Spetzler-Martin Grade III Arteriovenous Malformations: A Multicenter Propensity-Adjusted Analysis of the Effects of Preoperative Embolization

Neurosurgery 88:996–1002, 2021

Spetzler-Martin (SM) grade III arteriovenous malformations (AVMs) are at the boundary of safe operability, and preoperative embolizationmay reduce surgical risks.

OBJECTIVE: To evaluate the benefits of preoperative AVM embolization by comparing neurological outcomes in patients with grade III AVMs treated with or without preoperative embolization.

METHODS: All microsurgically treated grade III AVMs were identified from 2011 to 2018 at 2medical centers. Neurological outcomes,measured as final modified Rankin Scale scores (mRS) and changes in mRS from preoperative baseline to last follow-up evaluation, were compared in patients with and without preoperative embolization.

RESULTS: Of the 102 patients with grade III AVMs who were treated microsurgically, 57 (56%) underwent preoperative embolization. Significant differences were found between the patients with and without embolization in AVM eloquence (74% vs 93%, P = .02), size ≥ 3 cm (47% vs 73%, P = .01), diffuseness (7% vs 22%, P = .04), and mean final mRS (1.1 vs 2.0, P = .005). Poor outcomes were more frequent in patients without embolization (38%) than with embolization (7%) (final mRS > 2; P < .001). Propensityadjusted analysis revealed AVM resection without embolization was a risk factor for poor outcome (mRS score > 2; odds ratio, 4.2; 95% CI, 1.1-16; P = .03).

CONCLUSION: Nonembolization of SM grade III AVMs is associated with an increased risk of poor neurological outcomes after microsurgical resection. Preoperative embolization of intermediate-grade AVMs selected because of large AVM size, surgical inaccessibility of feeding arteries, and high flow should be employed more often than anticipated, even in the context of increasing microsurgical experience with AVMs.

Stereotactic Radiosurgery for Spetzler-Martin Grade I and II Arteriovenous Malformations: International Society of Stereotactic Radiosurgery (ISRS) Practice Guideline

Neurosurgery 87:442–452, 2020

No guidelines have been published regarding stereotactic radiosurgery (SRS) in the management of Spetzler-Martin grade I and II arteriovenous malformations (AVMs).

OBJECTIVE: To establish SRS practice guidelines for grade I-II AVMs on the basis of a systematic literature review.

METHODS: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant search of Medline, Embase, and Scopus, 1986-2018, for publications reporting post-SRS outcomes in ≥ 10 grade I-II AVMs with a follow-up of ≥ 24 mo. Primary endpoints were obliteration and hemorrhage; secondary outcomes included SpetzlerMartin parameters, dosimetric variables, and “excellent” outcomes (defined as total obliteration without new post-SRS deficit).

RESULTS: Of 447 abstracts screened, 8 were included (n = 1, level 2 evidence; n = 7, level 4 evidence), representing 1102 AVMs, of which 836 (76%) were grade II. Obliteration was achieved in 884 (80%) at a median of 37 mo; 66 hemorrhages (6%) occurred during a median follow-up of 68 mo. Total obliteration without hemorrhage was achieved in 78%. Of 836 grade II AVMs, Spetzler-Martin parameters were reported in 680: 377 were eloquent brain and 178 had deep venous drainage, totaling 555/680 (82%) high-risk SRS-treated grade II AVMs.

CONCLUSION: The literature regarding SRS for grade I-II AVM is low quality, limiting interpretation. Cautiously, we observed that SRS appears to be a safe, effective treatment for grade I-II AVM and may be considered a front-line treatment, particularly for lesions in deep or eloquent locations. Preceding publications may be influenced by selection bias, with favorable AVMs undergoing resection, whereas those at increased risk of complications and nonobliteration are disproportionately referred for SRS.

A treatment paradigm for high-grade brain arteriovenous malformations: volume-staged radiosurgical downgrading followed by microsurgical resection

A treatment paradigm for high-grade brain arteriovenous malformations- volume-staged radiosurgical downgrading followed by microsurgical resection

J Neurosurg 122:419–432, 2015

The surgical treatment of many large arteriovenous malformations (AVMs) is associated with substantial risks, and many are considered inoperable. Furthermore, AVMs larger than 3 cm in diameter are not usually treated with conventional single-session radiosurgery encompassing the entire AVM volume. Volume-staged stereotactic radiosurgery (VS-SRS) is an option for large AVMs, but it has mixed results. The authors report on a series of patients with highgrade AVMs who underwent multiple VS-SRS sessions with resultant downgrading of the AVMs, followed by resection.

Methods. A cohort of patients was retrieved from a single-institution AVM patient registry consisting of prospectively collected data. VS-SRS was performed as a planned intentional treatment. Surgery was considered as salvage therapy in select patients.

Results Sixteen AVMs underwent VS-SRS followed by surgery. Four AVMs presented with rupture. The mean patient age was 25.3 years (range 13–54 years). The average initial Spetzler-Martin grade before any treatment was 4, while the average supplemented Spetzler-Martin grade (Spetzler-Martin plus Lawton-Young) was 7.1. The average AVM size in maximum dimension was 5.9 cm (range 3.3–10 cm). All AVMs were supratentorial in location and all except one were in eloquent areas of the brain, with 7 involving primary motor cortex. The mean number of VS-SRS sessions was 2.7 (range 2–5 sessions). The mean interval between first VS-SRS session and resection was 5.7 years. There were 4 hemorrhages that occurred after VS-SRS. The average Spetzler-Martin grade was reduced to 2.5 (downgrade, -1.5) and the average supplemented Spetzler-Martin grade was reduced to 5.6 (downgrade, -1.5). The maximum AVM size was reduced to an average of 3.0 cm (downsize = -2.9 cm). The mean modified Rankin Scale (mRS) scores were 1.2, 2.3, and 2.2 before VS-SRS, before surgery, and at last follow-up, respectively (mean follow-up, 6.9 years). Fifteen AVMs were cured after surgery. Ten patients had good outcomes at last follow-up (7 with mRS Score 0 or 1, and 3 with mRS Score 2). There were 2 deaths (both mRS Score 1 before treatment) and 4 patients with mRS Score 3 outcome (from mRS Scores 0, 1, and 2 [n = 2]).

Conclusions Volume-staged SRS can downgrade AVMs, transforming high-grade AVMs (initially considered inoperable) into operable AVMs with acceptable surgical risks. This treatment paradigm offers an alternative to conservative observation for young patients with unruptured AVMs and long life expectancy, where the risk of hemorrhage is substantial. Difficult AVMs were cured in 15 patients. Surgical morbidity associated with downgraded AVMs is reduced to that of postradiosurgical/preoperative supplemented Spetzler-Martin grades, not their initial AVM grades.

Microsurgery for cerebral arteriovenous malformations: postoperative outcomes and predictors of complications in 264 cases

AVM PF

Neurosurg Focus 37 (3):E10, 2014

The authors conducted a study to assess the safety and efficacy of microsurgical resection of arteriovenous malformations (AVMs) and determine predictors of complications.

Methods. A total of 264 patients with cerebral AVMs were treated with microsurgical resection between 1994 and 2010 at the Jefferson Hospital for Neuroscience. A review of patient data was performed, including initial hemorrhage, clinical presentation, Spetzler-Martin (SM) grade, treatment modalities, clinical outcomes, and obliteration rates. Univariate and multivariate analyses were used to determine predictors of operative complications.

Results. Of the 264 patients treated with microsurgery, 120 (45%) patients initially presented with hemorrhage. There were 27 SM Grade I lesions (10.2%), 101 Grade II lesions (38.3%), 96 Grade III lesions (36.4%), 31 Grade IV lesions (11.7%), and 9 Grade V lesions (3.4%). Among these patients, 102 (38.6%) had undergone prior endovascular embolization. In all patients, resection resulted in complete obliteration of the AVM. Complications occurred in 19 (7.2%) patients and resulted in permanent neurological deficits in 5 (1.9%). In multivariate analysis, predictors of complications were increasing AVM size (OR 3.2, 95% CI 1.5–6.6; p = 0.001), increasing number of embolizations (OR 1.6, 95% CI 1.1–2.2; p = 0.01), and unruptured AVMs (OR 2.7, 95% CI 1–7.2; p = 0.05).

Conclusions. Microsurgical resection of AVMs is highly efficient and can be undertaken with low rates of morbidity at high-volume neurovascular centers. Unruptured and larger AVMs were associated with higher complication rates.

Stereotactic radiosurgery for Spetzler-Martin Grade III arteriovenous malformations

Spetzler-Martin grade III AVMs

J Neurosurg 120:973–981, 2014

The purpose of this study was to define the outcomes and risks of stereotactic radiosurgery (SRS) for Spetzler-Martin (SM) Grade III arteriovenous malformations (AVMs).

Methods. Between 1987 and 2009, SRS was performed in 474 patients with SM Grade III AVMs. The AVMs were categorized by scoring the size (S), drainage (D), and location (L): IIIa was a small AVM (S1D1L1, N = 282); IIIb was a medium/deep AVM (S2D1L0, N = 44); and IIIc was a medium/eloquent AVM (S2D0L1, N = 148). The median target volume was 3.8 ml (range 0.1–26.3 ml) and the margin dose was 20 Gy (range 13–25 Gy). Eighty-one patients (17%) underwent prior embolization, and 58 (12%) underwent prior resection.

Results. At a mean follow-up of 89 months, the total obliteration rates documented by angiography or MRI for all SM Grade III AVMs increased from 48% at 3 years to 69% at 4 years, 72% at 5 years, and 77% at 10 years. The SM Grade IIIa AVMs were more likely to obliterate than other subgroups. The cumulative rate of hemorrhage was 2.3% at 1 year, 4.4% at 2 years, 5.5% at 3 years, 6.4% at 5 years, and 9% at 10 years. The SM Grade IIIb AVMs had a significantly higher cumulative rate of hemorrhage. Symptomatic adverse radiation effects were detected in 6%.

Conclusions. Treatment with SRS was an effective and relatively safe management option for SM Grade III AVMs. Although patients with residual AVMs remained at risk for hemorrhage during the latency interval, the cumulative 10-year 9% hemorrhage risk in this series may represent a significant reduction compared with the expected natural history.