Local analgesia without anesthesia using peripheral perineural morphine injections.

Twenty-five patients with chronic pain were treated with nerve blocks. They were divided into two groups, A and B, according to the volume of local anesthetic required for surgical anesthesia by standard nerve block techniques. The 16 patients in group A had pain in the distribution of small nerves, which could be blocked with 5 ml or less. They were blocked in a random, double-blind crossover fashion using 0.5% bupivacaine or 0.02% morphine. The nine patients in group B were injected simultaneously with saline, 30 ml perineurally and 1 ml intramuscularly. Morphine (6 mg) was added, in a random, double-blind fashion, to one of the injections. A second pair of injections was subsequently done, using morphine by the alternative route. Perineural morphine provided statistically longer lasting pain relief than did either intramuscular morphine or perineural bupivacaine.

RCT Entities:   Population Interventions Outcomes