[Effect of ketamine on prevention of postmastectomy chronic pain. A pilot study]

This pilot study was designed to evaluate the feasibility of a trial to estimate the preventive effect of ketamine on postmastectomy pain syndrome (PMPS).

Double-blind, randomized, placebo-controlled pilot trial.

Thirty six patients scheduled for a radical mastectomy with axillary lymph node dissection were randomized in two groups (n=18 per group). Before skin incision, a bolus (0.5 mg/kg of ketamine or placebo) followed by a continuous infusion (0.25 mg/kg per hour of ketamine or placebo) was administered and discontinued at the end of surgical procedure. We studied the incidence and characteristics of PMPS three months after surgery as well as the feasibility of chosen methods.

Thirty patients were followed for three months (group ketamine n=12; group placebo n=18). At three months, there was no significant difference in the incidence of chronic pain, but a tendency to a decrease of hyperalgesia near the scar. There was no repercussion on the quality of life. The characteristics of the PMPS are similar to those described in the recent literature (intercostobrachial neuralgia 33%, neuroma pain 39%, and phantom breast pain 22%). The feasibility of the experimental study is established by the absence of difficulty during the clinical investigation period.

We found no preventive effect of ketamine on the development of PMPS. However, the non-statistically significant effect of ketamine on hyperalgesia three months after surgery could justify a larger study with the same methodology.