Effect of magnesium and lignocaine on post-craniotomy pain: A comparative, randomized, double blind, placebo-controlled study

BACKGROUND: Lignocaine and Magnesium have an analgesic action and reduce perioperative opioid requirements. We carried out this study to evaluate the effect of magnesium and lignocaine on postoperative pain as assessed using the visual analog scale (VAS) and fentanyl consumption. We also measured S-100 B levels and noted the side effect of drugs if any. MATERIALS AND METHODS: In this prospective preliminary study, 45 patients undergoing supratentorial craniotomy for tumor surgery were randomized to receive either lignocaine (group I-1.5 mg/kg bolus followed by 2 mg/kg/h infusion), saline (Group II) or magnesium (group III: bolus of 50 mg/kg followed by 25 mg/kg/hr) intraoperatively. The amount of fentanyl required, VAS over first 24 hours and any side effects were noted. S100 B levels were also measured to assess brain protective effect of these drugs, if any. Appropriate statistical tests were applied for analysis of data and a P value < 0.05 was considered statistically significant. RESULTS: None of the patient experienced any adverse hemodynamic effect intraoperatively secondary to the study drugs. The amount of intraoperative fentanyl consumption was comparable among the three groups. The mean VAS score was significantly less in group I and III [Group I (15.3 ± 6.0), Group II (24.8 ± 6.7), Group III (17.9 ± 7.6); (P < 0.01)]. The fentanyl consumed in first 24 hours was significantly less in those patients who received lignocaine and magnesium [Group I (204.4 ± 136.4), Group II (383 ± 168.2), Group III (194 ± 148.9); (P = 0.01)]. S100 value did not differ in the lignocaine and the saline group during the perioperative period. However, a significant decline was noted in the levels of S100 B in the magnesium group. CONCLUSION: Intraoperative infusion of lignocaine and magnesium results in lower VAS score and decreases the postoperative opioid requirement in patients undergoing craniotomy for excision of supratentorial tumors.