title: Focal cerebral ischemia after surgery in the "beach chair" position: the role of a congenital variation of circle of Willis anatomy.
abstract: A 50-year-old man underwent shoulder surgery in the beach chair position. His mean arterial blood pressure at arm level was approximately 65 mm Hg. Postoperatively, there was delayed awakening and a right hemiparesis. Radiologic evaluation revealed a congenital asymmetry of the circle of Willis that resulted in limited collateral flow to the left anterior and middle cerebral artery distributions. Similar anatomical variations are relatively common in the general population and may render some patients relatively and unpredictably more vulnerable to hypotension.
authors: Department of Anesthesiology, VA Medical Center, San Diego, CA 92161, USA. jdrummond@ucsd.edu
authors: John C
authors: JC
authors: Drummond
authors: Roland R
authors: RR
authors: Lee
authors: James P
authors: JP
authors: Howell
mesh_terms: D001794:Blood Pressure; D002545:Brain Ischemia / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D020785:Central Nervous System Vascular Malformations / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D002941:Circle of Willis / Q000002:abnormalities* / Q000503:physiopathology; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000009:adverse effects*; D010291:Paresis / Q000209:etiology / Q000503:physiopathology; D056888:Patient Positioning; D020127:Recovery of Function; D017006:Rotator Cuff / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D013997:Time Factors; D016896:Treatment Outcome