Fig. 4.

Naloxone does not change ongoing pain ratings or cause hyperalgesia. In a randomised, double blind, crossover design four of the DBS subjects were given either naloxone or saline and the effect on spontaneous and evoked pain assessed. (A) Naloxone did not produce hyperalgesia compared to saline alone. Graph shows the change in VAS (naloxone – saline) normalised to baseline VAS with positive values indicating that naloxone produced hyperalgesia (mean ±95%CI, One way rm-ANOVA, ns). (B) Assessment of the change from baselines in heat pain threshold and dynamic allodynia also showed no significant effect of naloxone on either measure. (lines indicate median values, paired t-test, ns).