Type Of Dural Arteriovenous Fistula Research Articles

Transarterial Embolization of Intracranial Dural Arteriovenous Fistulas Cognard Type V With Direct Drainage Into the Perimedullary Veins: Case Report and Literature Review.

Cognard type V fistula (CVF) is a rare type of dural arteriovenous fistula characterized by spinal perimedullary venous drainage. Owing to the lack of pathognomonic findings, misdiagnosis is common. Patients often undergo multiple spinal angiograms negative for spinal vascular malformations. Digital subtraction angiography is the gold standard diagnostic tool. The preferred treatment option is endovascular management with embolization through a transarterial, transvenous, or combined approach. Other options include open surgery, stereotactic radiosurgery, or a combination of both. The patient from case # 1 presented with progressive weakness and hypoesthesia in the bilateral lower extremities, with urinary and bowel incontinence. The DSA identified a CVF fed by the meningohypophyseal trunk and a draining perimedullary vein. Embolization with 0.1 ccs of Onyx-18 was performed with complete fistula occlusion. The patient from case # 2 developed bilateral lower extremity weakness, diffuse numbness, and urinary incontinence. The DSA showed a CVF fed by tributaries from the ascending pharyngeal artery and posterior meningeal artery branches of the V3 segment, draining into a perimedullary vein. Embolization with 0.3 cc of Onyx-18 was performed with 100% occlusion of the fistula. A 1-year follow-up angiogram confirmed complete fistula occlusion. Both patients consented to the procedure. Even if a patient only presents symptoms of myelopathy, CVF should be considered. Herein, we present 2 cases of CVF with direct drainage into the perimedullary veins which presented exclusively with myelopathy syndrome and describe treatment with trasarterial embolization with Onyx.

Role of surgery in management of intracranial dural arteriovenous fistulas.

Intracranial dural arteriovenous fistulas (DAVF) are abnormal connections between intracranial arterial and venous systems within the dural layers. Intracranial DAVFs are rare but can occur wherever dural components exist. The pathogenesis of DAVFs is controversial. Venous hypertension is considered as a main cause of clinical symptoms which are subclassified into asymptomatic, benign and aggressive manifestations. To date, several classification schemes have been proposed to stratify the natural course and risks of DAVFs. Currently, endovascular therapy is the main treatment modality. Moreover, the use of radiosurgery and radiotherapy has been limited. Open surgery is also selectively performed as a main treatment modality for specific types of DAVFs and an adjunctive modality for the endovascular approach. Herein, we present a review of the general perspectives of intracranial DAVFs with an emphasis on the role of surgery.

Overview of multimodal MRI of intracranial Dural arteriovenous fistulas

Dural arteriovenous fistulas (DAVFs) include a wide range of pathological conditions that are associated with intracranial vessel abnormalities. While some types of DAVFs present with typical neuroimaging characteristics, others share overlapping pathological and neuroimaging features that can hinder accurate differentiation. Hence, misclassification of the various types of DAVFs is common. Thorough knowledge of DAVF imaging findings is essential to avoid such misinterpretations. Traditional digital subtraction angiography (DSA) is considered the gold standard for diagnosing and evaluating DAVFs. However, angiography cannot detect changes in a patient's brain structure. Conventional magnetic resonance imaging (MRI) sequences, including MR angiography (MRA), allow the evaluation of DAVFs without ionizing radiation or invasiveness. Advanced MRI techniques, such as susceptibility-weighted imaging (SWI) and dynamic contrast-enhanced MRA, provide added value to real-time physio-pathological data regarding the hemodynamics of DAVFs. Beyond these techniques, new insights using high-resolution vascular wall MRI are incorporated for the noninvasive evaluation of DAVFs. This article reviews the pathophysiology of DAVFs, focusing on the specifics of MRI findings that facilitate their classification. The role of conventional and advanced MRI sequences for DAVFs was assessed using insights derived from the data provided by structured reports of multimodal MRIs to evaluate DAVFs.

Adult dural arteriovenous fistulas in Galen region: More to be rediscovered.

Dural arteriovenous fistulas (DAVFs) in the Galen region are the most deeply located and most complex type of dural arteriovenous fistulas. However, cases of DAVFs in this region have not been well described. Thus, we aimed to summarize the characteristics of Galenic DAVFs involving clinical symptoms, anatomical architecture, and drainage patterns, providing experientially therapeutic strategies for these lesions based on our 20 years of clinical experience. We retrospectively examined 31 patients with Galenic DAVFs between January 2000 and June 2021. A comprehensive analysis was carried out based on the symptoms, imaging features, feeding arteries, draining veins, number and location of the fistulas, choice of treatment methods, and prognosis assessment. Twenty-nine patients received endovascular embolization, and no perioperative deaths occurred. A transarterial approach was performed in 27 patients, and a combined transarterial and transvenous approach in one. And in one case, access was established by surgical drilling and embolization was done via the venous route. Twenty-four cases were completely obliterated after first embolization, and another five cases received a second period treatment. Only one patient developed cognitive dysfunction after embolization, and the outcomes of the remaining patients were improved at long-term follow-up. The understanding of symptoms of non-hemorrhagic neurological deficits in DAVF needs to be further clarified. Lesions with pial feeders may be considered first when determining surgical orders. Multi-approach and multi-stage embolization would be safe and effective. Excessive embolization and deep-vein system obstruction should be avoided. Approach creation by surgery would be an innovative interventional therapy.

A new subtype of intracranial dural AVF according to the patterns of venous drainage.

A well-known classification of dural arteriovenous fistulas (DAVFs) according to the patterns of venous drainage was described in 1977 by Djindjian, Merland etal. and later revised by Cognard, Merland etal. in 1995. They described 5 types of DAVFs assuming that the type of venous drainage is directly correlated with neurologic symptoms and in particular with hemorrhagic risk. We present a series of cases that combines type IV (DAVF with cortical venous drainage associated with venous ectasia) and type V (DAVF with spinal venous drainage), which we named type IV + V. A retrospective study between 2012 and 2020 in 2 Hospitals was performed on patients that met inclusion criteria for a diagnosis of this type of DAVF. Demographics, location, clinical presentation and outcomes of endovascular embolization were studied. Five (2,3%) patients out of 220 had a type IV + V DAVF. All cases had an aggressive presentation, either subarachnoid hemorrhage, myelopathy or both. All patients were treated with endovascular transarterial embolization achieving complete angiographic occlusion in one session and total remission of symptoms at 3 months. This rare type of DAVF, combines two aggressive venous drainage patterns. For that reason, patients with type IV+V DAVF probably have a more aggressive natural history and worst outcome due to risk of intracranial and/or spinal hemorrhage and myelopathy, thus requiring urgent diagnostic and treatment. Larger studies are needed to better understand this type of DAVF.

Dural Arteriovenous Fistulas at the Petrous Apex

Dural arteriovenous fistulas (DAVFs) at the petrous apex are rare but may cause subarachnoid hemorrhage (SAH) or severe brainstem edema. This study aimed to summarize their clinical features and discuss the classification. During a 15-year period, 64 consecutive patients with DAVF at the petrous apex were reviewed. According to their angioarchitecture, these cases were classified as follows: type I, no venous ectasia (48.4%); type II, venous ectasia but with normal vein proximal to the fistula (29.7%); and type III, venous ectasia at the site of the fistula (21.9%). There were 53 men and 11 women included. Presented symptoms were SAH in 8 patients (12.5%), nonhemorrhagic neurologic defects (NHNDs) in 53 patients (82.8%), and no symptoms in 3 patients (4.7%). There were 49 patients who received transarterial embolization, 8 patients who received microsurgery, and 7 patients who received embolization and microsurgery. Complications occurred in 9 patients (14.1%), including transient cranial nerve palsy (4.7%), rebleeding (6.3%), and respiratory failure (3.1%). Of the type I patients, 96.77% presented with NHNDs and 77.42% presented with infratentorial drainage. However, SAH occurred more often in type II (21.05%)/type III cases (28.57%), and most patients carried a supratentorial drainage (63.16% and 85.71%, respectively). In different types of DAVFs, the necessity for embolization combined with microsurgery (6.45% in type I, 10.53% in type II, 21.43% in type III) and the occurrence of rebleeding complications (0% in type I, 10.53% in type II, and 14.29% in type III) were varied. Petrous apex DAVFs carried a high risk of embolization-related complications. Based on the vascular architecture, this classification may reflect their clinical features and provide some advice on the treatment of DAVFs at the petrous apex.

Dural Arteriovenous Fistulas at the Petrous Apex with Pial Arterial Supplies

Dural arteriovenous fistula (DAVF) at the petrous apex with pial arterial supplies possesses complicated angioarchitecture, associates with aggressive neurologic behaviors, and associates with high risk of complications. This study aimed to summarize our experience with this type of DAVF in the last 15 years. This retrospective study reviewed 26 consecutive patients diagnosed with DAVFs of the petrous apex with pial arterial supplies from February 2002 to June 2017. Clinical information was extracted from medical records, radiographic data, intraoperative images, and complications and follow-up records. The 26 patients included 24 men and 2 women, with a mean age of 46.54 ± 12.49 years (range, 28-73 years). Manifestations included nonhemorrhagic neurologic defects (19/26, 73.1%), subarachnoid hemorrhage (SAH) (5/26, 19.2%), and no symptoms (2/26, 7.7%). Supratentorial draining direction was detected in 89.47% of the lesions, and 80% of the patients with venous ectasia had SAH. Complete occlusion was achieved in 21 patients (80.77%) through transarterial embolization and 5 patients (19.2%) through preoperative embolization combined with microsurgery. Complications included transient cranial nerve palsy in 1 patient (3.8%) and rebleeding in 2 patients (7.7%). The Barthel Index scores ranged from 10 to 100 (average, 66.73) and improved significantly (average, 96.62) in the follow-up period (10-175 months; median, 85.6 months). Supratentorial draining direction may be a risk factor for venous ectasia and SAH in petrous apex DAVFs with pial arterial supplies. The feeding pial arteries appeared to be at risk of embolization-related hemorrhagic complication and are therefore suggested to be embolized first.

Dural arteriovenous fistula of the lateral foramen magnum region: A review.

The lateral foramen magnum region is defined as the bilateral occipital area that runs laterally up to the jugular foramen. The critical vasculatures of this region are not completely understood. Dural arteriovenous fistulas that occur in this region are rare and difficult to treat. Therefore, we searched PubMed to identify all relevant previously published English language articles about lateral foramen magnum dural arteriovenous fistulas, and we performed a review of this literature to increase understanding about these fistulas. Four types of dural arteriovenous fistulas occur in the lateral foramen magnum region. These include anterior condylar confluence and anterior condylar vein dural arteriovenous fistulas, posterior condylar canal dural arteriovenous fistulas, marginal sinus dural arteriovenous fistulas, and jugular foramen dural arteriovenous fistulas. These dural arteriovenous fistulas share similar angioarchitectures and clinical characteristics. The clinical presentations of lateral foramen magnum dural arteriovenous fistulas include pulsatile tinnitus, intracranial hemorrhage, myelopathy, orbital symptoms, and cranial nerve palsy. Currently, head computed tomography, computed tomography angiography, magnetic resonance imaging, magnetic resonance angiography and digital subtraction angiography (DSA) are useful for diagnosing dural arteriovenous fistulas, and of these, DSA remains the "gold standard." Most lateral foramen magnum dural arteriovenous fistulas need to be treated due to their aggressive symptoms, and transvenous embolization presents the best options. During treatment, it is critical to accurately place the microcatheter into the fistula point, and intraoperative integrated computed tomography and DSA data are very helpful. Other treatments, such as transarterial embolization, microsurgery or conservative treatment, can also be chosen. After appropriate treatment, most patients with lateral foramen magnum dural arteriovenous fistulas achieve satisfactory outcomes.

Surgical treatment of anterior cranial fossa dural arterio-venous fistulas (DAVFs): a two-centre experience.

Anterior cranial fossa dural arterio-venous fistulas (DAVFs) represent 6% of all intracranial DAVFs; characteristically they show an aggressive behaviour with high risk of intracranial haemorrhage. Peculiar anatomical features, such as feeding by the ethmoidal arteries and the pattern of venous drainage (frequently with varices that mimic aneurysmal dilatation), can be evaluated in detail only by digital subtraction angiography (DSA), which represents the "gold standard" in the diagnosis of such cranial fistulas. Recent technological developments in endovascular management of this type of DAVF have partially reduced the morbidity risk related to this modality of treatment. Our purpose is to present our experience in the surgical management of 14 patients with anterior cranial fossa DAVFs, with attention paid to the possible role of preoperative embolisation in these cases and to the surgical technique. Between 1999 and 2015, 14 patients with anterior cranial fossa DAVFs were submitted to surgery in two neurosurgical departments; the mean age was 63years old; nine DAVFs caused intracranial haemorrhage (subarachnoid haemorrhage in three cases, intracerebral haemorrhage in six cases). Pre-operative embolisation was attempted in an early case and was successfully done in one recent case. In all patients, the surgical approach chosen was a pterional craniotomy with a low margin on the frontal bone in order to gain the exposure of the anterior cranial fossa and especially of the olphactory groove region; the resection of the falx at its insertion on the crista galli was needed in five cases in order to get access to the contralateral afferent vessels. Cauterisation of all the dural feeders on and around the lamina cribrosa was needed in all cases; venous dilatations were evident in eight patients (in seven out of nine patients with ruptured DAVF and in one out of five patients with unruptured DAVF) and were removed in all cases. One patient harboured an ophthalmic artery aneurysm, which was excluded by clipping. One patient died 5days after surgery due to the severity of the pre-operative haemorrhage. Postoperative DSA showed the disappearance of the DAVF and of the venous pseudo-aneurysms in all cases. Clinical outcome was favourable (without neurological deficits) in 11 patients; three patients presented an unfavourable clinical outcome, due to the severity of the initial haemorrhage. Surgical exclusion of the anterior cranial fossa DAVFs still represents the gold standard for such lesions, due to low post-operative morbidity and to complete protection against future rebleedings; endovascular techniques may help the surgeon in complex cases.

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

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. 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. 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. 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.

Detection of Cortical Venous Drainage and Determination of the Borden Type of Dural Arteriovenous Fistula by Means of 3D Pseudocontinuous Arterial Spin-Labeling MRI.

The risk of intracranial dural arteriovenous fistula is linked to its pattern of venous drainage (Borden type), in particular the presence of cortical venous drainage. The purpose of this study was to assetss the accuracy of 3D pseudocontinuous arterial spin-labeling (ASL) MRI for noninvasive delineation of venous drainage. This retrospective study included 34 patients with a dural arteriovenous fistula who had undergone both digital subtraction angiography (DSA) and 3D pseudocontinuous ASL MRI. Two neuroradiologists blinded to the DSA results independently assessed ASL images for the presence of cortical vein hyperintensity (cortical venous drainage) and the distribution of venous hyperintensity (Borden type). DSA was used as the reference standard. The sensitivity and specificity of 3D pseudocontinuous ASL MRI for the detection of cortical venous drainage were determined. Intermodality and interobserver agreement for Borden type was determined by use of the weighted kappa statistic. Three-dimensional pseudocontinuous ASL MRI had high sensitivity (91%) and specificity (96%) for the detection of cortical venous drainage. Borden type was correctly identified with very good intermodality (weighted κ = 0.82) and interobserver (weighted κ = 0.85) agreement in 88% of patients. Three-dimensional pseudocontinuous ASL MRI is highly accurate for the detection of cortical venous drainage and determination of Borden type. With this technique, high-risk fistulas requiring treatment can be reliably differentiated from low-risk lesions. Although it cannot replace DSA, incorporating 3D pseudocontinuous ASL into an MRI protocol for assessment of dural arteriovenous fistula can facilitate treatment planning.

The Lurking Catastrophic Complication of an Equally Catastrophic Disease

Abstract BACKGROUND Medullary-bridging vein dural arteriovenous fistula (DAVF) is an uncommon type of DAVF with an aggressive clinical course due to direct fistulous shunting into medullary and brainstem veins. Important considerations need to be given to retrograde embolic migration or perforator involvement while treating these fistulas endovascularly with a liquid embolic agent. We report a lateral spinal artery feeding the DAVF, the recognition of which is important to avoid potential catastrophic complications during definitive therapy, and which has not been described before. OBJECTIVE To discuss the anatomy of the lateral spinal artery (LSA) and its communications with pial arteries such as the posterior inferior cerebellar artery (PICA) that may have important implications in the management of neurovascular diseases in and around the foramen magnum. METHODS A retrospective analysis of cerebral angiograms and 3-dimensional rotational angiograms of a patient with medullary-bridging vein DAVF treated by transarterial embolization under balloon protection was performed after the patient developed lateral medullary syndrome in the postoperative period. RESULTS Detailed analysis revealed a dural branch from the LSA feeding the DAVF which anastomosed with rudimentary PICA. CONCLUSION LSA has important anastomoses with perforating arteries of the medulla and cervical cord and, hence, it is important to recognize and identify LSA prospectively in the vascular pathologies of the foramen magnum to avoid fatal neurological complications during endovascular therapy. This is especially important while treating neurovascular pathologies using liquid embolic agents such as Onyx or SQUID, because they can percolate retrogradely through the anastomoses into PICA or other vertebrobasilar perforators.

Transarterial Onyx embolization of intracranial dural arteriovenous fistulas: A single center experience

BackgroundTransarterial embolization of intracranial dural arteriovenous fistulas (DAVFs) is usually associated with inadequate embolization. The purpose of this study was to report our experience of transarterial Onyx embolization of intracranial DAVFs with an emphasis on treatment outcome with this new embolic agent in different types of DAVFs. MethodsIn the past 3 years, a total of 14 intracranial DAVFs have been treated by transarterial Onyx embolization. Among these, there were nine males and five females, aged from 30 years to 82 years (mean = 62 years). We retrospectively analyzed the injection volume and time of Onyx embolization as well as outcomes in different types of DAVFs. ResultsThe locations of the DAVFs were sigmoid sinus (n = 6), tentorium (n = 3), sinus confluence (n = 2), transverse–sigmoid sinus (n = 1), sigmoid sinus–jugular bulb (n = 1) and the superior petrous sinus (n = 1). The mean volume and time of Onyx injection were 3.4 mL and 28 minutes, respectively (Cognard type I: 4.9 mL, 40 minutes; type II: 4.5 mL, 34 minutes; type III: 2.2 mL, 21 minutes; type IV: 2 mL, 22 minutes). Total fistula occlusion was achieved in six out of seven patients of type III and type IV DAVFs, and in four out of seven patients of type I and type II DAVFs. Nine patients had total resolution of their symptoms, whereas partial regression occurred in five patients. No significant periprocedural complication was found. Mean clinical follow-up period was 16 months. ConclusionTransarterial Onyx embolization of intracranial DAVFs is safe and effective. This technique is particularly useful in type III and type IV DAVFs with a high cure rate, and lower volume of Onyx as well as a short injection time.

Non-contrast-enhanced 4D MR angiography with STAR spin labeling and variable flip angle sampling: a feasibility study for the assessment of Dural Arteriovenous Fistula

This study aimed to evaluate the feasibility of non-contrast-enhanced 4D magnetic resonance angiography (NCE 4D MRA) with signal targeting with alternative radiofrequency (STAR) spin labeling and variable flip angle (VFA) sampling in the assessment of dural arteriovenous fistula (DAVF) in the transverse sinus. Nine patients underwent NCE 4D MRA for the evaluation of DAVF in the transverse sinus at 3T. One patient was examined twice, once before and once after the interventional treatment. All patients also underwent digital subtraction angiography (DSA) and/or contrast-enhanced magnetic resonance angiography (CEMRA). For the acquisition of NCE 4D MRA, a STAR spin tagging method was used, and a VFA sampling was applied in the data readout module instead of a constant flip angle. Two readers evaluated the NCE 4D MRA data for the diagnosis of DAVF and its type with consensus. The results were compared with those from DSA and/or CEMRA. All patients underwent NCE 4D MRA without any difficulty. Among seven patients with patent DAVFs, all cases showed an early visualization of the transverse sinus on NCE 4D MRA. Except for one case, the type of DAVF of NCE 4D MRA was agreed with that of reference standard study. Cortical venous reflux (CVR) was demonstrated in two cases out of three patients with CVR. NCE 4D MRA with STAR tagging and VFA sampling is technically and clinically feasible and represents a promising technique for assessment of DAVF in the transverse sinus. Further technical developments should aim at improvements of spatial and temporal coverage.

A Unique Type of Dural Arteriovenous Fistula at Confluence of Sinuses Treated with Endovascular Embolization: A Case Report

Dural arteriovenous fistula (DAVF) is classically defined as abnormal arteriovenous connections located within the dural leaflets. Though the exact etiology is still not clear, they are generally accepted as acquired lesions. However, some DAVFs formed as the congenital disorders are called dural arteriovenous malformations and these lesions with a marked cortical venous reflux are considered to be aggressive and warrant an early intervention. The authors describe a case of 35-year-old man presented with unique type of DAVF. The fistula was located adjacent to the confluence of venous sinuses with multiple feeders. The feeders drained into a large venous pouch just anterior to the confluence which had a bilateral venous drainage. This was associated with multiple cerebellar venous ectasia along the draining cortical vein. It was managed by staged endovascular procedures and complete cure could be achieved. The pathogenesis and technique of embolization of this complex fistula/malformation are also discussed.

Atypical Presentation and Disappearance of a Barrow Type A CCF With Glaucoma, Ptosis and 6th Nerve Palsy

The caroticocavernous fistula is a specific type of dural arteriovenous fistula characterized by abnormal arteriovenous shunting within the cavernous sinus. A caroticocavernous fistula results in high-pressure arterial blood entering the low-pressure venous cavernous sinus. This interferes with normal venous drainage patterns and compromises blood flow within the cavernous sinus and the orbit. We present a Barrow type A caroticocavernous fistula case, presented with glaucoma, ptosis and 6th nerve palsy without any history of trauma and atypically disappeared after acetolozomide theraphy. In conclusion, before beginning for an invasive treatment of a CCF, acetolozomide theraphy can be started initially because it may have a role in closure of CCF due to its vasoregulatory effects in the brain. doi:10.4021/jmc601w

Atypical Presentation and Disappearance of a Barrow Type A CCF With Glaucoma, Ptosis and 6th Nerve Palsy

The caroticocavernous fistula is a specific type of dural arteriovenous fistula characterized by abnormal arteriovenous shunting within the cavernous sinus. A caroticocavernous fistula results in high-pressure arterial blood entering the low-pressure venous cavernous sinus. This interferes with normal venous drainage patterns and compromises blood flow within the cavernous sinus and the orbit. We present a Barrow type A caroticocavernous fistula case, presented with glaucoma, ptosis and 6th nerve palsy without any history of trauma and atypically disappeared after acetolozomide theraphy. In conclusion, before beginning for an invasive treatment of a CCF, acetolozomide theraphy can be started initially because it may have a role in closure of CCF due to its vasoregulatory effects in the brain. J Med Cases. 2012;3(4):247-249 doi: https://doi.org/10.4021/jmc601w

Retrograde filling carotid–cavernous fistula: MSCT angiography findings

Carotid–cavernous fistulas (CCF) are a specific type of dural arteriovenous fistula and have abnormal communications between the arterial system and the venous cavernous sinus at the wall of the cavernous sinus. The cavernous sinus (CS) is different from other venous sinuses according to its location and structure. It is situated outside of the dura, but other dural sinuses are located between two dural walls. It is where an artery is completely surrounded by a venous structure. There are various cranial nerves in the CS. It has rich communications with the other sinuses and veins, with the transverse and sigmoid sinuses through the superior and inferior petrosal sinuses, with the cerebral cortical veins through the sphenoparietal sinus and with pterygoid plexus, and with the facial veins through the superior and inferior ophthalmic veins. CCF can demonstrate wide-range clinical presentations according to these communications, like ophthalmic signs and symptoms (proptosis, chemosis, and visual loss); cranial nerve pareses; bleeding from the mouth, nose, or ears; and intracranial hemorrhage. High-pressure arterial blood moves directly into the cavernous sinus and ophthalmic veins, leads to venous hypertensions after CCF, and causes the sign and symptoms above. CCFs are classified as direct and indirect based on etiology and pathophysiology. Direct CCFs may occur following a traumatic tear in the cavernous segment of the internal carotid artery (ICA) or aneurysmic rupture within this segment. Direct CCFs account for 70–80% of all cases. Indirect CCFs occur spontaneously and are abnormal communications between the smaller meningeal arterial branches of the internal or external carotid system and cavernous sinus. Indirect CCFs account for 20% of all cases.

Mechanism of the Formation of Dural Arteriovenous Fistula — The Role of the Emissary Vein

Dural arteriovenous fistula (DAVF) can be separated into two types: DAVF which drains through an affected sinus (sinus type) and DAVF with direct reflux to the cortical vein (non-sinus type). The present report attempted to clarify the mechanism of formation and development of DAVF focusing on the emissary vein (EV) hypothesis.First, inflammation occurs at the penetrating point of the EV on the dura due to idiopathic or secondary causes. Local inflammatory reactions induce vessel dilatation and neovascularization, and subsequently create arteriovenous (AV) connections on the arteriole level. Although EV communicating with dural arteries might play a role as draining routes at first, they start to degrade due to compression of enlarged emissary arteries or to a hemodynamic shift to the drainage pathway of least resistance. Following the occlusion of drainage pathway through EV into the sinus or cortical veins may form, resulting in clinically detectable DAVF. The AV shunt then expands to the surrounding dura associated with recruitment of feeders from distant sites induced by expression of angiogenetic factors and a shift in the hemodynamic balance. In sinus type DAVF, the sinus is progressively compartmentalized and finally occludes due to thrombogenesis with activated coagulopathy or to hemodynamic hypertrophy of the sinus wall. This progression results in the mature, aggressive DAVF with drainage impairments. Previous mechanistic hypotheses focusing on sinus hypertension and sinus thromboses cannot explain the pathogenesis of non-sinus type of DAVF. Although the etiology of DAVF may be concerned by the thrombo-occlusive change of sinus, the unique theory presented in this report may enable an understanding of the common etiology of both types of DAVF.

Ischemic Stroke in Patients With Intracranial Dural Arteriovenous Fistulas

Intracranial dural arteriovenous fistulas (DAVFs) can be complicated by ischemic stroke. This study investigated the frequency and determinants of ischemic stroke in patients with intracranial DAVF. We conducted a retrospective study of consecutive patients with intracranial DAVF. Patients with pure hemorrhagic stroke or without available brain imaging for clarifying stroke type were excluded. DAVF was diagnosed by cerebral catheter angiography. Cognard classification and location of DAVFs were ascertained. The clinical characteristics, outcome, and radiographic findings were recorded. Factors associated with occurrence of ischemic stroke in the patients with DAVFs were determined. A total of 134 patients were enrolled. Six patients (4.5%) had ischemic stroke (mean age: 53.8 ± 13.4 years) and 128 patients were free from stroke (mean age: 55.4 ± 15.2 years). Men accounted for 83% in the ischemic stroke group and 34% in the non-stroke group. Chemosis, exophthalmos and tinnitus were more frequent in the non-stroke group, whereas seizure and mental decline were more frequent in the ischemic stroke group. DAVF was associated with highest risk of ischemic stroke at locations other than the cavernous sinus or large sinuses. Ischemic stroke also correlated with types of DAVF involving cortical venous drainage, including type IIb (18%), III (15%), and IV (100%). No patient with DAVF type I and IIa had ischemic stroke. The rate of ischemic stroke in patients with concomitant DAVF and cerebral sinus thrombosis was higher than in DAVF patients without cerebral sinus thrombosis. Venous infarct was the major subtype of ischemic stroke in five DAVF patients. Endovascular therapy was the most common choice in both groups, and fewer patients in the ischemic stroke group did not receive any treatment for DAVFs. Location and type of DAVF were two important factors related to the occurrence of ischemic stroke in DAVF patients.