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Activity‐dependent conduction block in multifocal motor neuropathy
Author(s) -
Straver Dirk C.G.,
van den Berg Leonard H.,
van den BergVos Renske M.,
Franssen Hessel
Publication year - 2011
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.21843
Subject(s) - multifocal motor neuropathy , compound muscle action potential , mismatch negativity , medicine , nerve conduction velocity , cardiology , electrophysiology , anesthesia , electroencephalography , psychiatry
Previous studies suggested that activity‐dependent conduction block (CB) contributes to weakness in multifocal motor neuropathy (MMN). Obtaining more robust evidence for activity‐dependent CB is important because it may be a novel target for treatment strategies. We performed nerve conduction studies in 22 nerve segments of 19 MMN patients, before and immediately after 60 seconds of maximal voluntary contraction (MVC) of the relevant muscle. We employed supramaximal electrical stimulation, excluded nerves with marked axonal loss, and adopted criteria for activity‐dependent CB. Per segment, the segmental area ratio [area proximal compound muscle action potential (CMAP)/area distal CMAP] was calculated and, per nerve, total area ratio (area CMAP at Erb's point/area distal CMAP) was obtained. MVC induced no changes in mean area ratios and induced no activity‐dependent CB. In segments with CB before MVC, the MVC induced increased duration prolongation. In MMN, MVC induced temporal dispersion but no activity‐dependent CB. Muscle Nerve, 2011