Efficacy of Adding Clonidine to Bupivacaine 0.25% Versus Plain Bupivacaine 0.25% Infiltration in Scalp Blocks for Supratentorial Craniotomy.

Background Scalp blocks help attenuate hemodynamic responses and provide analgesia in neurosurgical procedures. Clonidine, an alpha-2 agonist, has been known to enhance the duration of analgesia when used as an adjuvant in peripheral nerve blocks. Our aim was to evaluate the efficacy of adding clonidine 2 mcg/kg to bupivacaine 0.25% versus plain bupivacaine 0.25% in scalp block infiltration in patients undergoing supratentorial craniotomy by comparing the duration of analgesia and perioperative hemodynamic parameters in both groups. Methods We enrolled 60 patients in this study based on our inclusion criteria. Patients were divided equally into two groups. Scalp blocks were administered after induction of general anaesthesia. Group A comprised 30 patients and received plain 0.25% bupivacaine infiltration. Group B consisted of 30 patients and received clonidine 2 mcg/kg with 0.25% bupivacaine scalp block infiltration. Heart rate (HR) and mean arterial pressure (MAP) were recorded from application of Mayfield® pins (Integra Lifesciences, Princeton, NJ) every five minutes till the opening of the dura and every five minutes from dura closure up to completion of procedures. Postoperatively, heart rate and MAP were recorded hourly up to four hours. Pain was assessed in terms of a numeric rating scale (NRS) every four hours for the first 24 hours (score 0: no pain; score 10: unbearable pain). A score of 3 was considered a threshold for administration of rescue analgesia. Intraperative hemodynamic complications were noted.  Results Group B has significantly lower NRS scores at 4 and 8 hours postoperatively. Group B also had significantly longer time before rescue analgesia at 792 +/- 190.8 minutes (13.2 +/- 3.18 hours) compared to Group A at 415.8 +/- 155.4 minutes (6.93 +/- 2.59 hours, p< 0.001). MAP was significantly lower in group B during the first 30 minutes from the pin application, however, there was no statistical difference in the heart rate between both the groups during this time interval. We observed a significantly lower heart rate in group B from 15 minutes onwards after dura closure, and this continued in the postoperative period. Mean arterial pressure was comparable between the groups until closure. Group B demonstrated a significantly lower MAP from the second hour in the postoperative period. Overall paracetamol consumption in the postoperative period and fentanyl requirement intraoperatively were also significantly higher in group A. Conclusion  Addition of clonidine to bupivacaine in scalp blocks significantly (p<0.001) enhanced analgesic efficacy and hemodynamic control in patients undergoing supratentorial craniotomy procedures.