There's new hope for people who suffer from carpal tunnel syndrome, a feeling of numbness, tingling or pain in the hand because of a squeezed nerve at the wrist. It comes in the form of a non-invasive and drug-free method of pain relief: acupuncture, according to a new study published in the journal Brain.
Acupuncture, an ancient technique of traditional Chinese medicine, has long been used to treat chronic pain, and studies have suggested that it relieves symptoms at least slightly better than a placebo. When coupled with electric stimulation, the technique can work similarly to a more conventional therapy for pain relief called transcutaneous electrical nerve stimulation (TENS).
But exactly how acupuncture works is still largely unknown. Because it’s often difficult to measure pain—and how it changes—objectively, how well it works also remains uncertain.
To address these unknowns, researchers from Massachusetts General Hospital recruited 80 people with mild to moderate carpal tunnel syndrome. It's an ideal condition for measuring the effectiveness of a treatment, because unlike most chronic pain disorders, carpal tunnel syndrome is associated with measurable, physiological changes in the body. Sufferers experience a slowdown of nerve impulses traveling across the wrist, which can be detected by electrodes attached to the skin. They also experience destructive changes in the somatosensory cortex, the part of the brain responsible for the sense of touch. Nerve signals from the hand become "blurred," says lead author Vitaly Napadow, associate professor at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital and Harvard Medical School. Brain cells that usually respond to touch signals from individual fingers start to respond to signals from multiple fingers, he says.
People in the study were split into three groups, two of which received 16 sessions of electro-acupuncture over eight weeks, either on their affected wrist and forearm or on their ankle opposite that arm. The third group received “sham” electro-acupuncture, which used needles that didn't penetrate the skin on fake acupuncture points.
After the treatments were over, all three groups reported improvements in pain and numbness. But the objective measure of nerve conduction at the wrist only improved in the groups who had real acupuncture. Those who had real acupuncture at the affected arm (but not at the ankle) also experienced significant brain remapping, Napadow says. Before-and-after MRI scans showed that some of the carpal-tunnel related damage to their somatosensory cortexes had been partially repaired.
People who got real acupuncture seemed to have longer term benefits, too. At a three-month follow-up, people who experienced this type of brain remapping were more likely to report sustained or continued improvement in functionality—and in symptoms like pain, numbness, and tingling—than those who didn't.
The study suggests that while sham and real acupuncture might both relieve pain temporarily, real acupuncture has the most potential for lasting change.
“I want to stress that we did not heal or cure anybody, but we did see improvements,” says Napadow. “The fact that improvement was retained three months later—we think that’s very interesting and very important.”
People with serious forms of carpal tunnel syndrome were not included in the study, and Napadow says that those with advanced cases will likely need surgery or another more intensive treatment. But for some people, he says, acupuncture could be a good first-line treatment. “When performed by a trained professional, it’s fairly safe and has a low risk of side effects,” he says. “It’s definitely something that could be tried before moving to something much more invasive and higher risk.”