Effects of different doses of fentanyl on brain areas activated by pain: evidence from functional magnetic resonance imaging

Abstract

Objective To investigate the effects of different doses of fentanyl on pain-activated brain areas as demonstrated by functional magnetic resonance imaging (fMRI) at 3.0 T.Methods Twenty healthy right-handed male volunteers aged 20-40 yr were randomly divided into 2 groups ( n =10 each); group F1 (fentanyl 1.0 μg/kg) and group F2 (fentanyl 1.5 μg/kg).Mechanical stimulation with von Frey filaments (vFFs,300 g) was delivered to left sole.The intensity of pain was assessed by VAS scores.fMRI was performed before and after fentanyl administration and the changes in the brain areas activated by pain were recorded.Results In group F1 ipsilateral (left) cingulate gyrus was activated after a bolus of fentanyl 1.0 μg/kg under stimulation with vFFs 300 g,while in group F2 bilateral cingulate gyrus and contralateral (right) insula were activated under vFFs stimulation after fentanyl 1.5 μg/kg.Conclusion Cingulate gyrus and insula may be the target brain areas of fentanyl analgesia. Key words: Fentanyl; Analgesia; Brain; Magnetic resonance imaging