Spinal intradural arteriovenous fistulas acquired in late adulthood: absent spinal venous drainage in pathogenesis and pathophysiology. Report of two cases

Intradural spinal arteriovenous fistulas (AVFs), a subtype of spinal arteriovenous malformation in which there is a direct communication between a spinal artery and a vein on the cord surface or in the subarachnoid space, are generally considered to be congenital lesions caused by maldevelopment of the embryonic vascular system. The authors present the cases of two patients with acquired AVFs of the terminal filum. In each patient an AVF between the distal segment of the anterior spinal artery and its accompanying vein on the terminal filum developed within 1 year of repeated lumbar myelography that had demonstrated no evidence of abnormal vascularity. In both patients spinal arteriography demonstrated the absence of medullary venous drainage in the thoracolumbar region, which, combined with the arterialized venous input from the AVF, permitted the development of venous congestion and myelopathy. The involved segment of the terminal filum was excised; in vitro microarteriography and the histopathological examination demonstrated a single, simple arteriovenous connection in both patients. The findings in these cases indicate that intradural AVF can spontaneously arise in later life. The development of these lesions and/or their clinical manifestation may require not only the presence of the AVF, but also deficiency of medullary spinal venous drainage. The epidemiology and anatomy of intradural AVFs are compatible with an acquired origin in many cases.     

An analysis of the venous drainage system as a factor in hemorrhage from arteriovenous malformations.

The authors studied the venous drainage system and its impairment in relation to risk of hemorrhage in 108 cases of supratentorial arteriovenous malformation (AVM). The proportion of AVM's undergoing hemorrhage (hemorrhagic rate) was calculated in relation to: 1) the number of draining veins (one, two, or three or more); 2) the presence or absence of impairment in venous drainage (severe stenosis or occlusion in draining veins); and 3) the location of draining veins (deep venous drainage alone, superficial venous drainage alone, or a combination of the two). Statistical analysis demonstrated that AVM's with the following characteristics had a high risk of hemorrhage: 1) one draining vein (hemorrhagic rate 89% in 54 patients); 2) severely impaired venous drainage (hemorrhagic rate 94% in 18 patients); and 3) deep venous drainage alone (hemorrhagic rate 94% in 32 patients). The present study suggests that the venous drainage system of AVM's is significantly associated with the risk of hemorrhage of these lesions. Therefore, careful preoperative angiographic evaluation of the venous drainage system is mandatory for decision making in the management of patients with AVM's.     

Dural arteriovenous fistula presenting as brainstem ischaemia

Summary Dural arteriovenous fistulas presenting with ascending myelopathy are characterised by the presence of an abnormal retrograde drainage through spinal veins. The authors present a case of cranial dural arteriovenous fistula causing brainstem dysfunction secondary to venous hypertension, treated by surgical interruption of the pial venous drainage which resulted in complete clinical and radiological resolution of the brainstem lesion.     

Developmental venous anomaly with an arteriovenous shunt and a thrombotic complication. Case report

Developmental venous anomalies (DVAs) are common congenital variations of normal venous drainage that are known for their benign natural history. Isolated cases of symptomatic DVAs with associated arteriovenous (AV) shunts have recently been reported. The present case, in which thrombosis occurred in a DVA involving an AV shunt, raises intriguing questions regarding the clinical characteristics of these lesions and can be used to argue in favor of considering such lesions to be arteriovenous malformations (AVMs). A 39-year-old man presented with acute thrombosis in a complex system of anomalous hemispheric venous drainage, which included two distinct DVAs, one of which involved an AV shunt. The hemodynamic turbulences induced by a communication between shunted and normal venous outflows were the possible predisposing factor of the thrombosis. Follow-up angiographic and magnetic resonance images revealed complete recanalization of the thrombosed vessel and provided a thorough visualization of the particular angioarchitecture of the DVA. Acute thrombosis within a DVA with an AV shunt has not been reported previously and, thus, this case can be added to other reports of complications that arise in this particular type of DVA. The authors hypothesize that the presence of an AV shunt in a DVA is a risk factor for aggressive clinical behavior of the anomaly, rendering those lesions prone to complications similar to AVMs. Although no treatment can be offered, the presence of an AV shunt in a DVA warrants close follow-up observation because such lesions may represent a particular subtype of AVM and, therefore, may exhibit an aggressive clinical behavior.     

Treatment of dural arteriovenous malformations and fistulas

Dural arteriovenous fistulas (DAVFs) or malformations consist of pathological vascular channels located within the substance of the dura mater and usually involve the walls of a dural sinus or adjacent cortical vein. DAVFs can affect a variety of cerebral venous structures and can present at various clinical stages. Although some fistulas can spontaneously thrombose, the clinical course usually involves progression from venous sinus pressurization to occlusion and retrograde cortical venous drainage. The spectrum of clinical presentation ranges from an irritating pulse-synchronous bruit to a disabling neurologic ischemic deficit or life-threatening intracranial hemorrhage from venous hypertension. The authors present their clinical experience in the radiographic diagnosis and endovascular treatment of these potentially dangerous lesions.     

Spinal dural arteriovenous fistula associated with a spinal perimedullary fistula: case report

Among spinal cord vascular malformations, dural arteriovenous fistulas (DAVFs) must be distinguished from intradural malformations. The concurrence of both is extremely rare. The authors report the case of a 35-year-old man who suffered from progressive myelopathy and who harbored both a DAVF and an intradural perimedullary fistula. During surgery, both fistulas were identified, confirmed, and subsequently obliterated. The fistulas were located at two levels directly adjacent to each other. Although the incidence of concurrent spinal DAVFs is presumed to be approximately 2%, the combination of a dural and an intradural fistula is exceedingly rare; only two other cases have been reported in the literature. One can speculate whether the alteration in venous drainage caused by the (presumably congenital) perimedullary fistula could possibly promote the production of a second dural fistula due to elevated pressure with concomitant venous stagnation and subsequent thrombosis. The authors conclude that despite the rarity of dual pathological entities, the clinician should be aware of the possibility of the concurrence of more than one spinal fistula in the same patient.     

Neurological manifestations of intracranial dural arteriovenous malformations

The authors describe their experience with four cases of dural arteriovenous malformation (AVM) which led them to analyze the clinical aspects of these lesions in an attempt to understand their pathophysiology. An additional 191 previously reported cases of dural AVM's were reviewed with special attention to the mechanism of intradural, central, and peripheral nervous system manifestations. Apart from the peripheral cranial nerve symptoms, which are most likely due to arterial steal, the central nervous system (CNS) symptoms appear to be related to passive venous hypertension and/or congestion. Generalized CNS symptoms can be related to cerebrospinal fluid malabsorption due either to increased pressure in the superior sagittal sinus, to venous sinus thrombosis, or to meningeal reaction resulting from minimal subarachnoid hemorrhages. These phenomena are not related to the anatomical type of venous drainage. On the other hand, focal CNS symptoms are specifically indicative of cortical venous drainage. Seizures, transient ischemic attacks, motor weakness, and brain-stem and cerebellar symptoms can be encountered depending on the territory of the draining vein or veins. Therefore, the localizing value of focal CNS symptomatology relates to the venous territory and not to the nidus or to the arterial supply characteristics of dural AVM's. Furthermore, the venous patterns of various dural AVM's at the base of the skull are expressed by differences in their clinical presentation. Dural AVM's of the floor of the anterior cranial fossa and of the tentorium are almost always drained by the cortical veins and, therefore, have a high risk of intradural bleeding. The remarkable similarities in the manifestations of dural and brain AVM's and the differences in the manifestations of dural and spinal dural AMV's are pointed out. High-quality angiograms and a multidisciplinary approach to the study of dural AVM's will provide the best understanding of their symptoms and, therefore, the most appropriate treatment strategy.     

Cerebellar hemorrhage caused by dural arteriovenous fistula: a review of five cases

OBJECT: In this study the authors performed a retrospective analysis of five cases in which the patients (three women and two men) were treated for intracranial dural arteriovenous fistulas (AVFs) associated with cerebellar hemorrhage. On the basis of their findings, the authors evaluated the characteristics of this unusual symptom. METHODS: The dural AVFs were located in the right cavernous sinus in one patient, the left transverse-sigmoid sinus in three patients, and the right superior petrosal sinus (SPS) in one patient. All patients presented with severe headache and/or loss of consciousness. Computerized tomography scans revealed a small cerebellar hemorrhage near the fourth ventricle and hydrocephalus in four cases, and a massive hemispheric cerebellar hemorrhage in the remaining case. The four patients with small hemorrhages underwent ventriculostomy and endovascular treatment; all recovered. The patient suffering from a massive hemorrhage because of a dural AVF in the SPS was treated by suboccipital craniectomy, hematoma evacuation, and removal of the vascular anomaly. This patient remains in a persistent vegetative state. In four cases, results of angiography demonstrated retrograde leptomeningeal venous drainage through the SPS to the anastomotic lateral mesencephalic vein (ALMV) and/or to the vein of the lateral recess of the fourth ventricle (VLR4V). Retrograde leptomeningeal venous drainage to the ALMV and/or VLR4V was responsible for cerebellar hemorrhage in these cases. CONCLUSIONS: Thus, it is important to consider dural AVF in cases in which there is even a small hemorrhage near the fourth ventricle accompanied by intraventricular perforation and a decreased level of consciousness.     

Restoration of venous outflow by simultaneous creation of an arteriovenous shunt and pedicle flap using a rat model of foot replantation.

Replantation of amputated rat feet utilizing an efferent arteriovenous shunt constructed between the distal posterior tibial artery and the proximal posterior tibial vein, in the absence of all other venous drainage, provides an alternative pathway to the normal venous drainage in a replanted rat foot. However, this substitute venous drainage was insufficient to prevent progressive ischemia and necrosis of some or all of a replanted rat foot. When a cutaneous pedicle flap supplemented the arteriovenous shunt, venous drainage was much improved, tissue hypoxia and edema began to subside on the third day, severe tissue necrosis was prevented, and seven of eight feet replanted by this technique survived. These observations may be useful in replantation in humans when veins in the amputated part are too small to be used or so damaged that they cannot be repaired or reconstructed by a vein graft, but arteries can still provide a means of returning blood from the amputated part. Constructing an alternative pathway to the normal venous drainage pattern may allow severely damaged parts to survive after replantation.     

Fistule durale intracrânienne à drainage veineux périmédullaire : considérations anatomiques,cliniques et thérapeutiques à propos d’un cas,et revue de la littérature

Intracranial dural arteriovenous fistulae with perimedullary venous drainage are unusual type of vascular brain malformations. Patients may present with a rapidly progressive ascending myelopathy associated with autonomic dysfunction, which can cause a misdiagnosis and delay the therapeutic management. These clinical signs must be quickly recognized to avoid a poor outcome. The authors report the case of a 60-year-old woman presenting with a progressive myelopathy due to a dural arteriovenous fistula with perimedullary venous drainage. The diagnosis was suspected on brain-spinal MRI and confirmed by brain arteriography visualizing the arteriovenous shunt in the middle segment of the superior petrous sinus. MRI showed edema in the medulla oblongata. The treatment was performed early by endovascular glue embolization of the arteriovenous shunt and of the origin of the vein. Brain arteriography and clinical follow-up, one month later, showed complete disappearance of the dural fistula and regression of clinical symptoms. MRI control showed the reduction of the brain stem edema. Because of the early pejorative prognosis of these kinds of fistulae, early diagnosis and treatment are needed.     

Salvage of an avulsion amputated thumb at the interphalangeal joint level using afferent arteriovenous shunting.

Replantation of digits following avulsion amputation is a challenge due to the severity of damage to the digital vessels. When the digital vessels are absent or severely injured, standard artery-to-artery or vein-to-vein anastomoses may be impossible and arteriovenous shunting can be used as a salvage procedure for arterial inflow or venous drainage. Previous cases of successful replantation of avulsed digits that were reperfused using afferent arteriovenous shunting reported small segments of tissues only, usually at the level of the distal phalangeal joint or distal to it. Our case demonstrates that afferent arteriovenous shunting can also provide adequate perfusion to a large piece of tissue in the thumb even when the amputation level is at the interphalangeal joint.     

Long saphenous vein grafts as an aid to microsurgical reconstruction of the trunk

The authors describe a method of closing truncal defects using free-tissue transfer when neither local tissue or vascular access are available. The long saphenous vein is dissected free as far distally as necessary and turned up, leaving its upper drainage intact. The distal end is then anastomosed to the femoral artery to create a temporary arteriovenous loop. After placing an appropriate free flap in the defect, the A-V loop is divided and used to provide both arterial supply and venous drainage for the flap. Anatomy, technique, and representative cases in which this method has been used for closing traumatic tissue defects of the trunk are presented and discussed.     

Evaluation of dural arteriovenous fistulas of cavernous sinus before and after endovascular treatment using time-resolved MR angiography

Digital subtraction angiography (DSA) is the preferred method for confirming dural arteriovenous fistulas (DAVFs), but it has the disadvantage of being invasive. In contrast, time-resolved magnetic resonance angiography (TR-MRA) is a useful, noninvasive imaging technique. The aim of this study was to compare the evaluation of DAVFs of the cavernous sinus (CS) using TR-MRA and DSA. TR-MRA and DSA were obtained in six patients with CS-DAVFs treated with endovascular surgery. TR-MRA and DSA before and after treatment were reviewed by one neuroradiologist without previous knowledge of the existence of CS-DAVFs for the detection and characterization (feeding artery and venous drainage) of CS-DAVFs. DSA showed six CS-DAVFs in the six patients. TR-MRA demonstrated a hyperintensity area in the CS at the arterial phase in six patients. DSA revealed feeding arteries and a drainage vein in all CS-DAVFs. In contrast, the feeding arteries could not be identified with TR-MRA. The details regarding venous drainage could only be speculated upon with TR-MRA as it was only partly visible on the TR-MRA images. DSA after embolization showed no CS-DAVFs in any of the six patients. TR-MRA showed no hyperintensity areas in the CS at the arterial phase in any of the six patients, and with no coil artifacts. In summary, TR-MRA could detect and diagnose CS-DAVF. However, the detail regarding anatomical feeders and draining veins remains poorly visualized by TR-MRA. In this small number of cases, TR-MRA can be a useful screening tool to detect CS-DAVF and possibly also to confirm persistent obliteration following definitive treatment.     

Complex right hemisphere developmental venous anomaly associated with multiple facial hemangiomas. Case report

Complex developmental venous anomalies (DVAs) represent variations of normal cerebral venous drainage and consist of dilation of the superficial and/or deep venous system. These rare anomalies can occur unilaterally or bilaterally, supratentorially or infratentorially, focally or they can affect the entire hemisphere. Some DVAs are associated with cervicofacial venous malformations or facial lymphatic malformations. Anomalies of this type are generally clinically silent, and cerebral dysfunction is usually absent. Symptoms, when they occur, are most commonly headache or mild seizure disorders. The angiographic findings are striking, with well-formed but enlarged transcerebral medullary and deep and/or superficial cortical veins. Opacification of these venous structures occurs within the same time frame as a normal angiographic venous phase. The authors report the case of a 33-year-old man in whom a large inoperable arteriovenous malformation had been previously diagnosed and who presented with seizures. Repeated magnetic resonance imaging and angiography demonstrated abnormally dilated transcerebral, superficial, and deep venous structures involving the entire right hemisphere with no identifiable nidus. Additionally, multiple bilateral benign facial hemangiomas were present in this patient. It is important to recognize this rare venous appearance as a developmental variant and not mistake it for an arteriovenous malformation or a partially thrombosed vein of Galen malformation. Because these venous anomalies are extreme variants of the normal venous system, hemorrhage rarely, if ever, occurs and the patient can be reassured that no interventional or surgical therapy is necessary or warranted.     

Angiographic architecture of intracranial vascular malformations and fistulas — pretherapeutic aspects

The authors describe the angio-architecture of intracranial vascular malformations. Several patterns can be identified thanks to the intracranial superselective angiograms that can now be performed. Schematically, the following features can be seen: 1. Direct arterial supply, 2. Indirect arterial supply, 3. Flow-related arterial ectasia (aneurysm), 4. Dysplastic aneurysm, 5. Direct arteriovenous fistula, 6. Intralesional arterial ectasia (aneurysm), 7. Intralesional venous ectasia (aneurysm), 8. Venous ectasia.Each of these elementary arrangements are illustrated and their clinical significance outlined whenever possible. Finally, the dural AVM drainage into the cortical venous system serves as an almost experimental model for the appreciation of the role played by the venous congestive phenomenon in brain AVM symptoms.     

Spinal epidural arteriovenous fistula with perimedullary drainage. Case report and pathomechanical considerations

The classic angiographically demonstrated features of spinal dural arteriovenous fistulas are shunts of radiculomeningeal branches with radicular veins draining exclusively in the direction of perimedullary veins and thereby causing venous congestion. These shunts are located at the point where the radicular vein passes the dura mater. Spinal epidural arteriovenous shunts, however, normally do not drain into the perimedullary veins and are, therefore, asymptomatic, presumably because of a postulated reflux-impeding mechanism between the dural sleeves. The authors report on a patient in whom an epidural arteriovenous shunt showed delayed retrograde drainage into perimedullary veins, leading to the classic clinical (and magnetic resonance imaging-based) findings of venous congestion. Intraoperatively the angiographically established diagnosis was confirmed. Coagulation of both the epidural shunt zone and the radicular vein resulted in complete obliteration of the fistula, as confirmed on repeated angiography. This rare type of fistula should stimulate considerations on the role of valvelike mechanisms normally impeding retrograde flow from the epidural plexus to perimedullary veins and suggest that, in certain pathological circumstances, epidural fistulas can drain retrogradely into perimedullary veins as an infrequent variant of spinal arteriovenous shunts.     

Spinal Epidural Arteriovenous Fistulas with Unusual Manifestation of Sudden Onset of Severe Neurological Deficits: Case Report

Spinal epidural arteriovenous fistulas with perimedullary venous drainage cause venous hypertension, and usually manifest as slowly progressive myelopathy. We treated two patients presenting with sudden onset of severe neurological deficits. Moreover, in Case 1, the venous drainage was exclusively epidural and no perimedullary venous drainage was present. Angiographic findings of this patient were characterized by a slow-flow fistula with marked retention of the epidural venous drainage. Rapidly progressing thrombosis of the epidural venous plexus may have caused the sudden onset of the symptoms. In Case 2, hematomyelia may also be possibly associated with the sudden onset of the symptoms. Early diagnosis and treatment are essential to achieve favorable outcome in such cases because venous congestion results in irreversible venous infarction within a short period.     

Arteriovenous shunt as a method of restoring venous drainage in rabbit ear replantation

An arteriovenous (AV) shunt as a method of restoring venous drainage during replantation was examined by use of the rabbit ear model. The results were compared to ears replanted using one vein (1:1) or two veins (2:1) for venous drainage. The success rate for AV shunt replantations was found similar to that of replantations with a 1:1 ratio, but lower than that of ears with a 2:1 ratio. Postoperatively, ears replanted using an AV shunt or a 1:1 ratio revealed more swelling and lower tissue oxygenation than ears with a 2:1 ratio. After 10–14 days, all ears that survived were similar in appearance, regardless of method of replantation. Microscopic venules crossing the replanted interface appeared at seven days following surgery in all groups. The authors conclude that the AV shunt method offers an alternative to venous anastomosis when vein-to-vein reconstruction cannot be established. © 1994 Wiley-Liss, Inc.     

Stealsyndrom nach Dialysezugang

After creation of a dialysis access a steal phenomenon (retrograde flow in the artery distal to the arteriovenous anastomosis) and mild symptoms of ischemia are frequently observed, whereas severe clinically relevant steal syndromes rarely occur. A thorough examination of the venous and arterial vascular systems allows the individual risk of developing a steal syndrome to be estimated. This should be taken into account when planning an arteriovenous access in order to minimize the risk as details of the access creation can play an important role during the later course. After development of a relevant steal syndrome the necessity of a correction of the arteriovenous access is determined by the character and extent of complaints. All therapeutic efforts aim at a relief of symptoms of peripheral ischemia while preserving a functional arteriovenous access. Flow and location of an arteriovenous access determine the correct procedure for correction. The underlying principles are the termination of the retrograde flow distal to the arteriovenous anastomosis, the creation of large caliber artificial collaterals (bypass) and the transposition of the arteriovenous anastomosis to a bigger, more proximal feeding artery.     

Selective disconnection of cortical venous reflux as treatment for cranial dural arteriovenous fistulas

OBJECT: A single-institution series of 119 consecutive patients with a dural arteriovenous fistula (DAVF) and cortical venous reflux was reviewed to assess the overall clinical outcome of multidisciplinary management after long-term follow up. The selective disconnection of the cortical venous reflux compared with the obliteration of the entire DAVF was evaluated. METHODS: Dural arteriovenous fistulas in patients in this series were diagnosed between 1984 and 2001, and treatment was instituted in 102 of them. The outcome of adequately treated patients was compared with that of a control group consisting of those with persistent cortical venous reflux and with data found in the literature. In cases of combined dural sinus drainage and cortical venous reflux, a novel treatment concept of selective disconnection of the cortical venous reflux that left the sinus drainage intact, and thus converted the aggressive DAVF into a benign lesion, was evaluated. Endovascular treatment, which was instituted initially in 78 patients, resulted in an obliteration or selective disconnection in 26 (25.5%) of 102 cases. In 70 cases (68.6%) the DAVFs were surgically obliterated or disconnected. In six cases (5.9%), patients were left with persistent cortical venous reflux. No lasting complications were noted in this series. Follow-up angiography confirmed a durable result in 94 (97.9%) of 96 adequately treated cases, at a mean follow up of 27.6 months (range 1.4-138.3 months). Selective disconnection was performed in 23 DAVFs with combined sinus drainage and cortical venous reflux. These patients' long-term outcomes were equal to those with obliterated DAVFs, and the complication rate was lower. CONCLUSIONS: Considering the ominous course of DAVFs with patent cortical venous reflux, multidisciplinary treatment of these lesions is highly effective and the complication rate is low. Selective disconnection provides a valid treatment option of DAVFs with combined dural sinus drainage and cortical venous reflux, as has been shown in cranial DAVFs with direct cortical venous reflux.