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Notes: Summary The prognostic value of the Spetzler's grading system is studied in a series of 52 AVMs treated by a combined management, using one or several of the 3 available techniques: surgical resection, endovascular embolization, radiosurgery. The symptoms at the time of treatment were haemorrhage 50%, seizures 31%, headache and deficit 19%. Three grade groups were considered: I and II (31%), III (33%), IV and V (36%). Overall, AVMs were managed as follows: resection alone 25%, embolization plus resection 23%, embolization alone 23%, radiosurgery with various combinations 29%. According to the grade groups, the most frequently used technique was resection alone for grade I–II AVMs (44%), radiosurgery for grade III AVMs (41%) and embolization alone for grade IV–V AVMs (42%). The clinical outcome was evaluated in terms of deterioration due to treatment. The best results were obtained in grade I–II AVMs (81% with no deterioration) then in grade III AVMs (65%) and in grade IV–V (58%). However, when we consider the outcome in terms of favourable results (no or only minor deterioration) we obtained a similar outcome for grade I–II and grade III AVMs (94% each), and only 79% for grade IV–V malformations. The angiographic outcome showed a better eradication rate in grade III AVMs (88% complete eradication), than in grade I–II AVMs (75%) and in grade IV–V (47%). Our conclusion is that the Spetzler's grading system in this series was well correlated with both the clinical and the angiographic outcome. However, we found no real difference between grade I–II and grade III AVMs. So, in terms of prognostic value, the grade I, II, and III AVMs could be considered together as low-grade malformations, with a better prognosis than the high-grade malformations (grade IV and V).

Notes: Summary A series of 100 patients treated for a cerebral arteriovenous malformation (AVM) is presented. Patients were admitted between 1985 and April 1992. Two groups are considered: the first group including 52 patients treated before the availability of radiosurgery (1985–1988), and the second group including 48 patients treated after the availability of radiosurgery (1989–1992). AVM's were classified in five grades according to the Spetzler's Grading System. Three techniques of treatment were used: surgical resection, intravascular embolization (with cyanoacrylate), and radiosurgery (linear accelerator). These three techniques were used either alone or in association, giving four types of management: surgical resection alone, embolization and resection, embolization alone, and radiosurgery (alone, or after embolization, or after surgical resection). From 1989 on, the availability of radiosurgery was responsible for the decrease of the “embolization and resection” group, which until then was predominantly used as well for low-grade (I, II, III) as for high-grade AVM's (IV, V). Overall, for the low-grade AVM's, the treatment of choice was surgical resection (79% of cases), with pre-operative embolization in one-half of these cases; the other low-grade AVM's were irradiated, with various combinations. For the high-grade AVM's, the treatment of choice was intravascular embolization (95% of cases), either alone, or followed by resection (45%) or radiosurgery (9%). Results were evaluated in terms of deterioration following treatment, in five groups: no deterioration (59%), minor deterioration (20%), long-lasting deficit (10%), major deterioration (5%), and death (6%). Overall, results improved after 1989: favourable outcome (no deterioration and minor deterioration) increased from 67% to 90%. Results were not related to the patients' age. More favourable results were obtained for low-grade AVM's (93%) than for high-grade AVM's (60%). For the low-grade AVM's the evolution from 1989 on (favourable outcomes increasing from 89% to 96%) occurred with the lowering of the mortality rate. For the highgrade AVM's, the evolution from 1989 onwards (favourable outcome increasing from 46% to 78%) occurred with the decrease of the cases with deficits. The angiographic results were strongly related to the management: 95% of complete eradication after surgical resection and 5% only after embolization alone. Concerning the results in irradiated cases, the follow-up is not long enough. The review of the neurosurgical literature since 1972 demonstrates progressive modifications in the therapeutic attitude as regards AVM's. The surgical management which was predominantly used at the beginning gave way progressively to a combined management, with a combination of embolization, surgery, and lately radiosurgery. The authors' present attitude is in favour of combined treatment using the three techniques. Direct surgical resection is proposed for small and readily accessible AVM's. Direct radiosurgery is proposed for small but deep AVM's or those located in highly functional areas. Intravascular embolization is proposed in every other situation. After embolization has been completed, totally eradicated AVM's are left in place; no further treatment is proposed for AVM's which are still large with high surgical risk. AVM's which are sufficiently reduced in size are either operated on (if accessible) or irradiated (if deeply situated). When the results of radiosurgery are assessed with long enough follow-up (in terms of eradication and clinical outcome) the authors' attitude may either increase the role of radiosurgery or return towards surgical resection, depending of the quality of the results.

Notes: Summary Between 1979 and 1989, 7 patients were admitted, with cerebral arteriovenous malformations (AVM) and associated aneurysms (7% of the AVM patients and 2% of the aneurysm patients admitted during the same period). 6 of these patients were admitted because of an intracranial haemorrhage (in 3 of them the AVM, angiographically occult, was discovered at surgery). The last patient was referred for seizures. Preoperatively it was supposed that the haemorrhage was related to the aneurysm in 3 cases, and to the AVM in 3 cases. But surgery allowed one to correct this supposition. Haemorrhage was due to AVM rupture in all 6 cases, and no aneurysm had ruptured. Overall three situations were demonstrated in this series: aneurysm and occult AVM (3 cases); AVM and independent aneurysm in the same area (2 cases); large AVM and aneurysm on a feeding artery (2 cases). All 6 patients admitted for haemorrhage were operated upon, at one operation in 5 of them. Both the malformations were excluded in these six patients. For the patient admitted for seizure, intra-vascular embolization of the AVM was performed, the aneurysm was not treated. The pathogenesis of the association AVM-aneurysm is discussed. In the authors' opinion, haemodynamic relationship should be considered in two cases (large AVM and aneurysm on a feeding vessel). For the other 5 cases, both the AVM and the coexisting aneurysm may be the end-result of a common congenital vascular malformation syndrome.

Notes: Summary 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% highgrade 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.