Ferrante M A, Wilbourn A J
EMG Laboratory, Neurology Department, Cleveland Clinic Foundation, Ohio 44195, USA.
Muscle Nerve. 1995 Aug;18(8):879-89. doi: 10.1002/mus.880180813.
To determine which sensory nerve conduction studies (S-NCS) are helpful in detecting supraclavicular axon loss brachial plexopathies, we selected 53 cases (of 417 reviewed) in whom complicating factors were absent and which, by needle electrode examination findings, involved only a single "truncal" element (upper, middle, or lower) of the brachial plexus. Extensive S-NCS included: median, recording thumb (Med-D1), index (Med-D2), and middle fingers (Med-D3); ulnar, recording fifth finger (Uln-D5); dorsal ulnar cutaneous, recording dorsum of the hand (DUC); radial, recording base of thumb; and both medial and lateral antebrachial cutaneous (MABC, LABC), recording forearm. Except for the median sensory fibers, the "cord" elements traversed by the sensory fibers assessed during the S-NCS listed above are anatomically defined (i.e., the sensory fibers enter the brachial plexus at only one cord). In regard to the median sensory fibers, however, there are two possible pathways through the infraclavicular plexus: (1) the lateral cord and/or (2) the medial cord. Because the lower trunk is only accessible via the medial cord, any sensory fibers found to be traversing the lower trunk had to first traverse the medial cord. Similarly, those traversing the upper and middle trunks must first be a component of the lateral cord. The frequency that the various S-NCS responses were abnormal (unelicitable, below laboratory normal value, or < or = 50% of the contralateral response) for a given brachial plexus element lesion was as follows: (1) upper trunk (UT): 25 of 26 Med-D1, 25 of 26 LABC, 15 of 26 radial, 5 of 26 Med-D2, 2 of 26 Med-D3; (2) middle trunk (MT): 1 of 1 Med-D3; (3) lower trunk (LT): 25 of 26 Uln-D5, 22 of 23 DUC, 11 of 17 MABC, 3 of 23 Med-D3. With lower trunk brachial plexopathies, both "routine" (Uln-D5) and "uncommon" (DUC; MABC) S-NCS are abnormal. With upper trunk brachial plexopathies, in contrast, only the "uncommon" S-NCS (Med-D1; LABC) are consistently affected. The "routine" median S-NCS recording digit 2 (Med-D2) is far less reliable than the median S-NCS recording digit 1 (Med-D1) in detecting upper trunk axon loss brachial plexopathies. Additionally, the various pathways traversed by the fibers contributing to the individual S-NCS responses can be predicted, an important point when the full extent of a brachial plexus lesion is sought.
为确定哪些感觉神经传导研究（S-NCS）有助于检测锁骨上轴突丢失性臂丛神经病，我们从417例回顾病例中选取了53例，这些病例不存在复杂因素，且根据针电极检查结果，仅累及臂丛神经的单个“干”成分（上干、中干或下干）。广泛的S-NCS包括：正中神经，记录拇指（Med-D1）、示指（Med-D2）和中指（Med-D3）；尺神经，记录小指（Uln-D5）；尺背侧皮神经，记录手背（DUC）；桡神经，记录拇指基部；以及前臂内侧皮神经和外侧皮神经（MABC、LABC），记录前臂。除正中感觉纤维外，上述S-NCS评估过程中感觉纤维所穿过的“束”成分在解剖学上是明确的（即感觉纤维仅从一个束进入臂丛神经）。然而，对于正中感觉纤维，有两条可能穿过锁骨下丛的途径：（1）外侧束和/或（2）内侧束。由于下干仅通过内侧束可及，任何被发现穿过下干的感觉纤维必定首先穿过内侧束。同样，那些穿过上干和中干的纤维必定首先是外侧束的组成部分。对于给定的臂丛神经成分损伤，各种S-NCS反应异常（无法引出、低于实验室正常值或≤对侧反应的50%）的频率如下：（1）上干（UT）：26例Med-D1中有25例、26例LABC中有25例、26例桡神经中有15例、26例Med-D2中有5例、26例Med-D3中有2例；（2）中干（MT）：1例Med-D3中有1例；（3）下干（LT）：26例Uln-D5中有25例、23例DUC中有22例、17例MABC中有11例、23例Med-D3中有3例。在下干臂丛神经病中，“常规”（Uln-D5）和“非常规”（DUC；MABC）S-NCS均异常。相比之下，在上干臂丛神经病中，只有“非常规”S-NCS（Med-D1；LABC）持续受到影响。在检测上干轴突丢失性臂丛神经病时，记录示指的“常规”正中S-NCS（Med-D2）远不如记录拇指的正中S-NCS（Med-D1）可靠。此外，有助于各个S-NCS反应的纤维所穿过的各种途径是可以预测的，这在探寻臂丛神经损伤的全貌时是一个重要要点。
