The clinical spectrum of small fiber neuropathy (SFN) encompasses manifestations related to the involvement of thinly myelinated A-delta and unmyelinated C fibers, including not only the classical distal phenotype, but also a non–length-dependent (NLD) presentation that can be patchy, asymmetrical, upper limb-predominant, or diffuse. This narrative review is focused on NLD-SFN. The diagnosis of NLD-SFN can be problematic, due to its varied and often atypical presentation, and diagnostic criteria developed for distal SFN are not suitable for NLD-SFN. The topographic pattern of NLD-SFN is likely related to ganglionopathy restricted to the small neurons of dorsal root ganglia. It is often associated with systemic diseases, but about half the time is idiopathic. In comparison with distal SFN, immune-mediated diseases are more common than dysmetabolic conditions. Treatment is usually based on the management of neuropathic pain. Disease-modifying therapy, including immunotherapy, may be effective in patients with identified causes. Future research on NLD-SFN is expected to further clarify the interconnected aspects of phenotypic characterization, diagnostic criteria, and pathophysiology.

中文翻译：

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非长度依赖性小纤维神经病变：不是长袜和手套的问题

小纤维神经病变 (SFN) 的临床表现包括与薄有髓 A-delta 和无髓 C 纤维受累相关的表现，不仅包括经典的远端表型，还包括非长度依赖性 (NLD) 表现，可以斑片状、不对称、上肢为主或弥漫性。这篇叙述性审查的重点是 NLD-SFN。NLD-SFN 的诊断可能存在问题，因为其表现多样且通常不典型，为远端 SFN 制定的诊断标准不适用于 NLD-SFN。NLD-SFN 的地形模式可能与局限于背根神经节小神经元的神经节病有关。它通常与全身性疾病有关，但大约有一半是特发性的。与远端 SFN 相比，免疫介导的疾病比代谢障碍疾病更常见。治疗通常基于神经性疼痛的管理。疾病修饰疗法，包括免疫疗法，可能对已确定病因的患者有效。未来对 NLD-SFN 的研究有望进一步阐明表型特征、诊断标准和病理生理学的相互关联的方面。