Rossini P M, Tecchio F, Sabato A, Finazzi-Agrò A, Pasqualetti P, Rossi S
Ospedale Fatebenefratelli, Isola Tiberina, Rome, Italy.
Muscle Nerve. 1996 Oct;19(10):1302-9. doi: 10.1002/(SICI)1097-4598(199610)19:10<1302::AID-MUS7>3.0.CO;2-I.
Latency and amplitude characteristics of motor evoked potentials (MEPs) from abductor digiti minimi (ADM) and first dorsal interosseus (FDI) muscles were evaluated in 7 healthy volunteers via magnetic transcranial stimulation of the hemiscalp overlying contralateral motor areas. MEPs in complete relaxation and during contraction were recorded in two different experimental conditions: before and following anesthesia of median (sensory + motor) and radial (sensory) nerve fibers at wrist. This procedure induced a complete loss of skin sensation from dorsal and palmar aspects of the hand area "enveloping" the FDI muscle. On the other hand, the skin overlying the ADM muscle, as well as the strength of ulnar nerve supplied muscles were spared. This selective sensory deprivation lead to the following short-term changes: the physiological latency "jump" toward shorter values in contracted MEPs vs. relaxation was partially lost in the FDI (3.0 +/- 1.4 ms in basal condition, 1.8 +/- 1.1 ms after anesthesia, P = 0.028), while it was still clearly evident in the ADM (3.7 +/- 0.9 ms and 3.3 +/- 1.0 ms, respectively). Moreover, minor amplitude changes of MEPs during active contraction in the two muscles were detected: MEPs recorded from the FDI muscle were less potentiated during voluntary contraction than those recorded from the ADM muscle. The role of the cutaneous input in governing latency/amplitude characteristics of MEPs is discussed.
通过对覆盖对侧运动区的半侧头皮进行磁刺激，在7名健康志愿者中评估了小指展肌（ADM）和第一背侧骨间肌（FDI）运动诱发电位（MEP）的潜伏期和波幅特征。在两种不同的实验条件下记录了完全放松和收缩时的MEP：在腕部正中（感觉+运动）和桡神经（感觉）纤维麻醉之前和之后。该操作导致“包裹”FDI肌肉的手部区域的背侧和掌侧皮肤感觉完全丧失。另一方面，ADM肌肉上方的皮肤以及尺神经支配肌肉的力量未受影响。这种选择性感觉剥夺导致了以下短期变化：与放松相比，收缩的MEP中生理潜伏期向更短值的“跳跃”在FDI中部分丧失（基础状态下为3.0±1.4毫秒，麻醉后为1.8±1.1毫秒，P = 0.028），而在ADM中仍明显可见（分别为3.7±0.9毫秒和3.3±1.0毫秒）。此外，还检测到两块肌肉在主动收缩期间MEP的微小波幅变化：FDI肌肉记录的MEP在自主收缩期间比ADM肌肉记录的MEP增强程度小。讨论了皮肤输入在控制MEP潜伏期/波幅特征中的作用。
