Electroacupuncture of the Ophthalmic Branch of the Trigeminal Nerve: Effects on Prefrontal Cortex Blood Flow.

Abstract

Objective: The current authors observed enhanced cerebral blood flow (CBF) in the prefrontal cortex (PFC) in response to 100-Hz electroacupuncture (EA) stimulation of the ophthalmic branch of the trigeminal nerve. However, it is not yet clear if responsiveness to 100-Hz EA depends on stimulus intensity. This study examined the effects of stimulus strength on PFC CBF during 100-Hz EA of the ophthalmic branch of the trigeminal nerve. Materials and Methods: Twelve subjects underwent 3 acupuncture sessions: I, control, no stimulation; II, 0.1 mA EA; and III, 0.2 mA EA). Needles were inserted 1 cm lateral of the head median line; the anterior insertion point was on the front hairline and the posterior insertion point was ∼7 cm behind the hairline. Stimulation frequency was set to 100-Hz. PFC CBF was measured in terms of oxygenated, deoxygenated, and total hemoglobin (OxyHb, DeoxyHb, TotalHb, respectively), using 16-channel (Ch) near-infrared spectroscopy. Results: Stimulation of 0.2 mA was associated with significant elevation of OxyHb levels in the 0.1 mA condition in Chs 6, 10, and 12. Ch 2-6, 10, 12 signals were notably higher than in the control condition. Stimulation of 0.2 mA and 0.1 mA were associated with significant declines in DeoxyHb levels, compared to the control condition in Ch 4. Finally, 0.2 mA stimulation in Chs 12 and 13 was associated with significant elevation of TotalHb levels in the control condition. Conclusions: Using 0.2-mA stimulation, 100-Hz EA of the ophthalmic nerve enhances PFC CBF more strongly than 0.1-mA stimulation.