Passive intraoperative motor fMRI under general anesthesia during open-craniotomy glioma surgery: a prospective...

Sensorimotor localization is important during peri-Rolandic glioma surgery. We assessed passive intraoperative motor functional MRI (pifMRI) under general anesthesia.

Can pifMRI provide useable sensorimotor maps before and after resection for neuronavigation and comparison with cortical stimulation?

Eight adults (24-72 years; median, 57.5) underwent pifMRI intraoperatively in a two-room 3-T intraoperative MRI setting. With cranium open, blood oxygen level-dependent signals were elicited by passive flexion-extension of digits II-V. Maps were integrated into neuronavigation and used for corticospinal tract tractography. Given the exploratory sample and absent systematic coordinate-level recording, analyses were descriptive.

Useable activation in the primary sensorimotor region was obtained in all patients. Stimulation at pifMRI-defined regions elicited motor responses in all patients. However, negative sites and coordinate-level distances were not recorded, precluding diagnostic-accuracy and distance analyses. Post-resection pifMRI was obtained in seven patients. Median tumor volume decreased from 17.05 to 2.78 cm³; median extent of resection was 84.5% (range, 44%-100%). Six patients developed new or worsened deficits; five recovered fully and one improved by 3 months. All five patients with preoperative focal motor seizures were Engel Ia at 3 months, an uncontrolled observation not attributable to pifMRI. Mean imaging time was 48 min 45 s; each pifMRI acquisition lasted about 5 min.

This prospective series supports the feasibility of acquiring and integrating pifMRI during glioma surgery, including after resection. Correspondence with positive stimulation sites is hypothesis-generating with no quantitative validation of mapping accuracy or clinical efficacy.