography (83.6% (41/49)). Conclusion The dilated middle meningeal artery sign is useful for identifying a cranial dural arteriovenous fistula. Dilatation of the occipital and ascending pharyngeal arteries and meningohypophyseal trunk should be assessed to facilitate the detection of a cranial dural arteriovenous fistula, particularly in the transverse-sigmoid and petrous regions.

Background Intracranial dural arteriovenous fistulae (dAVFs) with cortical venous drainage (CVD) require treatment because of their aggressive clinical presentation and natural history. Although endovascular treatment is effective for the majority of these lesions in the current endovascular era, surgical management has been required if the lesions are not amenable to or fail endovascular treatments. Objective To demonstrate the angioarchitecture that may necessitate surgical intervention. Methods A retrospective review of the patients with intracranial dAVFs with CVD treated at 2 academic institutions between January 1, 2009, and July 31, 2019 was performed. Patients who required surgical intervention were selected in this study, and angiographic findings were analyzed. Results A total of 81 dAVFs in 80 patients were treated during the study period. Endovascular treatments were attempted for 72 (88.9%) dAVFs, resulting in complete obliteration in 55 (76.4%). Surgical interventions were performed in 18 (22.2%) dAVFs, resulting in complete obliteration in all lesions. Overall, complete obliteration was achieved in 74 (93.7%) of 79 dAVFs with follow-up. In the surgically treated dAVFs, curative transarterial embolization was deterred by the angioarchitecture, which included dominant feeding vessels from the ophthalmic artery, meningohypophyseal trunk, posterior meningeal artery, pial artery, or ascending pharyngeal artery. Drainage through tortuous cortical vein, deep venous system, or isolated sinus made transvenous approach challenging. Conclusion Despite continued improvement in endovascular technology, surgical approaches to dAVFs are still of great value as initial and salvage treatment of dAVFs with angioarchitecture hampering endovascular treatment.

Background Foramen magnum dural arteriovenous fistula (DAVF) is a rare disease, with some reported cases of successful treatment. We achieved complete obliteration of the foramen magnum DAVF through microsurgery after complications of endovascular embolization. We reviewed the treatment modalities and outcomes, focusing on pathologic and anatomic features from the literature. Case Description A 65-year-old man was admitted to our hospital with sudden diplopia. Magnetic resonance imaging revealed a subarachnoid hemorrhage around the right side of the prepontine cistern, and a foramen magnum DAVF was diagnosed by angiography. Subsequent angiography revealed that the fistula was supplied by the right neuromeningeal trunk of the ascending pharyngeal artery and the right posterior meningeal artery of the vertebral artery (VA), and the veins of the pouch via the fistula were retrogradely draining into the intracranial veins. We aimed to treat complete occlusion endovascularly with balloon-augmented transarterial Onyx injection via the posterior meningeal artery, but Onyx was refluxed to the VA through the anastomosis between the VA and posterior meningeal artery. Onyx subsequently migrated to the top of the basilar artery, causing occlusion, so we urgently removed the Onyx with a stent retriever (Trevo). Several weeks later, we performed complete obliteration of the foramen magnum DAVF via a lateral suboccipital approach with a C1 laminectomy. Conclusions Most foramen magnum DAVFs were obliterated completely with only endovascular treatment. Microsurgery is an effective and reliable treatment for incomplete occlusion and complications.

Background Meningeal arterial injuries represent, Highlights • Traumatic intracerebral hemorrhage caused by meningeal artery injuries are rare, and usually involve the middle meningeal artery; lesions of the posterior meningeal artery remain even more obscure • Severe traumatic brain injury (TBI) associated with basilar skull fractures represents a pattern of injury for which CT angiography of the head can be useful in identifying meningeal vascular injuries • Critical care for severe TBI involves preventing secondary insult to cerebral tissue; strategies continue to evolve with hyperosmolar therapy, CSF drainage, prompt enteral nutritional support, and early tracheostomy

A 59-year-old female presented with severe headache and trouble of consciousness. The CT showed a subarachnoid hemorrhage FISHER IV with a hematoma of the right cerebellum. The angiography discovered a persistent left trigeminal artery associated with an aneurysm of the right posterior meningeal artery. The attempt of embolization failed and the patient suffered cerebral vasospasm and died. The persistence of a trigeminal artery is found in 0.1–0.6% of the population. It is the most frequent embryological carotid-vertebral anastomosis. It appears at the fifth week of development and disappears when the embryo reaches 5–7 mm. This embryological persistence is associated with numerous vascular abnormalities. The literature review showed the presence of those aneurysms in the trigeminal artery itself or the communicating artery. The association that we described is the first to our knowledge. Therefore, this association is particular and interesting to expose.

Background and Purpose The posterior meningeal artery (PMA) is known as a dura mater-nourishing vessel. We encountered a patient with Wallenberg syndrome during transarterial embolization of the PMA associated with the dural arteriovenous fistula (DAVF). Methods After development of Wallenberg syndrome in the patient, we assessed origins of the PMA patterns in 300 cases and divided them into 3 types. Case Presentation A 63-year-old man was incidentally diagnosed as having transverse-sigmoid sinus DAVF with a cortical venous reflux. During the transarterial embolization, the patient complained of vertigo and numbness of the right extremities. Postoperatively, the patient exhibited Wallenberg syndrome. Diffusion-weighted magnetic resonance imaging showed a high-intensity area on the lateral side of the right medulla. Conclusions While performing arterial embolization of the PMA that directly originates from the intracranial vertebral artery, the possibility of deficient brainstem nourishment must be considered.

The posterior meningeal artery, which arises from the vertebral artery, is a critical artery in neurological lesions. However, a comprehensive review of the importance of the posterior meningeal artery is currently lacking. In this study, we used the PubMed database to perform a review of the literature on the posterior meningeal artery to increase our understanding of its role in vascular lesions. The posterior meningeal artery provides the main blood supply to the paramedial and medial portions of the dura covering the cerebellar convexity. The posterior meningeal artery is often involved in dural arteriovenous fistulas occurring near the posterior fossa, and the posterior meningeal artery can be the path for transarterial embolisation or a path through which to monitor the degree of dural arteriovenous fistula embolisation. In posterior circulation ischaemia and moyamoya disease, the posterior meningeal artery can form transdural anastomoses with pial arteries at the surface of the brain, and these can help prevent ischemia. The posterior meningeal artery can also develop aneurysms, most of which are traumatic pseudoaneurysms; patients should therefore be treated in a timely manner or followed up carefully in cases of rebleeding. In addition, during a craniotomy, the posterior meningeal artery should be protected intraoperatively to avoid damaging any transdural anastomosis that may be present. In addition, when the posterior meningeal artery is the main feeding artery of an intracranial tumour, that artery is a satisfactory path for preoperative embolisation. Briefly, the posterior meningeal artery is a very important artery in neurosurgery.

The posterior meningeal artery (PMA) usually originates from the third segment of the vertebral artery. Many variations in its origin and course have been observed; however, as far as we know, the association of true aneurysm of the PMA and its anomalous origin from the internal carotid artery has not been reported previously. We reported the case of a 59-year-old woman who suddenly presented a loss of consciousness without head trauma, computed tomography (CT) revelated intracerebellous hematoma associated with a subarachnoid hemorrhage of the posterior cerebral fossa. Cerebral angiography demonstrated a true aneurysm of the PMA which originated from the internal carotid artery.

Moyamoya disease (MMD) and dural arteriovenous fistula (DAVF) are two distinct types of intracranial lesion that share different pathogenic mechanisms. Under rare circumstances, patients with MMD have been reported to have concurrent DAVF. The present case study reports on a 47-year-old male admitted due to sudden headache. Head CT revealed hemorrhage of the right thalamus with ventricular extension. On CT angiography, the normal vasculature in the anterior and posterior circulation disappeared and was replaced by moyamoya-like vessels. The patient received conservative management and was discharged 3 days later. After three months, the patient was readmitted for acute cerebellar hemisphere infarction. Angiogram indicated that the DAVF (Cognard classification Ⅰ) was supplied by the left middle meningeal artery, occipital artery and posterior meningeal artery and drained into the transverse-sigmoid sinus and occipital sinus. Conservative management of the DAVF was adopted. The patient was stable and lived independently during a 4-year follow-up. A literature review of the reported cases was also performed to further characterize this rare entity. The management of DAVF concurrent with MMD depends on its clinical presentation and invasiveness. For patients with symptoms or cortical venous drainage, endovascular intervention should be performed. For asymptomatic DAVFs or those without cerebral venous drainage, close follow-up is a reasonable option.

Transverse sinus-sigmoid sinus (TS-SS) dural arteriovenous fistula (dAVF) is common type of dAVF, on the other hand, anterior condylar confluence (ACC) dAVF is relatively rare. There has been no report presenting patients with TS-SS dAVF and ACC dAVF identified simultaneously yet. We present a case of TS-SS dAVF and ACC dAVF that developed subcortical hemorrhage of left temporal lobe. A 66-year-old woman with no past history was transferred to our hospital for sudden-onset consciousness disturbance, and was urgently admitted after the detection of a subcortical hemorrhage in the left temporal lobe. We suspected a dAVF based on magnetic resonance angiography and performed digital subtraction angiography (DSA). DSA revealed that the left occipital artery, left ascending pharyngeal artery, left middle meningeal artery, left tentorial artery, and posterior meningeal artery flowed into the TS-SS and ACC. DSA also showed outflow from the TS-SS to the brain surface through the vein of Labbe and the vein of Trolard. We performed transvenous embolization to prevent re-bleeding, she was then discharged from our hospital and her remaining sensory aphasia gradually improved. In the present study, the active investigation to determine the cause of subcortical hemorrhage led to a definitive diagnosis. The combination of ACC dAVF and TS-SS dAVF has not been reported thus far and this is considered a valuable case.

Background A dissecting aneurysm on the posterior inferior cerebellar artery (PICA) is a rare entity, and endovascular embolization is often adopted. During the procedure, if the parent artery is occluded, the distal PICA is usually supplied by the ipsilateral anterior inferior artery or contralateral PICA. In extremely rare circumstances, the distal PICA can establish collateral circulation by transdural anastomosis with the posterior meningeal artery (PMA). Case Description A 29-year-old woman was admitted complaining of thunderclap headache, nausea, and vomiting for 3 hours. Head computed tomography and digital subtraction angiography revealed subarachnoid hemorrhage and a dissecting aneurysm located at the tonsillomedullary segment of PICA. The parent artery distal to the aneurysm had no collateral circulation from the adjacent arteries. Selective endovascular coiling of the aneurysm with preservation of the parent artery was adopted for treatment. The patient experienced an uneventful postprocedural recovery. To our surprise, follow-up digital subtraction angiography 6 months later revealed complete occlusion of the aneurysm and parent artery at the site of aneurysm formation. A rare anastomosis between the distal PICA and PMA was established. Conclusions A report about this rare condition suggested that after occlusion of the PICA trunk, the distal PICA can form collateral circulation with the PMA. A potential collateral circulation may be present in advance between the PICA and PMA. When ischemia occurs in the distal PICA, this collateral circulation may open and could be reconstructed and enlarged to provide blood supply.

Background A case of dural arteriovenous fistula (dAVF) developed after radical neck dissection for lymph node metastasis 2 years after oral surgery for tongue cancer. Methods The patient was asymptomatic during follow-up visits with no evidence of metastasis on follow-up CT scan of the neck. However, diagnostic angiography showed left internal carotid artery (ICA) stenosis and dAVF involving the posterior meningeal artery and transverse sinus at the left posterior fossa with cortical venous reflux (Cognard type III). They were treated with carotid stenting and surgery, respectively. Results The postoperative course was uneventful. Follow-up angiography revealed obliteration of the dAVF. Conclusion This was a rare case of iatrogenic dAVF after surgical ligation of venous outflow during radical neck dissection. The surgical plan is presented along with a literature review regarding the development of iatrogenic dAVFs induced by direct surgical trauma. © 2015 Wiley Periodicals, Inc. Head Neck, 2015

Cognard Type V dural arteriovenous fistulas (dAVFs) are a unique type of cranial vascular malformation characterized by congestion of the perimedullary venous system that may lead to devastating spinal cord pathology if left untreated. The authors present the first known case of a pediatric patient diagnosed with a Type V dAVF. A 14-year-old girl presented with a 3-week history of slowly progressive unilateral leg weakness that quickly progressed to bilateral leg paralysis, sphincter dysfunction, and complete sensory loss the day of her presentation. MRI revealed an extensive T2 signal change in the cervical spine and tortuous perimedullary veins along the entire length of the cord. An emergency cranial angiogram showed a Type V dAVF fed by the posterior meningeal artery with drainage into the perimedullary veins of the cervical spine. The fistula was not amenable to embolization because vascular access was difficult; therefore, the patient underwent urgent suboccipital craniotomy and ligation of the arterialized venous drainage from the fistula. The patient’s clinical course immediately reversed; she had a complete recovery over the course of a year, and she remains asymptomatic at the 2-year follow-up. This report adds to a growing body of evidence that describes the diverse and unpredictable nature of Type V dAVFs and highlights the need to obtain a cranial angiogram in pediatric patients with unexplained myelopathy and cervical cord T2 signal change on MRI.

To analyze the angiographic and clinical results of transarterial embolization with Onyx (Medtronic-Covidien, Irvine, CA) in dural arteriovenous fistulas (DAVFs) partially fed by arteries arising from the carotid siphon or the vertebral arteries. We isolated 40 DAVFs supplied by either the tentorial artery of the internal carotid artery (ICA) or the posterior meningeal artery of the vertebral artery. These DAVFs were embolized with Onyx through the middle meningeal artery or the occipital artery. We reviewed the occurrence of reflux into the arteries of carotid or vertebral origin. In all the cases, reflux occurred into the first millimeters of the DAVF arterial feeders arising from carotid or vertebral arteries but slowly enough to be controlled by interruption of Onyx injection. Reflux was always minimal and Onyx never reached the ostium of the arteries. No cerebral ischemic complications occurred in our series. The behavior of Onyx is clearly different from that of cyanoacrylate glue, resulting in superior control during injection. Reflux into arteries arising from the ICA or vertebral artery during DAVF treatment always carries a risk of unintentional non-target embolization of normal cerebral vasculature but Onyx appears to be safe in this situation.

Dural arteriovenous fistulas (DAVFs) represent 10%–15% of all intracranial arteriovenous malformations. 1 DAVFs located in the posterior cranial fossa are rare and often present with intracranial hemorrhage and myelopathy. 2 Arterial supply could be provided by the meningeal branches of the vertebral artery and external and internal carotid arteries. 3 A 68-year-old man presented with progressive lower-extremity weakness ( Video 1 ). Magnetic resonance imaging revealed a patchy longitudinal cord signal abnormality extending from the cervicomedullary junction to C7. A tentorial DAVF supplied by the right posterior meningeal artery with drainage via dorsal and ventral perimedullary veins was identified on angiography. According to the Cognard classification, the patient's DAVF was determined to be high risk as a type V lesion with spinal venous drainage and progressive myelopathy. 4 The fistula was embolized with 50% ethanol resulting in near-complete occlusion. However, follow-up angiography revealed a persistent arteriovenous shunt and slightly worsening symptoms for the patient. He underwent a sitting supracerebellar approach with a torcular craniotomy for successful clip ligation of the dural arteriovenous fistula. The patient was discharged with improvements in lower-extremity strength and no residual arteriovenous shunting in postoperative imaging.

BACKGROUND AND PURPOSE: Recognition of shunted pouches dural arteriovenous fistula allows us to treat the disease effectively by selective embolization of the pouches at first. However, the shunted pouches in transverse-sigmoid sinus dural arteriovenous fistulas have not been well-documented. Our aim was to evaluate the angioarchitecture of transverse-sigmoid sinus dural arteriovenous fistulas, including the frequency and location of shunted pouches and their feeding arteries. MATERIALS AND METHODS Twenty-five consecutive cases of TSS-DAVFs that underwent rotational angiography and transvenous embolization between 2008 and 2011 were reviewed. Multiplanar reformatted images of rotational angiography and selective angiography were reviewed with a particular focus on the shunted pouches. RESULTS: All 25 cases showed SPs, with numbers ranging from 1 to 4 pouches (mean, 2.35). The SPs were located at the transverse-sigmoid junction in 16, close to the vein of Labbe in 9, at the dorsal-to-sigmoid sinus in 9, inferior to the sigmoid sinus in 6, at the sigmoid-jugular junction in 5, and inferior to the transverse sinus or the sinus confluence in 14. The SP at the sigmoid sinus was frequently fed by the jugular branch of the ascending pharyngeal artery and the stylomastoid artery. The SP at the transverse-sigmoid junction and the vein of Labbe was fed by the petrosal/petrosquamous and posterior branches of the middle meningeal artery and the transosseous branches of the occipital artery. The SP inferior to the transverse sinus and the sinus confluence was fed by the transosseous branches of the occipital artery and the posterior meningeal artery. All cases were successfully treated by transvenous embolization with sinus packing ( n = 13) or selective embolization of the SP ( n = 12). CONCLUSIONS: The presence of SP is a common angioarchitecture of TSS-DAVFs. Identification of the SPs would be useful for their treatment.

OBJECTIVE: An endovascular approach is often the first-line treatment of dural arteriovenous fistulae (DAVFs). Information on the use of Onyx (ev3 Neurovascular, Irvine, CA) for treating DAVFs, however, is limited. Therefore, we present our early experience, technical considerations, and complications associated with the use of Onyx for DAVF embolization. METHODS: Twenty-eight patients with 29 DAVFs treated with Onyx embolization were included in this analysis. Hospital records, operative reports, and angiograms were reviewed and analyzed. RESULTS: Forty Onyx procedures, including 39 transarterial and 1 transvenous approaches, were performed. Fifty-one external carotid artery branches, 8 posterior meningeal artery branches, and 3 internal carotid artery branches were used for Onyx embolization. Branches of the middle meningeal artery were embolized 32 times, and the occipital artery was embolized 15 times. Twenty-one fistulae (72%) were cured angiographically with endovascular therapy. Transarterial embolization via the middle meningeal artery cured 12 DAVFs (41%). Four complications (9.7%) were recorded, including 3 transient (7.3%) and 1 permanent neurological deficits (2.4%). Follow-up imaging, which was available for 8 fistulae with angiographic cures, showed no evidence of recurrence. CONCLUSION: Transarterial Onyx embolization of external carotid artery branches, particularly the middle meningeal artery, offers a high likelihood of cure. This technique provides a safe and effective method of embolization with few side effects and complications. However, long-term follow-up is needed to establish its efficacy.

✓ Acute ischemic infarction of the posterolateral bulbomedullary junction occurred in a 28-year-old man who underwent arterial embolization for the treatment of an intracranial dural arteriovenous malformation. The migration of the embolic agent in the posterior spinal artery via a peripheral anastomosis between the middle meningeal artery and the posterior meningeal artery was responsible for this complication. The cast of glue in the radiculopial system at the upper cervical level was visible on computed tomography scanning, and magnetic resonance imaging demonstrated circumscribed signal changes and restricted diffusion in the arterial territory of the bulbomedullary junction. The authors discuss the anatomical, clinical, and technical issues of this rare complication.

Background The craniocervical junction is a rare location for spinal dural arteriovenous fistulas (dAVFs). Typically, fistulas at this location present with findings related to intracranial cortical venous reflux or cervical myelopathy. We present a case of craniocervical junction dAVF with isolated clinical and radiographic findings of thoracolumbar myelopathy. Case Description A 54-year-old man presented with subacute onset of lower extremity weakness, paresthesias, and gait dysfunction. Routine spine magnetic resonance imaging demonstrated edema of the conus medullaris and distal thoracic spinal cord and prominent dorsal venous flow voids, suggestive of a thoracolumbar dAVF. Spinal angiography performed at an outside institution failed to demonstrate a fistula. Noninvasive spinal angiographic imaging with time-resolved magnetic resonance angiography (TR-MRA) performed at our institution was able to demonstrate presence of the fistula at the craniocervical junction. Subsequent cerebral angiography identified feeding vessels arising from the posterior meningeal artery and ascending pharyngeal artery on the right side. The fistula was successfully embolized with onyx embolic material, with rapid resolution of his clinical symptoms. Conclusions Isolated lower extremity myelopathic symptoms are a rarely reported finding in patients harboring craniocervical junction dAVFs. At our institution, noninvasive imaging with TR-MRA is routinely used to aid localization of dAVFs. This results in decreased contrast dose and radiation exposure, and inclusion of the cervical spine should be performed when thoracolumbar imaging fails to identify a dAVF prior to proceeding to invasive angiography.

We describe a case of reproducible asystole during endovascular treatment of a posterior fossa dural arteriovenous fistula. Catheterisation of the posterior meningeal artery, a branch of the vertebral artery in this patient, followed by dimethyl sulfoxide injection prior to Onyx administration resulted in two episodes of asystole. To the best of our knowledge, this is the first reported case of asystole occurring during endovascular intervention in the posterior meningeal artery. This may represent a previously undescribed variant of the trigemino-cardiac reflex (TGCR) caused by chemical stimulation of small areas of trigeminally innervated posterior fossa dura. Alternatively, this may represent a newly identified phenomenon with chemical stimulation of regions of posterior fossa dura innervated by branches of the vagus nerve leading to increased parasympathetic activity and resultant asystole. In either case, it is important to recognise the potential for such episodes in this vascular territory to allow case planning and management.

A 38-year-old man presented with a dissecting aneurysm of the left proximal posterior inferior cerebellar artery (PICA) manifesting as Wallenberg's syndrome. The patient was treated by endovascular occlusion of the aneurysm and parent artery. Immediately after the treatment, the PICA territory was supplied by collateral circulation via the ipsilateral anterior inferior cerebellar artery. Seven days later, endogenous revascularization of the distal PICA territory had occurred via collateral circulation from the posterior meningeal artery (PMA). This unusual collateral circulation was thought to occur through a pre-existing anastomotic channel between the primitive vessels of the PICA and the PMA during sub-clinical hypoperfusion of the distal PICA territory. This unusual case demonstrates the potential for delayed development of collateral circulation from the PMA to the PICA territory.

BACKGROUND Advances in microsurgical techniques made possible the removal of advanced jugular foramen (JF) lesions, which once had been accepted as unoperable. However, successful surgery requires detailed knowledge of the JF anatomy. METHODS Sixteen jugular foramina in eight formalin-preserved adult cadavers were scanned with axial and coronal high resolution computed tomography (HRCT) prior to dissection. After craniectomy and removal of brain tissue, the relationships of the neurovascular structures in the JF were determined by drilling the temporal bones from superior to inferior on planes parallel to the skull base. RESULTS No bony partition of the JF was observed. A dural band consistently divided the JF into two parts. Anterior to it was the glossopharyngeal nerve (IX) while the vagus (X) and accessory (XI) nerves were located posteriorly. There was a notch in which the IX nerve entered the JF. It was also identified on the CT scans and defined as the glossopharyngeal recess. The IX nerve made a genu within the JF in all specimens. Then, it ran inferiorly through a bony canal in three specimens (18.75%), and through an incomplete bony canal in two (12.5%), which were also defined on the CT images. The inferior petrosal sinus ran through a sulcus anteromedial to the glossopharyngeal recess. The posterior meningeal artery was found to be located between the X and XI nerves within the JF. CONCLUSIONS This study revealed a complex and highly variable pattern of the relationships of the neurovascular structures in the JF, and their HRCT images correlated well with the anatomic microdissections.

The vertebral arteries (VAs) are originated from the subclavian arteries and are major arteries for posterior circulation. The left and right VAs are typically described as having 4 segments each (V1 through V4), the first 3 of which are extracranial [1]: the V1 segments extend cephalad and posteriorly from the origin of the vertebral arteries between the longus colli and scalenus anterior muscles to the level of the transverse foramina, typically adjacent to the sixth cervical vertebra. The V2 segments extend cephalad from the point at which the arteries enter the most inferior transverse portion of the foramina to their exits from the transverse foramina at the level of the second cervical vertebra. These segments of the left and right VAs therefore have an alternating intraosseous and interosseous course, a unique anatomic environment that exposes the V2 segments to the possibility of extrinsic compression from spondylotic exostosis of the spine. Small branches from the V2 segments supply the vertebrae and adjacent musculature and, most importantly, may anastomose with the spinal arteries. The V3 segments extend laterally from the points at which the arteries exit the C2 transverse foramina, cephalad and posterior to the superior articular process of C2, cephalad and medially across the posterior arch of C1, and then continue into the foramen magnum. Branches of the V3 segments typically anastomose with branches of the occipital artery at the levels of the first and second cervical vertebrae. The V4 segments of each vertebral artery extend from the point at which the arteries enter the dura to the termination of these arteries at the vertebrobasilar junction. Important branches of the V4 segments include the anterior and posterior spinal arteries, the posterior meningeal artery, small medullary branches, and the posterior inferior cerebellar artery (PICA) [1].

BACKGROUND: We report an unusual case of a true dural aneurysm arising from the posterior meningeal artery that fed a symptomatic dural arteriovenous fistula located at the right transverse-sigmoid sinus junction. CLINICAL PRESENTATION: A 29-year-old right-handed white woman presented with aneurysmal dilatation of hypertrophied posterior meningeal artery feeding a partially treated dural arteriovenous fistula. INTERVENTION: The aneurysm, which measured approximately 3 mm in width and 5 mm in length, was located in the intracranial space with a thin-walled dome projecting toward the cerebellum. Its afferent and efferent vessels were identified, secured, and the lesion was excised en bloc. CONCLUSION: A thorough evaluation of all diagnostic studies should be performed for patients with vascular malformations to help identify these or other unusual lesions that may aid in the risk stratification process and management plan.

A decrease in vascular density in the endolymphatic sac was suspected as a factor in the pathogenesis of endolymphatic hydrops in Meniere's disease. The present study was undertaken to explore this possibility by cutting the posterior meningeal artery and the sigmoid sinus above and below the external aperture of the vestibular aqueduct or by incision of the dura adjacent to the sinus in 18 guinea pigs. The lesions in the sac were greater in the segmental ablation of the artery and sinus and were consistently associated with the development of endolymphatic hydrops. Among the lesions shown in the sac epithelia, the intermediate portion was most often and most severely affected with a decrease in rugose formation and a flattening of the tall epithelial cells or replacement of epithelial cells by squamous type cells. A high correlation between the lesions in the intermediate portion and occurrence of hydrops suggests that the intermediate portion plays a greater role in the pathogenesis of endolymphatic hydrops. The sac luminal precipitates known to be increased in human Meniere's cases were decreased or absent in this study, which suggests that the increased amount is unlikely to be the cause of endolymphatic hydrops. The evidence supports the hypothesis that these substances are secreted by the endolymphatic sac. The limited sensory cell lesions seen in the cochleae and saccules are likely to be due to a temporary vascular ischemia and endolymphatic hydrops.

Objective This is the first report of a ruptured aneurysm involving a collateral branch to the posterior inferior cerebellar artery (PICA) in a patient who had a subarachnoid hemorrhage. Clinical presentation A 56-year-old man initially presented with a subarachnoid hemorrhage and underwent 2 catheter-based 4-vessel angiograms with negative results. A delayed angiogram 4 weeks later revealed a dissecting aneurysm of the posterior meningeal artery, a branch of the vertebral artery. Intervention A 3-dimensional reconstruction of the vertebral angiogram showed proximal occlusion of the proximal left PICA and distal filling via a collateral branch from the posterior meningeal artery. A far-lateral approach was used for this patient. The aneurysm was found along the course of the collateral posterior meningeal artery and was clipped successfully. Conclusion Aneurysms involving collateral branches of the PICA are rare. It is important to recognize such collateral flow preoperatively because inadvertent sacrifice of these vessels during a surgical approach could lead to stroke and neurological deficits of the PICA territory.

Patients with dural arteriovenous fistulas (dAVFs) may present with cognitive impairment secondary to venous hypertension or ischemia.We present a patient with a dAVF supplied by the posterior meningeal artery who presented with severe encephalopathy and imaging consistent with bilateral thalamic ischemia.Detailed pre-operative neuropsychological testing documented severe cognitive deficits across multiple domains, localizing diffusely in the cerebral cortex, beyond that which would be expected from purely thalamic involvement. Approximately 2 months following a combined endovascular and surgical repair, repeat neuropsychological testing documented a dramatic improvement in cognitive symptoms while MRI abnormalities in the thalami resolved.Detailed neuropsychological testing may be useful in patients presenting with dAVFs in order to identify cognitive impairment, which may be out of proportion to imaging findings. Recognition of dAVF-associated cognitive impairment may lead to more aggressive, timely treatment in patients with otherwise lower-risk lesions. This detailed testing can also provide a baseline in order to document cognitive recovery after fistula repair.

After passing through the foramen magnum the vertebral artery gives rise to numerous branches before uniting with the opposite vertebral artery at the vertebral-basilar junction. Multiple small perforating arteries arise from the distal vertebral artery which supplies the lateral regions of the medulla. The posterior inferior cerebellar artery (PICA) usually arises from the distal vertebral artery 1-2 cm below the vertebral-basilar junction. These arteries are often asymmetric and their size can vary. There is a reciprocal relationship between the size of the PICA and that of the ipsilateral anterior inferior cerebellar artery (AICA) which arises from the basilar artery. When the AICA is large, the ipsilateral PICA is often small or sometimes can be absent. In this situation a large medial branch of the AICA supplies the PICA vascular territory. The PICA divides into branches supplying the ipsilateral cerebellar tonsil, inferior vermis, and the inferior cerebellar hemisphere. Small perforators from the proximal PICA can supply the lateral and posterior medulla. The anterior spinal artery usually arises from the distal 1 cm of the vertebral artery. This vessel often unites with the anterior spinal artery branch from the contralateral vertebral artery to form the main anterior spinal artery. The posterior meningeal artery which supplies the falx cerebelli arises from the distal vertebral artery near the foramen magnum. This vessel courses both posteriorally and superiorally. The vertebral arteries unite to form the basilar artery ventral to the superior medulla/inferior pons.

Hemangioblastomas are World Health Organization (WHO) Grade I neoplasms of the hindbrain and spinal cord, whose management can be complicated by preoperative hemorrhage. We report on a case of a young female in extremis with posterior fossa hemorrhage following rupture of a fusiform posterior meningeal artery aneurysm embedded within a medullary hemangioblastoma. We discuss management options, including operative staging and embolization, and review similar cases of hemangioblastoma associated with aneurysm.

✓ The microsurgical anatomy of the jugular foramen was studied in 10 fixed cadavers, each cadaver consisting of the whole head and neck. Five of the cadavers were injected with latex. The jugular foraminal region was exposed using the infratemporal fossa type A approach of Fisch and Pillsbury in five cadavers (10 sides) and the combined cervical dissection—mastoidectomy—suboccipital craniectomy approach in five cadavers (10 sides). The right foramen was larger than the left in seven cases (70%), equal in two cases (20%), and smaller in one case (10%). The dura covering the intracranial portal of the foramen had two perforations, a smaller anteromedial perforation through which passed the ninth cranial nerve (CN IX), and a larger posterolateral perforation, through which passed the 10th and 11th cranial nerves (CNs X and XI) and the distal sigmoid sinus. The perforations were separated by a fibrous septum in 16 specimens (80%). After exiting the posterior fossa, CNs IX, X, and XI all lay anteromedial to the superior jugular bulb (SJB) within the jugular foramen. The inferior petrosal sinus (IPS) entered the foramen between CNs IX and X in most cases; however, in 10% of our cases it entered the foramen between CNs X and XI, and in 10% it entered the foramen caudal to CN XI. The IPS terminated in the SJB in 90% of our cases; in 40%, the IPS termination consisted of multiple channels draining into both the SJB and internal jugular vein. This study shows that the arrangement of the neurovascular structures within the jugular foramen does not conform to the hitherto widely accepted notion of discrete compartmentalization into an anteromedial pars nervosa containing CN IX and the IPS and a posterolateral pars venosa containing the SJB, CNs X and XI, and the posterior meningeal artery.

OBJECTIVE The posterior meningeal artery (PMA) normally arises from the vertebral artery; however, its origin varies considerably as the result of its embryological development. This gains clinical significance when associated with vascular pathology. CLINICAL PRESENTATION A 65-year-old man presented to his local hospital with a sudden-onset, severe headache. Computed tomography of the head revealed diffuse subarachnoid hemorrhage, mostly in the left posterior fossa. A computed tomographic angiogram demonstrated an anomalous origin of the PMA from the posteroinferior cerebellar artery (PICA). Cerebral angiography showed the PICA to be enlarged, with a reduced caliber at the takeoff of the PMA, which is consistent with possible dissection. INTERVENTION The patient was taken to the operating room for trapping of the dissecting segment of the PMA. A clip was placed across the PMA at its origin from the PICA, and the vessel was coagulated and transected. The PICA was wrapped in muslin gauze. CONCLUSION The variable origin of the PMA and PICA may be the result of the persistence of embryological anastomoses between the arteries, with regression of the normal channel. Physical stress at the junction of the anomalous PMA and the PICA may have contributed to the abnormality of the PMA, consistent with possible dissection. Because the PMA has multiple anastomoses with the arteries of the falx cerebri, the proximal PMA may be occluded with no compromise to its vascular territory.

The authors present two cases of angiographically-confirmed anomalous origin of the posterior meningeal artery (PMA) from the lateral segment of the posterior inferior cerebellar artery (PICA) and describe briefly the probable embryogenesis of this anomaly.

The vascular anatomy of the endolymphatic sac in guinea pigs was examined following intravascular injection of silicone rubber (Microfil). Methacrylate resin of low viscosity (Mercox) was used to obtain vascular corrosion casts for scanning electron microscopy, which allowed more accurate differentiation between arteries and veins. The extensive vascular system around the sac comprises both arteries and veins, as well as lymphatic vessels. The arterial supply is derived mainly from the posterior meningeal artery in the posterior cranial fossa. In some cases a small artery also leads to the sac from the posterior vestibular artery in the labyrinth (in 7 of the 35 animals investigated). It courses together with the vein of the vestibular aqueduct along the walls of the endolymphatic duct. The blood is drained over the intermediate portion of the endolymphatic sac, which becomes lodged in a rich meshwork of capillaries, venules, veins and a few small arteries. A few venous trunks from both sac walls fuse with the vein of the vestibular aqueduct, which drains blood from the vestibule to the sigmoid sinus. Scanning electron microscopy also revealed numerous anastomosing vessels within bone channels with adjacent bone marrow sinusoids, which also probably contribute to the vascular supply of the endolymphatic sac.