Caro Xavier J, Galbraith Robert G, Winter Earl F
Southern California Fibromyalgia Research & Treatment Center, Northridge, California, 91325, USA.
Eur J Rheumatol. 2018 Jul;5(2):104-110. doi: 10.5152/eurjrheum.2018.17109. Epub 2018 Feb 13.
Whereas small fiber neuropathy (SFN) is now a recognized part of fibromyalgia (FM), surprisingly little attention has been paid to any findings of large fiber neuropathy (LFN) in this disorder. Since 90% to 95% of FM subjects seen in our outpatient facility routinely undergo EMG and nerve conduction studies (NCS) we elected to retrospectively review the EMG/NCS results garnered from a large cohort of unselected subjects in order to describe the electrodiagnostic features of LFN in FM.
Records from 100 consecutive, unselected clinic patients meeting the 1990 ACR criteria for FM, who had undergone EMG/NCS, were reviewed. The same electromyographer tested all subjects. After exclusion of FM patients with any other clinically relevant condition that might influence EMG results (e.g., familial neural degenerative conditions, diabetes mellitus, Vitamin B-12 deficiency, etc.) fifty-five FM subjects remained: 29 subjects with "FM Only," and 26 subjects with FM+Rheumatoid Arthritis ("FM+RA"). All subjects had also undergone ankle area skin biopsy for determination of epidermal nerve fiber density (ENFD). Fourteen other subjects, without FM or RA, examined by the same electromyographer, were used as an EMG/NCS comparison group.
Ninety percent of the "FM Only" subjects demonstrated a demyelinating and/or axonal, sensorimotor polyneuropathy, and 63% had findings of SFN (ENFD ≤7 fibers/mm), suggesting a mixed fiber neuropathy in most. Furthermore, 61% of the "FM Only" subjects showed EMG findings suggestive of non-myotomal lower extremity axonal motor denervation, most likely due to a polyneuropathy, and 41% satisfied published criteria for "possible" chronic inflammatory demyelinating polyneuropathy (CIDP). There was surprisingly little difference in the EMG/NCS findings between the "FM Only" and the "FM+RA" groups. With the exception of carpal tunnel syndrome, our EMG/NCS comparison group showed few to none of these findings.
Our review of the EMG/NCS results, gleaned from the largest FM cohort yet studied with these modalities, shows that electrodiagnostic features of polyneuropathy, muscle denervation, and CIDP are common in FM. Furthermore these electrodiagnostic findings are often seen coincident with SFN, and are not significantly influenced by the presence of RA. These results, particularly when taken as a whole, suggest that EMG/NCS may be clinically useful in detecting LFN in FM and help in better understanding the etiopathogenesis of this painful disorder.
鉴于小纤维神经病变（SFN）现已被公认为纤维肌痛（FM）的一部分，令人惊讶的是，在这种疾病中，大纤维神经病变（LFN）的任何发现都很少受到关注。由于在我们门诊就诊的90%至95%的FM患者常规接受肌电图（EMG）和神经传导研究（NCS），我们选择回顾性分析从一大群未经挑选的受试者中获得的EMG/NCS结果，以描述FM中LFN的电诊断特征。
回顾了100例连续的、未经挑选的符合1990年美国风湿病学会（ACR）FM标准且接受过EMG/NCS检查的门诊患者的记录。所有受试者均由同一位肌电图检查人员进行测试。在排除可能影响EMG结果的任何其他临床相关疾病（如家族性神经退行性疾病、糖尿病、维生素B12缺乏等）的FM患者后，剩下55例FM受试者：29例“仅FM”患者和26例FM合并类风湿关节炎（“FM+RA”）患者。所有受试者还接受了踝部皮肤活检以测定表皮神经纤维密度（ENFD）。另外14例未患FM或RA的受试者由同一位肌电图检查人员进行检查，作为EMG/NCS比较组。
90%的“仅FM”受试者表现出脱髓鞘和/或轴索性感觉运动性多神经病，63%有SFN表现（ENFD≤7根/毫米），提示大多数为混合性纤维神经病变。此外，61%的“仅FM”受试者的EMG表现提示非肌节性下肢轴索性运动神经失神经，很可能是由于多神经病所致，41%符合“可能的”慢性炎症性脱髓鞘性多神经病（CIDP）的既定标准。“仅FM”组和“FM+RA”组的EMG/NCS结果出人意料地几乎没有差异。除腕管综合征外，我们的EMG/NCS比较组几乎没有这些表现。
我们对通过这些方法研究的最大FM队列的EMG/NCS结果进行的回顾表明，多神经病、肌肉失神经和CIDP的电诊断特征在FM中很常见。此外，这些电诊断结果常与SFN同时出现，且不受RA存在的显著影响。这些结果，尤其是综合来看，表明EMG/NCS在检测FM中的LFN方面可能具有临床实用性，并有助于更好地理解这种疼痛性疾病的病因发病机制。
