A double-blind trial of naloxone in central post-stroke pain

Intravenous naloxone has been claimed to produce pain relief in opioid-resistant central post-stroke pain (CPSP, 'thalamic syndrome'). In a double-blind trial, carried out in 20 patients with established CPSP, naloxone (up to 8 mg in 20 ml vehicle) was tested against normal saline; each patient was randomly given naloxone or saline and the other substance 2 or 3 weeks later. VAS and verbal pain scores were obtained immediately before and after naloxone or saline injection, and subjective ratings followed for 2 weeks. Three patients obtained transient pain relief with naloxone, 4 with saline, and another 4 with both. Statistical tests failed to show any influence of giving naloxone first or second. In all cases except one, pain relief had disappeared by the evening of the day on which the test was performed; one case, following naloxone, continued to experience pain relief until the following morning. We therefore conclude that intravenous naloxone is of no value in alleviating the pain of CPSP.