Multifocal motor neuropathy (MMN) is a rare autoimmune disorder of the peripheral motor nerves leading to muscle weakness, secondary to conduction block, and ultimately axonal degeneration.
Debate emerged over the past decade as to whether MMN is a demyelinating or axonal neuropathy, although the debate seem rather academic as both processes may and do co-exist in a variety of “demyelinating” or better termed “autoimmune” neuropathies. In the May issue of JNNP, Shimizu and colleagues elegantly demonstrate the pathogenesis of sera from MMN patients, pointing to a clear “autoimmune” process. Specifically, sera from MMN patients were shown to disrupt the blood-nerve barrier by up-regulating vascular cell adhesion molecule-1 (VCAM-1) leading to an influx of inflammatory cells. It would be interesting to determine whether IVIg restored the blood-nerve barrier, a potential therapeutic effect, and whether this correlates with clinical improvement.
Read more at http://jnnp.bmj.com/content/85/5/526.abstract