Researchers have shown that stimulating a part of the brain using weak AC electricity through electrodes on the scalp can reduce, or in some cases eliminate, chronic pain.
Twenty patients with chronic back pain were given two 40-minute sessions of stimulation that took place one to three weeks apart. In one session the stimulation focused on the somatosensory cortex, associated with pain, and in the other session (a placebo or sham treatment) the stimulation was focused on another area of the brain. The patients could not feel the difference between the sham and real sessions.
All of them reported a significant reduction in pain immediately following the real treatments. Remarkably, some participants reported feeling no pain afterwards. Participants did not report the same pain reduction after the sham stimulation sessions.
Science Daily: Can stimulating the brain treat chronic pain?
The Journal of Pain: Identifying and Engaging Neuronal Oscillations by Transcranial Alternating Current Stimulation in Patients With Chronic Low Back Pain