A Case of Occipital Dural Arteriovenous Malformation Presenting Visual Field Defect and Positive Visual Phenomena

ABSTRACT

Although dural arteriovenous malformations(DAVM) involving the occipital lobe can be the cause of variable posi-tive visual phenomena, the mechanism of these visual disturbances is not fully understood. We report a 42-year-old man with a left occipital DAVM presenting headache and positive visual phenomena in the right hemianopic field. Occipital DAVM was not accompanied by parenchymal lesions in a brain magnetic resonance imaging. The cerebral angiography demonstrated the retrograde flow into the dilated occipital cortical veins as well as the left occipital DAVM having multiple arterial feeders and the drainage into the left transverse sinus. All clinical symptoms disap-peared after a transarterial embolization. Brain 99mTc-ECD single photon emission computed tomography also showed the improvement of hypoperfusion on the left occipital area after the embolization. We believe that the venous hyper-tension by occipital DAVM impeding the perfusion to the occipital lobe plays an important role in producing positive visual phenomena on the hemianopic field.