Is Supplemented Spetzler-Martin grading Superior? A comparative study in AVM microsurgery risk stratification

Area of Science:

• Neurosurgery
• Cerebrovascular Surgery
• Neurological Outcomes
• Arteriovenous Malformations

Background:

• The Spetzler-Martin (SM) grading system is the standard for classifying brain arteriovenous malformations (AVMs).
• The Supplemented Spetzler-Martin (Supp-SM) system was developed to enhance surgical risk stratification by including patient age, rupture status, and nidus diffuseness.
• Limited data exist comparing the predictive validity of the SM and Supp-SM grading systems for surgical outcomes.

Purpose of the Study:

• To investigate the predictive relevance of both the SM and Supp-SM grading systems for postoperative neurological morbidity after AVM microsurgery.
• To compare the accuracy of the SM and Supp-SM systems in stratifying surgical risk and predicting patient outcomes.

Main Methods:

• Retrospective review of 96 patients who underwent AVM microsurgical resection between 2015 and 2024.
• Postoperative morbidity was defined as an increased modified Rankin Scale (mRS) score at 90 days.
• Predictive accuracy was assessed using Receiver Operating Characteristic (ROC) curves, correlation with postoperative mRS scores, and analysis of the Supp-SM risk threshold.

Main Results:

• Postoperative morbidity occurred in 9.4% of patients.
• ROC analysis showed no significant difference in predictive accuracy between SM (AUROC 0.717) and Supp-SM (AUROC 0.667) grading systems (p=0.3899).
• Supp-SM scores demonstrated a stronger correlation with postoperative mRS changes (Spearman's ρ=0.269, p=0.008) compared to SM grades (Spearman's ρ=0.144, p=0.161).
• Patients with Supp-SM grades < 6 had a 3.2% morbidity risk, while those with scores ≥ 6 had a 20.6% risk (p=0.009).
• A Supp-SM threshold of 6 showed the highest discriminative accuracy for identifying high-risk surgical candidates.

Conclusions:

• While both SM and Supp-SM grading systems showed no significant difference in overall predictive accuracy, the Supp-SM system offers improved correlation with neurological morbidity.
• A Supp-SM score of 6 or greater is associated with substantially higher postoperative neurological morbidity.
• The findings support the adjunctive use of the Supp-SM grading system for more refined surgical risk assessment in patients with brain arteriovenous malformations.