Carpal tunnel syndrome
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Carpal tunnel syndrome comprises potentially disabling sensory and/or motor symptoms in the hand. Around 1 in 10 people develop carpal tunnel syndrome at some point, and it is particularly common in women (Hughes 2007), with one study in the UK indicating an incidence of 139.4 cases per 100,000 women per year and 67.2 cases per 100,000 men (Bland 2003). The condition carries considerable implications for employment and healthcare costs (Bland 2007).
The symptoms of carpal tunnel syndrome are caused by compression of the median nerve in the carpal tunnel at the wrist and include numbness, tingling, and burning sensations, and a dull ache in the hand and fingers (Hughes 2009). These symptoms are usually restricted to the thumb, index, middle and ring fingers, but may affect the little finger and/or the palm as well (Stevens 2005). They usually occur at night, often waking the patient from sleep, but can be relieved within a few minutes by shaking the hand (Stevens 2005). Pain sometimes radiates up the forearm as far as the elbow, and even as high as the shoulder or root of the neck (Stevens 2005). Other, less common, symptoms include weakness or clumsiness of the hand, and dry skin, swelling or colour changes in the hand (Bland 2007). Symptoms may recur during the day when the hands are used for carrying things, and for activities that involve holding them up, such as driving or using a keyboard (Stevens 2005).
Predisposing factors include genetic predisposition (Hakim 2002), diabetes mellitus, pregnancy, obesity, myxoedema, acromegaly, and infiltration of the flexor retinaculum in primary and hereditary amyloidosis (Stevens 2005). Carpal tunnel syndrome may also develop as a consequence of wrist joint involvement in rheumatoid arthritis or osteoarthritis, or deformity related to an old fracture (Stevens 2005). Whether overuse of the hands is a cause of the syndrome is not clear, although most patients report that symptoms are aggravated by heavy use of the hands (Bland 2007). Current standard treatment options are splinting, local corticosteroid injections and surgery.
How acupuncture can help
This Factsheet focuses on the evidence for acupuncture in the management of carpal tunnel syndrome. There are also factsheets on neuropathic pain, osteoarthritis and rheumatoid arthritis.
There has been one systematic review, which demonstrated that the evidence for acupuncture as a symptomatic therapy for carpal tunnel syndrome is encouraging but not convincing (Sim 2011).
In addition there are a few randomised controlled trials (RCTs) published since this systematic review. All were for mild-to-moderate carpal tunnel syndrome. Two compared acupuncture with sham acupuncture. In both cases acupuncture produced improvement over baseline levels but in one the real version was superior to the sham (Saeidi 2012) and in the other it was not (Yao 2012). Such contradictory results are common in sham acupuncture trials, for ‘sham’ interventions are not inert placebos, hence potentially underestimating the effect of ‘real’ acupuncture and making interpretation of the results difficult (Lundeberg 2011). In another two RCTs acupuncture was compared with orthodox treatments, either steroids (Yang 2009 and 2011) or splinting (Kumnerddee 2010). It was found to be at least as effective as these, and in some circumstances superior.
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 in the management of carpal tunnel syndrome by:
- 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);
- Regulating the limbic network of the brain, including the hypothalamus and amygdala (Napadow 2007a);
- Inducing beneficial cortical plasticity (i.e. conditioning the brain to stop processing sensory nerve input from the affected fingers maladaptively, which leads to improved symptoms) (Napadow 2007b).
- Lundeberg T et al. Is Placebo Acupuncture What It is Intended to Be? Evid Based Complement Alternat Med. 2011; 2011: 932407
- Bland JDP, Rudolfer SM. Clinical surveillance of carpal tunnel syndrome in two areas of the United Kingdom, 1991–2001. J Neurol Neurosurg Psychiatry 2003; 74: 1674–9.
- Bland JDP. Carpal tunnel syndrome. BMJ 2007; 335: 343–6.
- Hakim AJ et al. The genetic contribution to carpal tunnel syndrome in women: a twin study. Arthritis Rheum 2002; 47: 275–9.
- Hughes RAC et al. Peripheral nerve disorders. In: Candelise L et al (Eds). Evidence-based neurology. Management of neurological disorders. London; BMJ Books, 2007.
- Hughes RAC, Thomas PK. Diseases of the peripheral nerves. In: Warrell DA et al (Eds). Oxford textbook of medicine. London: Oxford University Press, 2009.
- Stevens JC. Median neuropathy. In: Dyck PJ, Thomas PK (Eds). Peripheral neuropathy. Philadelphia: Saunders, 2005.