Comparison of low-dose intrathecal and epidural morphine and bupivacaine infiltration for postoperative pain control after surgery for lumbar disc disease.

This prospective, blinded, placebo-controlled study was performed to compare the postoperative analgesic efficacy of low-dose intrathecal and epidural morphine with paraspinal muscle infiltration of bupivacaine in lumbar discectomy cases. Eighty ASA I-III adult patients undergoing elective surgery for lumbar disc disease were enrolled in the study. Patients were randomized to four groups by envelopes. Study groups were as follows: group 1 (n = 20), intrathecal morphine 0.1 mg; group 2 (n = 20), epidural morphine 2 mg; group 3 (n = 20), 30 mL of bupivacaine 0.25% paraspinal muscle infiltration; group 4 (n = 20), 30 mL of saline paraspinal muscle infiltration before wound closure. Recorded parameters were time to response to painful and verbal stimuli and postoperative pain assessed at 30 minutes and 2, 4, 6, 8, 12, and 24 hours by Visual Analog Scale (VAS) and Numeric Pain Scale (NPS). Hemodynamic data, sedation scores, and side effects were also recorded. Meperidine and naproxen sodium were used for postoperative analgesia. Follow-up was performed by a blinded investigator. Mean VAS scores were lower in groups 1 and 2 at 30 minutes (P < 0.05). Mean VAS score of group 2 was lower than that of group 4 at 4 hours postoperatively (P < 0.05). Mean NPS scores were lower in groups 1 and 2 at 2, 4, and 6 hours (P < 0.05) and in group 2 at 8 hours compared with the other groups. The number of patients requiring meperidine at early postoperative phase (0-6 hours) was less in groups 1 and 2 compared with groups 3 and 4 (P < 0.05). There were no statistically significant differences in the late postoperative analgesic requirements, after correction for multiple testing. In conclusion, low-dose intrathecal and epidural morphine provide lower postoperative pain scores and a reduction in early postoperative analgesic requirement with insignificant side effects compared with paraspinal bupivacaine or saline infiltration.