NCOG-40. Surgery for temporal lower-grade glioma: does extent of resection impair neurocognitive outcome?

INTRODUCTION With regard to superior long-term disease control, anterior temporal lobectomies (ATL) as a supra-total resection regime have gained growing attention in surgery for temporal lobe tumors. However, aggressive temporal tumor resection might be accompanied by an impairment of a patient’s neurocognitive functioning. We therefore analyzed our database with regard to postoperative changes in neurocognitive functioning following resection of temporal-located low-grade glioma depending on the extent of tumor resection. METHODS Between 1999 and 2018, 33 patients were surgically treated for temporal-located lower-grade gliomas via ATL or lesionectomy in terms of gross-total resection (GTR) at the authors’ institution. Histopathological analysis identified 15 WHO grade I pilocytic astrocytomas, 6 grade II pleomorphic xanthoastrocytomas, 7 grade II diffuse astrocytomas, 2 polymorphous low-grade neuroepithelial tumors of the young (PLNTY), 1 ganglioglioma, and 2 astrocytomas not otherwise specified. Seventeen of these tumors were reclassified according to the 2021 WHO classification of CNS tumors. Neuropsychological examination included attention, visuoconstruction, language as well as verbal and figural memory functions. All patients underwent testing preoperatively and approximately one year postoperatively. The analyses were conducted both at the individual level and at the group level, comparing preoperative and postoperative data. RESULTS Fourteen patients (42%) underwent ATL, and 19 patients (58%) received GTR. Depending on the domain, up to 70% of patients exhibited preoperative deficits, particularly in verbal and figural memory as well as language, with varying degrees of severity (verbal/figural memory: 69.7%/72.7%). Preoperative performance did not differ between ATL and GTR group. Postoperatively, about 30% showed measurable decline, mainly in memory tasks (verbal/figural memory: 31.2%/37.5%), while more patients demonstrated stability (34.4%/25%) or improvement (34.4%/37.5%). No significant differences were observed between the GTR and ATL groups at either the individual or group level. CONCLUSIONS ATL and GTR, as differing oncosurgical approaches, did not show significant differences in postoperative neurocognitive impairment rates. ATL, as a supra-total resection strategy, thus represents a safe surgical option for temporally located lower-grade gliomas.