General-Purpose B-Mode Intraoperative Ultrasonography in Perirolandic Brain Metastasis Surgery: Practical Value and Limitations.

BACKGROUND/OBJECTIVES: Perirolandic brain metastases are challenging to resect because small deviations from the surgical corridor may cause sensorimotor deficits. This study evaluated the stage-specific value and limitations of general-purpose, non-navigated B-mode intraoperative ultrasonography (iUS) with MRI-based frameless neuronavigation in a consecutive surgical cohort of perirolandic metastases. METHODS: In this single-center, single-surgeon retrospective case series, 15 consecutive adults underwent microsurgical resection of perirolandic brain metastases using MRI-based frameless neuronavigation and a general-purpose B-mode ultrasound system, without functional mapping or neurophysiological monitoring. Extent of resection was assessed on contrast-enhanced MRI obtained 24 to 36 h after surgery, and post-resection cavity iUS findings were compared descriptively with early postoperative MRI. RESULTS: Gross-total resection was achieved in 13 patients (86.7%). iUS modified intraoperative targeting in 6 of 15 patients: the entry point was repositioned after findings consistent with intraoperative brain shift in 4, and the lesion was localized in interhemispheric corridors in 2. Post-resection iUS suspected residual tissue in 7 of 14 patients, but only 1 corresponded to residual tumor on MRI; a thin remnant on the motor cortex was not identified as suspicious for residual tumor on iUS. A new or worsened motor deficit occurred in 2 patients (13.3%); at follow-up, this was persistent at 20 months in 1 and partially improved in the other. No patient required reoperation, and there was no 30-day mortality. CONCLUSIONS: General-purpose B-mode iUS aided exposure confirmation and trajectory refinement but had limited value for excluding thin residual tumor. When functional mapping or neurophysiological monitoring is unavailable, it may provide accessible real-time anatomical guidance; however, because it lacks functional information, it should not be considered an alternative to these functional adjuncts.