DOI: https://doi.org/10.36347/sjmcr.2026.v14i09.016

Pages: 2025-2028

Hemidiaphragmatic paresis caused by phrenic nerve blockade is a well-recognized consequence of interscalene brachial plexus block and is usually recognized by dyspnea, chest tightness, or reduced respiratory tolerance. We report an unusual case in which severe ipsilateral subcostal pain was the predominant symptom. A 70-year-old woman with a right rotator cuff tear scheduled for arthroscopic rotator cuff repair underwent an ultrasound-guided right interscalene brachial plexus block using 27 mL of a 1:1 mixture of 0.75% ropivacaine and 2% lidocaine, resulting in final concentrations of 0.375% ropivacaine and 1% lidocaine. Immediately after the block, she developed severe localized pain beneath the right costal margin, rated 7–8 on a numerical rating scale, despite having no previous pain or discomfort in that area. She repeatedly denied dyspnea, chest tightness, or difficulty breathing, and spontaneous ventilation and oxygen saturation remained stable. The pain decreased to an NRS score of 5–6 before propofol target-controlled infusion was initiated, and surgery proceeded with spontaneous ventilation and continuous respiratory monitoring. After surgery, the pain had decreased to an NRS score of 3–4, although persistent discomfort remained in the same subcostal region. A portable supine chest radiograph showed elevation of the right hemidiaphragm without definite pneumothorax. The patient remained clinically stable, and the discomfort resolved completely approximately 11 hours after the block. Chest computed tomography performed the following day showed no pneumothorax or other structural thoracic abnormality. The clinical course was most consistent with transient phrenic nerve blockade-associated hemidiaphragmatic paresis. This case suggests that focal ipsilateral subcostal pain may rarely be a predominant manifestation of hemidiaphragmatic paresis, even without dyspnea or oxygen desaturation. Clinicians should consider phrenic nerve involvement while appropriately