How does repeated verum acupuncture improve chronic pain in knee osteoarthritis?

Acupuncture has been effectively used to treat chronic pain conditions. However, the lack of understanding of underlying mechanisms of acupuncture, and reported cases of failure to produce greater clinical improvement, compared with sham acupuncture, have slowed down the incorporation of this modality into the mainstream of healthcare practice.

Functional magnetic resonance image (fMRI) showed that acupuncture stimulation caused changes in neuronal activity in many brain areas, including medial frontal cortex (MFC), hippocampus and periaqueductal gray (PAG). PAG is a pain-learning brain region as it is able to form long-term pain behavioural and nociceptive memory. Brain regional connectivity of PAG-MFC and PAG-hippocampus are believed to be associated with long-term pain learning process and pain memory.

Recently Dr. Jian Kong and colleagues in Harvard Medical School, the United States conducted a clinical study to assess the effect of repeated acupuncture specifically on brain regions known to support functions dysregulated in chronic pain conditions, such as knee osteoarthritis. Forty-nine patients with knee osteoarthritis were recruited and randomly divided into verum acupuncture and sham acupuncture groups. Patients in verum group were given acupuncture at ST35 and Xiyan points for the low-dose verum groups and additionally at GB34, SP9, GB39 and SP6 for the high-dose group, six times within one month. Treatments 1, 3, and 6 were conducted with the patient lying in a 3 Tesla MRI scanner. Treatments 2, 4 and 5 took place in a behavioural testing room. Sham acupuncture was performed with non-penetrating Streitberger needles at above acupoints.

It was shown at the end of study that verum acupuncture produced a significant decrease in knee pain and improved function in sport, and modulated connectivity of PAG-MFC and PAG-hippocampus, compared with sham acupuncture group.

Results of study have showed that repeated verum acupuncture might act by restoring the balance in the connectivity of the key pain brain regions, altering pain-related attention and memory. It also has implications for the assessment of the efficacy of acupuncture treatment with regard to reversal of chronic pain disorders.

Reference:

N Egorova et al., Repeated verum but not placebo acupuncture normalizes connectivity in brain regions dysregulated in chronic pain. NeuroImage: Clinical 9 (2015) 430–435.    http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0067485