Franssen Hessel, Notermans Nicolette C
Department of Clinical Neurophysiology, Neuromuscular Research Group, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands.
Ann Neurol. 2006 Feb;59(2):365-71. doi: 10.1002/ana.20785.
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.
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.
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.
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.
在与单克隆IgM丙种球蛋白病相关的多发性神经病中，神经传导研究可能显示出与节段性脱髓鞘一致的不成比例的远端减慢。这被认为代表了一种长度依赖性脱髓鞘过程，始于远端并向近端节段发展。由于对此的证据不完整，我们评估了IgM神经病中是否存在长度依赖性。
在22例IgM神经病患者、20例慢性炎症性脱髓鞘性多发性神经病（CIDP）疾病对照和36例正常对照中，我们研究了短轴突、中长轴突和长轴突神经的运动传导、感觉传导和针极肌电图，以及尺神经从近端到远端短节段的传导。为了比较不同长度神经的变量，我们将个体值相对于正常对照的中位数进行了标准化。
在IgM神经病中，远端减慢和轴突丢失特征随神经长度增加，排除肘部节段后，尺神经传导从近端到远端逐渐减慢。在CIDP中，除远端波幅外，未发现明显的长度依赖性。
假设由于普遍暴露于IgM，该过程是随机分布的，那么IgM神经病中不成比例的远端减慢可能是长度依赖性过程的一部分。
