Imaging Characteristics of Dural Arteriovenous Fistulas Involving the Vein of Galen: A Comprehensive Review

Pial arteriovenous fistula associated with vein of Galen dilatation in adult: A case report and MRI findings

Pial arteriovenous fistula (PAVF) is a rare intracranial vascular lesion where direct communication exists between one or more pial arteries and a cerebral vein, without an intervening nidus and located in the subpial meningeal space. When the drainage of PAVF involves a dilated, but already formed vein of Galen (VOG), it should be distinguished from other vascular lesions located in this area, because their angio-architecture, natural history and treatment options are different. A 33-year-old female was admitted to our hospital with a history of new-onset generalized tonic-clonic seizures. Clinical examination showed no neurological deficit. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) depicted an arteriovenous fistula that was fed by the pial branches from left posterior cerebral artery and drained into the medial atrial vein before joining the VOG confluence and causing VOG dilatation. No nidus between the feeding arteries and draining vein, dural feeding arteries, or anatomical variations commonly seen with true vein of Galen aneurysmal malformations (VOGM) were found. These finding suggested a diagnosis of a PAVF associated with vein of Galen dilatation, which was confirmed by digital subtraction angiography. The patient was treated with transarterial glue embolization in 1 section, resulting in nearly complete occlusion of the fistula. Conventional MRI and MRA are noninvasive modalities that can provide valuable information regarding the anatomic localization of the fistula point, the feeding arteries, the venous sac, and their relationship with surrounding structures. These techniques are helpful for accurate diagnosis and treatment planning.

[Vein of Galen aneurysmal malformation]

The vein of Galen aneurysmal malformation (VGAM) is a rare aneurysmatic cerebrovascular malformation in newborns and children. The VGAM results from an arteriovenous fistula between the persistent vein of Markowski (embryonic precursor of the vein of Galen) and deep choroidal arteries. The VGAM is the most common noncardiac cause of high-output cardiac failure in newborns. It may also cause hemorrhage, seizures, and liquor malabsorption resulting in hydrocephalus. Preferred treatment of VGAM is transarterial embolization (TAE) to reduce the arteriovenous shunt volume and allow normal brain development.

Arteriovenous Cerebral High Flow Shunts in Children: From Genotype to Phenotype

OBJECTIVE

To study the genotypes and phenotypes of cerebral arteriovenous fistulas that drain or do not drain through the vein of Galen, and true vein of Galen aneurysmal malformations, in order to determine whether genotyping could help improve classification of these malformations and their management.

METHODS

We carried out a retrospective review of genetic and phenotypic data in databases of four centers. All children with cerebral arteriovenous fistula or vein of Galen aneurysmal malformations aged below 18 years at onset were included. We recorded the nature of the genetic variant or absence of variant, age at onset, type of malformation, symptoms at onset (hemorrhage, neurological deficit, hydrocephalus, incidental, and heart failure), type of venous drainage and the long-term outcome.

RESULTS

One hundred and fifteen children were included. Autosomal dominant variants were identified in 39% of patients. The most frequent variant affected was the RASA1 gene (25%) followed by EPHB4 (8%) and the HHT-associated genes (5%). HHT gene variants were only observed in pial arteriovenous fistula not draining into the vein of Galen; on the contrary, EPHB4 variants were only seen in genuine vein of Galen aneurysmal malformation. RASA1 variants were identified in all types of shunts.

CONCLUSIONS

EPHB4 variants seem specific to the vein of Galen aneurysmal malformation, RASA1 variants are associated with either pial arteriovenous fistulas or with genuine VGAM and HHT gene variants seem specific to pial arteriovenous fistulas. The genetic data helps to classify these malformations and to guide treatment toward lowest risk of post-operative cerebral ischemic-hemorrhagic complications.

Galenic dural arteriovenous fistula in neurofibromatosis type 1 treated with Onyx

Galenic dural arteriovenous fistula (GDAVF) represents a unique, hard-to-treat subgroup of tentorial dural arteriovenous fistulae. Neurofibromatosis type 1 (NF1) has been infrequently associated with different cerebrovascular conditions that may lead to either ischemic or haemorrhagic stroke. Intracranial GDAVF has not been described in NF1 patients. We present an unusual case of GDAVF in a 37-year-old man with NF1. The fistula drained directly to the vein of Galen through multiple feeders. Complete occlusion of the fistula was achieved through trans-arterial embolisation with Onyx (ethylene vinyl alcohol copolymer) in a single treatment session. Deep venous drainage remained intact, and the patient recovered well. To our knowledge, this is the first report on complete closure of GDAVF with NF1 using trans-arterial embolisation. The preservation of functioning of the straight sinus may have contributed to the success of treatment.