Ultrasound guidance does not improve local anesthetic distribution in suprazygomatic maxillary nerve blocks in pediatric patients: a clinical, randomized, controlled, observer-blinded, crossover MRI trial.

Background Maxillary nerve blocks are often used as part of a multimodal postoperative pain management regimen for children undergoing cleft palate surgery. It has not been demonstrated yet that ultrasound guidance provides superior local anesthetic distribution and better success rates compared with the landmark-based block technique. The aim of the study was to compare the effect of ultrasound guidance for suprazygomatic maxillary nerve blocks on local anesthetic spread to the pterygopalatine fossa.Methods 20 pediatric patients scheduled for cleft palate repair received bilateral suprazygomatic maxillary blocks. Landmark technique was used on one side and ultrasound guidance on the contralateral side according to randomization. After the block procedure, MRI was used to determine the spread of the local anesthetic.Results Local anesthetic spread to the pterygopalatine fossa with contact to the maxillary nerve (defined as successful block) was observed in 13 (65%) of the landmark-based blocks and in 14 (70%) of the ultrasound-guided blocks (p=0.56). No adverse events or complications were observed during or after the block procedures.Conclusion Appropriate pain management for cleft palate repair can be achieved without the availability of imaging guidance. Future studies should focus on improving the success rate of maxillary nerve blocks, both with and without the aid of sonography.Trial Registration Number NCT05778903.