Abstract
Ketamine has been used to treat chronic pain; however, it is still unknown as to what types of chronic pain is ketamine effective against. To identify the effect of administration of subanesthetic-dose ketamine in patients with chronic pain and to clarify the mechanism of the effect, we retrospectively investigated brain functional connectivity using resting-state functional magnetic resonance imaging (rs-fMRI). Patients were divided into responders (Group R: ≥50% improvement on Numerical Rating Scale) and non-responders (Group NR). We compared the differences in terms of brain functional connectivity by seed-to-voxel correlation analysis. Two-sample t-test revealed significant lower connectivity between the medial prefrontal cortex (mPFC) and precuneus in Group R. We also found a significant negative correlation between the improvement rate and functional connectivity strength between the mPFC and precuneus. These findings suggest that subanesthetic-dose ketamine is effective in patients with chronic pain whose brain functional connectivity between the mPFC and precuneus is low. We believe that the current study explored for the first time the correlation between brain functional connectivity and the effect of subanesthetic-dose ketamine for chronic pain and indicated the possibility of use of the predictive marker in pharmacological treatment of chronic pain.
Highlights
In recent years, the rapid and sustained antidepressant effect of subanesthetic-dose ketamine has received considerable attention[1,2,3]
We revealed that the brain functional connectivity of the medial prefrontal cortex (mPFC) and precuneus was significantly lower in patients with chronic pain who responded to subanesthetic-dose ketamine
Li reported that subanesthetic dose ketamine decreased brain functional connectivity between posterior cingulate cortex (PCC) and mPFC and this functional connectivity decrease correlated with glutamatergic changes in perigenual anterior www.nature.com/scientificreports cingulate cortex[18]
Summary
The rapid and sustained antidepressant effect of subanesthetic-dose ketamine has received considerable attention[1,2,3] In these cases, brain imaging studies[4,5] using functional MRI (fMRI) to evaluate blood flow dynamic responses related to human and animal central nervous system activities were conducted. To the best of our knowledge, no previous study has examined the relationship between brain activity in patients with chronic pain and their responses to subanesthetic-dose ketamine. To identify the effect of administration of subanesthetic-dose ketamine to patients with chronic pain and to clarify the mechanism of the effect, we examined the differences between patients who responded to the treatment and those who did not based on brain functional connectivity using fMRI. By assessing rs-fMRI images prior to the treatment, we managed to identify the key region of therapeutic response to subanesthetic-dose ketamine in patients with chronic pain
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call