Brain activity during intraoperative general anesthesia using resting-state functional magnetic resonance
Junji Wakabayashi1, Yoshitetsu Oshiro2, Shigeyuki Kan3
1Department of Anesthesiology, Kobe University Graduate School of Medicine, 7-5-1, Kusunoki-Cho, Chuo-Ku, Kobe, Hyogo, Zip Code: 650-0017, Japan. oo22ver@yahoo.co.jp.
Background:
In recent years, the effects of general anesthetics on the brain have been widely studied at the sedation level using resting-state functional magnetic resonance imaging (rs-fMRI). Most anesthesia protocols use a single agent, and changes in spontaneous brain activity are examined to show the characteristics of each anesthetic agent. However, no studies have used rs-fMRI to evaluate the effects of anesthesia during actual surgery. We examined the feasibility of evaluating the effects of general anesthesia with sevoflurane using rs-fMRI during neurosurgery.
Methods:
We enrolled 20 adult patients scheduled for transsphenoidal surgery. We compared differences between before and during general anesthesia in terms of brain functional connectivity of the thalamus by seed-to-voxel correlation analysis and local neural activity using fractional amplitude of low-frequency fluctuations (fALFF) analysis. An exclusion mask was applied to exclude brain areas showing intraoperative spatial artifacts and correct for differences in the magnitude of intra- and preoperative head movements.
Results:
We analyzed 16 patients. Functional connectivity of the thalamus to the contralateral thalamus, bilateral caudate nucleus and globus pallidus were significantly decreased during anesthesia. The precuneus and posterior cingulate cortex showed significantly decreased fALFF values during anesthesia.
Conclusion:
These findings were consistent with previous studies and indicate the feasibility of intraoperative rs-fMRI during general anesthesia.
