Abstract
Anti-MAG antibody was known to be associated with polyneuropathy associated with immunoglobulin M (IgM) monoclonal gammopathy of undetermined significance, as we call anti-MAG neuropathy. Anti-MAG neuropathy is pathologically characterized by the presence of widely spaced myelin (WSM), which affects the structure of nodes of Ranvier. To help understand the physiological actions of anti-MAG antibody and WSM, we examined the effects on the excitability properties of peripheral motor axons. Four patients with anti-MAG neuropathy were studied. Multiple excitability measurements were made in the median nerve at the wrist, using computerized threshold-tracking (QTRACS with TRONDNF excitability protocol), and compared with normal control data. Subsequently we performed mathematical modeling of the excitability data, using the Bostock model of the human motor axon to simulate axonal excitability measurements (QTRACP with MEMFIT). Nerve excitability studies showed significantly smaller supernormality in recovery cycle and greater changes in excitability with depolarizing currents in threshold electrotonus. Mathematical modeling suggested that the results could be partially explained by abnormal fast K+ current and/or Na+ current at nodes of Ranvier. This study showed that patients with anti-MAG neuropathy exhibit abnormalities in their motor axons attributable to ion channel dysfunction at nodes. This suggests that anti-MAG antibody causes physiological dysfunction of nodes via changes caused by WSM in peripheral nerve.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
