Supramaximal resection in gliomas: a narrative review of surgical techniques, clinical outcomes, and ethical considerations

Background: Supramaximal resection (SMR) represents an evolving frontier in glioma surgery, extending tumor removal beyond conventional contrast-enhancing margins on magnetic resonance imaging (MRI) to include infiltrative, non-contrast-enhancing regions. Rooted in the understanding that gliomas spread microscopically beyond visible boundaries, SMR aims not only to delay recurrence but also to meaningfully prolong survival while preserving neurological integrity. Objective: This narrative review explores the conceptual foundations, surgical innovations, clinical outcomes, and ethical dimensions surrounding SMR in the management of diffuse gliomas. Methods: A structured review of the literature published between 2005 and 2025 was conducted across major medical databases. Search terms included “supramaximal resection,” “supratotal resection,” “glioma,” “5-ALA,” “intraoperative MRI,” “direct electrical stimulation,” “tractography,” and “connectomics.” Clinical trials, prospective and retrospective cohorts, and systematic reviews were synthesized to evaluate oncological benefits, functional outcomes, and practical feasibility. Results: Although definitions of SMR remain heterogeneous, advances in awake craniotomy, cortical and subcortical mapping, intraoperative MRI, fluorescence-guided surgery, and connectome-informed planning have redefined the boundaries of safe resection. Emerging evidence, primarily levels II–III, suggests that extending resection into FLAIR abnormalities beyond the contrast-enhancing tumor may improve overall and progression-free survival, particularly in selected high-grade gliomas. Importantly, functional mapping techniques allow surgeons to pursue oncologic maximization without disproportionately increasing permanent neurological deficits. Conclusion: SMR reflects a shift from purely anatomical resection toward function-guided precision surgery. While promising, its adoption requires standardized definitions, prospective validation, and careful shared decision-making. Ultimately, the goal of SMR is not only longer survival but survival lived with preserved cognition, independence, and dignity.