How does acupuncture relieve primary sciatica?

It has been know that acupuncture helps relieve pain in patients with sciatica. However how acupuncture exerts its action is not well understood. Recently a clinical study reported that arginine vasopressin, a hormone secreted in the particular areas of brain, played an important role in electroacupuncture analgesia. The study has been published in journal of Neuropetides.

Primary sciatica, also called piriformis syndromes, is a neuromuscular disorder that occurs when the sciatic nerve is compressed or otherwise irritated by the piriformis muscle. Primary sciatica usually starts with pain, tingling or numbness in the buttocks. Pain can be severe and extend down the length of sciatic nerve; and can be triggered by climbing, sitting for long periods of time or by applying firm pressure directly over piriformis muscle. However, most cases of sciatica are not due to piriformis syndrome. So many tests including MRI may be required to rule out other causes of sciatic nerve compression such as a herniated disc. Conventional approaches for primary sciatica include physiotherapy and anti-inflammatory medication which only provides temporary solution.

Recently Dr. XY Zhao and colleagues in China performed a clinical study to investigate the role of arginine vasopressin in the analgesic of acupuncture in patients with primary sciatica. Patients were divided into acupuncture group (n-45) and sham group (n=32). Patients in acupuncture group were given electroacupuncture at ST36 acupoint for 60 min while patients in sham group were given acupuncture at non-specific acupoint. Cerebrospinal fluid and serum were collected before, 30 min, 60 min and 120 min after acupuncture to detect the changes in arginine vasopressin levels. It was found that acupuncture stimulation at ST36 significantly increased the arginine vasopressin concentration in the cerebrospinal fluid but not in the serum. The increase in cerebrospinal arginine vasopressin level corresponded the pain relief level.

Arginine vasopressin in brain is reported to participate modulation of analgesia through its action to enhance the secretion of the endogenous opiate peptide such as beta-endorphin and dynorphin which are involved in pain modulation.

This study provides more evidence of central action of acupuncture analgesic effect.

Reference:

XY Zhao et al., The role of arginine vasopressin in electroacupuncture treatment of primary sciatica in human. Neuropeptides. 2015 Aug;52:61-5. doi: 10.1016 /j.npep.2015.06.002.   http://www.ncbi.nlm.nih.gov/pubmed/26142756