Chronic inflammatory demyelinating polyneuropathy (CIDP):An acute-onset form of CIDP should be considered when GBS deteriorates >9 weeks after onset or relapses at least three times.This neuropathy shares many features with the common demyelinating form of GBS, including elevated CSF protein levels and the Edx findings of acquired demyelination.The CSF is usually acellular with an elevated protein level.Biopsy typically reveals little inflammation and onion-bulb changes (imbricated layers of attenuated Schwann cell processes surrounding an axon) that result from recurrent demyelination and remyelination.CIDP responds to glucocoicoids, whereas GBS does not. Ref: Amato A.A., Hauser S.L. (2012). Chapter 385. Guillain-Barre Syndrome and Other Immune-Mediated Neuropathies. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.