Characterizing acupuncture stimuli using brain imaging with fMRI – a systematic review and meta-analysis of the literature

Abstract

Background: The mechanisms of action underlying acupuncture, including acupuncture point specificity, are not well understood. In the previous decade, an increasing number of studies have applied fMRI to investigate brain response to acupuncture stimulation. Our aim was to provide a systematic overview of acupuncture fMRI research considering the following aspects: 1) differences between verum and sham acupuncture, 2) differences due to various methods of acupuncture manipulation, 3) differences between patients and healthy volunteers, 4) differences between different acupuncture points.

Acupuncture-Related Modulation of Pain-Associated Brain Networks During Electrical Pain Stimulation: A Functional Magnetic Resonance Imaging Study

“…The chosen acupoints, among others, are commonly used for pain treatment in the present literature. 25 Needling was performed with 0.25 · 25-mm stainless steel needles. All needles were inserted perpendicularly, to a depth of about 1-2 cm, at LI4 and LV3 and about 2-3 cm deep at ST36 (Fig.…”

“…25 Thus, some evidence already shows acupuncture-specific effects on pain, reflected by modulation in certain brain regions responsible for pain processing, but these effects are far from being established. 25 Many of the magnetic resonance imaging (MRI) studies on acupuncture so far have focused on the direct effects of the needling procedure of acupuncture, either alone or in an ongoing pain process with a standardized pain stimulus. The current trial studied the effects of acupuncture on subsequent individualized pain stimuli.…”

“…24 Previous neuroimaging studies showed that acupuncture changed activations in sensory, affective, cognitive, and inhibitory regions, including neural networks for pain perception and transmission. 25 A recent review focused on the differences between verum and sham acupuncture, among various acupuncture methods, between patients and healthy volunteers, and among different acupuncture points with regard to activity changes in specific brain areas. 25 Thus, some evidence already shows acupuncture-specific effects on pain, reflected by modulation in certain brain regions responsible for pain processing, but these effects are far from being established.…”

“…25 A recent review focused on the differences between verum and sham acupuncture, among various acupuncture methods, between patients and healthy volunteers, and among different acupuncture points with regard to activity changes in specific brain areas. 25 Thus, some evidence already shows acupuncture-specific effects on pain, reflected by modulation in certain brain regions responsible for pain processing, but these effects are far from being established. 25 Many of the magnetic resonance imaging (MRI) studies on acupuncture so far have focused on the direct effects of the needling procedure of acupuncture, either alone or in an ongoing pain process with a standardized pain stimulus.…”

Effects of Acupuncture on Sensory Perception: A Systematic Review and Meta-Analysis

“…Brain imaging studies have shown that acupuncture alters activation patterns in brain areas associated with pain processing [9]. It is postulated that in response to the needle stimulation mechanisms of the endogenous pain modulation such as diffuse noxious inhibitory controls (DNIC), segmental inhibition, and descending pain control pathways lead to a decrease in pain perception [10,11].…”