Division of Plastic Surgery, Department of Surgery, University of Alberta, Edmonton, Alberta, Canada.
Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, Missouri.
J Bone Joint Surg Am. 2019 Apr 17;101(8):730-738. doi: 10.2106/JBJS.18.00554.
Cubital tunnel syndrome has a spectrum of presentations ranging from mild paresthesias to debilitating numbness and intrinsic atrophy. Commonly, the classification of severity relies on clinical symptoms and slowing of conduction velocity across the elbow. However, changes in compound muscle action potential (CMAP) amplitude more accurately reflect axonal loss. We hypothesized that CMAP amplitude would better predict functional impairment than conduction velocity alone.
A retrospective cohort of patients who underwent a surgical procedure for cubital tunnel syndrome over a 5-year period were included in the study. All patients had electrodiagnostic testing performed at our institution. Clinical and electrodiagnostic variables were recorded. The primary outcome was preoperative functional impairment, defined by grip and key pinch strength ratios. Multivariable regression identified which clinical and electrodiagnostic variables predicted preoperative functional impairment.
Eighty-three patients with a mean age of 57 years (75% male) were included in the study. The majority of patients (88%) had abnormal electrodiagnostic studies. Fifty-four percent had reduced CMAP amplitude, and 79% had slowing of conduction velocity across the elbow (recorded from the first dorsal interosseous). On bivariate analysis, older age and longer symptom duration were significantly associated (p < 0.05) with reduced CMAP amplitude and slowing of conduction velocity across the elbow, whereas body mass index (BMI), laterality, a primary surgical procedure compared with revision surgical procedure, Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire scores, and visual analog scale (VAS) scores for pain were not. Multivariable regression analysis demonstrated that reduced first dorsal interosseous CMAP amplitude independently predicted the loss of preoperative grip and key pinch strength and that slowed conduction velocity across the elbow did not.
Reduced first dorsal interosseous amplitude predicted preoperative weakness in grip and key pinch strength, and isolated slowing of conduction velocity across the elbow did not. CMAP amplitude is a sensitive indicator of axonal loss and an important marker of the severity of cubital tunnel syndrome. It should be considered when counseling patients with regard to their prognosis and determining the necessity and timing of operative intervention.
Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
肘管综合征的表现范围从轻度感觉异常到衰弱性麻木和内在萎缩不等。通常，严重程度的分类依赖于临床症状和肘部传导速度的减慢。然而，复合肌肉动作电位（CMAP）幅度的变化更能准确反映轴索丢失。我们假设 CMAP 幅度比单独的传导速度更能预测功能障碍。
本研究纳入了在过去 5 年内接受手术治疗的肘管综合征患者的回顾性队列。所有患者均在我院进行电诊断测试。记录临床和电诊断变量。主要结果是术前功能障碍，定义为握力和关键捏力比。多变量回归确定了哪些临床和电诊断变量预测术前功能障碍。
研究纳入了 83 名平均年龄为 57 岁（75%为男性）的患者。大多数患者（88%）的电诊断研究异常。54%的患者 CMAP 幅度降低，79%的患者肘部传导速度减慢（记录自第一背侧骨间肌）。在单变量分析中，年龄较大和症状持续时间较长与 CMAP 幅度降低和肘部传导速度减慢显著相关（p < 0.05），而体重指数（BMI）、侧别、初次手术与翻修手术、手臂、肩部和手部残疾问卷（DASH）评分以及疼痛视觉模拟量表（VAS）评分则没有。多变量回归分析表明，第一背侧骨间肌 CMAP 幅度降低独立预测术前握力和关键捏力丧失，而肘部传导速度减慢则不能。
第一背侧骨间肌 CMAP 幅度降低预测术前握力和关键捏力减弱，而肘部传导速度减慢则不能。CMAP 幅度是轴索丢失的敏感指标，也是肘管综合征严重程度的重要标志物。在为患者提供预后咨询和确定手术干预的必要性和时机时，应考虑这一因素。
预后 IV 级。请参阅作者说明，以获取完整的证据水平描述。
