Triple Transcranial Static Magnetic Field Stimulation System ("SHIN jiba") Modulates the Neural Activity of the Lumbar Spinal Cord: A Cross-over and Single-Blind Study in Healthy Subjects.

Objectives: The triple transcranial static magnetic field stimulation (tSMS) system (SHIN jiba), a new form of tSMS, can generate a stronger magnetic field that reaches deeper regions than the conventional tSMS method. Although SHIN jiba suppresses the neural activity of the brain, the neuromodulatory effects on the spinal cord remain unclear. The aim of this study was to investigate the effects of SHIN jiba on the activity of spinal cord circuits and the ascending neural pathways in the lumbar spinal cord by measuring H-reflex and somatosensory evoked potentials (SEPs).

Materials and methods: This study comprised two experiments involving 19 healthy subjects and an additional experiment involving 15 healthy subjects. All experiments were cross-over and single-blind studies. In all experiments, SHIN jiba or sham stimulation was applied over the lumbar region (between the 11th and 12th thoracic vertebrae) for 20 minutes. In experiment 1, H-reflex after the electrical stimulation of the right tibial nerve was recorded before, immediately after, and 15 minutes after the intervention. In experiment 2, SEPs after the electrical stimulation of the right posterior tibial nerve were recorded at the same point as experiment 1.

Results: The H-reflex amplitude was significantly suppressed immediately after SHIN jiba stimulation for 20 minutes. In contrast, the SEP amplitudes did not change before and after SHIN jiba stimulation.

Conclusions: These findings suggest that SHIN jiba has different effects on the activity of spinal cord circuits and the ascending neural pathways in the lumbar spinal cord. SHIN jiba can be a new tool for modulating the neural activity of the spinal cord.