Randomized clinical trial of intraoperative superficial cervical plexus block versus incisional local anaesthesia in thyroid and parathyroid surgery.

Moderate wound pain and opiate analgesia requirement is reported following thyroid and parathyroid surgery. A randomized clinical trial was performed to investigate whether intraoperative superficial cervical plexus block (SCPB) would decrease postoperative pain and analgesia use. Patients were randomized to incisional local anaesthesia (control) or incisional local anaesthesia plus intraoperative SCPB. The primary outcome measure was pain, assessed by a visual analogue scale (VAS). Secondary outcome measures were analgesia use (strong opiates defined as having potency at least as strong as that of oral morphine), respiratory rate and sedation score. Primary outcome measures were analysed with non-parametric tests, as well as with receiver operating characteristic (ROC) curves calculated as area under the curve (AUC) to discriminate between trial limbs. Twenty-nine patients were randomized to each group. Pain (VAS) scores were lower in patients who received intraoperative SCPB than in controls 30 min after surgery and subsequently (P < 0·020 at all time points), with a median pain score of zero on the day of operation in the SCPB group. Corresponding analysis of ROC curves showed differences between groups at 30 min (AUC = 0·722, P = 0·012), 90 min (AUC = 0·747, P = 0·005), 150 min (AUC = 0·803, P < 0·001) and 210 min (AUC = 0·849, P < 0·001) after surgery, and at 07.00 hours on postoperative day 1 (AUC = 0·710, P = 0·017). Fewer patients in the SCPB group required strong opiates (5 of 29 versus 16 of 29 in the control group; P = 0·003) and rescue opiates (6 of 29 versus 20 of 29; P < 0·001). Intraoperative SCPB reduces pain scores following thyroid and parathyroid surgery, and reduces the requirement for strong and rescue opiates. 2009-012671-98 (https://www.clinicaltrialsregister.eu).