Menkes D L, Swenson M R, Sander H W
Department of Neurology, University of Louisville School of Medicine, KY, USA.
Electromyogr Clin Neurophysiol. 2000 Jun;40(4):205-10.
Current Perception Threshold (CPT) evaluation quantifies the sensory threshold to transcutaneous electrical stimulation of three sensory fiber subtypes: A-beta (2,000 Hz), A-delta (250 Hz) and C fibers (5 Hz). Demyelinating polyneuropathies tend to affect larger myelinated fibers before smaller unmyelinated fibers, and they usually begin at the proximal nerve roots or terminal axons, due to relative weakness of the blood-nerve barrier in these locations. Axonal polyneuropathies tend to affect smaller fibers before larger fibers, in a distal to proximal gradient. Ten patients with demyelinating polyneuropathy and ten patients with axonal polyneuropathy underwent CPT testing. CPT comparisons were made with regard to side-to-side asymmetries, fiber type involvement, and the ratio of fiber types involved. The C2, lateral antebrachial cutaneous, and sural distributions were examined bilaterally. Demyelinating polyneuropathies were detected with 50% sensitivity and 100% specificity. This diagnostic sensitivity is similar to that of published criteria based upon motor nerve conduction. CPT testing can distinguish demyelinating from axonal polyneuropathies. It may be particularly helpful in patients with predominantly sensory symptoms in whom EMG/NCS data may be equivocal, or in patients who decline EMG/NCS studies.
电流感觉阈值（CPT）评估可量化经皮电刺激三种感觉纤维亚型的感觉阈值：Aβ（2000赫兹）、Aδ（250赫兹）和C纤维（5赫兹）。脱髓鞘性多发性神经病往往先影响较大的有髓纤维，而后影响较小的无髓纤维，并且通常始于近端神经根或终末轴突，这是由于这些部位血神经屏障相对薄弱。轴索性多发性神经病往往先影响较小的纤维，而后影响较大的纤维，呈远端到近端的梯度变化。10例脱髓鞘性多发性神经病患者和10例轴索性多发性神经病患者接受了CPT测试。对CPT进行了双侧不对称性、纤维类型受累情况以及受累纤维类型比例方面的比较。对双侧的C2、前臂外侧皮神经和腓肠神经分布区域进行了检查。脱髓鞘性多发性神经病的检测灵敏度为50%，特异性为100%。这种诊断灵敏度与基于运动神经传导的已发表标准相似。CPT测试能够区分脱髓鞘性和轴索性多发性神经病。对于主要有感觉症状且肌电图/神经传导速度（EMG/NCS）数据可能不明确的患者，或者拒绝接受EMG/NCS检查的患者，它可能特别有用。
