Seror P
Electromyography Laboratory, Rhumatology, 146 av. Ledru Rollin, 75011 Paris, France.
Clin Neurophysiol. 2004 Oct;115(10):2316-22. doi: 10.1016/j.clinph.2004.04.023.
This was to demonstrate the ability to electrodiagnosed mild lower brachial plexus lesion only through abnormal medial antebrachial cutaneous nerve (MABCN) conduction study.
We report 16 cases of unilateral, atypical pains and paresthesias of the upper limbs without motor deficit or atrophy. Patients were referred as carpal tunnel syndrome in 12 cases. All patients had needle examination of the impaired upper limb from C5 to T1. Motor and sensory conductions of median and ulnar nerves were bilaterally studied. MABCN was antidromically (16 cases) and orthodromically (9 cases) studied at the elbow in the both sides. MABCN abnormality was defined by an interside amplitude ratio of the sensory nerve action potential equal or greater than 2 (mean + 3 SD).
No patient had a definitive and accurate diagnosis, before MABCN abnormality determination. MABCN testing was abnormal in all the 16 cases with a mean interside amplitude ratio of 7.2 (mean + 25 SD), when all other motor and sensory nerve conductions were normal. All except four patients showed normal needle examination from C5 to T1. In 5 cases, an obvious cause (traumatic and neoplastic) explained the mild lower brachial plexus lesion. In 2 cases, a mild neurogenic thoracic outlet syndrome (NTOS) was confirmed by surgical findings. In the 9 other cases, the mild lower brachial plexus lesion defined by MABCN findings, was without cause and was considered as a mild NTOS.
These 16 cases, support a new electrodiagnostic pattern to define a mild lower brachial plexus lesion: comparatively low or low MABCN SNAP amplitude, normal median and ulnar SNAP/Compound motor action potential amplitudes and normal or slightly reduced interference pattern in some C8-T1 innervated muscles. This pattern can be found in patients with 'carpal tunnel syndrome like' symptoms who have normal electro-diagnostic examination, or in patients with clinical features suggesting a lower brachial plexus lesion.
本研究旨在证明仅通过异常的前臂内侧皮神经（MABCN）传导研究来对轻度下臂丛神经损伤进行电诊断的能力。
我们报告了16例单侧上肢非典型疼痛和感觉异常且无运动功能障碍或萎缩的病例。其中12例患者初诊为腕管综合征。对所有患者受损上肢从C5至T1进行针极肌电图检查。双侧研究正中神经和尺神经的运动和感觉传导。在双侧肘部对MABCN进行逆向（16例）和顺向（9例）研究。MABCN异常定义为感觉神经动作电位的双侧波幅比等于或大于2（均值+3标准差）。
在确定MABCN异常之前，没有患者得到明确准确的诊断。当所有其他运动和感觉神经传导均正常时，16例患者的MABCN检测均异常，平均双侧波幅比为7.2（均值+25标准差）。除4例患者外，其余患者从C5至T1的针极肌电图检查均正常。5例患者有明显病因（创伤性和肿瘤性）可解释轻度下臂丛神经损伤。2例患者经手术证实为轻度神经源性胸廓出口综合征（NTOS）。在其他9例患者中，由MABCN检查结果定义的轻度下臂丛神经损伤无明确病因，被认为是轻度NTOS。
这16例病例支持一种新的电诊断模式来定义轻度下臂丛神经损伤：MABCN感觉神经动作电位波幅相对较低或低，正中神经和尺神经感觉神经动作电位/复合运动动作电位波幅正常，部分由C8 - T1支配肌肉的干扰相正常或略有降低。这种模式可在电诊断检查正常但有“腕管综合征样”症状的患者中发现，或在具有提示下臂丛神经损伤临床特征的患者中发现。
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