Navigated Intraoperative Ultrasound in Functionally Eloquent Tumour Resection: A Descriptive Single-Centre Series...

Background/Objectives: Navigated intraoperative ultrasound (N-ioUS) compensates for brain shift, but its place within a multimodal workflow alongside neuronavigation, 5-aminolevulinic acid (5-ALA) fluorescence and neurophysiological monitoring is not well defined. We describe functional and surgical outcomes in a single-centre series of functional-eloquent tumours resected with N-ioUS within such a workflow. Methods: Retrospective descriptive cohort study, reported per STROBE, of 104 consecutive patients who underwent N-ioUS-assisted resection of functionally eloquent intracranial tumours between 2011 and 2023. N-ioUS was an inclusion criterion, so no comparison group was available; the same-institution 5-ALA cohorts are cited as context only. Results: The cohort comprised WHO grade 4 gliomas (n = 42), WHO grade 2-3 gliomas (n = 33), metastases (n = 21) and other tumours (n = 8); 5-ALA was used in 74.0% and neurophysiological monitoring in 94.2%. No residual tumour was described in 22.5% of grade 4 gliomas, 53.3% of grade 2-3 gliomas and 73.7% of metastases with a documented extent of resection. Among patients at risk with documented postoperative status, a new motor deficit occurred in 4/16 (25.0%) grade 4, 4/21 (19.0%) grade 2-3 and 1/7 (14.3%) metastases patients. Median overall survival was 12.7 months for grade 4 gliomas and 22.2 months for metastases and was not reached for grade 2-3 gliomas; within grade 4 gliomas, no difference by extent of resection was detected in an underpowered exploratory comparison (log-rank p = 0.593). Conclusions: In this single-arm series the resection endpoint in eloquent tumours was set by functional rather than anatomical boundaries, and rates of complete resection and new deficit were in keeping with that constraint. The design permits no inference about the independent effect of N-ioUS, whose contribution may be greatest where the endpoint is anatomical, as in metastases, and requires prospective controlled evaluation.