Objective: Functional magnetic resonance imaging (fMRI) studies in healthy volunteers have shown alterations in brain connectivity following anesthesia as compared to the awake state. It is not known if the anesthesia-induced changes in brain connectivity are different in a pathological state. This study aims to evaluate changes in the resting state functional connectivity in the brain, after propofol anesthesia, in patients with chronic back pain (CBP).
Materials and methods: Fourteen adults with CBP were included in this prospective study over 6 months. After excluding structural brain pathology, a resting state fMRI was performed in the awake state, and the sequences were repeated after propofol anesthesia. The primary outcome measure was change in resting state connectivity after propofol. Student's t-test was performed between the pre and post-propofol sedation data of all patients with total brain volume as covariates of interest. A repeated measures analysis of variance was used to compare pre- and post-propofol changes in cardiorespiratory parameters.
Results: There were 8 male and 6 female patients in the study, and the mean age of the study population was 46.9 ± 11.3 years. Propofol sedation resulted in an increased strength of functional connectivity between the posterior cingulate cortex (PCC) and thalamus in patients with CBP, whereas there was a generalized decrease in functional integration within the large scale brain networks. The changes in cardiorespiratory parameters before and after propofol administration were not statistically significant.
Conclusion: Strengthening of functional connectivity was seen between PCC and thalamus with decrease in large scale brain networks following propofol anesthesia in patients with CBP. These changes are similar to those previously described in normal volunteers.