Topographic and anatomic justification of regional anesthesia in thyroid and parathyroid gland surgery: an experiment on unfixed cadaveric material

Introduction. Widespread thyroid gland (TG) diseases highlight the need to improve surgical treatment. Regional anesthesia (RA) is effective to improve perioperative outcomes, reduce morbidity, enhance analgesia and accelerate recovery. However, safety of intermediate cervical plexus block (ICPB), pericapsular block (PCB), and Berry ligament block (BLB) remains insufficiently studied. Objective. To evaluate the safety of RA techniques in TG and parathyroid gland (PTG) region through research of local anesthetic spread in fascial and interfascial cervical spaces. Material and methods. The study was conducted on 35 cadavers. We injected the dyed local anesthetic into fascial spaces under ultrasound guidance and simulated ICPB, PCB and BLB. For ICPB and PCB, 5-mL, 10-mL and 15-mL volumes were tested, while 2-mL and 5-mL were used for BLB. Diffusion of anesthetic to nearby neural structures (vagus nerve, phrenic nerve, sympathetic trunk and recurrent laryngeal nerve) was analyzed. Results. In case of ICPB, local anesthetic volumes up to 10 mL were safe without nerve staining. Injection of 15 mL was followed by vagus nerve staining in 3 cases and phrenic nerve staining in 2 cases. Statistical analysis confirmed that anesthetic volume <10 mL reduced the risk of nerve involvement during ICPB. In case of PCB, volumes <10 mL ensured adequate anesthetic distribution around TG without nerve involvement. Injection of 15 mL was followed by vagus nerve staining in 1 case. BLB with any volumes was followed by staining of recurrent laryngeal nerve due to anatomical proximity of Berry ligament. Conclusion. RA in thyroid surgery, particularly ICPB and PCB, is safe in case of anesthetic volume <10 mL. BLB inherently involves recurrent laryngeal nerve that requires careful technique and minimization of complications. Ultrasound guidance is essential for safe blocks. Further clinical studies with larger samples are necessary to validate these findings.