Intracranial DAVFs are rare, acquired or congenital aberrant connections between dural arteries and Dural venous sinuses, meningeal veins, or cortical veins that rare as 10% of children intracranial vascular lesions. Untreated lesions consist of fatal events such as cardiac failure, cerebral hemorrhage or infarction. The pathogenesis of DAVFs justify by two main hypotheses. 1-“dormant channels” that are opened in response to venous hypertension between arteries and the venous pathways within the dura mater. 2- new vascular connections are induced by hypoxia or venous hypertension (1). Clinical presentations are variable by the age, the location, grading of the fistula and the related vascular lesions. Clinical syndromes may be categorized into three groups. Group 1, neonatal group, presents with heart failure, cyanosis, and cranial bruits and developmental delays with poor prognosis. Group 2 infant ages and is the largest group. They are present with macro-crania due to hydrocephalus or intracranial rising, seizure, hemorrhage and prominent facial veins with short-term prognosis better than that for group 1, neurological sequels are present months to years after diagnosis. Group 3 are the patients older than 2 years. They are present with a headache, focal neurological deficits, syncope, seizures, and hemorrhage (1-3). Dural AV shunts in children are classified into three groups: 1. Dural Sinus Malformation (DSM) with AV shunts, mostly occur in neonates, 2. Infantile Dural AV shunts (IDAVS), which occur in children, and 3. Adult-type Dural AV Shunts (ADAVS), which are less frequent but also occur in children. DSM is a developmental anomaly of the Dural sinus and usually seen as a giant Dural sinus lake(2).
Dural arteriovenous fistulas (DAVFs) management is multidisciplinary manner, but the mainstay of them is endovascular transarterial or transvenous embolization. More than one therapeutic modality or multiple stage treatment is necessary for some patients to produce a favorable outcome. Especially in complex lesions that immediate cure can result in more complication. In this situations, the goal of treatment is symptom relief to eliminate the potential irreversible effect of lesion that promising complete cure of lesion in future with less complication(4).
Treatment of high-flow lesions is critical because their natural history is devastating. Partial embolization is a reasonable goal to eliminate retrograde leptomeningeal flow and disabling symptoms without the need for the immediate obliteration of the fistulas (3, 5).
Transarterial embolization with Onyx is the treatment of choice for DAVFs. Potential issues with DAVF anatomy include small, inaccessible feeders, arterial feeders that supply cranial nerves, and dangerous external carotid–internal carotid anastomoses. In these instances, embolization can be an adjunctive treatment to open surgery as a way to decrease blood loss during surgical ligation and to assist intraoperative identifying the fistula anatomy(1).
Transvenous embolization was considered the first-line endovascular treatment for DAVFs Before the widespread use of Onyx. Embolization of the sinus should be avoided if it drains some normal brain parenchyma because it can lead to the neurologic deficit. The decision to partial embolization of a DAVF can be potentially devastating event due to worsening the cortical venous reflux by eliminating the anterograde Outflow. Some patients have parallel venous drainage of DAVFs, that sinus occlusion without obliteration of these channels will worsen the fistula. Transvenous embolization is useful in DAVFs with anatomic inaccessible feeders. Direct catheterization and embolization by bur hole or craniotomy rarely have been done. Compressive neuropathy due to the mass of coils can be avoided with onyx (6, 7).
Symptomatic patients and asymptomatic patients with high-risk angiographic risk factors must be treated. Treatment of asymptomatic fistulas is controversial, and some groups recommend only observation. Staged embolization is a viable option for delaying the surgical intervention in neonates. Partial embolization improves clinical and mental outcome. Multi-staged embolization decreases dural venous thrombosis risk by gradual fistula obliteration, which permits sinus remodeling was done naturally. The definitive cure should be delayed as long as the patient can tolerate conservative management.
Management of recanalized DAVFs is more difficult than the primary lesion in children. The endovascular approach in previously coiled arterials is often unreachable. Outcome of pediatric DAVF management even by experienced centers is still far from satisfactory (3, 4, 7)
Multiple or complex DAVFs in pediatric are more than adults and cannot be approached with any single guideline. Management should be based individually the case by case. Incompletely occluded fistulas are high risk for aggressive behavior and evolution. Understanding of the detailed anatomic and physiologic architecture of the lesion is essential to achieve cure (1, 3, 4, 7).Management is the same adult with a critical difference that venous sinus preservation is important. Other differences are the clinical and developmental statuses of pediatrics that increase potential anesthetic and surgical complications. pediatric DAVFs are often high-flow lesions with anatomic variation, that cause increasing the complications such as; 1- Iatrogenic injury during endovascular access to the fistula, 2- Embolization of normal vessels, 3- Femoral access complications, 4- Limitation in contrast volume using, and 5- unknown long-term ionizing radiation effect in young age(4).
In spite of above hazards, the overall complication of endovascular approach is not higher than adults in high-volume centers(8).
Prevention of Dural sinus thrombosis was done by adding anticoagulants, diuretics, and inotropic agents or multi-staged embolization.
Dural sinus scarifications were depended on normal brain venous sinus draining potency via collateral sinuses(7)
Radiosurgery has been used in small size DAVFs, benign angiographic pattern, multifocal or in combination of endovascular embolization.(1, 3, 4, 7, 9)
Adult-type DAVFs may be spontaneously thrombosed. A persistent lesion was treated by endovascular or combined endovascular and radiosurgery or open surgical approach(7).
Anticoagulation drugs are recommended in pediatric DAVFs for 8-week post-embolization especially in DSM types that thrombosis can be developed in largely sized sinuses due to blood stagnation. This is important in neonates that early thrombosis of dural sinuses can compromise the normal venous development that may interfere with recurrence or new formation of the vascular lesion