Microsurgery Versus Embolization for Spinal Cord Arteriovenous Malformations: A Proposed Grading System

Neurosurgery 98:786–798, 2026

This study proposes a four-parameter grading system to stratify angioarchitectural complexity of spinal cord arteriovenous malformations (SCAVMs) and compares clinical outcomes of microsurgery versus endovascular embolization across five grades in a 714-patient multicenter cohort. The grade sums points for metameric manifestation, lesion diameter ≥2 cm, anterior sulcal artery supply, and lesion depth, predicting incomplete resection with strong ROC (receiver-operating characteristic) performance.

Results show embolization as the preferred primary treatment owing to lower immediate risk, while microsurgery achieves higher complete obliteration for low-grade lesions (scores 0–1) but carries greater treatment-related deterioration and worse long-term prognosis for higher grades (scores 2–4). Recommendations prioritize embolization, reserving microsurgery for select low-grade or high-risk patients when embolization fails.

Study aim Compare outcomes of microsurgery vs endovascular embolization for SCAVMs by introducing a grading system that stratifies angioarchitectural complexity to enable fairer comparisons.

Cohort & design Retrospective multicenter analysis of 714 SCAVM patients treated (2007–2022); 308 received microsurgery (often after failed/partial embolization) and 406 received exclusive embolization.

Grading system (0–4 points) One point each for anterior sulcal artery supply, metameric manifestations, maximum lesion diameter ≥2 cm, and embedded (deep) lesion depth; total score defines grade.

Predictors basis & performance The four grading variables were independent predictors of incomplete resection in microsurgical cases, and the score showed strong ROC discrimination in modeling and validation groups (AUC ≈ 0.83).

Overall treatment tradeoff Microsurgery achieved a higher complete obliteration rate (61.7% vs 24.4%) but had higher treatment-related deterioration (19.8% vs 4.2%) and higher poor prognosis at last follow-up (52.3% vs 36.2%) than exclusive embolization.

Low grades (0–2) obliteration For scores 0–2, microsurgery produced significantly higher complete obliteration than embolization; for scores 3–4, complete obliteration rates were similar between methods.

Long-term deterioration & prognosis by grade Long-term clinical deterioration after embolization was higher for score 1 (significant) and also higher for score 0 (not significant); for scores 2–4, long-term deterioration risk was comparable, while poor prognosis was generally worse with microsurgery except score 0 (similar).

Treatment strategy Embolization should be the primary approach for SCAVMs; microsurgery is an alternative if embolization fails to fully obliterate lesions in score 0 (recommended) and selected 1-point patients (optional, especially higher clinical risk), but not first-line for scores 2–4.

A novel proposed grading system for cerebellar arteriovenous malformations

J Neurosurg 132:1105–1115, 2020

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.

 

A novel proposed grading system for cerebellar arteriovenous malformations

J Neurosurg 132:1105–1115, 2020

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.

 

Cranial Chordoma: A New Preoperative Grading System

Neurosurgery 83:403–415, 2018

Chordomas are rare but challenging neoplasms involving the skull base. A preoperative grading system will be useful to identify both areas for treatment and risk factors, and correlate to the degree of resection, complications, and recurrence.

OBJECTIVE: To propose a new grading system for cranial chordomas designed by the senior author. Its purpose is to enable comparison of different tumors with a similar pathology to clivus chordoma, and statistically correlate with postoperative outcomes.

METHODS: The numerical grading system included tumor size, site of the tumor, vascular encasement, intradural extension, brainstem invasion, and recurrence of the tumor either after surgery or radiotherapy with a range of 2 to 25 points; it was used in 42 patients with cranial chordoma. The grading system was correlated with number of operations for resection, degree of resection, number and type of complications, recurrence, and survival.

RESULTS: We found 3 groups: low-risk 0 to 7 points, intermediate-risk 8 to 12 points, and high-risk≥13 points in the grading system. The 3 groupswere correlated with the following: extent of resection (partial, subtotal, or complete; P < .002); number of operative stages to achieve removal (P < .014); tumor recurrence (P = .03); postoperative Karnofsky Performance Status (P < .001); and with successful outcome (P = .005). The grading system itself correlated with the outcome (P = .005).

CONCLUSION: The proposed chordoma grading system can help surgeons to predict the difficulty of the case and know which areas of the skull base will need attention to plan further therapy.

Brainstem Cavernous Malformations: Surgical Results in 104 Patients and a Proposed Grading System to Predict Neurological Outcomes

Brainstem Cavernous Malformations- Surgical Results in 104 Patients and a Proposed Grading System to Predict Neurological Outcomes

Neurosurgery 76:265–278, 2015

Once considered inoperable lesions in inviolable territory, brainstem cavernous malformations (BSCM) are now surgically curable with acceptable operative morbidity. Recommending surgery is a difficult decision that would be facilitated by a grading system designed specifically for BSCMs that predicted surgical outcomes.

OBJECTIVE: Informed by our efforts to develop a supplementary grading system for arteriovenous malformations, we hypothesized that a similar system might predict long-term outcomes and guide clinical decision-making.

METHODS: A consecutive, single-surgeon series of 104 patients was used to assess preoperative clinical and imaging predictors of microsurgical outcomes. Univariable logistic regression identified predictors and a multivariable logistic regression model tested the association of the combined predictors with final modified Rankin Scale scores. A grading system assigned points for lesion size, location crossing the brainstem’s midpoint, presence of developmental venous anomaly, age, and time from last hemorrhage to surgery.

RESULTS: Average maximal diameter of BSCMs was 19.5 mm; 50% crossed the axial midpoint; 54.8% had developmental venous anomalies; mean age was 42.1 years; and median time from last hemorrhage to surgery was 60 days. One patient died (0.96%), and 15 patients (14.4%) experienced worsened cranial nerve or motor dysfunction, of which 10 increased their modified Rankin Scale scores (9.6%). BSCM grades ranged from 0 to 7 points and predicted outcomes with high accuracy (receiver operating characteristic = 0.86, 95% confidence interval: 0.78-0.94).

CONCLUSION: Rather than developing a grading system for all cerebral cavernous malformations that is weak with BSCMs, we propose a system for the patients who need it most. The BSCM grading system differentiates patients who might expect favorable surgical outcomes and offers guidance to neurosurgeons forced to select these patients.

ABC Surgical Risk Scale for skull base meningioma

J Neurosurg 111:1053–1061, 2009.DOI: 10.3171/2007.11.17446

Surgery for skull base meningiomas (SBMs) can lead to complications because these lesions are difficult to approach and can involve cranial nerves and arteries. The authors propose a scoring system to evaluate the relative risks and benefits of surgical treatment of SBMs.

Methods. The authors used a 2-step process to construct their scale. First, they derived significant predictive variables from retrospective data on 132 SBM cases treated surgically (primary surgeries only) between May 2000 and December 2005. Next, they validated the predictive accuracy of their scoring system in 60 consecutive cases treated surgically between January 1995 and April 2000, including both primary and repeated surgeries. Finally, they investigated the effect of the surgery on the patients’ preoperative symptoms for consecutive cases treated surgically between January 1995 and December 2005, including both primary surgeries and retreatments.

Results. Five items that predicted surgical risk were identified: 1) tumor attachment size; 2) arterial involvement; 3) brainstem contact; 4) central cavity location; and 5) cranial nerve group involvement. The authors named their scoring system the ABC Surgical Risk Scale, after the initial letters of these items. Each factor was assigned a score of 0–2 points, and an additional point was added for previous surgical treatment or for radiation, giving a possible total score of 12 points. On average, the scoring system allocated 2 points for gross-total resections, 6.1 points for near-total resections, and 9 points for subtotal resections, with significant differences between groups. For cases scoring ≥ 8 points, the percentage of cases showing neurological deterioration postoperatively exceeded the percentage showing improvement.

Conclusions. The authors conclude that this scoring system can be used to predict the extent of tumor removal and that the scores reflect the surgical risk.