Botulinum toxin infiltration for pain control after mastectomy and expander reconstruction.

INTRODUCTION: We hypothesized botulinum toxin (BT) infiltration of the chest wall musculature after mastectomy would create a prolonged inhibition of muscle spasm and postoperative pain, facilitating tissue expander reconstruction.

METHODS: An Institutional Review Board (IRB)-approved prospective study was conducted of all patients undergoing mastectomy with tissue expander placement during a 2-year period. Study patients versus controls had 100 units of diluted BT injected into the pectoralis major, serratus anterior, and rectus abdominis insertion. Pain was scored using a visual analog scale of 0 to 10. Wilcoxon rank sum test was used for continuous variables and the chi2 test for nominal level data to test for significance.

RESULTS: Forty-eight patients were entered into the study; 22 (46%) with and 26 (54%) without BT infiltration. Groups were comparable in terms of age (55 +/- 11 years versus 52 +/- 10 years; P = 0.46), bilateral procedure (59% versus 61%; P = 0.86), tumor size (2 +/- 2 cm versus 2 +/- 3 cm; P = 0.4), expander size and volume (429 +/- 119 mL versus 510 +/- 138 mL; P = 0.5). The BT group did significantly better with pain postoperatively (score of 3 +/- 1 versus 7 +/- 2; P < 0.0001), during initial (score of 2 +/- 2 versus 6 +/- 3; P = 1.6 x 10(-6)), and final expansion (1 +/- 1 versus 3 +/- 2; P = 0.009). Volume of expansion per session was greater thus expansion sessions required less in the BT group (5 +/- 1 versus 7 +/- 3; P = 0.025). There was a significant increase in narcotic use in control patients in the first 24 hours (17 +/- 10 mg versus 3 +/- 3 mg; P < 0.0001), initial as well as final expansion periods (P = 0.0123 and 0.0367, respectively). One expander in the BT group versus 5 in the control group required removal (P = 0.13). There were no BT-related complications.

CONCLUSION: Muscular infiltration of botulinum toxin for mastectomy and tissue expander placement significantly reduced postoperative pain and discomfort without complications.