Arteriovenous Fistulas in the Head with Unusual Drainage Routes

Some brain arteriovenous fistulas (AVFs) present with clinical signs that suggest their anatomical site. We describe successful treatment of 2 cases with unexpected fistula locations.Case 1: A 69-year-old man presented with progressive chemosis in his right eye 6 months after suffering head trauma and cervical spine dislocation. From his clinical course, we expected to find a carotid-cavernous sinus fistula. However, the lesion was in the temporal muscle and drained into the superior ophthalmic vein.Case 2: A 58-year-old man developed rapidly deteriorating paraparesis, associated with upper extremity motor weakness and brainstem symptoms. Although we strongly suspected a spinal dural AVF, the lesion was found between the tentorial artery and veins that fed through the brainstem vein into the spinal vein.In both cases, the clinical symptoms were caused by unusual AVF drainage patterns. Venous or sinus thrombosis and collateral venous pathways apparently contributed to these unusual patterns. A complete brain vascular study is necessary to avoid missing such lesions.