Effects of acupuncture at GB20 on CO2 reactivity in the basilar and middle cerebral arteries during hypocapnia in healthy participants.

Abstract

The acupoint GB20 is known to affect vertebrobasilar blood flow regulation. However, no previous study has used transcranial Doppler imaging to examine whether acupuncture at GB20 has a selective effect on blood flow in various cerebral arteries, such as the basilar artery (BA) and the middle cerebral arteries (MCAs). Therefore, this study sought to determine the specific effects of GB20 acupuncture on cerebral blood flow (CBF). Blood flow velocity and CO(2) reactivity were measured by transcranial Doppler imaging with a 2-MHz pulsed Doppler probe observed through both temporal windows for the MCAs and through the suboccipital window for the BA before and after GB20 acupuncture treatment in 15 healthy young male volunteers. The changes in hyperventilation-induced CO(2) reactivity and corrected blood flow velocities at 40 mmHg (CV40) were assessed for the BA and both MCAs. Blood pressure and heart rate were measured before and after the acupuncture treatment. CO(2) reactivity in the BA increased significantly after GB20 acupuncture treatment compared with baseline (p=0.041). In contrast, CO(2) reactivity in both MCAs remained unchanged. The CV40 in the BA and the MCAs showed no change after the GB20 acupuncture treatment. The mean heart rate decreased significantly after the GB20 acupuncture, whereas the mean blood pressure showed no change. This study demonstrated that acupuncture treatment on GB20 increases CO(2) reactivity specifically in the BA, with no effect in the MCAs. These results clinically support the use of GB20 to treat disorders of posterior cerebral circulation and support the idea that particular acupoints affect specific brain regions and cerebral arteries.