Patients and techniques: A series of 67 patients treated for cerebral AVMs with a multidisciplinary approach is reported, with special attention for the complications due to treatment. The malformations were classified after the Spetzler Grading Scale, with 67% low-grade and 33% high-grade AVMs. Three modes of treatment were used: surgical resection, endovascular embolization, and radiosurgery (linear accelerator technique). The actual treatment was: resection alone (25% of cases), embolization plus resection (24%), embolization alone (21%), and radiosurgery (30%), either alone or after embolization or surgery. The following eradication rates were obtained: overall 80%, after resection (with or without embolization) 91%, after embolization alone 13%, after radiosurgery 87%.
Clinical outcome: The outcome was evaluated in terms of deterioration due to treatment. A deterioration after treatment occurred in 19 patients (28%), and was a minor deterioration (19%), a neurological deficit (4%), or death (4%). As far as the mode of treatment is concerned, surgical resection was responsible for deterioration (minor) in 17% of all cases operated upon. Radiosurgery was followed by a minor deterioration in 10% of irradiated cases. Embolization gave a complication in 25% of all embolized cases (minor or neurological deficit, or death). The mechanism of the complications was: resection or manipulation of an eloquent area during surgery, radionecrosis after radiosurgery, ischaemia and haemorrhage (50% each) following embolization. In most cases of haemorrhage due to embolization, occlusion of the main venous drainage could be demonstrated.
Discussion: The haemodynamic disturbances to AVMs and to their treatment are reviewed in the literature. The main haemodynamic mechanisms admitted at the beginning of a complication after treatment of cerebral AVMs are the normal perfusion pressure breakthrough syndrome, the disturbances of the venous drainage (venous overload or occlusive hyperaemia), and the retrograde thrombosis of the feeding arteries.
Conclusions: According the authors' experience, the emphasis of treatment for cerebral AVMs has now shifted from surgical resection to endovascular embolization. One of the explanations is that endovascular techniques are now employed in the most difficult cases (high grade AVMs). As severe complications of endovascular embolization may also occur for low-grade malformations, the question arises whether surgery or radiosurgery should not be used first for this low-grade group even if embolization is feasible.