Shoulder surgery often causes severe pain after the operation. To control this pain, doctors commonly perform a nerve block (interscalene brachial plexus block), which numbs the shoulder area. However, when the effect of a single-injection nerve block wears off, many patients experience sudden, intense pain known as "rebound pain".
One way to prevent rebound pain is to place a thin catheter near the nerves so that local anesthetic can be given continuously for a longer period (continuous nerve block). However, this method is technically demanding and can cause problems such as catheter dislodgement, infection, and inconvenience for patients. Another simpler option is to give a single-injection nerve block together with an intravenous (IV) injection of dexamethasone, a steroid medication known to prolong the effect of nerve blocks and reduce rebound pain.
The purpose of this study is to determine whether a single-injection nerve block combined with IV dexamethasone (5 mg) is not inferior to a continuous nerve block in preventing rebound pain after shoulder surgery. A total of 92 adult patients scheduled for elective shoulder surgery will be randomly assigned to one of the two groups. The main outcome is the rebound pain score, defined as the difference between the last pain score recorded in the recovery room (while the nerve block is still working) and the highest pain score reported within the first 24 hours after the nerve block. The investigators expect that the simpler single-injection method with IV dexamethasone will provide comparable pain control while avoiding the complications and inconvenience of catheter-based continuous nerve blocks.