Resting-State Functional Connectivity in Neurosurgical Patients Under Propofol Anesthesia: Detectability and Variability Between Patients and Between Sessions.

BACKGROUND:Intraoperative assessment of functional connectivity (FC) provides a new possibility for mapping the eloquent brain region before, during, and after tumor resection. The aim of this study was to perform a systematic analysis of detectability of FC and its variation between subjects and sessions. METHODS:FC was analyzed in 10 patients with pituitary adenoma under propofol anesthesia before and after tumor resection. FC of each session (20 sessions total) was correlated to a reference matrix of a group of healthy subjects to evaluate variations of overall, interhemispheric, and intrahemispheric FC between sessions. RESULTS:Resting-state patterns could be detected during anesthesia (F1,9 = 112.14, P < 0.001). There was a significant effect of session (F1,9 = 19.401, P = 0.002), which included a reduction in resting state from the first to second session. There was no effect of connection type (F2,8 = 1.498, P = 0.280), and there was no interaction between connection type and session (F2,8 = 0.187, P = 0.833). The correlation between the observed reduction in resting-state activity between the sessions and the time span between sessions was not significant (r = 0.25, P = 0.29). FC of the first session showed a significant correlation to the initial dose of anesthesia (r = 0.7, P = 0.007). However, there was no significant correlation between the total dose of propofol and FC of the second session (r = 1.7, P = 0.6). CONCLUSIONS:Significant FC could be detected under anesthesia but showed a significant decrease in the second session. To implement FC intraoperative brain mapping, further studies are required to optimize the depth sedation to obtain stable FC between sessions.