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两个新的实务参考系数可望在评估远端对称性多神经病变(distal symmetrical polyneuropathy，DSP)上，对实验室与基因检测、自律神经检测与神经与皮肤切片等提供证据基础的指引。
本文是由美国神经医学会(AAN)、美国神经肌肉与电子诊断医学会、美国物理治疗医学会共同合作，于神经学期刊出刊前线上发表于12月3日，也将同步登载在其他两个机构的Muscle & Nerve 以及Archives of Physical Medicine and Rehabilitation这两本期刊。
主要作者、路易斯安那州大学健康科学中心的John England医师在AAN.com的访问中表示，此规范开始于假设并用神经病变症状、征兆与电子诊断发现，可以有效用来准确诊断远端对称性多神经病变；他表示，两项新规范提供了目前有关引起DSP原因与诊断之适当检测方法的最佳证据 。
【常见的异常】
作者写道，多神经病变是相当常见的神经异常，整体流行率约每100,000人有2.4%，55岁以上者则每100,000人增加 8%；由于多神经病变有许多病因，需要有系统的临床方法来评估与处置。
新规范的系数是根据对1980至2007年3月间的发表文献进行证据回顾，利用4等级的证据分类这些文章，等级A之证据力最强。目标之一是对实验室与基因检测、之二是对自律神经检测、神经切片与皮肤切片等提供有证据基础的规范。
实验室与基因检测之规范包括：
* 作者声明，筛检实验室检测可以用于全部的多神经病变病患(等级A)。他们写道，提供最大范围的检测是血糖、血清B12 与代谢物(甲基丙二酸或者同半胱胺酸(可有可无))，以及血清蛋白质免疫固定电泳(等级C)。如果常规血糖检测没有明确的糖尿病，那可以考虑对远端不对称性感觉性多神经病变进行葡萄糖失耐(IGT)检测 (等级 C)。
* 作者写道，基因检测应用于遗传神经病变的诊断与分类 (等级A)。他们指出，基因检测可以考虑用于遗传神经病变类型之不明原因的多神经病变(等级C)。他们写道，初步基因检测需透过临床显型、遗传模式与电子诊断特征引导，且须聚焦在最常见的异常。这些包括CMT1A成双/HNPP缺损、Cx32 (GJB1)、与MFN2突变筛检。
作者指出，对于非遗传神经病变显型之不明原因多神经病变病患的常规基因检测，没有足够证据证明没有用(等级U)。
自律神经检测、神经切片与皮肤切片之规范包括：
* 这一部份结论为，自律神经检测应作为评估多神经病变之病患的自律神经系统失能(等级 B)。作者指出，疑似自律神经病变(等级 B)与远端小纤维感觉性神经病变(等级C)，特别需考虑进行自律神经检测。他们写道，建议以有效检测的综合测验来达到最佳的诊断准确度(等级B)。
* 作者指出，虽然神经切片一般视为可有用于评估神经病变，如疑似淀粉样蛋白神经病变或者因为血管炎引起的多发性单一神经病变，但文献尚不足以提供何时进行神经切片，以评估DSP最有用(等级U)。
* 最后，作者结论表示，皮肤切片是有效确认表皮内神经纤维密度的技术，可考虑用于DSP诊断，特别是小纤维感觉性多神经病变 (等级C)。
他们写道，需要其他前溯研究，以在未来发展更实际的规范。
这三个组织目前合作进行疼痛型糖尿病多神经病变的实务系数管理。
England医师报告在过去24个月内，他接受TEVA提供的个人报酬作为演讲费用。他曾担任Current Treatment Options in Neurology的副编辑。他在同时间准备一个二硫化碳有毒侵害案例的具结。在过去5年间，他曾接受Pfizer药厂提供的研究支持。其他作者的宣告请见内文。
Neurology. 线上发表于2008年12月3日。
New Guidance on Evaluation of Distal Symmetric Polyneuropathy
By Susan Jeffrey
Medscape Medical News
Two new practice parameters aim to give evidence-based guidance on the role of laboratory and genetic testing, autonomic testing, and nerve and skin biopsy in the evaluation of distal symmetric polyneuropathy (DSP).
The documents were developed as a collaboration of the American Academy of Neurology (AAN), the American Association of Neuromuscular and Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation and are published online December 3 ahead of print in Neurology. They are also being published simultaneously in Muscle & Nerve and the Archives of Physical Medicine and Rehabilitation, the journals of the other 2 organizations.
"The guidelines start with the premise that the combination of neuropathic symptoms, signs, and electrodiagnostic findings are useful for the accurate diagnosis of distal symmetric polyneuropathy," lead author John England, MD, from Louisiana State University Health Sciences Center, in New Orleans, said in an interview with AAN.com, published on the AAN site. "The 2 new guidelines provide the current best evidence regarding the appropriate choice of tests to refine the diagnosis and get at the cause of DSP," he said.
Common Disorder
Polyneuropathy is a relatively common neurologic disorder, the authors write, with an overall prevalence of about 2.4% per 100,000, rising to 8% per 100,000 among those over 55 years old. "Since there are many etiologies of polyneuropathy," they write, "a logical clinical approach is needed for evaluation and management."
The new practice parameters were developed based on a review of evidence published between 1980 and March 2007. Articles were classified using a 4-tiered level of evidence scheme, with level A considered the strongest.
The aim was to provide evidence-based guidelines on the role of laboratory and genetic tests in the first document and the role of autonomic testing, nerve biopsy, and skin biopsy in the second.
The guidelines for laboratory and genetic testing include the following:
Screening laboratory tests may be considered for all patients with polyneuropathy (level A), the authors state. Tests that provide the highest yield, they write, are blood glucose, serum B12 with metabolites (methylmalonic acid with or without homocysteine), and serum protein immunofixation electrophoresis (level C). If there is no definite evidence of diabetes by routine blood glucose testing, then testing for impaired glucose tolerance may be considered in distal asymmetric sensory polyneuropathy (level C).
Genetic testing should be conducted for the accurate diagnosis and classification of hereditary neuropathies (level A), the authors write. Genetic testing may be considered in patients with cryptogenic polyneuropathy who exhibit a hereditary neuropathy phenotype (level C), they add. Initial genetic testing should be guided by the clinical phenotype, inheritance pattern, and electrodiagnotistic features and should focus on the most common abnormalities, they write. These include the CMT1A duplication/HNPP deletion, Cx32 (GJB1), and MFN2 mutation screening.
"There is insufficient evidence to determine the usefulness of routine genetic testing in patients with cryptogenic polyneuropathy who do not exhibit a hereditary neuropathy phenotype (level U)," the authors note.
The guidelines for autonomic testing, nerve biopsy, and skin biopsy include the following:
The second document concludes that autonomic testing should be considered in the evaluation of patients with polyneuropathy to document autonomic nervous system dysfunction (level B). Autonomic testing should be considered especially for the evaluation of suspected autonomic neuropathy (level B) and distal small-fiber sensory polyneuropathy (level C), the authors note. A battery of validated tests is recommended to achieve the highest diagnostic accuracy (level B), they write.
Although nerve biopsy is generally accepted as useful in the evaluation of neuropathies such as suspected amyloid neuropathy or mononeuropathy multiplex due to vasculitis, the authors point out, "the literature is insufficient to provide a recommendation regarding when a nerve biopsy may be useful in the evaluation of DSP (level U)."
Finally, the authors conclude that skin biopsy is a validated technique for determining intraepidermal nerve-fiber density and may be considered for the diagnosis of DSP and particularly of small-fiber sensory polyneuropathy (level C).
Additional prospective studies are required for the development of more exact guidelines in future, they write.
The 3 organizations are now collaborating on a practice parameter for the management of painful diabetic polyneuropathy.
Dr. England reports that within the past 24 months, he has received personal compensation from TEVA as an honorarium for speaking. He has served as associate editor for Current Treatment Options in Neurology. He prepared a deposition in a toxic tort case involving carbon disulfide in the same period. In the past 5 years, he has received research support from Pfizer. Disclosures for other coauthors appear in the documents.
Neurology. Published online December 3, 2008.