Neuropathies motrices multifocales avec bloc de conduction

Multifocal motor neuropathies with conduction block are defined by a clinical syndrome characterized by the progressive onset of a motor deficit, associated with a more or less asymmetric and marked amyotrophy corresponding, at least at the beginning, to the distal parts of the upper limbs (in a truncal distribution). Sensory symptoms are mild or absent. Frequently, tendon reflexes are suppressed or diminished. There is no sign of any involvement of the central nervous system or bulbar lesion. Cranial nerves are rarely involved. The course of the disease may be progressive and generally it lasts several years. The hallmark of the diagnosis is the presence of partial focal motor conduction blocks, detected by electrophysiology. High amounts of anti-GM1 antibodies are found in nearly one third of the patients. Most patients show a good response to intravenous immunoglobulin. This syndrome may be considered a dysimmune neuropathy although its position amongst this type of diseases is still debated.