XXXX : pathologic alterations at the site of conduction block.

@entity1 @entity17 @entity16 @entity425 @entity1897 @entity854 @entity194 @entity528
The pathologic changes of nerves in @entity1897 ( @entity1897 ), a rare @entity16 with selective focal conduction block of motor fibers in mixed nerves, remain essentially unstudied. Fascicular nerve biopsy of 8 forearm or arm nerves in 7 @entity1 with typical @entity1897 was undertaken for diagnostic reasons at the site of the conduction block. @entity854 were seen in 7 of 8 nerves, including a varying degree of multifocal fiber @entity528 , an altered fiber size distribution with fewer large fibers, an increased frequency of remyelinated fiber profiles, and frequent and prominent regenerating fiber clusters. Small epineurial perivascular inflammatory infiltrates were observed in 2 nerves. We did not observe @entity17 or onion bulb formation. We hypothesize that an antibody-mediated attack directed against components of axolemma at nodes of Ranvier could cause conduction block, transitory paranodal @entity17 and regeneration. Alternatively, the antibody attack could be directed at components of paranodal myelin. We favor the first hypothesis because in nerves studied by us, axonal pathological alteration predominated over myelin pathology. Irrespective of which mechanism is involved, we conclude that the unequivocal multifocal fiber @entity528 and regenerative clusters at sites of conduction block explains the observed clinical @entity425 and @entity194 and alterations of motor unit potentials. The occurrence of conduction block and multifocal @entity528 and regeneration at the same sites suggests that the processes of conduction block and @entity528 and regeneration are linked. Finding discrete multifocal @entity528 may also provide an explanation for why the functional abnormalities remain unchanged over long periods of time at discrete proximal to distal levels of nerve and may emphasize a need for early intervention (assuming that efficacious treatment is available).
