To determine the diagnostic accuracy of anti-GM1 antibody testing in patients suspected of having multifocal motor neuropathy (MMN) using a reference standard of the diagnosis of MMN as made by the authors and according to the accepted criteria at the time of the study; or enough clinical and electrophysiological data on the published participants to fulfil the EFNS/PNS criteria for definite or probable MMN.

To determine the diagnostic accuracy of anti-GM1 antibody testing in patients suspected of having multifocal motor neuropathy but without conduction block using a reference standard consisting of the clinical criteria that were appropriate at the time of the study and, additionally, a documented response to IVIg treatment.

We will investigate heterogeneity by determining the effects of different clinical criteria used as reference standards; and different ELISA methods, cut-off values for anti-GM1 antibody test positivity, and class of antibodies (IgM or IgG).