Electroacupuncture on the Ophthalmic Branch of the Trigeminal Nerve Affects Cerebral Blood Flow in the Frontopolar Cortex During Mental Arithmetic: A Randomized Crossover Trial

Abstract

Objective: The aim of this study was to examine the effect of cerebral blood flow (CBF) in the frontopolar cortex (FPC) during mental arithmetic tasks by 0.2 mA electroacupuncture (EA) stimulation of the trigeminal nerve's ophthalmic branch. Materials and Methods: This study was a crossover, randomized clinical trial. The participants (19) were divided into a control and an EA group, and both groups performed 10-minute mental-arithmetic tasks. Subsequently, the control group was seated for 5 minutes, while the EA group received EA stimulated at 0.2 mA, 100 Hz, for 5 minutes. Then, the mental-arithmetic tasks were repeated. The primary outcome was oxygenated hemoglobin (OxyHb) levels in the FPC during the mental-arithmetic tasks. Data from 15 of the original 19 participants were analyzed. Results: EA stimulation elevated OxyHb levels significantly. In the right FPC, this occurred in channel (Ch) 4 and 6 (P < 0.05) and Ch 3 (P < 0.01). In the left FPC, this occurred in Ch 10 and 15 (P < 0.05) and Ch 11 and 14 (P < 0.01). EA stimulation affected Ch 11 especially. There was also a significant positive correlation between OxyHb levels during the mental-arithmetic tasks in Ch 11 and changes in the numbers of answers and correct answers (ρ = 0.48; P < 0.05). Conclusions: These results suggest that 0.2 mA EA stimulation increased OxyHb levels in the FPC, particularly associated with increased CBF in the left FPC. Furthermore, the OxyHb levels in the left FPC positively correlated with the changes in the numbers of answers and correct answers.