Basal forebrain glioma: Clinical characteristics and surgical treatment

Surgical resection of basal forebrain (BFB) gliomas involving the anterior perforated substance (APS) is associated with a high risk of surgical complications due to multiple perforating arteries that traverse this region. Despite these challenges, surgery in this region serves several important purposes, including cytoreduction, histopathological diagnosis, and seizure control.

This study included a consecutive series of 67 patients with gliomas either confined to the BFB (13 cases) or extending to adjacent anatomical regions (54 cases) who underwent surgery at the Burdenko Neurosurgery Center between 2016 and 2023. Three main approaches were used: transsylvian, anterior interhemispheric, and supraorbital subfrontal. In 5 cases, the tumor was removed using a microsurgical burr-hole technique.

BFB tumors were classified according to 2 features: 1) involvement of anatomical regions adjacent to the BFB and 2) localization of the tumor within the BFB: the septal region (S), anterior APS segment (Pa), and posterior APS segment (Pp). Isolated BFB tumors were found in 13 cases (19.4%), including 4 localized to the septal region. Among 59 patients with early postoperative MRI, median EOR was 82%. EOR 70-90% was achieved in 23 of 59 patients (39.0%), and EOR ≥ 90% in 25 of 59 (42.4%). With extension into the Pp segment, EOR ≥ 90% was achieved less often than in the remaining cohort: 8 of 31 (25.8%) versus 17 of 28 (60.7%), respectively (p = 0.009). Postoperatively, hemiparesis developed in 9 patients (13.4%) and speech disturbances in 12 (17.9%), most often because of injury to the lenticulostriate arteries. Hemiparesis resolved in 2 patients, whereas speech disturbances improved in 10 patients and persisted in 2 patients at 3-6 months. Complete seizure control was achieved in 31 of 44 patients (70.4%). Seizure control was better when EOR exceeded 70%. Multivariable Cox models including EOR and WHO grade showed no significant association between EOR and OS or PFS, whereas higher WHO grade was associated with worse OS and PFS. In the sensitivity analysis restricted to WHO grade 2-3 gliomas, greater EOR was associated with better OS (HR per 10% increase, 0.53; 95% CI, 0.29-0.99; p = 0.047), but not with PFS.

Resection of BFB gliomas is feasible with an acceptable risk of complications and provides effective seizure control. Greater EOR may be associated with better OS in WHO grade 2-3 gliomas. Tumor extension into the posterior portion of APS is associated with an increased risk of surgical morbidity during BFB glioma resection.