Dural arteriovenous fistula
One episode of epilepsy.
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A most unusual dural arteriovenous fistula is present, with extensive areas of fistulation shown on the lateral wall of the right cavernous sinus.
Arterial supply coming from:
- markedly enlarged distal branches of the right internal maxillary artery ( artery of the foramen rotundum, vidian artery included )
- markedly enlarged recurrent meningeal branches from the proximal right ophthalmic artery
- branches of the right inferolateral trunk
- branches of the right meningohypophyseal trunk
- middle meningeal artery but at level of foramen spinosum
Shunting appears over the inferior right cavernous sinus and cavernous sinus dura, with the vein lying along the lateral wall passing directly superiorly, and with dysplastic segments of different calibre, eventually passing to a venous varix of 6 mm diameter lying directly above the ICA bifurcation, with the vein continuing posteriorly & medially to join the basal vein of Rosenthal and eventually vein of Galen, with a high-grade stenosis just prior to this.
Further reflux occurs into a lateral mesencephalic vein which appears to connect to the petrosal vein, and superior petrosal sinus and to other posterior fossa veins related to the cerebellar hemisphere.
A discrete middle meningeal artery appears to reach the foramen spinosum but the artery above this is not clearly shown.
No supply is identified from either the vertebrobasilar system or contralateral left carotid system.
Conclusion: DSA confirms a complex dural arteriovenous fistula centred on the lateral wall of the right cavernous sinus-there is no history of nor angiographic evidence of drainage into the superior ophthalmic veins of the orbit or of the inferior petrosal vein. As there is a combination of either an isolated sinus or direct drainage into the vein, with reflux and cortical venous drainage together with varicosities, this represents a high cognard grade ( grade 4 ) fistula. Clinical features and MR confirm venous hypertension with haemorrhage into the mesial right temporal lobe, the explanation for the complex partial seizures.
Complex dural-AVF (DAVF).
DAVF make up 10-15% of all cerebral vascular malformations. They typically have multiple feeders and are usually acquired. Trauma and previous craniotomy are possible etiopathogenic explanations along with idiopathic fistulae. Supply is typically from the same branches that supply meningeal arterial supply:
- supratentorial: middle meningeal artery (ECA)
- anterior cranial fossa: ethmoidal branches of the ophthalmic artery (from ICA)
- cavernous sinus: dural branches from the ICA and accessory meningeal branch of the maxillary artery (via foramen ovale) - branch of ECA
- posterior cranial fossa: dural branches from the vertebral arteries, branches from occipital and ascending pharyngeal arteries
Treatment and prognosis:
- conservative (especially Borden type I and Cognard types I and IIa)
- higher grades (Borden types II and III, Cognard types IIb-V) have an annual mortality rate of ~10% and an annual risk of intracranial haemorrhage of ~8%, so treatment should be considered:
- surgical resection
- stereotaxic radiosurgery