Interscalene Brachial Plexus Block Versus Serratus Posterior Superior Intercostal Plane Block for Arthroscopic Shoulder Surgery

Arthroscopic shoulder surgery is associated with moderate to severe postoperative pain that may delay recovery and rehabilitation. Interscalene brachial plexus block (ISB) is widely used for postoperative analgesia in shoulder surgery; however, it may be associated with complications such as phrenic nerve paralysis. The serratus posterior superior intercostal plane (SPSIP) block is a recently described fascial plane block that may provide effective analgesia while avoiding some of the limitations of ISB. This prospective, randomized, double-blind controlled trial aims to compare the analgesic efficacy of ISB and SPSIP block in patients undergoing elective arthroscopic shoulder surgery under general anesthesia. The primary outcome is total postoperative opioid consumption during the first 24 hours after surgery. Secondary outcomes include postoperative pain scores, quality of recovery, time to first rescue analgesia, rescue analgesic requirements, intraoperative opioid consumption, sensory block distribution, motor block characteristics, and block-related complications.

Inclusion Criteria: * Age between 18 and 75 years * ASA physical status I, II, or III * Scheduled for elective arthroscopic shoulder surgery under general anesthesia * Provision of written informed consent Exclusion Criteria: * Refusal to participate in the study * Coagulopathy * Current anticoagulant therapy * Infection at the block site * Previous surgery involving the planned block site * Known allergy or history of toxicity to local anesthetics * Hepatic failure * Renal failure * Uncontrolled diabetes mellitus * Cognitive impairment or mental disability preventing reliable assessment * Chronic opioid use or ongoing chronic pain treatment * Pregnancy, suspected pregnancy, or breastfeeding * Chronic pulmonary disease (e.g., COPD or asthma) * Failed block