Brachial Plexus Block Following Serratus Anterior Plane Block After Minimally Invasive Cardiac Surgery Identified Using Contrast X‐Ray: A Case Report

A serratus anterior plane block is effective for pain management after minimally invasive cardiac surgery (MICS) but may cause rare complications. In this study, we present a case of upper limb neurological symptoms following a serratus anterior plane block (SAPB) administered after MICS, which was visualized via contrast x-ray imaging. A 74-year-old woman with severe aortic stenosis underwent aortic valve replacement via minithoracotomy. We preoperatively inserted a SAPB catheter deep into the serratus anterior muscle (SAM). Postoperative x-ray imaging with contrast medium revealed its distribution extending from the chest wall (second to fourth ribs), detached from the thorax, toward the right upper arm. We initiated a programmed intermittent bolus infusion (PIBI) via the catheter, but the patient developed reduced grip and sensory deficits in the right arm. Discontinuation of PIBI on postoperative day five led to neurological symptom resolution by day six. The clinical course and contrast distribution suggested that the catheter tip may have migrated to the superficial layer of the SAM. These findings highlight the importance of confirming catheter placement and carefully monitoring neurological symptoms when atypical contrast spread patterns are observed.