P078 It's not what it seems

Abstract

Background and Aims A 62-year-old ASA II patient underwent elective shoulder arthroscopy under combined interscalene brachial plexus block (ISB) and general anaesthesia (GA). He had a history of thoracic outlet syndrome treated with cervical rib resection two years earlier, complicated by postoperative bleeding requiring video-assisted thoracoscopic surgery (VATS). His initial presentation at that time included severe hiccups. Methods An ultrasound-guided ISB was performed uneventfully, with the patient mildly sedated. Surgery lasted 90 minutes in the beach-chair position and was completed without complications. The patient was pain-free postoperatively and discharged after four hours. However, 20 hours later, he developed persistent hiccups causing marked discomfort. Given his medical history, he was reassured and treated conservatively with hyoscine butylbromide and lansoprazole. Symptoms resolved within six hours. Results The delayed onset of hiccups suggested phrenic nerve irritation. ISB is known to cause temporary phrenic nerve palsy in up to 50% of cases due to anatomical proximity (C4- C6). In this case, however, the hiccups were more likely caused by mechanical irritation rather than paresis. Contributing factors may have included beach-chair positioning (causing stretch), neck oedema from irrigation fluid, and fibrosis from previous surgery. These factors could have irritated the phrenic nerve, but the block initially masked symptoms by interrupting afferent and efferent signalling. Once the block wore off, the symptoms-manifesting as hiccups-became apparent. Conclusions While phrenic nerve palsy is a recognised complication of ISB, nerve irritation from perioperative factors-such as positioning, oedema, or pre-existing anatomical changes- may also lead to unexpected symptoms. Moreover, regional anaesthesia can transiently mask such effects, delaying presentation. Clinicians should be alert to this mechanism, especially in patients with prior cervical or thoracic surgery, to avoid misinterpretation and ensure timely, appropriate management.