Epilepsy in adult-type diffuse low-grade gliomas: clinical, imaging and surgical outcome evaluation

Abstract

Background: Adult-type diffuse low-grade gliomas (LGGs) are frequently associated with epilepsy, which may represent the initial clinical manifestation and significantly impact patients’ quality of life. The relationship between extent of resection and postoperative seizure control remains a key issue in neuro-oncology, particularly in the context of intraoperative decision-making, where maximizing tumor removal must be carefully balanced against the risk of functional impairment, especially in eloquent brain areas. Objective: To characterize the clinical profile of epilepsy in patients with adult-type diffuse low-grade gliomas and to evaluate the impact of extent of resection on seizure outcomes, as well as changes in seizure patterns over time and their potential impact on patients’ quality of life. Methods: This retrospective observational study included adult patients with histopathologically confirmed WHO grade 2 diffuse low-grade gliomas treated at a tertiary referral center between 2010 and 2025. Demographic, clinical, imaging, surgical, and molecular information was systematically retrieved from medical records. Tumor characteristics, including location, and extent of resection were evaluated, with surgical extent confirmed by postoperative imaging. Seizure outcomes were determined according to the Engel classification at follow-up. Results: A total of 47 patients were evaluated (61.7% male; mean age 38.8 years), with preoperative seizures identified in 39 cases (83.0%). Tumor distribution was predominantly frontal (n=18) and temporal (n=16), with insular involvement observed in 14 patients. Partial resection was carried out in 38 patients, whereas complete resection was achieved in 5. Engel classification was available for most patients, with 20 (42.6%) classified as Engel I, 7 (14.9%) as Engel II, 8 (17.0%) as Engel III, and 6 (12.8%) as Engel IV. Favorable seizure outcomes (Engel I–II) were observed in 57.4% of the cohort, occurring more frequently in patients undergoing total resection (4/5; 80.0%) compared to those with partial resection (21/38; 55.3%), although interpretation is limited by the small number of total resections. Tumor recurrence was identified in 29 of 44 patients with available follow-up (65.9%), with a mean interval of 3 years (range 1–10 years). Among patients with recurrence and detailed follow-up, 12 demonstrated changes in seizure patterns. IDH1 R132H mutation was identified in 19 of 22 tested cases (86.4%). Conclusion: Epilepsy is highly prevalent in adult-type diffuse low-grade gliomas. A greater extent of resection appears to be associated with improved seizure control, although the limited number of total resections represents an important constraint. Changes in seizure patterns during follow-up may serve as a relevant clinical indicator of tumor recurrence and should prompt early imaging reassessment.