Gliomas present significant challenges in neurosurgery due to their complex interactions with brain function and anatomy. This chapter explores how clinical onset, including pre-existing neurological deficits, impacts surgical decision-making and resection goals in glioma surgery. The primary objective is to balance tumor resection with the preservation of neurological function, aiming to extend survival while minimizing postoperative deficits. In patients with pre-existing deficits, the decision to proceed with surgery is particularly complex, as further deterioration could compromise their quality of life and limit their ability to engage in subsequent treatments.