Multifocal motor neuropathy presenting as chronic progressive proximal leg weakness

Multifocal motor neuropathy

Multifocal motor neuropathy (MMN) is a rare disorder in which the symptoms are caused by persistent conduction block lesions. The mononeuropathy multiplex progresses over time with increasing axonal loss. The cause of the conduction blocks and axonal loss are not completely understood but immune mechanisms are involved and response to intravenous immunoglobulin has been established. The importance of MMN goes beyond its clinical incidence as the increasing understanding of the pathogenesis of this disorder has implications for other peripheral nerve diseases and for our knowledge of peripheral nerve biology.

Monomelic neurogenic syndromes: a prospective study

Monomelic neurogenic syndromes are rare. Their classification and prognostic features have not been addressed in the European population. A prospective study of 17 patients with monomelic neurogenic amyotrophy, of upper or lower limb onset, with progression limited to one limb for three or more years. Clinical and neurophysiological studies were performed in the subsequent 3 or more years. Fifteen patients were of European origin and two were Asian. Those presenting with proximal monomelic weakness or with involvement of the posterior compartment of the lower leg showed no further progression after the initial period of development of the syndrome. Brisk reflexes in wasted muscles did not predict progression. Electromyographic signs of denervation in the opposite limb at presentation did not predict later progression. Transcranial magnetic stimulation (TMS) features of corticospinal dysfunction were a useful predictor of subsequent progression (p=0.01). One patient with lower limb onset developed conduction block with weakness in an upper limb nine years after presentation, and this upper limb weakness responded to IVIg therapy. This adult-onset European group of patients is different as compared with juvenile-onset Asian cases. The clinical syndromes appear heterogeneous, but neurophysiological investigations, in particular TMS, can be helpful in determining prognosis. Multifocal motor neuropathy should be considered when there is progression, even years after onset.

[Autoimmune neuropathies--current aspects of immunopathologic diagnostics and therapy]

The group of autoimmune neuropathies includes the Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuritis, multifocal motor neuropathy, neuropathies associated with monoclonal gammopathies, and vasculitic neuropathies. This educational review first addresses diagnostic pathways that facilitate more rational diagnostic decisions. Many therapies are effective for treating immune neuropathies. Unfortunately, none of the available therapies are specific. In the acute phase, glucocorticosteroids, plasmapheresis, and intravenous immunoglobulins play key roles. The list of long-term therapies includes azathioprine, cyclosporine, cyclophosphamide, and immunoglobulins. The therapeutic mechanisms involved are not clear for most of these compounds. Modern immunotherapy has to consider medical aspects, available therapeutic evidence, and long-term economic burden.