DEfiNING THE RELATIONSHIP BETWEEN EXTENT OF RESECTION AND NEUROLOGICAL DEfiCIT IN ELOQUENT TUMOUR RESECTIONS UTILISING IONM

Abstract AIMS To assess the relationship between degree of resection and clinical outcome in tumour resection cases utilising intraoperative neuromonitoring (IONM) METHODS Single centre retrospective review of patients undergoing resection of supratentorial tumours with IONM from January 2019 to December 2023. Adults undergoing resection of eloquently located tumours using IONM. Tu- mours of all histopathological types; awake and asleep cases; and primary and redo surgeries were included. The minimum follow-up period was 1 year. Data was collected retrospectively through case file review. Pre and postoperative tumour volumes were obtained using Brainlab. Data was analysed using GraphPad Prism software. Statistical significance was defined as a p-value <0.05. RESULTS 53 patients were identified, of which most were male (69.8%). Mean age was 40 years with a range of 18-72. Redo surgeries presented 32.1%. Frontal lobe involvement was the most frequent. 20.8% involved multiple lobes. Diffuse astrocytoma comprised 26.4%, followed by anaplastic astrocytoma (18.9%), oligodendroglioma (17%) and glioblastoma (17%). 30.2% of cases were performed awake. Median length of stay (LOS) following surgery was 4 days. 54.7% of patients developed a neurological deficit post-operatively. Frontal lobe tumour infiltration was the only factor significantly associated with the likelihood of deficit. At discharge 92.5% patients were graded as having a good mRS (0-2), this rose to 98.1% at 1 year follow-up. 69.8% underwent a near total resection (>90% of tumour). Subtotal resection (STR) was significantly associated with female sex, left sided tumour laterality and if the case was performed awake. There was no significant difference in mRS outcomes or mortality between the NTR and STR groups. CONCLUSION A high proportion of patients experienced deficits immediately post-operatively despite reassuring IONM feed- back. It appeared that these deficits resolved quickly and without significant impact upon LOS or activities of daily living.