Comparative Analysis of Anterior Suprascapular and Interscalene Nerve Blocks in Shoulder Arthroscopy: Implications for Diaphragmatic Preservation and Pain Control

Background: Shoulder arthroscopy is frequently associated with significant postoperative pain, necessitating effective regional anaesthesia methods.The anterior suprascapular nerve block, a newer method, targets the suprascapular nerve while sparing the phrenic nerve, potentially providing adequate pain relief with better respiratory outcomes.To compare the analgesic efficacy, diaphragmatic function preservation, and safety profiles of ISB and ASSNB in patients feeling arthroscopic shoulder surgery.Methods: In a prospective, randomised controlled trial, 60 patients undergoing elective shoulder arthroscopy were assigned to receive either ISB or ASSNB under ultrasound guidance.Diaphragmatic excursion was measured using M-mode ultrasonography at 30 minutes and 24 hours post-block.Postoperative pain was evaluated using the Numerical Rating Scale at multiple intervals, and cumulative opioid consumption was recorded.Secondary outcomes included motor blockade, respiratory adverse effects, and ease of block performance.Results: Both groups had comparable demographic and surgical characteristics.At 30 minutes post-block, 83.3% of ISB patients exhibited partial or complete diaphragmatic paresis versus only 16.6% in the ASSNB group (p < 0.001).At 24 hours, diaphragmatic function had normalised in most ASSNB patients, while ISB-related paresis persisted in a significant number (p < 0.001).Pain scores and opioid consumption were similar across groups, although ISB showed slightly better immediate analgesia.However, ASSNB patients experienced earlier motor recovery, fewer respiratory difficulties, and faster initiation of rehabilitation. Conclusion:The study has concluded that there is a significant difference between the Interscalene and Anterior Suprascapular Nerve Block groups in terms of diaphragmatic movement at both 30 minutes and 24 hours post-block.