Chung Kevin C, Florczynski Matthew M, Hearn Sandra L, Kim Hyungjin M, Burns Patricia B, Malay Sunitha
Charles B. G. de Nancrede Professor of Surgery, Section of Plastic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, MI.
Assistant Professor, Department of Orthopaedic Surgery, University of Cincinnati College of Medicine, Cincinnati, OH,
Plast Reconstr Surg. 2024 Nov 6. doi: 10.1097/PRS.0000000000011859.
In ulnar neuropathy at the elbow, weakness is classically a sign of severe disease. Weakness is associated with motor axonal loss as measured by decreased distal compound muscle action potential (CMAP) amplitude. Conduction block, a demyelinating phenomenon that recovers readily, can also cause weakness, creating ambiguity for the treating clinician.
This cross-sectional study evaluated baseline blinded data collected from 2020-2023 from the Surgery of the Ulnar Nerve randomized controlled trial comparing in-situ decompression versus transposition procedures. Adult patients underwent electrodiagnostic testing, clinical motor and sensory testing, and completed the Michigan Hand Questionnaire and Carpal Tunnel Questionnaire.
177 patients were categorized into 3 distinct groups based on normal distal CMAP amplitudes (77 patients), presence of conduction block with or without distal CMAP amplitude loss (37 patients), or pure axonal loss with distal CMAP amplitude loss in the absence of conduction block (63 patients). Compared to the normal group, patients with conduction block had significantly decreased pinch strength and worse function domain scores on the Michigan Hand Questionnaire and Carpal Tunnel Questionnaire, but shorter duration of disease. Patients with pure axonal loss had decreased pinch strength, worse 2-point discrimination, and worse overall, function and aesthetics domain scores on the Michigan Hand Questionnaire. There was a significant interaction between the effects of conduction block and distal CMAP amplitude on pinch strength, indicating that higher degrees of conduction block resulted in more pronounced loss of pinch strength in patients with relatively preserved distal CMAP amplitude.
Our findings support the paradigm that ulnar neuropathy at the elbow presenting with conduction block represents a distinct and intermediate pathophysiology, distinguished by quicker onset with less advanced neurological deficits.
Prognostic Level II.
在肘管综合征中，肌无力通常是严重疾病的体征。肌无力与运动轴突损失相关，可通过远端复合肌肉动作电位（CMAP）波幅降低来衡量。传导阻滞是一种易于恢复的脱髓鞘现象，也可导致肌无力，给临床治疗医生带来困扰。
这项横断面研究评估了2020年至2023年从尺神经手术随机对照试验中收集的基线盲法数据，该试验比较了原位减压与转位手术。成年患者接受了电诊断测试、临床运动和感觉测试，并完成了密歇根手问卷和腕管问卷。
177例患者根据远端CMAP波幅正常（77例患者）、存在或不存在远端CMAP波幅降低的传导阻滞（37例患者）或不存在传导阻滞的远端CMAP波幅降低的纯轴突损失（63例患者）分为3个不同组。与正常组相比，传导阻滞患者的捏力显著降低，在密歇根手问卷和腕管问卷上的功能域评分更差，但病程较短。纯轴突损失患者的捏力降低，两点辨别能力更差，在密歇根手问卷上的总体、功能和美学域评分更差。传导阻滞和远端CMAP波幅对捏力的影响之间存在显著交互作用，表明在远端CMAP波幅相对保留的患者中，更高程度的传导阻滞导致更明显的捏力丧失。
我们的研究结果支持这样一种模式，即伴有传导阻滞的肘管综合征代表一种独特的中间病理生理学，其特点是发病较快，神经功能缺损较轻。
预后II级。
