Intraoperative resting state functional connectivity and resting state networks in patients with intracerebral lesions: detectability and variations between sessions

Abstract Objective Evaluation of the functional connectivity (FC) and resting state networks (RSN) in patients under anesthesia operated for resection of intracerebral lesions. Methods we performed intraoperative resting state fMRI (irs-fMRI) in 24 patients under anesthesia before and after lesion resection. Correlation matrices were established for each session (total 48 sessions). The change in the overall FC, and FC of the healthy and operated hemispheres between the first and second session was analyzed. We tested the correlation between changes in the FC and the clinical outcome, the duration, rate and total dosage of anesthesia. Furthermore, we performed a group analysis to detect topographic changes in RSNs in patients under anesthesia. A single subject analysis was performed to detect clinically relevant RSNs in each patient. Results The FC decreased significantly in the second session. The interhemispheric connectivity decreased significantly in the second session. The decrease in the pathological hemisphere was significant, and was significantly more than the decrease in the intrahemispheric connectivity of the healthy hemisphere. The change of the FC was not correlated to the clinical outcome, duration, rate and dosage of anesthesia. Group analysis showed topographic changes in RSN, especially the high level networks like default mode and salience networks. Identification of clinically relevant networks was also possible. Conclusion FC and resting state networks could be identified under anesthesia and used for extended brain mapping. Further studies are required for optimization of the depth of hypnosis to stabilize the FC between sessions.