Diabetic neuropathy can be defined as: ‘The presence of symptoms and/or signs of peripheral nerve dysfunction in people with diabetes after other causes have been excluded’ (Boulton et al, 1998).
The most common diffuse neuropathy is chronic distal symmetric sensorimotor polyneuropathy. This affects the lower legs and feet and can cause chronic neuropathic pain (Boulton, 2000). Neuropathic pain can cause significant morbidity and impairment of quality of life (Benbow et al, 1998). About 10 % of people with diabetes develop painful neuropathy (Young et al, 1993); however, some studies suggest that the number of people with neuropathic symptoms is nearer 20 % (Dyck et al, 1993).
Diagnosis of neuropathy
In our health district (Bolton), each GP surgery’s patients receive diabetic foot screening from a podiatrist. The patient’s general medical history is discussed and a neurological assessment is carried out. This includes the neuropathy disability score using a Neurotip (Owen Mumford, Oxford), a 128 kHz tuning fork, hot and cold rods and a tendon hammer, as recommended by Abbott et al (2002). The severity of neuropathic pain is assessed by completing the neuropathic symptom score (Figure 1). This helps to inform the decision whether or not to refer the individual for treatment of neuropathic pain.
Treatment of painful diabetic neuropathy
Local guidelines for the treatment of neuropathic pain are shown in Figure 2.
Improving glycaemic control
Tight glycaemic control has been shown to reduce the development of neuropathy (Diabetes Control and Complications Trial Research Group, 1995). Improving glycaemic control is, therefore, the first line of treatment for PDN in the authors’ locality. Transient neuropathic pain, its causes and treatments in the newly diagnosed person with diabetes or those with recent metabolic disruption, such as ketoacidosis, is discussed with the individual. In order to assess glycaemic control and exclude other causes of neuropathic symptoms, biochemical parameters, such as HbA1c and vitamin B12 levels, and thyroid function are determined.
If the extent and site of pain are suitable, an effective treatment for neuropathic pain is a film dressing applied directly to the affected area (Foster et al, 1994).
Drugs such as imipramine and amitriptyline have been in use since the 1960s and their benefits have been documented (Low and Nelson, 1996). The drugs do, however, have some side effects, which include limited pain relief, drying of the mouth and drowsiness.
Although anticonvulsants also have an established role in the treatment of PDN (McQuay et al, 1996), gabapentin remains the only one licensed for the treatment of PDN in the UK. Pain scores were found to be drastically reduced when doses of up to 1800 mg gabapentin were taken daily (Young et al, 1993), although reported side-effects included dizziness, somnolence, diarrhoea, headache and confusion.
Capsaicin may be applied topically up to four times a day. The active ingredient of Axsain cream (Zeneus, Stevenage), capsaicin (derived from chilli peppers), may cause an increased burning sensation on application. The frequency of application thus limits its use.
Pregabalin (Lyrica; Pfizer, Walton-on-the-Hill, Surrey) is the first drug to be licensed in the UK for neuropathic pain. Doses of 300 mg pregabalin have been shown to produce significant improvement in symptoms when compared with placebo (Stacey, 2002). Twice-daily dosing was also shown to be of advantage in some people with PDN.
A brief history of acupuncture
The practice of acupuncture can be traced as far back as 1000 BC in China. It is a part of traditional Chinese medicine. It has only has been known to the West since the 17th Century. The term ‘acupuncture’ is derived from the Latin for ‘needle prick’ (the standard Mandarin word roughly translated to ‘needle therapy’). The first ‘needles’ to be used were carved from stone (Wikipedia, 2006).
Acupuncture theory suggests that needles puncture the skin at specific points and tap into channels called meridians. These channels carry the body’s energy (‘chi’), which has to flow freely to create harmony within the body. A blockage of chi is thought to produce painful symptoms. Acupuncture theory holds that these symptoms may be reduced or eliminated by restoring the balance of chi (Wikipedia, 2006). This may seem at odds with Western medicine, but it is used to treat many conditions and it is increasingly popular for treating pain.
Its mechanism of action in relieving pain is not fully understood, but it is thought that acupuncture stimulates the body to produce its own natural pain killers, primarily endorphin and serotonin. Serotonergic pathways have been implicated in pain relief, and have been found useful in relieving pain in neuropathy (Goodnick et al, 2000). Serotonin is synthesised in the central nervous system – its synthesis has been shown to increase following acupuncture (Han et al, 1979).
Acupuncture may also affect the vibration perception threshold (VPT) in the foot (Nwabudike and Ionescu-Tirgoviste, 2000). In a study of 46 patients with chronic painful peripheral neuropathy, 34 of the 44 participants who completed the study noticed an improvement in their painful symptoms following a course of acupuncture (Abuaisha et al, 1998); however, it is worth noting that this study demonstrated no significant difference in VPT following treatment.
To the best of the authors’ knowledge, many studies are currently in progress that aim to investigate the effectiveness of acupuncture for a number of symptoms, such as osteoarthritis of the knee, chronic low back pain and chronic headache.
The acupuncture service
Referral and assessment
People with PDN are referred to the acupuncture service by podiatrists, GPs, practice nurses, diabetologists and diabetes specialist nurses following foot screening.
Before the initial appointment two information sheets are posted to the patient. The first gives information on painful neuropathy and a simple explanation of possible causes and available treatments. The second gives information about acupuncture, including a brief explanation of the uses of acupuncture and how it is thought to work. It also lists groups of people for whom acupuncture would not be suitable. These include pregnant women, people with epilepsy, and people with needle phobia or metal allergies (Acupuncture Association of Chartered Physiotherapists, 2000).
The initial appointment is a 1-hour session during which the individual completes and signs a consent form. A full and complete pain history is taken and a patient record is completed. The patient record contains up-to-date medical information, including current and previous occurrences of and treatments for PDN. While recording the drug history, the podiatrist may make recommendations on the correct administration of current drug regimens. A full pain history is crucial to allow differential diagnosis. The following parameters are documented: site, timing, duration, pain relief, distribution, acute or chronic pain, sleep deprivation. It is important to explain to people that they may not experience total or even partial pain relief, although approximately three-quarters of participants reported some reduction in pain in a study by Abuaisha et al (1998).
A short form of the McGill questionnaire is completed and scored at this first appointment. The original McGill questionnaire was not used because of time constraints, and results from the short form have been shown to correlate well with those from the original long form of the questionnaire (Melzack, 1987). Initially a visual analogue scale (a 10cm linear scale) was used to assess pain. Patients were asked to record their pain on a scale of 0–9 (0, no pain; 9, worst pain) at weeks 1 and 6. However, this was subsequently omitted from the patient appointment as it was felt that it did not add to the information gained from the McGill questionnaire.
Symptoms of neuropathic pain
The symptoms of neuropathic pain vary enormously, with many of those affected being, in the author’s opinion, unable to describe the pain exactly. The wide range of symptoms can develop spontaneously or in response to a particular stimulus. Most symptoms are reported to be more severe nocturnally (Watkins et al, 1996). Commonly reported symptoms include burning, shooting or lancinating pain, paraethesia, aching and allodynia. The site of pain may also vary tremendously, but early symptoms usually affect toes and then spread proximally to involve the lower leg. The hands may also become affected.
Acupuncture treatment plan
The needles are inserted into six acupuncture points bilaterally. These points are chosen for their pain relief properties (Abuaisha, 1998). Most patients feel very little discomfort upon insertion of the needles, but occasionally some experience acute pain. The needles are left in situ for 20 minutes. The acupuncture is then repeated weekly for five further visits, using the exact same acupuncture points and leaving the needles in for 20 minutes. At week 6 the pain questionnaire is completed again and the scores at weeks 1 and 6 are compared and recorded in the database.
Bolton Diabetes Centre study
Aim and method
In 2004 we conducted a study to determine the effectiveness of acupuncture in treating PDN (McLennon et al, 2005). We looked at 88 people with diabetes who received acupuncture over a 6-week period (47 were female, mean age was 51 years and 7 had type 1 diabetes). Participants were assessed using the procedures outlined above and the scores were recorded on McGill questionnaires at weeks 1 and 6.
The results were analysed using Student t-tests.
- Mean pain scores were 20.1 pre-acupuncture treatment compared with 10.7 post-acupuncture treatment.
- Seventy-six participants experienced pain reduction following their course of acupuncture. However, it is important to note that in most cases symptoms were reduced rather than completely eradicated.
- Twenty-nine remained on monthly ‘top up’ acupuncture.
- Ten reduced or ceased PDN medication by the end of the course of acupuncture.
Acupuncture, like other complementary therapies, has generated great interest among practitioners of Western medicine for use in pain relief. A number of studies have shown that acupuncture has a place in the NHS for the treatment of chronic pain (McClennon et al, 2005; Walker, 2001). Acupuncture is most often used as a second- or third-line treatment when everything else has failed.
In our clinics, acupuncture has played a role in enabling patients to improve their quality of life through better sleep patterns and reduced pain. Some people in the study experienced great relief of symptoms either during or immediately after treatment, whereas others only noticed an improvement after the sixth and final treatment. Only 12 of the 88 participants obtained no improvement. Some patients still required medication in conjunction with the acupuncture.
Acupuncture cannot be regarded as a cure for PDN, but the results of our study indicate that it is effective in improving pain relief, sleep and wellbeing. In another study, 85 % of patients reported an improvement in pain, sleep, mobility and mood (Walker, 2001).
PDN remains a challenge, and further research is required to find the most effective treatment. Acupuncture offers a relatively safe, non-pharmacological alternative to conventional treatments. Our findings support the contention that acupuncture be used as first-line treatment for PDN. Our aim is to further develop our acupuncture service in the future. We hope that our experience will encourage others to introduce acupuncture as a treatment for PDN.