Effect of different pressure stimulation of muscle on the excitability of the spinal anterior horn cells

Abstract

We investigated the effect of different pressure stimulation intensities on the abductor pollicis brevis muscle on the excitability of spinal cord anterior horn cells. The subjects were 25 healthy right-handed adults. Pressure stimulation was applied vertically on the skin surface of the abductor pollicis brevis muscle for 30 seconds. The median nerve was electrically stimulated before and after the pressure stimulus was applied, and the F wave was recorded from the abductor pollicis brevis muscle. Two pressure stimulation intensities were applied: the pain threshold intensity and 50% of the pain threshold intensity. The analysis of the F-wave persistence and F/M amplitude ratio. No significant change was observed in the appearance F-wave persistence (before: 47.3±16.7%, after: 48.1±15.9%) and F/M amplitude ratio (before: 1.13±0.49%, after: 1.11±0.51%) after pressure stimulation at the pain threshold intensity compared with those before pressure stimulation. After pressure stimulation at 50% of the pain threshold intensity, the appearance F-wave persistence (before: 50.8±18.5%, after: 41.6±17.1%) and F/M amplitude ratio (before: 1.21±0.61%, after: 1.02±0.48%) decreased compared with those before pressure stimulation (p<0.05). This study suggests that the excitability of the anterior horn cells of the spinal cord was unchanged after compression stimulation at pain threshold intensity and decreased after compression stimulation at 50% of pain threshold intensity.