Acupuncture for neuropathic pain: focusing on the sympathetic nerve system

Following peripheral nerve injury, the sympathetic nervous system responds to noxious inputs that induce or exacerbate pain. Dorsal root ganglion (DRG) sympathetic sprouting after peripheral nerve injury may induce abnormal firing of neurons. Moreover, the areas of the brain that respond to nociceptive stimuli overlap with those areas activated by the sympathetic nervous system. Acupuncture is a widely used alternative therapy for neuropathic pain. It has been demonstrated that it has positive effects on the regulation of function in the autonomic nervous system. Based on previous studies, there are several possibilities for the regulation of sympathetic nerves by using acupuncture to relieve neuropathic pain. Acupuncture may act on the brain areas of pain and the sympathetic nervous system, decrease sympathetic nerve activity during neuropathic pain, attenuate sympathetic sprouting, and reduce the abnormal firing of neurons. Further studies are required to confirm these hypotheses. This review will help to better understand the potential mechanisms of acupuncture in neuropathic pain. Graphical abstract: http://links.lww.com/AHM/A62.