Abstract
Operating on an arterio-venous malformation (AVM) deep in the occipital lobe is difficult with some approaches because the main feeder consists of branches of the posterior cerebral artery. Particular care must be given to the approach route and the position of the spatula to protect the visual center. Thus, the deep-seated AVM is difficult to excise. For this condition we prefer the interhemispheric approach in a prone position. We have performed surgical resection on 12 cases of AVM, the main feeder of which was the posterior cerebral artery; the feeders involved seven calcarine arteries, four parieto-occipital arteries, four temporo-occipital arteries and one anterio-inferior temporal artery. All of the patients returned to routine life, except for visual field defects. Eight of the patients had had visual field defect preoperatively, consisting of two homonymous hemianopia, four upper quadrantic hemianopia, two lower quadrantic hemianopia. Postoperatively, these symptoms improved in two patients and were unchanged in three. In three patients, these symptoms were aggravated or new symptoms appeared. To minimize these symptoms, much care is required in determining the positional relations among feeder, nidus and drainer and the hemodynamics. This involves the full use of serial angiography and cinema angiography, careful determination of the neccessary extent of the craniotomy, and care in the use of the spatula, particularly when treating the feeders.
