Brachial Plexus and Lumbosacral Plexus Disorders By Michael Rubin, MDCM, New York Presbyterian Hospital-Cornell Medical Center Reviewed / Revised Apr 2022 | Modified Sep 2022 View Patient Education Symptoms and Signs Diagnosis Treatment Key Points Topic Resources Plexuses Disorders of the brachial or lumbosacral plexus cause a painful mixed sensorimotor disorder of the corresponding limb.