Intracranial dural arteriovenous fistulas: A Review

Transarterial embolization in non-cavernous and cavernous sinus dural arteriovenous fistulas: A systematic review and meta-analysis of proportions

BACKGROUND

Transarterial embolization (TAE) is pivotal in managing non-cavernous and cavernous sinus dural arteriovenous fistulas (CSDAVFs).

METHODS

Systematic searches were conducted across ScienceDirect, Medline, and Cochrane databases for longitudinal studies on TAE outcomes in non-CSDAVFs and CSDAVFs. Post-procedural outcomes, including complete, incomplete, and failed AVFs obliteration, and end-study outcomes were analyzed.

RESULTS

Our meta-analysis involved 27 studies with 643 patients and 736 fistulas. Symptoms in both groups included tinnitus (29.74 %), ocular/visual symptoms (29.12 %), hemorrhage (19.42 %), and headache (19.11 %). Feeding arteries mainly originated from the meningeal arteries (49.16 %). In non-CSDAVFs cases, fistula locations were within sinus complexes (69.23 %) and specific dural areas (28.31 %). Complete AVFs obliteration was 81 % (95 %CI: 70 % - 90 %), slightly higher in non-CSDAVFs (82 %, 95 % CI: 69 % - 92 %) than CSDAVFs (79 %, 95 %CI: 58 % - 95 %). Incomplete obliteration occurred in 14 % (95 %CI: 5 % - 39 %), with rates of 11 % (95 %CI: 2 % - 26 %) in non-CSDAVFs and 19 % (95 % CI: 5 % - 39 %) in CSDAVFs. Failed obliteration was rare (1 %, 95 %CI: 0 % - 3 %), with similar rates in both groups. At end-study follow-up, resolution of AVFs was achieved in 97 % of cases (95 %CI: 92 % - 100 %). However, complications occurred in 17 % of cases (95 %CI: 10 % - 25 %), with a higher incidence in CSDAVFs (22 %, 95 %CI: 9 % - 37 %) compared to non-CSDAVFs (13 %, 95 %CI: 6 % - 23 %).

CONCLUSIONS

TAE with embolic agents demonstrates favorable outcomes in non-CSDAVFs and CSDAVFs, with high rates of AVFs obliteration and resolution. Complications, particularly in CSDAVFs, warrant careful consideration in treatment decisions.

Pipeline embolization device as a standalone curative approach for recurrent sigmoid sinus DAVF

Dural arteriovenous fistulas (dAVFs) can occur as complications after surgical procedures, especially following the resection of meningiomas near the dural sinus. This case report presents a 74-year-old male who developed a recurrent sigmoid dAVF following meningioma resection. Initially treated with transvenous embolization and middle meningeal artery embolization, the dAVF recurred with worsening clinical symptoms. Conventional treatment options, including sinus sacrifice and transarterial embolization, were unsuitable due to the critical role of the patient's dominant right sigmoid sinus in cerebral venous drainage. Consequently, a reconstructive approach was employed using a pipeline embolization device (PED) construct. The PED successfully occluded the dAVF while preserving the function of the sigmoid sinus. A follow-up angiogram confirmed stable occlusion and normalization of intracranial venous drainage. This case underscores the potential of flow diversion as a viable treatment option for dAVFs, particularly in scenarios where preserving venous sinus function is paramount.

Intracranial dural arteriovenous fistulas with pial arterial supply: A narrative review

Intracranial dural arteriovenous fistula (DAVF) is a relatively complex intracranial condition, and its clinical presentation and treatment strategies often vary significantly due to various factors. Although the cure rate of intracranial DAVF is currently high, there is still a lack of understanding of its etiology and pathogenesis. There is ongoing controversy regarding the treatment strategies for DAVF associated with the pial arteries, and there is a lack of understanding of its pathogenesis. The author conducted a brief literature review on DAVF with pial arterial supply and presented some treatment experiences from their own medical center. Large-scale retrospective cohort studies and prospective research in future are expected to address these issues.

Coexistence of cerebral venous thrombosis and dural arteriovenous fistula in an adolescent: A case report

Key Clinical Message

Clinicians should consider central venous thrombosis (CVT) as a differential diagnosis in young adolescents with persistent headaches. It is essential to assess for concurrent CVT and dural arteriovenous fistula (DAVF), particularly in those with a history of CVT.

Abstract

Cerebral venous thrombosis (CVT) and dural arteriovenous fistula (DAVF) are uncommon vascular disorders with diverse clinical presentations. The coexistence of CVT and DAVF is a rare but important association that may impact the management and prognosis of affected patients. Prothrombotic conditions generally ranging from acquired to genetic, oral contraceptives, malignancy, puerperium, infection, and head injury are the common risk factors for cerebral venous thrombosis. Here, we present a case of 18 years males who developed recurrent cerebral thrombosis on the background of the presence of an arteriovenous fistula.

Clinical Reasoning: A 25-Year-Old Woman With Eye Swelling and Headache

Cerebral venous sinus thrombosis (CVST) is uncommon. Risk factors include inherited and acquired factors. Rapid diagnosis and treatment is essential and can help prevent complications, which can include seizures and visual disturbance. A 25-year-old woman with a background history of CVST and intermittent warfarin use presented to the hospital in 2021 with a 3-month history of progressive eye swelling and headache. Her headache was located in the right frontal region and worsened with movement. Her workup was consistent with recurrent CVST and dural arteriovenous fistula. IR-guided embolization of the fistulas and stenting of her sinuses was performed. She was treated with dual antiplatelet therapy and therapeutic tinzaparin. Her symptoms improved markedly over several days, with improvement in headache and visual acuity. This case illustrates the potential for severe complications including visual disturbance in untreated CVST, as well as the importance of a thorough history and examination in aiding the recognition of the condition.

Dural arteriovenous fistula causing reversible cognitive impairment

A previously independent 82-year-old woman presented with 5 months of worsening confusion, mobility and cognitive decline, with deficits in orientation, language and executive function. A cerebral dural arteriovenous fistula was identified and successfully embolised, after which her cognitive ability and independence dramatically improved. Although rare, a dural arteriovenous fistula may mimic a rapidly progressive dementia, but its early recognition and treatment can completely reverse the dementia.

Intracranial dural arteriovenous fistula: a comprehensive review of the history, management, and future prospective

Dural arteriovenous fistulas (DAVF) are abnormal acquired intracranial vascular malformations consisting of pathological connections located within the dura between the pial arteries and the veno vasora, comprising the walls of the dural sinuses, bridging veins, or transosseous emissary veins. Dural arteriovenous fistulas are distinguished from arteriovenous malformations by their arterial supply from the vessels that perfuse the dura mater and lack of a parenchymal nidus. They are most commonly situated at the transverse and cavernous sinuses. The mechanism of development behind dural arteriovenous fistula can be explained by the molecular and anatomical factors. Multiple classification systems have been proposed throughout history including; Djindjian and Merland, Cognard, and Borden classification systems. The aggressiveness of the clinical course in intracranial dural arteriovenous fistula can be predicted through the angiographic patterns of venous drainage, more specifically, the presence of cortical venous drainage, the presence of venous ectasia, and the aggressiveness of clinical presentation. Intracranial dural arteriovenous fistulas might be discovered incidentally. However, if symptomatic, the clinical presentation ranges from mild neurological deficits to severe, lethal intracranial hemorrhage. Angiography is the imaging of choice to investigate, diagnose, and plan treatment for intracranial dural arteriovenous fistula. The management algorithm of intracranial dural arteriovenous fistula can be broadly divided into conservative, surgical, endovascular, and/or radiosurgical options. With the advent of endovascular therapies, surgery has fallen out of favor for managing intracranial dural arteriovenous fistulas. In the present article, the pathophysiology, classifications, natural history, clinical manifestations, radiological features, management, and complications are comprehensively reviewed.

Differential subsampling with cartesian ordering: A high spatial-temporal resolution dixon imaging sequence for assessment of dural arteriovenous fistula

Objective

To evaluate the accuracy of differential subsampling with cartesian ordering (DISCO) in comparison to time of flight (TOF) in detecting dural arteriovenous fistulas (DAVF), cerebral venous thrombosis (CVT) and hemodynamics.

Methods

Sixty-two cases (24 female; aged 14–75; mean age, 51.3 years) were included in our study, with 42 positive and 20 negative cases via Digital Subtraction Angiography (DSA). Two neuroradiologists independently evaluated the DISCO and TOF. The sensitivity, specificity, and accuracy of the DISCO and TOF-MRA were individually calculated using DSA as the gold standard. Inter-observer reliability was assessed by using a weighted Cohen's kappa (κ) test; P < 0.05 was set as the threshold for statistical significance.

Results

Diagnostic sensitivities of DISCO and TOF for DAVF were 92.86 and 64.29%; specificities were 95.0% and 95.0%; while accuracies were 93.55 and 74.19% respectively. For detected CVT, sensitivities of DISCO and TOF were 100 and 92.31%; specificities were 96.55 and 93.10%; with accuracies 97.62 and 92.86% respectively. In hemodynamic analysis, sensitivity of DISCO for reflux was 95.45%; with a specificity of 95.0%; and accuracy 95.24%. The inter-observer kappa values were 0.857 for DISCO (P < 0.001).

Conclusion

DISCO showed a high degree of sensitivity and specificity, suggesting its effectiveness in detecting DAVF with or without CVT. Intracranial hemodynamics can be identified using DISCO in DAVF patients, providing accurate evaluation of cerebral blood flow dynamics during the pre-treatment phase.

Novel experimental model of brain arteriovenous malformations using conditional Alk1 gene deletion in transgenic mice

OBJECTIVE

Hereditary hemorrhagic telangiectasia is the only condition associated with multiple inherited brain arteriovenous malformations (AVMs). Therefore, a mouse model was developed with a genetics-based approach that conditionally deleted the causative activin receptor-like kinase 1 (Acvrl1 or Alk1) gene. Radiographic and histopathological findings were correlated, and AVM stability and hemorrhagic behavior over time were examined.

METHODS

Alk1-floxed mice were crossed with deleter mice to generate offspring in which both copies of the Alk1 gene were deleted by Tagln-Cre to form brain AVMs in the mice. AVMs were characterized using MRI, MRA, and DSA. Brain AVMs were characterized histopathologically with latex dye perfusion, immunofluorescence, and Prussian blue staining.

RESULTS

Brains of 55 Tagln-Cre+;Alk12f/2f mutant mice were categorized into three groups: no detectable vascular lesions (group 1; 23 of 55, 42%), arteriovenous fistulas (AVFs) with no nidus (group 2; 10 of 55, 18%), and nidal AVMs (group 3; 22 of 55, 40%). Microhemorrhage was observed on MRI or MRA in 11 AVMs (50%). AVMs had the angiographic hallmarks of early nidus opacification, a tangle of arteries and dilated draining veins, and rapid shunting of blood flow. Latex dye perfusion confirmed arteriovenous shunting in all AVMs and AVFs. Microhemorrhages were detected adjacent to AVFs and AVMs, visualized by iron deposition, Prussian blue staining, and macrophage infiltration using CD68 immunostaining. Brain AVMs were stable on serial MRI and MRA in group 3 mice (mean age at initial imaging 2.9 months; mean age at last imaging 9.5 months).

CONCLUSIONS

Approximately 40% of transgenic mice satisfied the requirements of a stable experimental AVM model by replicating nidal anatomy, arteriovenous hemodynamics, and microhemorrhagic behavior. Transgenic mice with AVFs had a recognizable phenotype of hereditary hemorrhagic telangiectasia but were less suitable for experimental modeling. AVM pathogenesis can be understood as the combination of conditional Alk1 gene deletion during embryogenesis and angiogenesis that is hyperactive in developing and newborn mice, which translates to a congenital origin in most patients but an acquired condition in patients with a confluence of genetic and angiogenic events later in life. This study offers a novel experimental brain AVM model for future studies of AVM pathophysiology, growth, rupture, and therapeutic regression.

Computed tomographic and digital subtraction angiography evaluation of ophthalmic-ethmoidal artery dural arteriovenous fistula

Ophthalmic-ethmoidal dural arteriovenous fistula (DAVFs) is a rare type of dural arteriovenous fistulas and usually presenting with spontaneous subarachnoid hemorrhage, subdural hemorrhage or ocular symptoms. We present a case of a 59-year old gentleman presenting with acute headache, vomiting and generalized weakness. CT study of the brain revealed a large left frontal hematoma and abnormal aneurysmal sac with dilated cortical vein, communicating with the superior sagittal sinus. Conventional angiography confirmed diagnosis of ruptured ophthalmic-ethmoidal DAVF, resulting in a frontal intra-axial hemorrhage. Anterior fossa DAVFs are extremely rare, difficult to diagnose and treat. CT angiography is initial method of diagnosis, but digital substruction angiography remains the gold standard of confirming dural fistulas.

Cerebral venous thrombosis: imaging patterns

Cerebral venous thrombosis (CVT) is an uncommon condition that is potentially reversible if properly diagnosed and promptly treated. Although CVT can occur at any age, it most commonly affects neonates and young adults. Clinical diagnosis is difficult because the clinical manifestations of CVT are nonspecific, including headache, seizures, decreased level of consciousness, and focal neurologic deficits. Therefore, imaging is crucial for the diagnosis. Radiologists should be able to identify the findings of CVT and to recognize potential imaging pitfalls that may lead to misdiagnosis. Thus, the appropriate treatment (anticoagulation therapy) can be started early, thereby avoiding complications and unfavorable outcomes.

Foramen Caecum Vein Involved in Dural Arteriovenous Fistula Fed by Sphenopalatine Arteries: A Case Report

Anterior cranial fossa (ACF) dural arteriovenous fistulas (ACF DAVFs) are an infrequent subtype of cranial DAVFs that are usually fed by the anterior ethmoidal artery (AEA) and ophthalmic artery (OA) branches. Due to the lack of dural venous sinus in the ACF, they directly drain into cortical veins, resulting in high bleeding tendency. For this reason, ACF DAVFs have to be treated regardless of whether they are symptomatic or not. A 74-year-old man, with hypertension history, came to our attention because of ear pain, dizziness, and impaired hearing for 2 months. No other pathological conditions have been found in his medical history. The patient underwent brain magnetic resonance imaging (MRI) scan and subsequently second level diagnostic investigations with digital subtraction angiography (DSA), showing a foramen caecum (FC) patency and a persistent, enlarged, arterialized FC vein (FCV) involved in an incidental ACF DAVF (Cognard IV), fed mainly by sphenopalatine arteries (SPAs) branches bilaterally. The patient underwent open surgery performed by small high frontal craniotomy with DAVFs complete closure and without any complications. To the best of our knowledge, this is the first case ever described of FCV persistence with involvement in an intracranial vascular malformation. It has been managed by surgical intervention that can be considered, despite the large skin incision, a minimally invasive approach with an excellent cosmetic result and minimal risk of complications.

Direct Cannulation of a Calvarial Diploic Vein for Embolization of a Symptomatic Intraosseous Arteriovenous Fistula: A Case Report

Diploic arteriovenous fistulas (AVFs) or intraosseous dural AVFs are rare arteriovenous shunts. A diploic AVF is formed between a meningeal artery and an intraosseous diploic vein or the transosseous emissary vein, and the nidus is located exclusively within the bone. Currently, endovascular embolization with a transvenous approach is considered the treatment of choice for most dural AVFs. However, in the absence of an accessible venous channel, an alternate treatment approach should be considered. Herein, we report a case of a diploic AVF that was treated using embolization with transosseous direct cannulation.

Ensemble of Deep Learning Cascades for Segmentation of Blood Vessels in Confocal Microscopy Images

Detection, segmentation, and quantification of microvascular structures are the main steps towards studying microvascular remodeling. Combined with appropriate staining, confocal microscopy imaging enables exploration of the full 3D anatomical characteristics of microvascular systems. Segmentation of confocal microscopy images is a challenging task due to complexity of anatomical structures, staining and imaging issues, and lack of annotated training data. In this paper, we propose a deep learning system for robust segmentation of cranial vasculature of mice in confocal microscopy images. The proposed system is an ensemble of two deep-learning cascades consisting of two coarse-to-fine subnetworks with skip connections in between. One cascade aims to improve sensitivity, while the other aims to improve precision of the segmentation results. Our experiments on mice cranial vasculature showed promising results achieving segmentation accuracy of 92.02% and dice score of 81.45% despite being trained on very limited confocal microscopy data.

Rare Neurovascular Diseases in Korea: Classification and Related Genetic Variants

Rare neurovascular diseases (RNVDs) have not been well-recognized in Korea. They involve the central nervous system and greatly affect the patients' lives. However, these diseases are difficult to diagnose and treat due to their rarity and incurability. We established a list of RNVDs by referring to the previous literature and databases worldwide to better understand the diseases and their current management status. We categorized 68 RNVDs based on their pathophysiology and clinical manifestations and estimated the prevalence of each disease in Korea. Recent advances in genetic, molecular, and developmental research have enabled further understanding of these RNVDs. Herein, we review each disease, while considering its classification based on updated pathologic mechanisms, and discuss the management status of RNVD in Korea.

Clinical and radiological response of aggressive dural arteriovenous fistula after combined glue embolization and hypofractionated helical TomoTherapy

Purpose:

We reported the clinical and radiological outcome of an aggressive dural arteriovenous fistula (DAVF) after combined glue embolization and hypofractionated helical TomoTherapy (Hypo-HT).

Materials and methods:

Eleven patients whose radiological examinations are consistent with aggressive DAVF were treated with combined glue embolization and Hypo-HT 30–36 Gy in 5–6 fractions. The dosimetric analysis, clinical response and radiological imaging obliteration rate by magnetic resonance angiography or computed tomography angiography were investigated.

Results:

There were eight males and three females with a male and female ratio of 2·67. The mean age was 51·2 years old (range 37–69). Anatomical imaging sites of disease included transverse-sigmoid sinuses (n = 7), superior sagittal sinus (n = 3) and tentorium cerebelli (n = 1). The mean pitch and MF of treatment plans were 0·273 ± 0·032 and 1·70 ± 0·31, respectively. The average size of PTV were 15·39 ± 7·74 cc whereas the Reff,PTV was 1·50 ± 0·25 cm. The average Dmax and Dmin were 37·52 ± 3·34 and 31·77 ± 2·64 Gy, respectively. HI, CI and CI50 were 0·16 ± 0·06, 1·80 ± 0·56 and 7·85 ± 4·16, respectively. The R eff,Rx and R eff,50%Rx were 1·80 ± 0·24 and 2·90 ± 0·45 cm, respectively. The R eff between 50%Rx and 100%Rx was 1·10 ± 0·28 cm on average. With a mean follow up of 28·5 months (range 9–48), the complete recovery of symptoms was found in 72·7 % (eight patients) within 2–12 months after completion Hypo-HT. Partial recovery was reported in 18·2% (two patients). No clinical response was found in 9·1% (one patient). The total radiographic obliteration rate was 27·3% (three patients), subtotal obliteration was 27·3% (three patients) and partial obliteration was 45·4% (five patients).

Conclusions:

Satisfactory clinical response of aggressive DAVF was found in all treated patients by combining glue embolization and Hypo-HT. All dosimetric parameters were acceptable. We still need an extended follow up time to assess further radiographic obliteration rate and late side effects of the treatment.

Changes in Angioarchitecture After Stereotactic Radiosurgery for Dural Arteriovenous Fistula

INTRODUCTION

Dural arteriovenous fistulae (DAVF) are intracranial vascular abnormalities encountered in neurosurgery practice. Treatment options are microsurgical disconnection, endovascular embolization and/or radiosurgery. Past studies have reported the efficacy, safety, and predictors of success of radiosurgery. In this study, we investigated the angioarchitecture of fistulae at the time of radiosurgery and how the anatomy changed in the time after treatment based on angiogram follow-ups.

METHODS

A retrospective analysis was performed on patients with angiographic diagnosis of DAVF treated with Gamma Knife radiosurgery (GKRS) between 2013 and 2018. Data collection included demographics, symptoms, grading scores, vascular anatomy, radiation data, treatment strategy, angiographic results, and length of patient follow-up.

RESULTS

Our study reports data on 10 patients with a total of 14 fistulae. On follow-up angiography, 8 (57%) had complete occlusion of the fistula with a median time to follow up of 19.5 months. The remaining 6 (43%) were deemed as near-complete occlusion of fistula with a median time to follow up of 12.0 months. Time from radiosurgery to angiogram revealing incomplete vs. angiogram revealing complete obliteration was significantly different (p=0.045). Nearly all AVFs had decreased feeders over time after treatment with only one AVF developing an additional feeder post-treatment. Arterial feeders, drainage site, sex, Borden type, lesion volume and treatment volume had no predictive value of obliteration outcome.

CONCLUSIONS

This study provides data on the angioarchitecture of fistulae treated with GKRS and also serves as an extension of previous studies reporting the safety and efficacy of GKRS treatment for DAVF in a specific patient population.

The Top-100 most cited articles on dural arteriovenous fistula: A bibliometric analysis

Objective

Dural arteriovenous fistula (DAVF) is a rare pathological vascular lesion with variable clinical manifestations. Since 1968, several articles have been published to address spinal and cranial DAVFs. The aim of this study is to identify, analyse, and review the pertinent literature of the top-100 most cited articles on DAVFs published to date.

Methods

A title-specific, keyword-based search with no time restriction was performed in June 2020. The Scopus database was used to identify the top-100 most cited articles on DAVFs. The term “dural arteriovenous fistula” was used as a search keyword. The search results were arranged in descending order based on the total citation count. The top-100 articles were categorized into ten categories.

Results

Between 1968 and 2020, a total of 2298 articles were published on DAVFs. The top-100 most cited articles were published between 1983 and 2012. The total number of citations for the top-100 articles was 12393 (123 citations/article). Most articles (34%) were investigating the clinical aspect of DAVFs. The country contributing to the most impactful and highest volume of publications (46%) was the United States. The Mayo Clinic was the most active institute in contribution. Most articles (29%) were published by the Journal of Neurosurgery.

Conclusions

In the top-100 most cited articles on DAVF, most studies were published in neurosurgery/neuroradiology-dedicated journals. This bibliometric analysis identifies the publication trends and provides a comprehensive overview of the most influential articles addressing DAVFs.

Imaging in Pulsatile Tinnitus: Case Based Review

Tinnitus refers to auditory perception of internal origin. It is a relatively common problem and affects men and women equally. Clinically, it may be divided as pulsatile or non-pulsatile and subjective and objective. Although pulsatile tinnitus (PT) is less common, it is more likely to be associated with underlying vascular tumors, lesions or anomalies. Imaging forms the baseline for evaluation of objective tinnitus, primarily in the form of computed tomography or magnetic resonance imaging. We present a review of common causes of PT, along with emphasis on key imaging findings.

Stereotactic Radiosurgery for Cavernous Sinus Versus Noncavernous Sinus Dural Arteriovenous Fistulas: Outcomes and Outcome Predictors

BACKGROUND

Dural arteriovenous fistulas (DAVFs) can be categorized based on location.

OBJECTIVE

To compare stereotactic radiosurgery (SRS) outcomes between cavernous sinus (CS) and non-CS DAVFs and to identify respective outcome predictors.

METHODS

This is a retrospective study of DAVFs treated with SRS between 1988 and 2016 at 10 institutions. Patients' variables, DAVF characters, and SRS parameters were included for analyses. Favorable clinical outcome was defined as angiography-confirmed obliteration without radiological radiation-induced changes (RIC) or post-SRS hemorrhage. Other outcomes were DAVFs obliteration and adverse events (including RIC, symptomatic RIC, and post-SRS hemorrhage).

RESULTS

The overall study cohort comprised 131 patients, including 20 patients with CS DAVFs (15%) and 111 patients with non-CS DAVFs (85%). Rates of favorable clinical outcome were comparable between the 2 groups (45% vs 37%, P = .824). Obliteration rate after SRS was higher in the CS DAVFs group, even adjusted for baseline difference (OR = 4.189, P = .044). Predictors of favorable clinical outcome included higher maximum dose (P = .014) for CS DAVFs. Symptomatic improvement was associated with obliteration in non-CS DAVFs (P = .005), but symptoms improved regardless of whether obliteration was confirmed in CS DAVFs. Non-CS DAVFs patients with adverse events after SRS were more likely to be male (P = .020), multiple arterial feeding fistulas (P = .018), and lower maximum dose (P = .041).

CONCLUSION

After SRS, CS DAVFs are more likely to obliterate than non-CS ones. Because these 2 groups have different total predictors for clinical and radiologic outcomes after SRS, they should be considered as different entities.

COVID-19 Pandemic and Its Impact on Neurosurgery Practice in Malaysia: Academic Insights, Clinical Experience and Protocols from March till August 2020

The newly discovered coronavirus disease 2019 (COVID-19) is an infectious disease introduced to humans for the first time. Following the pandemic of COVID-19, there is a major shift of practices among surgical departments in response to an unprecedented surge in reducing the transmission of disease. With pooling and outsourcing of more health care workers to emergency rooms, public health care services and medical services, further in-hospital resources are prioritised to those in need. It is imperative to balance the requirements of caring for COVID-19 patients with imminent risk of delay to others who need care. As Malaysia now approaches the recovery phase following the pandemic, the crisis impacted significantly on neurosurgical services throughout the country. Various emergency measures taken at the height of the crisis may remain as the new normal in the provision of neurosurgical services and practices in Malaysia. The crisis has certainly put a strain on the effective delivery of services and as we approach the recovery era, what may have been a strain may prove to be a silver lining in neurosurgical services in Malaysia. The following details are various measures put in place as the new operational protocols for neurosurgical services in Malaysia.

Cognard Grade IV Tentorial Dural Arteriovenous Fistula Presenting as Trigeminal Neuralgia: Endovascular Management

Tentorial dural arteriovenous fistulas have an increased risk of rupture and hemorrhage, and therefore require urgent treatment to occlude the fistula and proximal venous drainage. This is usually accomplished via endovascular treatment. We present a case of a Cognard grade IV dural arteriovenous fistula that presented as trigeminal neuralgia. This video showcases the angiographic vascular composition of the lesion with main feeders coming from the middle meningeal artery and the tentorial artery of Bernasconi and Cassinari. Details, benefits, and risks of the procedure were thoroughly discussed with the patient and consent was obtained prior to the procedure. We performed endovascular Onyx embolization through a distal branch of the right middle meningeal artery. We were able to successfully occlude the lesion using Onyx embolization and the patient had significant improvement of her pretreatment trigeminal neuralgia.

Suboccipital, Supracerebellar, Infratentorial Approach for Microsurgical Clipping of a Ruptured Tentorial, Straight Sinus Type Dural Arteriovenous Fistula

BACKGROUND

Dural arteriovenous fistulas (dAVFs) can often be successfully treated with endovascular embolization; however, surgery is occasionally still required.

CASE DESCRIPTION

Herein, we discuss a 65-year-old male patient who presented with a Hunt-Hess IV subarachnoid hemorrhage, intraventricular hemorrhage, and cerebellar intracranial hemorrhage secondary to a ruptured Borden type III tentorial (straight sinus) dAVF. Angiography revealed supply from the left occipital and posterior meningeal arteries and direct drainage into the cerebellar cortical veins with venous aneurysms in both cerebellar hemispheres. Both transarterial and transvenous embolization were attempted, without success. Therefore, the patient was taken to the operating room for clip ligation of the dAVF. The operative video demonstrates a bilateral suboccipital craniotomy and supracerebellar infratentorial approach for surgical clipping of the dAVF.

CONCLUSIONS

The case and operative video provide a valuable addition to surgical literature in an era where surgical management of dAVFs has become relatively rare.

Dural Arteriovenous Fistula Complicated with Cerebral Venous Sinus Thrombosis

BACKGROUND

Cerebral venous sinus thrombosis (CVST) is always confused with dural arteriovenous fistula (DAVF) in clinical practice; however, both of them are very rare cerebral vascular diseases. In this report, we provide one case of DAVF combined with CVST.

CASE DESCRIPTION

A 75-year-old woman complained of headache with nausea and vomiting for 4 days. Magnetic resonance venography revealed filling defect in the torcular, left transverse, and sigmoid sinus, which strongly suggested sinus thrombosis. The patient underwent anticoagulation treatment for 9 days. However, the manifestation was not alleviated, magnetic resonance imaging detected the lesion was enlarged, and the midline shifted to the left. Digital subtraction angiography examination detected that one fistula classified as Borden type IA was fed by the left superficial temporal artery and drained into the left transverse and sigmoid sinus. Endovascular embolization with ethylene vinyl alcohol was conducted.

CONCLUSIONS

Follow-up at 6 months indicated that the patient recovered without any sequelae.

Delayed Onset of Dural Arteriovenous Fistula Following Trauma

Dural Arteriovenous Fistulas (dAVF) are pathological shunts that are often idiopathic in presentation. However, it is reported that many patients presenting with dAVF have past medical histories notable for surgeries, hypercoagulation disorders, infections, and trauma. In trauma-linked dAVF, presentation generally occurs within 48 h post-incident. In the present case, the authors discuss the delayed onset of a Borden type II dAVF in a patient 12 hospital days post-trauma, as well as the course of treatment. This unique case provides a compelling demonstration for providers to be aware of the development of dAVF, even after the typical 48-hour post-trauma window. By being aware of the possibility of delayed dAVF presentation, delayed diagnosis or misdiagnosis can be avoided and emergent action can be taken.

Myelopathy Due to Intracranial Dural Arteriovenous Fistula with Perimedullary Venous Drainage: Clinical and Medicolegal Aspects in a Case of Diagnostic Pitfall

BACKGROUND

Intracranial dural arteriovenous fistula (DAVF) consists of a meshwork of arteriovenous shunts. Drainage of the fistula may be into a dural sinus or directly into cortical veins. Rarely, dural arteriovenous fistulas drain exclusively into perimedullary veins. Prompt diagnosis is important, as the clinical course is potentially life threatening.

CASE DESCRIPTION

A 67-year-old man presented with difficulties in walking and bladder retention. Magnetic resonance imaging showed central myelopathy, edema from C6 to T8, and dilated posterior medullary veins. Spinal angiography showed no abnormalities. The diagnostic impression was one of inflammatory demyelinating disease, and the patient was treated with corticosteroids. Three days later, the patient had become paraparetic. Brain magnetic resonance imaging showed abnormal vascular structures around the lower brainstem and cervical cord. Cerebral angiography showed a dural fistula at the skull base supplied by the neuromeningeal branch of the ascending pharyngeal artery and draining into the posterior medullary veins. Following neurosurgical referral, the draining vein was clipped just beyond the arterial feeders. At that time, the patient was wheelchair-bound and needed assistance in daily activities.

CONCLUSIONS

Early diagnosis of this rare vascular malformation is challenging; angiographic studies must include the cranial vasculature when spinal studies are normal or if the abnormality on magnetic resonance imaging is maximal in the upper spinal cord. In the case described, as only medullary angiography was performed, the intracranial dural arteriovenous fistula with perimedullary venous drainage was not diagnosed. Delayed diagnosis is likely to lead to severe neurologic consequences.

Embryological Consideration of Dural AVFs in Relation to the Neural Crest and the Mesoderm

Intracranial and spinal dural arteriovenous fistulas (DAVFs) are vascular pathologies of the dural membrane with arteriovenous shunts. They are abnormal communications between arteries and veins or dural venous sinuses that sit between the two sheets of the dura mater. The dura propria faces the surface of brain, and the osteal dura faces the bone. The location of the shunt points is not distributed homogeneously on the surface of the dural membrane, but there are certain areas susceptible to DAVFs. The dura mater of the olfactory groove, falx cerebri, inferior sagittal sinus, tentorium cerebelli, and falx cerebelli, and the dura mater at the level of the spinal cord are composed only of dura propria, and these areas are derived from neural crest cells. The dura mater of the cavernous sinus, transverse sinus, sigmoid sinus, and anterior condylar confluence surrounding the hypoglossal canal are composed of both dura propria and osteal dura; this group is derived from mesoderm. Although the cause of this heterogeneity has not yet been determined, there are some specific characteristics and tendencies in terms of the embryological features. The possible reasons for the segmental susceptibility to DAVFs are summarized based on the embryology of the dura mater.

Endovascular Treatment of a Dural Arteriovenous Fistula after Cerebral Sinovenous Thrombosis in a Child

BACKGROUND

Dural arteriovenous fistula (DAVF) is rare in children. Development theories postulate a response to cerebral sinovenous thrombosis (CSVT) or to venous hypertension. The symptoms are highly nonspecific and depend on lesion location. Standard treatment of thrombosis is based on antithrombotic therapy, while the main therapy for DAVF is embolization.

CASE REPORT

An 8-year-old boy presented with headache was diagnosed with CSVT and treated with anticoagulant. He developed tinnitus, mental confusion, and lowering of consciousness. Magnetic resonance imaging showed a DAVF draining through a single stenotic venous sinus. Successful endovascular treatment was performed with arterial embolization of multiple feeders and stent and balloon sinus angioplasty.

CONCLUSION

Risk factors associated with sinus thrombosis must be always investigated; endovascular treatment is safe and reasonable in a clinical deterioration scenario.

A dural arteriovenous fistula associated with an encephalocele presenting as otitis media with effusion

OBJECTIVE

This case report illustrates an unusual case of a dural arteriovenous fistula and an associated encephalocele presenting as otitis media with effusion.Case reportA 53-year-old man presented with right-sided hearing loss and aural fullness of 2 years' duration. Examination revealed ipsilateral post-auricular pulsatile tenderness. Computed tomography showed transcalvarial channels suggestive of dural arteriovenous fistula. Further magnetic resonance imaging demonstrated the presence of a temporal encephalocele herniating through the tegmen tympani defect, as well as the abnormal vascularity. Angiography confirmed a Cognard type I dural arteriovenous fistula, which is being managed conservatively. Surgical repair of the encephalocele was recommended but declined by the patient.

CONCLUSION

Dural arteriovenous fistula is an uncommon intracranial vascular malformation rarely seen by otolaryngologists, with pulsatile tinnitus being the usual presentation. To our knowledge, this is the first reported case of dural arteriovenous fistula presenting with conductive hearing loss and otalgia.

Recurrent epistaxis due to cribriform plate dural arteriovenous fistula: are they related? Should the treatment be from venous, pial or arterial side?

PURPOSE

Dural arteriovenous fistula (DAVF) of the anterior cranial fossa with cortical venous reflux is an aggressive neurovascular entity with a high rate of intracranial bleeding. Only two cases of anterior cranial fossa DAVF presenting with epistaxis alone have been reported. Endovascular approaches have emerged as the primary and safer treatment modality for most DAVFs. Certain fistulas are better treated with open surgical approaches and disconnection.

CASE DESCRIPTION

A 55 years old male presented with the history of multiple episodes of severe epistaxis. Cerebral angiography revealed an anterior cranial fossa DAVF of the cribriform plate with cortical venous reflux and a venous varix. The patient was successfully managed with a bifrontal craniotomy and disconnection from the arterial side.

CONCLUSION

Atypical or severe epistaxis may arise from a DAVF. Surgical arterial disconnection my be a curative treatment option.

Papilledema revisiting after sinus angioplasty of chronic cerebral venous sinus thrombosis

This case series aimed to review the significance of revisiting papilledema after successful cerebral venous sinus thrombosis (CVST) management with sinus angioplasty. Four patients presented with blurring and transient obscuration of vision with papilledema, headache, tinnitus, and vomiting. On magnetic resonance venography and digital subtraction angiography, chronic transverse sinus thrombosis was diagnosed for which patients underwent endovascular intervention (stenting). After the resolution of CVST, patients developed the recurrence of symptoms which on digital subtraction angiography revealed dural arteriovenous malformation (DAVM). DAVM and papilledema resolved with endovascular embolization. This case series highlights a need of constant monitoring of CVST cases after the endovascular intervention.

Optic Nerve Sheath Dural Arteriovenous Fistula Misdiagnosed As A Carotid Cavernous Fistula

Dural arteriovenous fistulas (dAVf) are uncommon, acquired vascular lesions. Their location and vascular anatomy produces varied signs and symptoms and are misdiagnosed as other vascular anomalies. We present an atypical case of a dAVf identified along the left optic nerve sheath. The patient presented with progressive ophthalmological signs and was initially misdiagnosed with a left carotid-cavernous fistula. The aetiology, classification and treatment options are discussed.

Pial Artery Supply as an Anatomic Risk Factor for Ischemic Stroke in the Treatment of Intracranial Dural Arteriovenous Fistulas

BACKGROUND AND PURPOSE

Although intracranial dural arteriovenous fistulas are principally supplied by dural branches of the external carotid, internal carotid, and vertebral arteries, they can also be fed by pial arteries that supply the brain. We sought to determine the frequency of neurologic deficits following treatment of intracranial dural arteriovenous fistulas with and without pial artery supply.

MATERIALS AND METHODS

One hundred twenty-two consecutive patients who underwent treatment for intracranial dural arteriovenous fistulas at our hospital from 2008 to 2015 were retrospectively reviewed. Patient data were examined for posttreatment neurologic deficits; patients with such deficits were evaluated for imaging evidence of cerebral infarction. Data were analyzed with multivariable logistic regression.

RESULTS

Of 122 treated patients, 29 (23.8%) had dural arteriovenous fistulas with pial artery supply and 93 (76.2%) had dural arteriovenous fistulas without pial arterial supply. Of patients with pial artery supply, 4 (13.8%) had posttreatment neurologic deficits, compared with 2 patients (2.2%) without pial artery supply (P = .04). Imaging confirmed that 3 patients with pial artery supply (10.3%) had cerebral infarcts, compared with only 1 patient without pial artery supply (1.1%, P = .03). Increasing patient age was also positively associated with pial supply and treatment-related complications.

CONCLUSIONS

Patients with dural arteriovenous fistulas supplied by the pial arteries were more likely to experience posttreatment complications, including ischemic strokes, than patients with no pial artery supply. The approach to dural arteriovenous fistula treatment should be made on a case-by-case basis so that the risk of complications can be minimized.

Multiple Dural Arteriovenous Fistulas Presenting as Pulsatile Tinnitus Treated with External Manual Compression

Dural arteriovenous fistula (DAVF) have been treated by transarterial or transvenous embolization, surgery, and radiosurgery. Besides these treatment options, the external compression technique is a non-invasive, low-cost form of treatment. This article reports that a 60-year-old man with DAVF between multiple arterial branches and transverse/sigmoid sinus was treated by repeated external manual compression method.

Endovascular treatment of a dural arteriovenous fistula in a patient with Loeys-Dietz syndrome: A case report

Background Loeys-Dietz syndrome (LDS) is a recently recognized autosomal dominant connective tissue disease. The manifestations of LDS include vascular tortuosity, scoliosis, craniosynostosis, aneurysm and aortic dissections. Clinical presentation A 35-year-old woman treated with Stanford type B aortic dissection and breast cancer was referred to us for Borden type II dural arteriovenous fistula (dAVF) draining to the vein of Galen, involving the midline of tentorium cerebelli. The dAVF was treated successfully by combined transarterial and transvenous embolization. Because of tortuosity of vertebral arteries, a genetic test was conducted confirming LDS type 2. Conclusions To our knowledge, this is the first case report of dAVF associated with LDS. The relationship between LDS and dAVF is unknown but this report shows the possibility that mutation of transforming growth factor β receptors 2 ( TGFBR2) related to LDS may be related to shunt diseases. Because intervention in LDS seems to be feasible compared to Ehlers Danlos syndrome and Marfan syndrome, it is important to make the correct diagnosis.

Angio-Architectural Features of High-Grade Intracranial Dural Arteriovenous Fistulas: Correlation With Aggressive Clinical Presentation and Hemorrhagic Risk

BACKGROUND: High-grade dural arteriovenous fistulas (dAVFs) can present shunts with very different angio-architectural characteristics. Specific hemodynamic factors may affect clinical history and determine very different clinical courses.

OBJECTIVES: To evaluate the relationship between some venous angio-architectural features in high-grade dAVFs and clinical presentation. Specific indicators of moderate or severe venous hypertension were analyzed, such as altered configurations of the dural sinuses (by a single or a dual thrombosis), or overload of cortical vessels (restrictions of outflow, pseudophlebitic cortical vessels, and venous aneurysms).

METHODS: The institutional series was retrospectively reviewed (49 cases), and the pattern of venous drainage was analyzed in relationship with clinical presentation (benign/aggressive/hemorrhage).

RESULTS: Thirty-five of 49 cases displayed cortical reflux (high-grade dAVFs). This subgroup displayed a benign presentation in 31.42% of cases, an aggressive in 31.42%, and hemorrhage in 37.14%.

CONCLUSIONS: Our data confirm that within high-grade dAVFs, 2 distinct subpopulations exist according to severity of clinical presentation. Some indicators we examined showed correlation with aggressive nonhemorrhagic manifestations (outflow restriction and pseudophlebitic cortical vessels), while other showed a correlation with hemorrhage (dual thrombosis and venous aneurysms). Current classifications appear insufficient to identify a wide range of conditions that ultimately determine the organization of the cortical venous drainage. Intermediate degrees of venous congestion correlate better with the clinical risk than the simple definition of cortical reflux. The angiographic aspects of venous drainage presented in this study may prove useful to assess dAVF hemodynamic characteristics and identify conditions at higher clinical risk.

Epidemiology, clinical presentation, diagnostic evaluation, and prognosis of cerebral dural arteriovenous fistulas

Dural arteriovenous fistulas are abnormal communications, within the dural leaflets, between meningeal arteries and dural venous sinuses and/or subarachnoid veins. Although many fistulas remain clinically silent and do not require treatment, presence of cortical venous reflux, intracranial bleed, and intolerable symptoms are the main indications for treatment. A thorough understanding of the natural history is of prime importance in the decision making and management of these lesions. In this chapter we discuss the epidemiology and natural history of intracranial dural arteriovenous fistulae.

Quantifying the Cerebral Hemodynamics of Dural Arteriovenous Fistula in Transverse Sigmoid Sinus Complicated by Sinus Stenosis: A Retrospective Cohort Study

BACKGROUND AND PURPOSE

Sinus stenosis occasionally occurs in dural arteriovenous fistulas. Sinus stenosis impedes venous outflow and aggravates intracranial hypertension by reversing cortical venous drainage. This study aimed to analyze the likelihood of sinus stenosis and its impact on cerebral hemodynamics of various types of dural arteriovenous fistulas.

MATERIALS AND METHODS

Forty-three cases of dural arteriovenous fistula in the transverse-sigmoid sinus were reviewed and divided into 3 groups: Cognard type I, type IIa, and types with cortical venous drainage. Sinus stenosis and the double peak sign (occurrence of 2 peaks in the time-density curve of the ipsilateral drainage of the internal jugular vein) in dural arteriovenous fistula were evaluated. "TTP" was defined as the time at which a selected angiographic point reached maximum concentration. TTP of the vein of Labbé, TTP of the ipsilateral normal transverse sinus, trans-fistula time, and trans-stenotic time were compared across the 3 groups.

RESULTS

Thirty-six percent of type I, 100% of type IIa, and 84% of types with cortical venous drainage had sinus stenosis. All sinus stenosis cases demonstrated loss of the double peak sign that occurs in dural arteriovenous fistula. Trans-fistula time (2.09 seconds) and trans-stenotic time (0.67 seconds) in types with cortical venous drainage were the most prolonged, followed by those in type IIa and type I. TTP of the vein of Labbé was significantly shorter in types with cortical venous drainage. Six patients with types with cortical venous drainage underwent venoplasty and stent placement, and 4 were downgraded to type IIa.

CONCLUSIONS

Sinus stenosis indicated dysfunction of venous drainage and is more often encountered in dural arteriovenous fistula with more aggressive types. Venoplasty ameliorates cortical venous drainage in dural arteriovenous fistulas and serves as a bridge treatment to stereotactic radiosurgery in most cases.

Gamma Knife radiosurgery for the treatment of intracranial dural arteriovenous fistulas

Background Intracranial dural arteriovenous fistulae (DAVF) may present a treatment challenge. Endovascular embolization is in most cases the first line of treatment but does not always achieve cure. Gamma Knife (GK) radiosurgery represents an alternative treatment option, and the purpose of this study was to further evaluate its utility. Methods We reviewed all cases of DAVF treated between 2009 and 2016 at our institution with GK radiosurgery independently, or following failed/refused endovascular or surgical management. Patients' clinical files, radiological images, catheter angiograms, and surgical DAVF disconnection reports were retrospectively reviewed. Results Sixteen DAVF (14 patients) treated by GK radiosurgery were identified. Eleven fistulae were aggressive and five were benign. Marginal doses ranged from 15 to 25 Gy. Target volumes ranged from 0.04 to 4.47 cm³. In all symptomatic patients, GK treatment resulted in symptom palliation. In 13/15 lesions, cure of symptoms (86.0%) was reported. One lesion was asymptomatic. Angiographic cure was achieved in eight cases (50%), small residual DAVF occurred in four, and four were unchanged. One patient developed headache that resolved at one year. No hemorrhage occurred during the follow-up period. There was no significant association between Borden type and cure rate. Prior failed endovascular treatment and small target volume were associated with lower rates of cure. Conclusions Stereotactic radiosurgery is viable treatment for DAVF. It is very effective in palliating symptoms as a de novo approach or adjunctive to endovascular therapy. In our experience it is only somewhat effective in achieving complete angiographic cure.

The remnant of primary head sinus found in the case of dural arteriovenous fistula: A case report

In the embryo, the primary head sinus (PHS) is the first venous drainage channel in the craniocervical region. During embryonic development, this channel regresses and usually disappears completely; accordingly, a remnant of the PHS is an extremely rare condition and has been described in only a few previous studies. Here, we report a case of remnant of the PHS with a dural arteriovenous fistula (dAVF) in an adult. The remnant of the PHS had penetrated the petrous bone to run from the middle fossa to the jugular bulb and served as a drain for the middle fossa dAVF. We used digital subtraction angiography and reconstructed cone-beam computed tomography in 3D rotational angiography to obtain detailed anatomic information about the remnant PHS and additionally scrutinised and discussed its features.

Application of 4-Dimensional Digital Subtraction Angiography for Dural Arteriovenous Fistulas

BACKGROUND

Three-dimensional reconstruction of digital subtraction angiography (3D-DSA) is a useful imaging modality for assessing complex cerebrovascular lesions. However, due to the importance of flow over time in certain vascular lesions, 3D-DSA is of less value as it lacks the temporal resolution. Dural arteriovenous fistulas (AVFs) are complex lesions in which an arteriovenous shunt exists between meningeal arteries and a dural venous sinus or cortical vein. Traditional 2D-DSA, especially with superselective injections of feeding arteries, is currently the gold standard for assessment, but overlapping of opacified vessels can complicate interpretation. A novel imaging technique, 4D-DSA, merges 3D reconstructions of multiple temporal series. It offers a unique perspective on complex cerebrovascular lesions and may offer several advantages in the assessment of dural AVF.

METHODS

4D-DSA images were acquired in 5 patients who presented with dural AVFs. All relevant clinical data, imaging, and procedural/operative reports were reviewed retrospectively. 4D-DSA images were reconstructed on a separate 3D workstation and compared to 2D and 3D-DSA images in an offline fashion.

RESULTS

In all 5 cases, 4D-DSA proved to be useful in lesion assessment and treatment planning. This included observation (n = 2), microsurgery (n = 1), and endovascular embolization (n = 2).

CONCLUSIONS

In the small series of patients in which it has been evaluated, 4D-DSA offers several advantages in assessing dural AVFs. The ability to see and manipulate feeding arteries in 3D combined with temporal resolution was useful in assessment and treatment planning. Continued experience with this imaging technique will be needed to identify its optimal use.

Dural Arteriovenous Fistulae: Imaging and Management

Intracranial dural arteriovenous fistulae (DAVF) are pathologic arteriovenous shunts between meningeal arteries and dural venous sinuses or veins. They account for approximately 10% to 15% of all intracranial vascular malformations and are most common in middle-aged patients. DAVF are the most common vascular cause of pulsatile tinnitus. Digital subtraction angiography remains the gold standard for diagnosing these lesions. The pattern of venous drainage determines the type of DAVF and their risk for hemorrhage. Endovascular treatment has become a first-line option for their management. This article describes the natural history, clinical presentation, classification, imaging features, and management options of intracranial DAVF.