Dural tentorial arteriovenous fistula causing isolated trochlear nerve palsy: remission after endovascular embolization

Objectives To report an exceptional case of dural arteriovenous fistula of the tentorial incisura presenting as transient and recurrent isolated paresis of the fourth cranial nerve, and treated by endovascular embolization. Case report A 63-year-old man presented several episodes of intermittent diplopia which appeared during sudden head movements and in the left lower gaze. Magnetic resonance and cerebral angiography showed a dural arteriovenous fistula of the right tentorial incisura fed mainly by branches of the right occipital artery as well as intracavernous branches of the right internal carotid artery. Embolization of the occipital artery branches resulted in significantly decreased flow within the fistula and in rapid and complete remission of diplopia. Stereotactic radiosurgery of the residual malformation was then performed. The treatment resulted in a good clinical and radiological outcome at the 5-year follow-up. Conclusion An arteriovenous fistula of the tentorial incisura may exceptionally cause intermittent diplopia owing to compression of the trochlear nerve due to transient increase of blood flow within the malformation. Remission of diplopia may be achieved by endovascular embolization. Dural arteriovenous fistulas with low risk of hemorrhage and brain neurological symptoms may successfully be treated by partial endovascular embolization and radiosurgery.