Author: Peter Bakes, M.D. Educational Pearls:   Rare disease with 1-2 patients out of 100,000. About 60% of patients report a preceding diarrheal illness and classically presents with an ascending motor weakness. Pathophysiology is likely due to molecular mimicry where the immune system creates antibodies against a pathogen (C. jejuni ) which appears similar to the myelin of peripheral nerves resulting in autoimmune demyelination. Diagnosis is made by clinical presentation +/- a spinal tap with a characteristic high protein count but without cells. Treatment is IVIG or plasmapharesis. It is important to monitor respiratory function because about 15% of patients progress to respiratory failure.   References: Sejvar, James J.; Baughman, Andrew L.; Wise, Matthew; Morgan, Oliver W. (2011). "Population incidence of Guillain–Barré syndrome: a systematic review and meta-analysis" van den Berg, Bianca; Walgaard, Christa; Drenthen, Judith; Fokke, Christiaan; Jacobs, Bart C.; van Doorn, Pieter A. (15 July 2014). "Guillain–Barré syndrome: pathogenesis, diagnosis, treatment and prognosis". Nature Reviews Neurology. 10 (8): 469–482. Yuki, Nobuhiro; Hartung, Hans-Peter (14 June 2012). "Guillain–Barré Syndrome". New England Journal of Medicine. 366 (24): 2294–2304.