Pseudoaneurysm after interscalene block for a rotator cuff repair

We present a case of a 68-year-old female patient who had an interscalene nerve block (ISB) complicated by compression of her brachial plexus by a pseudoaneurysm. The complication occurred after the patient received an ISB as anesthesia for an outpatient shoulder procedure. Review of this complication should alert surgeons to consider this diagnosis as a possibility in patients with postoperative pain and/or neurologic compromise after receiving an ISB.