Interscalene brachial plexus anesthesia for shoulder surgery: report of a complicated intraoperative course.

We present a case of abrupt hemodynamic and mental status changes that occurred during shoulder surgery. During interscalene anesthesia for rotator cuff repair, there was abrupt onset of altered mental status and hemodynamic changes, which had a variety of possible contributing causes. Complete recovery occurred during care in the post-anesthesia care unit. A variety of physiologic changes can occurred during interscalene anaesthesia for shoulder surgery, which require prompt identification and management.