Please confirm that an ethics committee approval has been applied for or granted: Yes: I’m uploading the Ethics Committee Approval as a PDF file with this abstract submission

Background and Aims Severe postoperative pain due to tonsillectomy inhibits patients’ early oral intake and recovery after surgery. The maxillary and glossopharyngeal nerves doubly innervate the tonsils, and it is unclear which nerve is more involved in the pain. Although ultrasound-guided maxillary nerve block (MaxNB) has been administered to the dental surgery, the postoperative analgesic efficacy of MaxNB for tonsillectomy has not yet been studied in controlled trials.

Methods This study was approved by the ethics committee of Sapporo Medical University Hospital (322-294). Forty-four patients aged 18 years or older undergoing tonsillectomy under general anaesthesia were randomly allocated to the block or placebo group. Both groups received ultrasound-guided bilateral MaxNB under general anaesthesia, with 5 mL of 0.375% ropivacaine per site in the block group and the same volume of saline in the placebo group. Patients were provided with intravenous fentanyl patient-controlled analgesia after surgery. The primary outcome was a visual analogue scale (VAS) pain score at rest at return to the ward, 2, 4, 8, and 24 hours after return.

Results One patient was excluded due to refusal to participate in the study. Twenty and 23 patients completed the study in the block and placebo groups, respectively. The VAS scores were not significantly different between the groups at any point during the 24 hours postoperatively. Median [IQR] cumulative fentanyl consumption was not significantly different (block: 50 [20-170] vs. placebo: 40 [0-140] μg/day, p=0.62).

Conclusions MaxNB for adult patients undergoing tonsillectomy did not decrease VAS scores and fentanyl consumption for 24 hours postoperatively compared to placebo.