title: Length dependence in polyneuropathy associated with IgM gammopathy.
abstract: OBJECTIVE
  In polyneuropathy associated with monoclonal IgM gammopathy, nerve conduction studies may show disproportionate distal slowing consistent with segmental demyelination. This was suggested to represent a length-dependent demyelinating process, starting in distal and proceeding to proximal segments. Because the evidence for this is incomplete, we assessed whether length dependence occurs in IgM neuropathy.
  
  
  METHODS
  In 22 patients with IgM neuropathy, 20 disease controls with chronic inflammatory demyelinating polyneuropathy (CIDP) and 36 normal controls, we investigated motor conduction, sensory conduction, and needle electromyography for nerves with short, intermediate-length, and long axons as well as conduction in short segments of the ulnar nerve from proximal to distal. To compare variables in nerves of different length, we normalized individual values with respect to the median in normal controls.
  
  
  RESULTS
  In IgM neuropathy, distal slowing and features of axon loss increased with nerve length, and ulnar nerve conduction became gradually slower from proximal to distal when the elbow segment was excluded. In CIDP, no clear length dependence was found except for distal amplitude.
  
  
  CONCLUSIONS
  The disproportionate distal slowing in IgM neuropathy may be part of a length-dependent process, assuming that this process is randomly distributed due to a generalized exposure to IgM.
authors.affiliation: Department of Clinical Neurophysiology, Neuromuscular Research Group, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands. h.franssen@umcutrecht.nl
authors.forename: Hessel
authors.initials: H
authors.lastname: Franssen
authors.forename: Nicolette C
authors.initials: NC
authors.lastname: Notermans
mesh_terms: D000368:Aged; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D010265:Paraproteinemias / Q000150:complications*; D010525:Peripheral Nerves / Q000473:pathology* / Q000503:physiopathology*; D011115:Polyneuropathies / Q000150:complications* / Q000276:immunology / Q000473:pathology; D020277:Polyradiculoneuropathy, Chronic Inflammatory Demyelinating / Q000276:immunology / Q000503:physiopathology; D011930:Reaction Time / Q000502:physiology*; D018709:Statistics, Nonparametric
chemical_list: D007075:Immunoglobulin M