磁気刺激法と電気刺激法を組み合わせた脊髄運動細胞の興奮性試験の試み

The present experiment was performed whether H-reflex may be recorded in the intrinsic muscles of the human hand. To test this possibility, combined magnetic stimulation (MS) of the scalp and supramaximal (SM) ulnar nerve stimulation elicited EMG activity after the direct motor response in the first dorsalinterosseus (FDI) muscle. Presumable H-reflex were recorded only when there was a corticospinal volley capable of freeing the motor axons, through collision, from the antidromic motor volley set up by the SM nerve stimulation. We elicited presumable H-reflex three out of six subjects tested (50%). In particular, one out of three subjects showed clear H-refelx of FDI muscle at MS-SM interval at 4-8 ms (30-60% of maximum motor potential: M-wave). Therefore, it was suggested that this method is usefull for testing spinal excitability of intrinsic muscles which are difficult of eliciting H-reflex. Although H-reflexes can indeed be revealed using a collision technique, this method must be still more examined for establishing validity in the future.