Neuropathic pain results from damage to, or dysfunction of, the system that normally signals pain. The International Association for the Study of Pain (IASP 2007) defines neuropathic pain as follows: Pain initiated or caused by a primary lesion or dysfunction in the nervous system. Peripheral neuropathic pain occurs when the lesion or dysfunction affects the peripheral nervous system. Central pain may be retained as the term for when the lesion or dysfunction affects the central nervous system. A review of the epidemiology of chronic pain found that there is still no accurate estimate available for the population prevalence of neuropathic pain.(Smith and Torrance 2010)
Neuropathic pain is often chronic, and can be severe and difficult to treat.(NICE 2010) The origin of neuropathic pain can be metabolic, inflammatory, infective or neoplastic, or can be due to an injury, compression or infiltration (e.g. by tumour) of peripheral nerves. Various conditions can cause neuropathic pain include diabetic neuropathy, postherpetic neuralgia and trigeminal neuralgia, pain following chemotherapy and HIV infection.
Neuropathic pain is commonly described as burning, stabbing, stinging, shooting, aching or electric shock-like in quality.(Sykes 1997; Galer 1995) The pain may superficial or deep, intermittent or constant, and can be spontaneous or be triggered by various stimuli.
Conventional management often involves the combined use of a range of pharmacological (e.g. amitriptyline, gabapentin, opioids, NSAIDs, topical treatments such as capsaicin and lidocaine) and non-drug approaches, (e.g. transcutaneous electrical nerve stimulation, psychological treatments, and specialist procedures to stimulate, block or destroy discrete areas of the nervous system.(Sykes 1997).
In general, acupuncture is believed to stimulate the nervous system and cause the release of neurochemical messenger molecules. The resulting biochemical changes influence the body’s homeostatic mechanisms, thus promoting physical and emotional well-being.
Research has shown that acupuncture treatment may specifically help to relieve neuropathic pain by:
Reducing hypersensitivity induced by spinal nerve ligation, an effect dependent on the opioid system (Cidral-Filho 2011);
Inhibiting paclitaxel-induced allodynia/hyperalgesia through spinal opioid receptors (Meng 2011);
Influencing the neurotrophic factor signalling system, which is important in neuropathic pain (Dong 2006).
Acting on areas of the brain known to reduce sensitivity to pain and stress, as well as promoting relaxation and deactivating the analytical brain, which is responsible for anxiety and worry (Hui 2010; Hui 2009);
Increasing the release of adenosine, which has antinociceptive properties (Goldman 2010);
Improving muscle stiffness and joint mobility by increasing local microcirculation (Komori 2009), which aids dispersal of swelling;
Reducing inflammation, by promoting release of vascular and immunomodulatory factors (Kavoussi 2007);