Regional block and mexiletine: the effect on pain after cancer breast surgery

Breast surgery for cancer is associated with chronic pain and sensory abnormalities. The present study investigates the effect of regional block, oral mexiletine, and the combination of both, on acute and chronic pain associated with cancer breast surgery.

One hundred patients scheduled for cancer breast surgery received either regional block with 18 mL of 1% ropivacaine intraoperatively and oral mexiletine for the first 6 postoperative days (R + M group), or regional block and placebo (R + PL), or normal saline instead of ropivacaine and mexiletine (PL + M), or normal saline and placebo (PL + PL). Postoperative analgesic requirements were recorded daily. Pain was assessed 0, 3, 6, 9, and 24 hours in the postanesthesia care unit (PACU) and on the second to sixth day postoperatively, at rest, and after movement using the visual analog scale (VAS). Three months after surgery, patients were interviewed for the presence and intensity of pain, abnormal sensations, and analgesic requirements.

Regional block reduced the number of intramuscular (IM) injections required the first 24 hours (P =.05), the R + PL group requiring less injections versus the PL + M group (P =.037). Lonarid tablet (paracetamol and codeine) consumption from the second to the fifth postoperative day differed among the 4 groups (P =.0304), the R + M group requiring fewer tablets than the PL + PL group (P =.009). Three hours postoperatively, the R + PL group had less pain at rest when compared with all other groups (P <.05 for all comparisons). On the second postoperative day, VAS at rest and after movement was less in the R + M versus the R + PL group (P <.01 and P <.05, respectively). Three months after surgery, the 4 groups were similar with regard to incidence or intensity of pain or analgesic requirements. The R + PL group had a lower incidence (77%) of reduced or absent sensation (P =.016).

Regional block reduced the analgesic requirements in the early postoperative period, while mexiletine combined with regional block reduced the total analgesic requirements during the next 5 postoperative days. Although chronic pain was not affected by these treatments late-abnormal sensation may be diminished by combination of these treatments. Reg Anesth Pain Med 2001;26:223-228.