Stereotactic radiosurgery for Spetzler-Martin Grade III arteriovenous malformations: an international multicenter study

Abstract

OBJECTIVE Because of the angioarchitectural diversity of Spetzler-Martin (SM) Grade III arteriovenous malformations (AVMs), the management of these lesions is incompletely defined. The aims of this multicenter, retrospective cohort study were to evaluate the outcomes after stereotactic radiosurgery (SRS) for SM Grade III AVMs and to determine the factors predicting these outcomes. METHODS The authors analyzed and pooled data from patients with SM Grade III AVMs treated with SRS at 8 institutions participating in the International Gamma Knife Research Foundation. Patients with these AVMs and a minimum follow-up length of 12 months were included in the study cohort. An optimal outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes (RICs). Data were analyzed by univariate and multivariate regression analyses. RESULTS The SM Grade III AVM cohort comprised 891 patients with a mean age of 34 years at the time of SRS. The mean nidus volume, radiosurgical margin dose, and follow-up length were 4.5 cm, 20 Gy, and 89 months, respectively. The actuarial obliteration rates at 5 and 10 years were 63% and 78%, respectively. The annual postradiosurgery hemorrhage rate was 1.2%. Symptomatic and permanent RICs were observed in 11% and 4% of the patients, respectively. Optimal outcome was achieved in 56% of the patients and was significantly more frequent in cases of unruptured AVMs (OR 2.3, p < 0.001). The lack of a previous hemorrhage (p = 0.037), absence of previous AVM embolization (p = 0.002), smaller nidus volume (p = 0.014), absence of AVM-associated arterial aneurysms (p = 0.023), and higher margin dose (p < 0.001) were statistically significant independent predictors of optimal outcome in a multivariate analysis. CONCLUSIONS Stereotactic radiosurgery provided better outcomes for patients with small, unruptured SM Grade III AVMs than for large or ruptured SM Grade III nidi. A prospective trial or registry that facilitates a comparison of SRS with conservative AVM management might further clarify the authors' observations for these often high-risk AVMs.

Cyst formation after stereotactic radiosurgery for brain arteriovenous malformations: a systematic review

“…54 These findings suggest that the pathophysiology of delayed cyst formation is distinct from that of post-SRS hemorrhage. 2,15,34,65,66 Indeed, histopathological examination of resected cysts suggests that cyst formation occurs secondary to a chronic, organized response to radiation-induced vascular telangiectasia and wall damage, which promotes microhemorrhage and protein exudation. 59 It is possible that prior AVM hemorrhage and embolization increase tissue susceptibility to damage, thereby increasing the risk of cyst formation.…”

Expert consensus on the management of brain arteriovenous malformations

“…Population-based data suggest that the annual incidence of discovery of a symptomatic AVM is approximately 1/100,000 population. [12456] Although the ARUBA study was a major contribution to the literature, it has been the object of many criticisms by the scientific community[78910] because of its discordances with the results of many published reports[111213] and the experience of the clinicians dealing with AVMs.…”

Surgical Approaches for Symptomatic Cerebral Cavernous Malformations of the Thalamus and Brainstem

“…The elevated risk of both initial and repeat hemorrhage for these deep-seated CCMs compared to cortical CCMs favors intervention, whereas the relatively high rate of neurological morbidity associated with surgical resection of these lesions supports a more conservative approach 41)42). Although radiosurgery is a conceptually attractive alternative to surgical resection of eloquent CCMs, the radiosurgery-induced complication rate is significantly higher for CCMs than for AVMs, and CCMs cannot be radiologically monitored for obliteration after radiosurgery 3)5)6)8)9)10)12)13)14)15)16)17)18)19)20)21)22)23)25)26)27)28)29)30)31)32)33)34)35)36)37)43)44)49)50)52)53)56)59)63)64)65)66)67)68). Instead, the proposed effect of radiosurgery on CCMs is a decreased risk of symptomatic hemorrhages, which is controversial due to temporal clustering of CCM hemorrhages 4).…”