Tumor location and anatomical characteristics were carefully documented, including whether tumors had infiltrated brain areas presumed to be eloquent ( Fig. and M.W.M.), who were blinded to patient outcome to control for observer bias and surgeon operative preference. Preoperative MR images were independently reviewed by 2 investigators (E.C. The KPS score was classified as follows: 100 (asymptomatic, incidental findings), 90 (minor symptoms, such as a presenting seizure or persistent headaches), 80 (normal activity with effort, with some signs or symptoms of disease). Clinical variables including age, sex, and KPS score were recorded. Cases in which tumors were confirmed to be in an eloquent location were designated as “true eloquent” compared with those that were determined by mapping to be adjacent but not directly overlapping eloquent brain (“false eloquent”).Īll demographic and radiographic features were derived from hospital records.

Those patients with tumors in presumed eloquent locations were considered to be “high-risk” and were further stratified by whether they underwent intraoperative functional mapping. Preoperative MR images from 281 patients with LGGs were blindly reviewed for tumor location that occupied presumed eloquent locations, based upon anatomical criteria. The specific aims of this study were as follows: 1) to determine PFS and OS for patients with LGGs that infiltrate eloquent brain areas 2) to determine if intraoperative functional mapping modifies the risk of progression or modifies duration of survival in patients with LGGs presumed to involve eloquent cortex based on preoperative imaging and 3) to determine if functional mapping increases the extent of resection of these lesions.Īlgorithm for analysis and grouping by treatment in this study. We conducted a comprehensive review of a large cohort of 281 patients with LGGs that were treated surgically at our tertiary brain tumor referral center. While this technique has been shown to greatly minimize morbidity, its adoption has been limited by the fact that no study to date has demonstrated that its application can affect long-term survival. Those areas deemed to be essential for motor or language function are carefully preserved during resection. Mapping is usually conducted by applying direct electrical stimulation to successive neighboring cortical or subcortical areas to evoke either movement of the face, arms, or legs (motor mapping) or the interruption of speech (language mapping). One approach to minimizing these potential risks of surgery, while aiming for a maximal resection, is the use of intraoperative functional brain mapping. 3, 14, 28 However, injury of eloquent brain regions can result in significant neurological impairments that can have devastating consequences on quality of life and survival. Recent studies have demonstrated that greater extent of resection is associated with improved long-term survival. This issue is especially critical for patients with LGGs in eloquent areas, as the risks of surgery are potentially greater than for patients with tumors in noneloquent locations. 6, 7Ĭurrent surgical decision making relies upon weighing impressions about the benefit of resection on long-term survival versus the perceived risks of surgery.

1, 6, 7, 12, 13, 15, 19, 26, 31 Few studies have been conducted with sufficient long-term follow-up after the widespread application of MR imaging, the current standard for detection of LGGs. 8Īlthough many investigations have addressed risk factors for survival, almost all have overlooked eloquence as one of the most important and unique aspects related to cerebral neoplasms. Unlike malignant gliomas, LGGs often spare neural function in the process of slow infiltration or instead induce cortical reorganization. Eloquent brain areas in the cerebral hemispheres are defined practically as the essential areas for carrying out basic neurological functions and include the sensorimotor cortex, language cortex, and subcortical structures such as the basal ganglia and internal capsule. Low-grade gliomas are infiltrative cerebral neoplasms characterized by insidious progression, frequently invading functionally critical or “eloquent” brain regions.