The team used an fMRI to take images before beginning the procedure and again after several months of treatment so that they could mark any changes that may have occurred in the brain. Participants were split into three groups and received three different treatments: the first received electro-acupuncture in the affected hand, the second received electro-acupuncture in the ankle opposite of the affected hand, and the third received sham electro-acupuncture (in which placebo needles were used) in the affected hand.
Patients in all conditions reported an improvement in their carpal tunnel-related pain, meaning that the sham acupuncture made use of the placebo effect. However, real acupuncture in the affected hand contributed to measurable physiological improvements in the wrist and brain, while real acupuncture in the ankle showed improvements in the wrist only. In contrast, no physiological improvements were linked to the sham acupuncture treatment.
Senior author of the study Dr. Vitaly Napadow explained how acupuncture remaps the brain in carpal tunnel patients, stating, “Sham acupuncture may ‘work’ by modulating known placebo circuitry in the brain. In contrast, real acupuncture may improve CTS [carpal tunnel syndrome] symptoms by rewiring the primary somatosensory cortex, in addition to modulating local blood flow to the peripheral nerve in the wrist. In other words, both peripheral and central neurophysiological changes in CTS may be halted or even reversed by electro-acupuncture interventions that provide more prolonged and regulated input to the brain – something that future, longer-term neuroimaging studies should explore.”
Carpal tunnel syndrome is classified as a neuropathic pain disorder, as previous studies have found that parts of the brain, most notably the somatosensory cortex that receives signals related to touch, are remapped by the disorder. Therefore, acupuncture’s effectiveness in reversing and rewiring these changes makes it an invaluable tool for treating the chronic pain associated with carpal tunnel.
Related: Carpal tunnel syndrome on the rise due to obesity