A novel proposed grading system for cerebellar arteriovenous malformations

Abstract

ABBREVIATIONS AUROC = area under the receiver operating characteristic curve; AVM = arteriovenous malformation; CI = confidence interval; GKS = Gamma Knife surgery; LY = Lawton-Young; mRS = modified Rankin Scale; OR = odds ratio; PoNS = postoperative neurological status; PrNS = preoperative neurological status; SM = Spetzler-Martin; SP = Spetzler-Ponce. OBJECTIVEThe objective of this study was to evaluate the existing Spetzler-Martin (SM), Spetzler-Ponce (SP), and Lawton-Young (LY) grading systems for cerebellar arteriovenous malformations (AVMs) and to propose a new grading system to estimate the risks associated with these lesions. METHODS Data for patients with cerebellar AVMs treated microsurgically in two tertiary medical centers were retrospectively reviewed. Data from patients at institution 1 were collected from September 1999 to February 2013, and at institution 2 from October 2008 to October 2015. Patient outcomes were classified as favorable (modified Rankin Scale [mRS] score 0-2) or poor (mRS score 3-6) at the time of discharge. Using chi-square and logistic regression analysis, variables associated with poor outcomes were assigned risk points to design the proposed grading system. The proposed system included neurological status prior to treatment (poor, +2 points), emergency surgery (+1 point), age > 60 years (+1 point), and deep venous drainage (deep, +1 point). Risk point totals of 0-1 comprised grade 1, 2-3 grade 2, and 4-5 grade 3. RESULTS A total of 125 cerebellar AVMs of 1328 brain AVMs were reviewed in 125 patients, 120 of which were treated microsurgically and included in the study. With our proposed grading system, we found poor outcomes differed significantly between each grade (p < 0.001), while with the SM, SP, and LY grading systems they did not (p = 0.22, p = 0.25, and p = 1, respectively). Logistic regression revealed grade 2 had 3.3 times the risk of experiencing a poor outcome (p = 0.008), while grade 3 had 9.9 times the risk (p < 0.001). The proposed grading system demonstrated a superior level of predictive accuracy (area under the receiver operating characteristic curve [AUROC] of 0.72) compared with the SM, SP, and LY grading systems (AUROC of 0.61, 0.57, and 0.51, respectively). CONCLUSIONS The authors propose a novel grading system for cerebellar AVMs based on emergency surgery, venous drainage, preoperative neurological status, and age that provides a superior prognostication power than the formerly proposed SM, SP, and LY grading systems. This grading system is clinically predictive of patient outcomes and can be used to better guide vascular neurosurgeons in clinical decision-making. https://thejns.org/doi/abs/

Systematic review of brain arteriovenous malformation grading systems evaluating microsurgical treatment recommendation

“…All scoring systems predominantly contained seven factors: bAVM size, nidus location (or so-called eloquence), venous drainage, arterial feeders, nidus compactness, hemorrhagic presentation, and patient age. The factors which were most often included as a contributing factor to risk assessment were location/eloquence of the AVM [27,31,[36][37][38][39]41] and venous drainage [14,27,29,[36][37][38][39] (7/13 scores, 54%), followed by nidus size in 6/13 scores (46%) [27,31,36,38,39,41]. Consideration of arterial feeders was popular in historical studies [13,21,31,36,41] but is not a contributing factor in any scores presented after 1992.…”

“…On the other hand, observations of nidus compactness and hemorrhagic presentation were only taken into consideration in scores developed from 2006 onwards [2,14,19,27,37]. The two scores of Höllerhage [13] and Nisson [29] put an additional emphasis on clinical presentation before surgery. The two scores for ruptured bAVM only [2,27] include Glasgow Coma Scale (GCS) score on admission, intraventricular blood, hemorrhage volume, and age as relevant factors in predicting outcome.…”

“…The scores included 3tier [29,39], 4tier [21,36,41], 5tier [19,38], 6tier [14], 7tier [2,13], 10tier [37], and 12tier [27] system, and the most elaborate 66-point system by Pertuiset [31]. In the latter, the score is subsequently subdivided into five categories.…”

“…In consequence, posterior fossa bAVMs are more likely to rupture and patients with these lesions are more likely to present with symptomatic hemorrhage. The grading system by Nisson et al deals exclusively with bAVM of the posterior fossa [29]. The study originated in the USA and was co-authored by Spetzler and Lawton.…”

“…accepted use, the Spetzler-Martin grade may not be the best predictor of outcome in certain subpopulations of bAVM patients, such as ruptured bAVM or bAVM of the posterior fossa. For these subgroups, other scoring systems have been designed that may better predict surgical risks or outcomes [2,27,29]. In order to create an overview of all existing grading systems with regard to microsurgical treatment of bAVM, we systematically reviewed the literature for all surgical bAVM grading systems and suggested a workflow for selecting the best applicable grading system for each bAVM subgroup.…”