Impact of Preoperative Mapping and Intraoperative Neuromonitoring in Minimal Invasive Parafascicular Surgery for Deep-seated Lesions.

BACKGROUND: Transsucal tubular retractor-assisted Minimal Invasive Parafascicular Surgery (tsMIPS) changes the surgical strategy for deep-seated lesions by promoting a deficit sparing approach. When integrated with preoperative brain mapping and intraoperative neuromonitoring (IONM) this may potentiate better patient outcomes. In this paper, we aim to assess the impact of preoperative brain mapping and intraoperative neuromonitoring in tubular retractor assisted neuro-oncological surgery.

METHODS: A retrospective single centre cohort study of patients admitted for tsMIPS surgical resection of deep-seated brain tumours from 2016-2022. The cohort was divided into 3 groups. Group 1: No preoperative mapping nor intraoperative monitoring (17 patients); Group 2: Intraoperative neuromonitoring only (25 patients); Group 3: Both preoperative mapping and intraoperative neuromonitoring (38 patients).

RESULTS: 80 patients were analysed (33 males and 47 females) with a median age of 46.5 (1 - 81). There was no significant difference between the mean tumour volume, 26.2 cm3 (1.07 - 97.4 cm3 ), p = .740 and the mean preoperative depth of the tumour, 31mm (3 - 65mm), p = .449) among the groups. A higher proportion of high-grade gliomas and metastases present within Group 3 (p = .003). IONM was related with less motor (p = .041) and language deficits (p = .032) at hospital discharge. Preoperative mapping and IONM was also related to shorter length of stay (LOS) (p = .008).

CONCLUSIONS: Preoperative and intraoperative brain mapping and monitoring enhances tsMIPS surgery in neuro-oncology. Patients had a reduced length of stay and prolonged overall survival. IONM alone reduces postoperative neurological deficit.