Fisher M A
Department of Neurology, Michael Reese Hospital and Medical Center, University of Chicago Pritzker School of Medicine, IL 60616.
Muscle Nerve. 1991 Feb;14(2):120-3. doi: 10.1002/mus.880140206.
F waves were recorded from the abductor pollicis brevis stimulating the median nerve at the wrist. These data were compared to responses obtained after preceding supramaximal stimulation of digital fibers of the second (II) finger or the median nerve at the wrist. The time between conditioning and test stimuli were 50 msec. Following conditioning stimuli, F wave latencies were significantly increased while F amplitudes, durations, and persistences were all decreased. Chronodispersion was not significantly affected. These changes were associated with increased repetition of individual F responses. The most prominent changes were found after stimulation of fibers of digit II but only at levels of stimulation supramaximal for the sensory nerve action potential. Some, but relatively limited, changes were present after stimulation of digital fibers of the fifth finger. The results are consistent with afferent fiber, probably A delta, inhibition of antidromic motoneuron activation with associated decrease in central motor neuron pool excitability. The study also demonstrates that, except for chronodispersion, changes in F waves found with peripheral nerve injury may also occur due to physiological changes in the central nervous system.
通过刺激腕部正中神经，从拇短展肌记录F波。将这些数据与在之前对第二指（示指）的指纤维或腕部正中神经进行超强刺激后获得的反应进行比较。条件刺激和测试刺激之间的时间间隔为50毫秒。在条件刺激后，F波潜伏期显著延长，而F波振幅、时限和出现率均降低。时间离散度未受到显著影响。这些变化与单个F反应的重复增加有关。最显著的变化出现在刺激示指指纤维后，但仅在感觉神经动作电位的超强刺激水平时出现。在刺激第五指的指纤维后也出现了一些但相对有限的变化。这些结果与传入纤维（可能是Aδ纤维）抑制逆向运动神经元激活以及相关的中枢运动神经元池兴奋性降低一致。该研究还表明，除时间离散度外，周围神经损伤时F波的变化也可能由于中枢神经系统的生理变化而发生。
