Introduction

Although polyneuropathy in patients with immunoglobulin light chain (AL) amyloidosis has been considered to be attributable to axonal degeneration resulting from amyloid deposition, patients with nerve conduction parameters indicating demyelination that mimics chronic inflammatory demyelinating polyneuropathy (CIDP) have also been reported anecdotally.

Methods

We evaluated the electrophysiological and pathological features of 8 consecutive patients with AL amyloidosis who were referred for sural nerve biopsy.

Results

Although findings of axonal neuropathy predominantly in the lower limbs were the cardinal feature, all patients showed one or more abnormalities of nerve conduction velocities or distal motor latencies. In particular, 2 of these patients fulfilled the definite electrophysiological for CIDP defined by the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS). On electron microscopic examination of sural nerve biopsy specimens, Schwann cells apposed to amyloid fibrils became atrophic in all patients, suggesting that amyloid deposits directly affect neighboring tissues. Additionally, detachment of the neurilemma from the outermost compacted myelin lamella was seen where amyloid fibrils were absent in 4 patients. Electrophysiological findings suggestive of demyelination were more conspicuous in these patients compared with the other patients. The detachment of the neurilemma from the outermost compacted myelin lamella was particularly conspicuous in patients who fulfilled the definite EFNS/PNS electrophysiological criteria for CIDP.

Conclusion

Abnormalities of myelinated fibers unrelated to amyloid deposition may frequently occur in AL amyloidosis. Disjunction between myelin and the neurilemma may induce nerve conduction abnormalities suggestive of demyelination.

中文翻译：

---

免疫球蛋白轻链（AL）淀粉样变性病的两种神经病变机制

介绍

尽管已认为免疫球蛋白轻链（AL）淀粉样变性患者的多发性神经病可归因于淀粉样蛋白沉积导致的轴突变性，但也有报道报道神经传导参数表明脱髓鞘的患者可模仿慢性炎症性脱髓鞘性多发性神经病（CIDP）。

方法

我们评估了连续8例接受腓肠神经活检的AL淀粉样变性患者的电生理和病理学特征。

结果

尽管主要在下肢发现轴突性神经病是主要特征，但所有患者均显示一种或多种神经传导速度异常或远端运动潜伏期。特别是，其中2位患者符合欧洲神经病学会/周围神经协会（EFNS / PNS）定义的CIDP的明确电生理要求。在对腓肠神经活检标本进行电子显微镜检查后，与淀粉样蛋白原纤维结合的雪旺细胞在所有患者中均萎缩，表明淀粉样蛋白沉积直接影响邻近组织。另外，在4例患者中未见淀粉样蛋白原纤维的地方，可见神经膜从最外层的髓鞘薄层脱离。与其他患者相比，这些患者中提示脱髓鞘的电生理结果更为明显。在满足明确的EFNS / PNS CIDP电生理标准的患者中，神经膜从最外层的紧密髓鞘薄层脱离尤为明显。

结论

与淀粉样蛋白沉积无关的有髓纤维异常可能经常发生在AL淀粉样变性病中。髓鞘和神经膜炎之间的脱节可能引起神经传导异常，提示脱髓鞘。