Lesser E A, Venkatesh S, Preston D C, Logigian E L
Division of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
Muscle Nerve. 1995 May;18(5):503-7. doi: 10.1002/mus.880180505.
In patients with carpal tunnel syndrome, low action potential amplitude after stimulation at the wrist (proximal to the lesion) is due to either demyelination or axonal degeneration. Demyelination can be distinguished from axonal degeneration by the presence of amplitude drop across the lesion. Amplitude drop is determined by comparison of action potential amplitude evoked by stimulation at the palm (distal to the lesion) with that of the wrist. Of 59 consecutive CTS patient hands, 36 (61%) showed significant reduction in CMAP and/or antidromic SNAP amplitudes at the wrist compared to the palm, indicating the presence of focal demyelination resulting in conduction block vs. pathologic dispersion with phase cancellation. Moreover, the smaller the wrist-evoked action potential amplitude, the greater the amplitude drop across the lesion. We conclude that in patients with CTS, as in other entrapment neuropathies, stimulation both proximal and distal to the lesion provides important pathophysiological information about the median nerve lesion.
在腕管综合征患者中，手腕（病变近端）刺激后动作电位幅度降低是由于脱髓鞘或轴索变性所致。脱髓鞘可通过病变部位存在幅度下降与轴索变性相鉴别。幅度下降通过比较手掌（病变远端）刺激诱发的动作电位幅度与手腕刺激诱发的动作电位幅度来确定。在连续59例腕管综合征患者的手部中，36例（61%）与手掌相比，手腕处复合肌肉动作电位（CMAP）和/或逆行感觉神经动作电位（SNAP）幅度显著降低，表明存在局灶性脱髓鞘导致传导阻滞与相位抵消的病理性离散。此外，手腕诱发的动作电位幅度越小，病变部位的幅度下降越大。我们得出结论，在腕管综合征患者中，与其他卡压性神经病一样，在病变近端和远端进行刺激可提供有关正中神经病变的重要病理生理信息。
