Safety of Yamamoto New Scalp Acupuncture in Healthy Subjects and the Relationship Between Shoulder Stiffness, Diagnosis Points, and Stimulation Points

Yamamoto New Scalp Acupuncture (YNSA) has been used in clinical practice for pain symptoms worldwide. However, the safety of YNSA and the role of the diagnosis and stimulation points have never been investigated. This study aimed to investigate the safety of YNSA and the relationship between the diagnosis points, the stimulation points, and changes in shoulder stiffness. YNSA was performed at the shoulder point A, acupuncture at the non-shoulder point D, and no intervention as a control in 15 healthy participants three times with a washout period of 1 week. Adverse reactions (changes in blood pressure, changes in heart rate, or bleeding), objective evaluation of the pressure pain threshold (PPT) and muscle hardness (MH) scores at the shoulder, and subjective evaluation of shoulder stiffness with a visual analog scale (VAS) were recorded before, during, and 20 min after stimulation. In the safety evaluation, no adverse reactions such as hypotension, bradycardia, or bleeding/hematoma were observed. PPT and MH revealed no significant difference between the conditions. There was a significant difference in the VAS between all three conditions (p = 0.039). Post-hoc analysis showed a significant difference between controls and D-point stimulation (p = 0.034), but no significant difference between A- and D-point stimulation. VAS subanalysis and post-hoc analysis in right-LI4-positive subjects (n = 4) showed a significant difference in VAS between A-point stimulation and controls (p = 0.01, 0.015, respectively). Our pilot investigation exhibited the safety of YNSA. Diagnosis and stimulation points may relate to changes in shoulder stiffness; however, further comparative studies with YNSA are required.