A multidisciplinary approach to the treatment of brain vascular malformations

EMBOLIZATION BEFORE RADIOSURGERY REDUCES THE OBLITERATION RATE OF ARTERIOVENOUS MALFORMATIONS

OBJECTIVE

To evaluate the arteriovenous malformation (AVM) obliteration rate and the clinical outcome after radiosurgery in patients with and without previous embolization.

METHODS

Of 244 patients who underwent linear accelerator radiosurgery for AVMs at the Sunnybrook Health Sciences Centre between 1989 and 2000, 61 patients had embolization before radiosurgery and complete follow-up for at least 3 years. For 47 of these 61 patients (Group A, embolization plus radiosurgery), we were able to find 47 matching patients without previous embolization (Group B, radiosurgery alone). This group of matching patients had the same AVM volume (after embolization in Group A), location, and marginal dose. The radiosurgery-based AVM score and the obliteration prediction index were calculated.

RESULTS

The median follow-up period was 44 months. Nidus obliteration was achieved in 22 patients in Group A (47%) and 33 patients in Group B (70%, P = 0.036). Permanent deficit related to hemorrhage or radiation occurred in three patients (6%) in Group A and three patients (6%) in Group B. During the first 3 years after radiosurgery, two patients (4%) in Group A experienced hemorrhage; in Group B, five patients (11%) experienced hemorrhage (P = 0.2). In Group B, two patients (4%) died and two patients (4%) had their AVM surgically removed. Both deaths were related to hemorrhage during the latency period. The excellent outcome (obliteration plus no deficit) in Group A was 47% compared with 64% in Group B (P = 0.146). There was no difference in the obliteration prediction index and the radiosurgery-based AVM score between Groups A and B. The predicted rates of obliteration and excellent outcome were 55 and 62.5%, respectively, according to the obliteration prediction index and the radiosurgery-based AVM score.

CONCLUSION

Embolization before radiosurgery significantly decreases the obliteration rate, even in AVMs with the same volume, location, and marginal dose. Although an excellent outcome rate was higher in the group without embolization, this was not statistically significant.

Large and deep brain arteriovenous malformations are associated with risk of future hemorrhage

BACKGROUND AND PURPOSE

The correlation between features present in brain arteriovenous malformations (AVMs) such as size, location, and angioarchitecture at presentation with subsequent risk of hemorrhage may be valuable in predicting the behavior of AVMs and therefore guiding management.

METHODS

We prospectively followed up 390 patients with brain AVMs at the University of Toronto Vascular Malformation Study Group. Location, size, angioarchitecture details, blood supply, and clinical presentation were recorded at baseline. Intracranial hemorrhages during follow-up were recorded. Significant factors from univariate analyses were used to construct a multivariate model relating the above features to the occurrence of hemorrhage.

RESULTS

Thirty-eight patients had bleeding caused by the AVM in a follow-up of 1205 patient-years (mean, 3.1 years per patient). In analyses adjusted for multiple AVM characteristics, large AVMs bled more frequently than small lesions (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.41 to 4.35; P<0.0001), and deep-seated AVMs had more bleeding in follow-up than those located at superficial sites (OR, 5.56; 95% CI, 2.63 to 12.5; P<0.0001).

CONCLUSIONS

Deep-seated and large AVMs were significantly more prone to hemorrhage during prospective follow-up. The distinction between factors associated with hemorrhagic presentation and the natural history risk of hemorrhage will be emphasized.

Angioarchitectural factors present in brain arteriovenous malformations associated with hemorrhagic presentation

BACKGROUND AND PURPOSE

Associations between clinical presentation of brain arteriovenous malformations (AVMs) and their angioarchitecture have been described. This study aims to identify significant factors related to the initial hemorrhagic event through multivariate statistical methodology.

METHODS

The authors studied the initial clinical presentation of 390 consecutive patients with brain AVMs at the University of Toronto Vascular Malformation Study Group. Angiographic features present at that time, such as location, size, and blood supply, were recorded following a standard protocol and associated, through multivariate analysis techniques, with type of presentation.

RESULTS

Patients had hemorrhagic presentation in 146 cases (37.4%). Hemorrhage was the initial presentation in 59.5% of the deep-seated AVMs (odds ratio [OR]=3.26; 95% CI=1.15 to 9.2; P=0.03). A single draining vein was associated with bleeding at presentation in 57.6% AVMs (OR=1.78; 95% CI=1.12 to 2.82; P=0.01), and 72.8% of the patients with venous ectasia had bleeding as initial evidence (OR=3.9; 95% CI=1.63 to 9.28; P=0.002). Hemorrhage was the initial presentation in 47.6% (111/233) of AVMs <3 cm, 22.5% (32/142) in sizes between 3 and 6 cm, and 20% in malformations >6 cm (3/15), but these differences were not significant in multivariate analyses.

CONCLUSIONS

For initial hemorrhagic presentation, a small number of draining veins, deep location, and the presence of venous ectasias were significant associated factors. In contrast with many previous reports, AVM size was not associated with hemorrhage at presentation in adjusted analyses.

Cavernous-venous malformation of brain stem--report of a case and review of literature

BACKGROUND

Because of improved imaging techniques, the association of cavernous and venous malformations is now being seen more often in neurosurgical practice. However, only a few cases have been subjected to surgery. Surgical excision of the cavernous malformation, sparing the venous component, has been the method of choice advocated by most authors. This, however, is not possible when the components are intimately associated with each other. It thus becomes important to predict the surgical outcome in such lesions, especially when they are located in an eloquent area. A surgically excised case of cavernous-venous malformation in the dorsal pontomedullary region is presented here; the histology confirmed the intimate association of both components. The relevant literature is also discussed.

CASE DESCRIPTION

This 20-year-old male presented with episodic vomiting, giddiness, and persistent cerebellar signs over a six-year period. Neuroimaging studies-computed tomography scan/magnetic resonance imaging (CT/MRI) were suggestive of a cavernous malformation. MRI also showed a draining vein close to the lesion. Following total excision, histopathology confirmed the intimate association of both cavernous and venous malformations. The patient made an uneventful recovery. MRI at follow up confirmed total excision.

CONCLUSIONS

The presence of venous channels draining into a lesion that otherwise appears to be a cavernous malformation may indicate an intimately associated venous component. Selective surgical excision of the cavernous component may be difficult in such cases. Surgical outcome, though favorable in this case, will be difficult to comment upon unless more such cases are reported. This may be of greater significance in lesions located in eloquent areas.

Radiosurgery for arteriovenous malformations: the University of Toronto experience

BACKGROUND

From July 1989 to February 1996, 130 patients underwent stereotactic radiosurgery. We report the results of the first 50 patients eligible for a minimum of three years of follow-up.

METHODS

Twenty women and 30 men, (mean age: 37.5 years) were treated by dynamic rotation on a 6 MV linear accelerator. Prior treatment was embolization in seventeen, surgery in three and embolization and surgery in six. All had DSA and enhanced CT scanning, while some had MRI. Forty-seven treatments used a single isodose. Restricting eloquent normal tissue to 15 Gy, margin doses (at 50-90% isodose) were 12 Gy (one patient); 15 Gy (sixteen patients); 20 Gy (31 patients); 25 Gy (two patients). Maximum diameters were: < 1.5 cm (12 patients); < 2.0 cm (nine patients); < 2.5 cm (twelve patients); < 3.0 cm (thirteen patients; 3.0 cm (four patients).

RESULTS

Forty-five patients were evaluable at three years, with thirty-nine having angiography. Twenty-five had angiographically confirmed obliterations; two had parenchymal AVMs obliterated but with residual dural components; four had MRI evidence of obliteration (refused angiography). One patient acutely had a seizure; one patient (with hemorrhages, resection, and embolizations preceding two applications of radiosurgery, separated by 3.5 years) had worsening of memory.

CONCLUSIONS

Our uncorrected (five patients unevaluable at three years) and corrected angiographically confirmed obliteration rates are 54% and 60% respectively. Our follow-up (98% accounting of cohort; 78% angiographic rate) and explicit derivation of denominators help delineate the efficacy of radiosurgery at these doses.

Cavernomas of the central nervous system in children. A report of 22 cases

A series of 22 patients under the age of 15 years with cavernomas were treated at the Section of Paediatric Neurosurgery of the Catholic University of Rome between 1981 and 1995. The most common symptoms at presentation were epilepsy, in 12 children, and intracranial hypertension, in 9 children; seizures were present on admission in 14 patients; no patient had a family history of cerebro-vascular malformations, two had multiple lesions. Radiological signs of significant acute and subacute haemorrhage were found in 17 cases. The supratentorial compartment was the most frequent location of the lesions, with only three subtentorial cavernomas. The post-surgical results were good: only four children had a persistence of pre-surgical neurological signs, even though they were ameliorated by the treatment. No patient showed a progression of pre-operative neurological signs, nor the onset of new deficits. Only one child died, but his clinical condition was critical before surgery, because of deep coma, with bilaterally dilated and fixed pupils, and no response to any stimulation. Our results suggest that the younger children present significant haemorrhage more frequently than the older ones; this is demonstrated by the analysis of the mean age of the patients with macro-haemorrhage (= 7 years) and the average age of those without macro-haemorrhage (= 11 years). The removal of cavernomas was always able to control the seizure disorders of our patients, proving that in these cases lesionectomy alone may be sufficient to resolve epilepsy.

The combined management of cerebral arteriovenous malformations. Experience with 100 cases and review of the literature

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 high-grade 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.(ABSTRACT TRUNCATED AT 400 WORDS)