To describe a case of a dural arteriovenous fistula as an atypical cause of gait instability

Dural arteriovenous fistulas (dAVF) are abnormal shunts between arteries and veins which can cause blood to bypass the capillary bed and enter the venous system with a higher velocity, increasing the risk of hemorrhage and non-hemorrhagic neurological deficits (NHND). A classification system, the Borden classification, stratifies dAVF’s into three subtypes based on site of drainage and number of fistulae, with type three associated with the greatest risks of bleeding and NHND.

A 70 year old male was admitted with fatigue and progressive gait instability for six months, requiring a cane. Neurology was initially consulted to rule out Parkinson’s disease given concern for tremor and gait difficulty. Physical examination did not reveal resting tremor or bradykinesia, but the patient displayed a broad-based gait with bilateral intention tremor. MRI brain with contrast was obtained which was notable for numerous T2 flow voids, SWI hemosiderin deposits, and gadolinium enhancement morphologically resembling vasculature. Cerebral angiography revealed a Borden type 3 dAVF with feeding vessels from the bilateral occipital, right middle meningeal, and left posterior meningeal arteries draining into the inferior sagittal sinus through cerebellar veins, which was later embolized. Gait improvement was seen immediately, as the patient was safe for discharge home rather than a nursing facility. At follow up visit three weeks after discharge, his gait continued to improve, and the patient was not reliant on a cane. Romberg test was negative and his intention tremor had disappeared.  

Dural AV fistulas can cause NHNDs, particularly in the posterior fossa. Given the hemorrhagic risk, they are important to identify. There should be a low threshold for neuroimaging in gait decline with no attributable medical cause.