Radiosurgery for large cerebral arteriovenous malformations.
ABSTRACT Radiosurgery is an effective treatment option for patients with small to medium sized arteriovenous malformations. However, it is not generally accepted as an effective tool for larger (>14 cm(3)) arteriovenous malformations because of low obliteration rates. The authors assessed the applicability and effectiveness of radiosurgery for large arteriovenous malformations.
We performed a retrospective study of 46 consecutive patients with more than 14 ml of arteriovenous malformations who were treated with radiosurgery using a linear accelerator and gamma knife (GK). They were grouped according to their initial clinical presentation-17 presented with and 29 without haemorrhage. To assess the effect of embolization, these 46 patients were also regrouped into two subgroups-25 with and 21 without preradiosurgical embolization. Arteriovenous malformations found to have been incompletely obliterated after 3-year follow-up neuroimaging studies were re-treated using a GK.
The mean treatment volume was 29.5 ml (range, 14.0-65.0) and the mean marginal dose was 14.1 Gy (range, 10.0-20.0). The mean clinical follow-up periods after initial radiosurgery was 78.1 months (range, 34.0-166.4). Depending on the results of the angiography, 11 of 33 patients after the first radiosurgery and three of four patients after the second radiosurgery showed complete obliteration. Twenty patients received the second radiosurgery and their mean volume was significantly smaller than their initial volume (P = 0.017). The annual haemorrhage rate after radiosurgery was 2.9% in the haemorrhage group (mean follow-up 73.3 months) and 3.1% in the nonhaemorrhage group (mean follow-up 66.5 months) (P = 0.941). Preradiosurgical embolization increased the risk of haemorrhage for the nonhaemorrhage group (HR, 28.03; 95% CI, 1.08-6,759.64; P = 0.039), whereas it had no effect on the haemorrhage group. Latency period haemorrhage occurred in eight patients in the embolization group, but in no patient in the nonembolization group (P = 0.004).
Radiosurgery may be a safe and effective arteriovenous malformation treatment method that is worth considering as an alternative treatment option for a large arteriovenous malformation.
- SourceAvailable from: hhttoronto.com[show abstract] [hide abstract]
ABSTRACT: To analyze the effect of stereotactic radiosurgery on the hemorrhage rate of arteriovenous malformations (AVMs), we reviewed the clinical and angiographic characteristics of 315 patients with AVMs before and after radiosurgery. One hundred ninety-six patients sustained 263 bleeds in 10,939 patient-years before radiosurgery, for an annual nonfatal hemorrhage rate of 2.4%. Clinical follow-up after radiosurgery was available in 312 patients (mean, 47 +/- 20 mo); follow-up > or = 24 months was obtained in 295 patients (94%). Twenty-one patients had AVM bleeds at a median of 8 months (range, 1-60 mo) after radiosurgery. Two additional patients had three aneurysmal bleeds (at 5, 27, and 32 mo, respectively) for a 7.4% total risk of hemorrhage per patient. The actuarial hemorrhage rate until AVM obliteration was 4.8% per year (95% confidence interval, 2.4-7.0%) during the first 2 years after radiosurgery and 5.0% per year (95% confidence interval, 2.3-7.3%) for the third to fifth years after radiosurgery. Multivariate analysis of clinical and angiographic factors demonstrated that the presence of an unsecured proximal aneurysm was associated with an increased risk of postradiosurgical hemorrhage (relative risk, 4.56; 95% confidence interval, 1.77-11.70%; P < 0.001). No AVM hemorrhages were observed after radiosurgery in seven patients with intranidal aneurysms. No protective effect against hemorrhage was observed in patients who received an "optimal" radiation dose (> or = 25 Gy to the AVM margin) compared with patients who received < 25 Gy to the AVM margin (P = 0.36). No patient suffered a hemorrhage after angiography had confirmed complete obliteration (n = 140) or suffered from an early draining vein without residual nidus (n = 19). Stereotactic radiosurgery was not associated with a significant change in the hemorrhage rate of AVMs during the latency interval before obliteration. No protective benefit was conferred on patients who had incomplete nidus obliteration in early (< 60 mo) follow-up after radiosurgery. AVM patients with unsecured proximal aneurysms should have aneurysms obliterated either before radiosurgery or at the time of surgical resection of their AVMs.Neurosurgery 05/1996; 38(4):652-9; discussion 659-61. · 2.53 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Stereotactic radiotherapy delivered in a high-dose single fraction is an effective technique to obliterate intracranial arteriovenous malformations (AVM). To attempt to analyze the relationships between dose, volume, and obliteration rates, we studied a group of patients treated using single-isocenter treatment plans. From May 1986 to December 1989, 100 consecutive patients with angiographically proven AVM had stereotactic radiotherapy delivered as a high-dose single fraction using a single-isocenter technique. Distribution according to Spetzler-Martin grade was as follows: 79 grade 1-3, three grade 4, 0 grade 5, and 18 grade 6. The target volume was spheroid in 74 cases, ellipsoid in 11, and large and irregular in 15. The targeted volume of the nidus was estimated using two-dimensional stereotactic angiographic data and, calculated as an ovoid-shaped lesion, was 1900 +/- 230 mm3 (median 968 mm3; range 62-11, 250 mm3). The mean minimum target dose (Dmin) was 19 +/- 0.6 Gy (median 20 Gy; range: 3-31.5). The mean volume within the isodose which corresponded to the minimum target dose was 2500 +/- 300 mm3 (median 1200 mm3; range 75-14 900 mm3). The mean maximum dose (Dmax) was 34.5 +/- 0.5 Gy (median 35 Gy; range 15-45). The mean angiographic follow-up was 42 +/- 2.3 months (median 37.5; range 7-117). The absolute obliteration rate was 51%. The 5-year actuarial obliteration rate was 62.5 +/- 7%. After univariate analysis, AVM obliteration was influenced by previous surgery (p = 0.0007), Dmin by steps of 5 Gy (p = 0.005), targeted volume of the nidus (< or = 968 mm3 vs. >968 mm3; p = 0.015), and grade according to Spetzler-Martin (grade 1-3 vs. grade 4-6; p = 0.011). After multivariate analysis, the independent factors influencing AVM obliteration were the Dmin [relative risk (RR) 1.9; 95% confidence interval (CI) 1.4-2.5; p < 0.0001] and grade distribution according to Spetzler-Martin (RR 1.4; 95% CI 1.1-1.7; p = 0.010). Delayed complications were observed in eight patients. The 5-year actuarial rate of delayed complications was 7.4%. After stereotactic radiotherapy delivered in a single high dose using a single-isocenter technique, the success rate for complete obliteration is independently correlated to Dmin but does not seem to be influenced by Dmax and the targeted volume of the nidus.International Journal of Radiation OncologyBiologyPhysics 07/1998; 41(4):855-61. · 4.52 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: The authors conducted a long-term follow-up study of 168 patients to define the natural history of clinically unruptured intracranial arteriovenous malformations (AVM's). Charts of patients seen at the Mayo Clinic between 1974 and 1985 were reviewed. Follow-up information was obtained on 166 patients until death, surgery, or other intervention, or for at least 4 years after diagnosis (mean follow-up time 8.2 years). All available cerebral arteriograms and computerized tomography scans of the head were reviewed. Intracranial hemorrhage occurred in 31 patients (18%), due to AVM rupture in 29 and secondary to AVM or aneurysm rupture in two. The mean risk of hemorrhage was 2.2% per year, and the observed annual rates of hemorrhage increased over time. The risk of death from rupture was 29%, and 23% of survivors had significant long-term morbidity. The size of the AVM and the presence of treated or untreated hypertension were of no value in predicting rupture.Journal of Neurosurgery 04/1988; 68(3):352-7. · 3.15 Impact Factor