Patients and techniques: A series of 67 patients treated for cerebral AVMs using a multidisciplinary approach is reported, paying special attention to the complications due to treatment. The malformations were classified according to 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: 80% overall, 91% after resection (with or without embolization), 13% after embolization alone, 87% after radiosurgery.
Clinical outcome: The outcome was evaluated in terms of deterioration due to treatment. Treatment-related deterioration occurred in 28% of cases and consisted of a minor deterioration (19%), a neurological deficit (4%), or death (4%). As far as the mode of treatment is concerned, surgical resection was followed by deterioration in 20% of all operated cases (minor 17%, deficit 3%). Radiosurgery was followed by a minor deterioration in 10% of irradiated cases. Embolization resulted in complication in 25% of all embolized cases (minor 12.5%, neurological deficit 5%, or death 7.5%). The mechanism of the complication was: resection on manipulation of a functional area and the haemorrhage for cases treated by surgery, radionecrosis for radiosurgery, ischemia and haemorrhage (50% each) for embolization. In 4 out of the 5 cases of haemorrhage due to embolization, an occlusion of the main venous drainage could be demonstrated.
Discussion: The haemodynamic disturbances relating to AVMs and to their treatment are reviewed in the literature. The main haemodynamic mechanisms at the origin of a complication after treatment of cerebral AVMs are the normal perfusion pressure breakthrough syndrome, venous drainage defects (venous overload or occlusive hyperemia), and retrograde thrombosis of the feeding arteries.
Conclusions: Improved treatment of cerebral AVMs has been achieved through the multidisciplinary approach, and especially through the endovascular embolization technique. Such an improvement is especially visible in the field of high-grade malformations, which are the most difficult and the most dangerous to treat. As a consequence, the risk of the treatment has naturally shifted from surgical resection towards endovascular embolization which is the first procedure to be performed in difficult cases. Careful consultation between the various specialists is necessary in this pathology, particularly as some of these AVMs are a good indication for each of the three available methods of treatment.