Background: A bilateral superficial cervical plexus block provides good analgesia for neck surgery, including thyroidectomy. However, the duration of a single shot nerve block is usually short. Therefore, adjuvants are used in peripheral nerve blocks, especially with ambulatory surgery, where the analgesia duration is very important.

Methods: Sixty patients scheduled for thyroidectomy were randomly assigned to one of two groups. Group C received general anesthesia and a bilateral intermediate cervical plexus block with isobaric 10 ml bupivacaine 2% + 2ml NS deposited on each side. Group D received general anesthesia and bilateral intermediate cervical plexus block with 10 ml isobaric bupivacaine 2% + 4mg (2ml) dexamethasone deposited on each side. Primary outcome was postoperative analgesia evaluated by the VAS score. Secondary outcomes were perioperative IL6, blood glucose level, and postoperative nausea and vomiting.

Results: Postoperative pain VAS scores were significantly lower in the dexamethasone group than control group; mean VAS score at 6h postoperatively was 0.4 in Group D vs. 1.8 in Group C; P <0.001, at 8h it was 0.4 vs. 2.6; P <0.001 in Group D and C, respectively, and in 24h it was 3.5 in Group D vs. 5 in Group C; P 0.003.  Analgesia duration was significantly longer in the dexamethasone group: 12h versus 6 h in the control group; P<0.001. Postoperative IL-6 at 8 and 24 hours postoperatively were significantly lower in the dexamethasone group than the control group (36.8 vs 21; P <0.001) and (18.9 vs 13; P<0.001), respectively. Non-significant changes could be detected between both groups in intraoperative bleeding and postoperative glycemic control.

Conclusion: The addition of 8 mg dexamethasone to ultrasound-guided intermediate cervical plexus block can enhance analgesia duration and reduce postoperative opioid consumption and postoperative IL-6 levels with no significant effect on postoperative glycemic control in non-diabetic patients undergoing thyroidectomy under general anesthesia.

Keywords: ultrasound-guided cervical plexus block, perineural dexamethasone, thyroidectomy.