Resting state functional connectivity in neurosurgical patients under propofol anesthesia: detectability and variability between patients and between sessions.

BACKGROUND: Intraoperative assessment of the functional connectivity (FC) provides a new possibility of mapping the eloquent brain region before, during, and after tumor resection. a systematic analysis of the detectability of FC and its variation between subjects and session.

METHODS: the FC was analyzed in 10 pituitary adenoma patients under propofol anesthesia before and after tumor resection. The FC of each session (totally 20 sessions) was correlated to a reference matrix of a group of healthy subjects to evaluate the variations of the overall, interhemispheric and intrahemispheric FC between sessions.

RESULTS: The resting state patterns could be detected during anesthesia (F(1,9) = 112.14; p<0.001)There was a significant effect of session (F(1,9)= 19,401; p=0.002), which included a reduction in resting state from first to the second session. There was no effect of connection type (F(2,8) =1,498; p=0.280), nor was there an interaction between connection type and session (F(2,8) ,=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). The 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 the FC of the second session (r=1.7; p=0.6).

CONCLUSION: Significant FC could be detected under anesthesia but showed a significant decrease in the second session. To implement the FC intraoperative brain mapping, further studies are required to optimize the depth sedation in order to obtain stable FC between sessions.