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. 2019 Mar 8;132(4):1105-1115.
doi: 10.3171/2018.12.JNS181677. Print 2020 Apr 1.

A novel proposed grading system for cerebellar arteriovenous malformations

Peyton L Nisson  1   2 , Salman A Fard  1 , Christina M Walter  3 , Cameron M Johnstone  3 , Michael A Mooney  4 , Ali Tayebi Meybodi  4 , Michael Lang  4 , Helen Kim  2 , Heidi Jahnke  4 , Denise J Roe  5 , Travis M Dumont  3 , G Michael Lemole  3 , Robert F Spetzler  4 , Michael T Lawton  2   4
Affiliations

A novel proposed grading system for cerebellar arteriovenous malformations

Peyton L Nisson et al. J Neurosurg. .

Abstract

Objective: The 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.

Keywords: arteriovenous malformations; cerebellar; grading system; outcomes; prognosis; risk assessment; vascular disorders.

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Conflict of interest statement

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Figures

FIG. 1.
FIG. 1.
Flowchart of patient selection for study inclusion.
FIG. 2.
FIG. 2.
Preoperative vertebral angiograms (posterior-anterior [A], lateral oblique [B], and lateral [C] views) illustrate a 3.99-cm, SM grade III cerebellar AVM located in the left cerebellar hemisphere. This 64-year-old patient (+1 point) presented in good neurological status with an mRS score of 2 (+0 points). After performing preoperative imaging, which showed a deep venous draining cerebellar AVM (+1 point) with active hemorrhaging, the patient was taken for immediate surgical intervention (+1 point). Using our proposed grading system, this patient scores a 3, making it a grade 2 lesion with moderate risk. Complete obliteration was achieved, and this patient experienced a favorable outcome, with his/her most recent 2-year follow-up mRS score = 1.
FIG. 3.
FIG. 3.
Patient outcomes by each risk grading classification system for cerebellar AVMs, including the SM, SP, LY, and proposed grading systems.
FIG. 4.
FIG. 4.
AUROC listed for each grading system according to predictive accuracy, including the SM, SP, LY, and proposed grading systems.
See this image and copyright information in PMC

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