MMP9 and neoplasm: During resection, VS that are adherent from the brainstem or cranial nerves are difficult, if not impossible, to completely remove.49 There are currently few tools to determine the degree of tumor adherence prior to surgery that also correlate with postoperative outcomes.50 The value of MMP9 as a biomarker lies in its ability to aid in predicting the intraoperative experience and postoperative outcomes.