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Natural history of 46 patients with multifocal motor neuropathy with conduction block

journal contribution
posted on 2023-05-17, 07:00 authored by Bruce TaylorBruce Taylor, Wright, RA, Harper, CM, Dyck, PJ
We studied 46 consecutive patients with multifocal motor neuropathy with conduction block (MMN-CB). Typically, asymmetric weakness and atrophy of the hands or arms developed insidiously, but spontaneous improvement (without treatment) or death from this disease did not occur and 94% remained employed. For 18 patients examined on multiple occasions using the weakness subscore of the neuropathy impairment score [NIS(W)] for a median time of 2.3 years, worsening of 1.3 points per year was observed; many patients, however, had received intensive immunomodulating therapy. Median worsening to our first evaluation (generally without treatment) was estimated at 4.2 points per year, perhaps suggesting that treatment had influenced course. Three criteria for conduction block (CB) were compared, but the least stringent was sensitive for the diagnosis. Conduction block accompanied by weakness and atrophy typically affected only motor fibers, especially of midforearm nerves, and these sites of dysfunction persisted for months or years. Neurological signs and electrodiagnostic features were consistent with CB, axonal degeneration, a variable degree of reinnervation, and segmental demyelination. Although this study did not focus on therapy, intravenous gammaglobulin and cyclophosphamide appeared to be associated with neurological improvement, which was seldom complete or sustained. Axonal degeneration and faulty regeneration may in part explain this muted response. Possibly, treatment must be earlier, more intense, or different.

History

Publication title

Muscle and Nerve

Volume

23

Issue

6

Pagination

900-908

ISSN

0148-639X

Department/School

Menzies Institute for Medical Research

Publisher

John Wiley & Sons Inc

Place of publication

111 River St, Hoboken, USA, Nj, 07030

Repository Status

  • Restricted

Socio-economic Objectives

Clinical health not elsewhere classified

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