Multifocal motor neuropathy presenting as ophthalmoplegia

A 45-year-old man developed ophthalmoplegia and subsequently multiple cranial nerve palsies in association with bibrachial paresis. Investigations revealed evidence of conduction block occurring at a very proximal location (i.e., the spinal roots) and seemingly sparing sensory fibers. Other causes were ruled out and a diagnosis of multifocal motor neuropathy with conduction block (MMN) was suggested. The patient responded to cyclophosphamide. Differentiating features between MMN and chronic inflammatory demyelinating polyradioneuropathy (CIDP) are discussed. This case demonstrates that MMN may rarely present with ophthalmoparesis and also demonstrates that features of MMN and CIDP may overlap.