Twenty patients with vertebral arteriovenous fistulas (eight spontaneous, six traumatic without vertebral artery transection, and six traumatic with vertebral artery transection) were treated by transvascular embolization techniques, resulting in complete fistula closure in all patients. The fistulas were located at C1-C2 in 45%, C2-C3 in 25%, C4-C5 in 15%, C5-C6 in 10%, and C6-C7 in 5%. Trauma was the most common cause: 30% followed knife wounds, 20% followed gunshot injuries, and 10% followed blunt trauma. Eight patients had spontaneous fistulas, two associated with fibromuscular dysplasia. Three patients-all with large, long-standing fistulas-developed neurologic deficits coincident with the abrupt closure of the fistula, which resolved with reestablishment of fistula flow. Two of these patients were treated by staged closure; the other one by gradual closure. In all three cases the result was complete fistula closure without neurologic sequelae. The remaining spontaneous fistulas were all closed by ba...