Okada Yohei, Shiozaki Tomoyuki, Nakamura Junji, Azumi Yuji, Inazato Miyo, Ono Moe, Kondo Honoka, Sugitani Miyuki, Matsugi Akiyoshi
Department of Physical Therapy, Faculty of Health Sciences.
Department of Motor Control, Neurorehabilitation Research Center, Kio University.
Neuroreport. 2018 Sep 5;29(13):1135-1139. doi: 10.1097/WNR.0000000000001086.
Modulation of the soleus H-reflex following galvanic vestibular stimulation (GVS) has been used to evaluate vestibulospinal tract function. It is not known whether this modulation is because of vestibular stimulation and/or cutaneous stimulation, and the suitable stimulating intensity of GVS for the modulation is not established. We investigated the influence of GVS intensity and cutaneous stimulation on the soleus H-reflex in healthy adults. We applied cathodal GVS (at 1, 2, and 3 mA) or 3-mA cutaneous stimulation as a conditioning stimulation in a random order to 17 individuals in the prone position with the head facing forward, and we examined the changes in the right soleus H-reflex amplitude. We maintained the interval between the conditioning stimulation's onset and the tibial nerve stimulation evoking the soleus H-reflex constant at 100 ms. The amplitude of all conditioned H-reflexes was significantly larger than that of the unconditioned H-reflexes. The greatest facilitation of the H-reflex occurred when 3-mA GVS was applied. The degree of facilitation of the H-reflex by 3-mA GVS was significantly larger than that produced by the 3-mA cutaneous stimulation. These findings indicate that (a) the facilitation of the soleus motor neuron pool excitability by GVS is derived from both vestibular stimulation and cutaneous stimulation, and (b) the intensity of GVS affects the degree of facilitation. When this technique is used to examine vestibulospinal tract function, no less than 3 mA GVS may be appropriate as the conditioning stimulation.
利用直流电前庭刺激（GVS）后比目鱼肌H反射的调制来评估前庭脊髓束功能。目前尚不清楚这种调制是由于前庭刺激和/或皮肤刺激，并且尚未确定用于调制的GVS的合适刺激强度。我们研究了GVS强度和皮肤刺激对健康成年人比目鱼肌H反射的影响。我们将阴极GVS（1、2和3毫安）或3毫安的皮肤刺激作为条件刺激，以随机顺序施加于17名俯卧位且头部朝前的个体，并检查右侧比目鱼肌H反射幅度的变化。我们将条件刺激开始与诱发比目鱼肌H反射的胫神经刺激之间的间隔保持在100毫秒不变。所有条件性H反射的幅度均显著大于非条件性H反射的幅度。当施加3毫安GVS时，H反射的促进作用最大。3毫安GVS对H反射的促进程度显著大于3毫安皮肤刺激所产生的促进程度。这些发现表明：（a）GVS对比目鱼肌运动神经元池兴奋性的促进作用源于前庭刺激和皮肤刺激两者；（b）GVS强度影响促进程度。当使用该技术检查前庭脊髓束功能时，不少于3毫安的GVS作为条件刺激可能是合适的。
