Taniguchi Tomoya, Kinukawa Tomoaki Alex, Takeuchi Nobuyuki, Sugiyama Shunsuke, Nishihara Makoto, Nishiwaki Kimitoshi, Inui Koji
Department of Anesthesiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Neuropsychiatric Department, Aichi Medical University, Nagakute, Japan.
Front Neurosci. 2022 Feb 23;16:837340. doi: 10.3389/fnins.2022.837340. eCollection 2022.
Wind-up like pain or temporal summation of pain is a phenomenon in which pain sensation is increased in a frequency-dependent manner by applying repeated noxious stimuli of uniform intensity. Temporal summation in humans has been studied by observing the increase in pain or flexion reflex by repetitive electrical or thermal stimulations. Nonetheless, because the measurement is accompanied by severe pain, a minimally invasive method is desirable. Gradual augmentation of flexion reflex and pain induced by repetitive stimulation of the sural nerve was observed using three stimulation methods-namely, bipolar electrical, magnetic, and monopolar electrical stimulation, with 11 healthy male subjects in each group. The effects of frequency, intensity, and number of repetitive stimuli on the increase in the magnitude of flexion reflex and pain rating were compared among the three methods. The reflex was measured using electromyography (EMG) from the short head of the biceps femoris. All three methods produced a frequency- and intensity-dependent progressive increase in reflex and pain; pain scores were significantly lower for magnetic and monopolar stimulations than for bipolar stimulation ( < 0.05). The slope of increase in the reflex was steep during the first 4-6 stimuli but became gentler thereafter. In the initial phase, an increase in the reflex during the time before signals of C-fibers arrived at the spinal cord was observed in experiments using high-frequency stimulation, suggesting that wind-up was caused by inputs of A-fibers without the involvement of C-fibers. Magnetic and monopolar stimulations are minimally invasive and useful methods for observing the wind-up of the flexion reflex in humans. Monopolar stimulation is convenient because it does not require special equipment. There is at least a partial mechanism underlying the wind-up of the flexion reflex that does not require C-fibers.
痛觉增敏或疼痛的时间总和是一种现象，即通过施加强度均匀的重复有害刺激，疼痛感觉会以频率依赖的方式增加。通过观察重复电刺激或热刺激引起的疼痛增加或屈曲反射，对人类的时间总和进行了研究。然而，由于这种测量伴随着剧烈疼痛，因此需要一种微创方法。使用三种刺激方法，即双极电刺激、磁刺激和单极电刺激，观察了11名健康男性受试者腓肠神经重复刺激引起的屈曲反射和疼痛的逐渐增强，每组11名。比较了三种方法中重复刺激的频率、强度和次数对屈曲反射幅度增加和疼痛评分的影响。使用股二头肌短头的肌电图（EMG）测量反射。所有三种方法均产生了频率和强度依赖性的反射和疼痛逐渐增加；磁刺激和单极刺激的疼痛评分明显低于双极刺激（<0.05）。反射增加的斜率在最初的4-6次刺激期间陡峭，但此后变得平缓。在初始阶段，在使用高频刺激的实验中观察到，在C纤维信号到达脊髓之前的时间内反射增加，这表明痛觉增敏是由A纤维输入引起的，而不涉及C纤维。磁刺激和单极刺激是观察人类屈曲反射痛觉增敏的微创且有用的方法。单极刺激很方便，因为它不需要特殊设备。屈曲反射的痛觉增敏至少有部分机制不涉及C纤维。
