Hemodynamic and metabolic disturbances in patients with intracranial dural arteriovenous fistulas: positron emission tomography evaluation before and after treatment

Abstract

✓ In patients with intracranial dural arteriovenous fistulas (AVFs), clinical symptoms and angiographic findings vary. The relevance of disturbed venous drainage to clinical symptoms and prognosis has been recognized. However, the roles of cerebral hemodynamics and metabolism, which are impaired by shunt flow or disturbed venous drainage, have not been fully evaluated. The authors studied the cerebral hemodynamic and metabolic status in 10 patients with intracranial dural AVFs using positron emission tomography (PET) scanning. Ten patients with dural AVFs underwent a PET study before treatment. The regional cerebral blood flow (rCBF), regional oxygen extraction fraction (rOEF), regional cerebral metabolic rate of oxygen (rCMRO2), and regional cerebral blood volume (rCBV) were measured using the 15O-labeled gas inhalation steady-state method. The PET parameters that were obtained were analyzed and compared with the patients' neurological and angiographic findings. In six of the 10 patients, a PET study was also performed after treatment. Before treatments, all four patients with cerebral symptoms showed a severe reduction in rCBF and a mild elevation in the rOEF. The areas showing reduced rCBF corresponded with areas in which retrograde venous drainage into the cortical veins and delayed parenchymal circulation were seen on angiograms. In another two patients with occlusion of the affected sinus and/or retrograde drainage into the cortical veins, mild abnormalities were demonstrated in rCBF mapping. In the remaining four patients, all PET parameters except rCBV were within normal limits and venous flow was not impaired on the angiograms. In four patients who underwent surgical excision or transvenous embolization of the affected sinus, the cerebral hemodynamics and metabolism were improved, as were the clinical symptoms. In two patients who underwent transarterial embolization of the feeding vessels only or craniotomy, no hemodynamic improvement was achieved. Our results indicate that hemodynamic insufficiency detected by the PET study corresponded well with cerebral symptoms and angiographic findings of retrograde venous drainage into the cortical veins and delayed parenchymal circulation, but not with sinus occlusion or arterial blood supply. Eradication or prevention of retrograde venous drainage from the affected sinus into the cortical veins should be a treatment goal in patients with dural AVFs.