title: The refractory period of transmission is impaired in axonal Guillain-Barré syndrome.
abstract: Guillain-Barré syndrome (GBS) is classified as acute motor axonal neuropathy (AMAN) or acute inflammatory demyelinating polyneuropathy (AIDP). Motor nerve conduction block is frequently found in both subtypes of GBS. To compare patterns of conduction block and the safety factor for impulse transmission in AMAN and AIDP, pairs of supramaximal stimuli at intervals of 1-5 ms were delivered to stimulate the median nerve at the wrist. At the 2- and 3-ms intervals, compound muscle action potentials (CMAPs) to the second stimulus were significantly smaller in AMAN patients (n = 7) than in normal subjects (n = 10) and AIDP patients (n = 6). Over 4 weeks from onset, the amplitude of both conditioned and unconditioned CMAPs returned toward normal, consistent with improvement in the safety factor for impulse transmission. The refractory period of transmission is impaired in AMAN, and the site of transmission failure is likely to be the motor nerve terminals. In addition to axonal degeneration, the critically but reversibly reduced safety factor is important in the pathophysiology of AMAN, and consistent with the rapid resolution of distal conduction block often seen in AMAN patients.
authors.affiliation: Department of Neurology, Chiba University School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. kuwabara@med.m.chiba-u.ac.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kuwabara
authors.forename: Hugh
authors.initials: H
authors.lastname: Bostock
authors.forename: Kazue
authors.initials: K
authors.lastname: Ogawara
authors.forename: Jia-Ying
authors.initials: JY
authors.lastname: Sung
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Kanai
authors.forename: Masahiro
authors.initials: M
authors.lastname: Mori
authors.forename: Takamichi
authors.initials: T
authors.lastname: Hattori
authors.forename: David
authors.initials: D
authors.lastname: Burke
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000293:Adolescent; D000328:Adult; D000368:Aged; D001369:Axons / Q000502:physiology*; D003213:Conditioning, Psychological / Q000502:physiology; D005260:Female; D020275:Guillain-Barre Syndrome / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D012032:Refractory Period, Electrophysiological / Q000502:physiology*; D015222:Sodium Channels / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D015222:Sodium Channels