多发性神经病是轴索和/或髓鞘损伤引起的一种外周神经广泛性病变。据估计，一般人群的患病率为 2%-7%。[1]Italian General Practitioner Study Group (IGPSG). Chronic symmetric symptomatic polyneuropathy in the elderly: a field screening investigation in two Italian regions. I. Prevalence and general characteristics of the sample. Neurology. 1995;45:1832-1836.
http://www.ncbi.nlm.nih.gov/pubmed/7477977?tool=bestpractice.com
[2]Bharucha NE, Bharucha AE, Bharucha EP. Prevalence of peripheral neuropathy in the Parsi community of Bombay. Neurology. 1991;41:1315-1317.
http://www.ncbi.nlm.nih.gov/pubmed/1650932?tool=bestpractice.com
[3]Savettieri G, Rocca WA, Salemi G, Meneghini F, et al. Prevalence of diabetic neuropathy with somatic symptoms: a door-to-door survey in two Sicilian municipalities. Sicilian Neuro-Epidemiologic Study (SNES) Group. Neurology. 1993;43:1115-1120.
http://www.ncbi.nlm.nih.gov/pubmed/8170554?tool=bestpractice.com
多发性神经病是系统性疾病的常见神经系统表现。例如，约 50% 的糖尿病患者和晚期 HIV 感染患者出现神经病变。[4]Dyck PJ, Kratz KM, Karnes JL, et al. The prevalence by staged severity of various types of diabetic neuropathy, retinopathy, and nephropathy in a population-based cohort: the Rochester Diabetic Neuropathy Study. Neurology. 1993 Apr;43(4):817-24.
http://www.ncbi.nlm.nih.gov/pubmed/8469345?tool=bestpractice.com
[5]Simpson DM, Kitch D, Evans SR et al. HIV neuropathy natural history cohort study: assessment measures and risk factors. Neurology. 2006;66:1679-1687.
http://www.ncbi.nlm.nih.gov/pubmed/16769940?tool=bestpractice.com
中毒和代谢因素造成的大多数神经病变是轴索病变。关于脱髓鞘性多发性神经病（例如格林-巴利综合征 [Guillain-Barre syndrome, GBS]、慢性炎性脱髓鞘性多发性神经根神经病、单克隆免疫球蛋白血症、某些遗传性神经病）的病因，目前知之甚少。
临床表现
多神经病变最常见的表现是双脚和下肢远端的对称性麻木、感觉异常和感觉迟钝（远端对称性感觉运动性多发性神经病）。在重度病例中，感觉症状和体征向近端进展，呈袜子-手套样分布。平衡和步态可能受损。早期的运动体征包括足内在肌萎缩和踝关节无力。自主神经系统可能受累，由此导致的症状包括早饱、腹泻或便秘、勃起功能障碍、泌汗障碍和直立性头晕。可能会出现其他临床表型，包括单纯感觉性或单纯运动性症状以及有急性表现的多发性神经病（例如 GBS）
小纤维神经病不会累及通过神经传导检查评估的大纤维，但会在活检时显示神经纤维密度的变化，并在感觉定量检测时显示异常。小纤维神经病可能表现为疼痛的单纯感觉性综合征，并且可能为特发性，或者继发于各种系统性病因。[6]Oaklander AL, Nolano M. Scientific Advances in and Clinical Approaches to Small-Fiber Polyneuropathy: A Review. JAMA Neurol. 2019 Sep 9;:.
https://www.doi.org/10.1001/jamaneurol.2019.2917
http://www.ncbi.nlm.nih.gov/pubmed/31498378?tool=bestpractice.com
[7]Devigili G, Rinaldo S, Lombardi R, et al. Diagnostic criteria for small fibre neuropathy in clinical practice and research. Brain. 2019 Dec 1;142(12):3728-3736.
https://www.doi.org/10.1093/brain/awz333
http://www.ncbi.nlm.nih.gov/pubmed/31665231?tool=bestpractice.com
[8]Gondim FAA, Barreira AA, Claudino R, et al. Definition and diagnosis of small fiber neuropathy: consensus from the Peripheral Neuropathy Scientific Department of the Brazilian Academy of Neurology. Arq Neuropsiquiatr. 2018 Mar;76(3):200-208.
https://www.doi.org/10.1590/0004-282x20180015
http://www.ncbi.nlm.nih.gov/pubmed/29809227?tool=bestpractice.com
[9]de Greef BTA, Hoeijmakers JGJ, Gorissen-Brouwers CML, et al. Associated conditions in small fiber neuropathy - a large cohort study and review of the literature. Eur J Neurol. 2018 Feb;25(2):348-355.
https://www.doi.org/10.1111/ene.13508
http://www.ncbi.nlm.nih.gov/pubmed/29112785?tool=bestpractice.com
对于非对称性神经病，或以上肢症状、体征为首发表现的神经病，临床医生应注意修正诊断，包括神经卡压症（局灶性神经病）、血管炎性神经病（多灶性神经病）。局灶性神经病和多灶性神经病的鉴别诊断常有重叠，但与多神经病则大不同
反射亢进或其他上运动神经元异常表现提示检查者应考虑中枢神经系统病变。多发性腰骶神经根病也可能类似于多发性神经病的表现