Arteriovenous fistulas at the craniocervical junction: a review.

Craniocervical junction (CCJ) arteriovenous fistulas (AVFs) are rare vascular malformations and are characterized by complex angioarchitecture and variable clinical presentation. The most common manifestations are subarachnoid hemorrhage and venous hypertensive myelopathy, with hemorrhagic presentation more often associated with ascending intradural or intracranial venous drainage, venous varices, aneurysmal structures, and spinal arterial feeders. Because the natural history remains incompletely defined, accurate angiographic characterization is essential for classification and treatment planning. Microsurgery remains the main treatment for most CCJ AVFs because of its high obliteration rate and durability, whereas endovascular treatment is useful in selected anatomically favorable lesions but may be limited by incomplete occlusion, recurrence, and ischemic risk in complex cases. Prognosis depends on presentation, lesion subtype, venous drainage pattern, age, baseline neurological status, timing of diagnosis, and treatment-related complications; hemorrhagic onset generally has a better outcome than venous hypertensive myelopathy. Structured angiographic follow-up remains important after treatment.