Peripheral Neuropathy among Patients Living with Diabetes

Peripheral Neuropathy among Patients Living with Diabetes Update on Foot Care: Identifying Early signs of Peripheral Neuropathy among  Patients Living with Diabetes Mellitus Bernice S. Samuel DNP  and  Susan J. Appel, PhD, APRN-BC, CCRN, FAHA Introduction Among those individuals living with diabetes, peripheral neuropathy (PNP) is a major contributor in the development of foot ulcers.1 Even though there has been a decline in recent limb amputations due to advanced management of foot ulcers, 7% of those affected with type 2 diabetes (T2D) will still develop foot ulcers.2 Diabetes-related foot ulcers not only cause further physical disability, they also reduce the quality of life and increase the risks of lower extremity amputations. 3 The CDC 4 reports that 65,700 non-traumatic lower-limb amputations were performed among people living with diabetes. While diabetes is a major cause of complications such as vasculopathies and PNP, foot ulcers are the most easily prevented complications. 5 Therefore, practitioners must be fully apprised of tools and methods used to identify early PNP and prevent foot ulcers. Practitioners should also focus on actively educating the patient and family regarding PNP. Most practitioners are familiar with the Semmes-Weinstein Monofilament testing (SWMT) as the gold standard used in primary care to assess for PNP. Mayfield and Sugarman reported the use of the SWMT as a useful tool in the primary care office for practitioners to assess patients for PNP, but indicated it is not without limitations. 6 Further interventions are needed when there is a loss of sensation detected, such as proper footwear and patient education, to prevent trauma and foot ulcers. 6 Research has shown that practitioners can continue to assess patients with diabetes using the monofilament testing as long as PNP is not present. Once PNP is noted, additional assessment and management techniques are warranted. A yearly thorough foot exam by a podiatrist has been recommended by the American Diabetes Association for those living with diabetes. 7 In addition, persons with diabetes and one or more risk factors need frequent assessments of their feet during routine office visits. 5 Patients with known risk factors for foot ulcers (e.g., poor vision, previous foot ulcers or amputation, monofilament insensitivity, and fungal infections of skin or nails) deserve special attention. 8 When practitioners have available clinical information that can help to predict the development of diabetes- related foot ulcers, patients will have better outcomes. 8 These predictors were found to be helpful in accurately targeting clients at high risks of contracting foot ulcers for preventative interventions. The use of proper footwear such as diabetes specialized shoes with proper diabetes foot insoles has been found to be a protective intervention. Pathophysiology of Foot Ulcers Diabetes related foot lesions occur as a result of two or more risk factors: PNP and peripheral arterial disease (PAD). 9 Diabetes-related PNP is a leading contributor to foot lesions. 10 The presence of PAD increases the risk for foot infections and ulcers among people living with diabetes. 11 Foot lesions are less likely to heal due to vascular insufficiency. 12 Research shows that there are three factors that leads to foot ulcers and infections: foot deformities, PNP, and minor trauma. 13 It is important to understand that the longer an individual lives with elevated blood glucose, the more likely he or she will develop PNP. 2 Long term hyperglycemia can affect the skin and delay wound healing if minor cuts or sores occur on the foot. 14 PNP According to Benbow, 14 PNP can be classified as sensory, autonomic or motor. In sensory system PNP, an individual with diabetes has no feeling of sensation on his or her feet, does not feel hot or cold temperature, and does not feel cuts or trauma to his or her feet. 14 When PNP affects the autonomic system an individual will experience a decrease in sweat, resulting in cracked or fissured skin, dilated dorsal veins and an increase in temperature of their feet. 14 When the motor system is affected by PNP, the patient will be at risk for developing foot deformities such as Charcot foot. 14 Commonly, these patients report symptoms of aches and pains with tingling in their feet when PNP is present. 13 Foot Deformities According to Abad Safdar, 13 foot deformities are the second causative factor that leads to foot ulcers among people living with diabetes. People affected by neuropathy have decreased sensation in their feet, and are more prone to foot deformities. 13 These foot deformities affect the muscles and bones of the foot leading to bony protrusions that put the individual at increased risk for ulceration especially when PNP is present. 13 The correlation of PNP and foot deformities was examined by Soyupek, Ceceli, Suslu, Yorgancioglu, 15 utilizing x-rays. Their study showed that the patients with PNP commonly also have foot deformities such as pes planus, pes cavus, tendon calcifications and osteoporosis. 15 Patients living with type 1 diabetes are particularly at risk for developing Charcot neuropathy that causes destruction of the bones of the foot. 16The resultant bone thinning causes the bones to be fragile and leads to foot deformities. 16 Foot Trauma Abad Safar 13 identify foot trauma as the third factor that can lead to foot ulcers. Foot ulceration occurs when there is breaking of the skin, which leads to impaired healing of the lesion. 12 People affected by PNP have sensory loss of their feet and are unable to identify foot pain, trauma, calluses or injury to their feet. 13 Wearing ill-fitting shoes, calluses, onychomycosis, and foot infections that are not treated are all causes of foot trauma leading to ulceration. Once ulceration occurs due to trauma, the wound becomes infected. Testing Tuning Fork and Neurothesiometer A study by Kà ¤stenbauer, Sauseng, Brath, Abrahamian, Irsigler 17 investigated the effectiveness of the Rydel-Seiffer tuning fork in helping with the detection of diabetes-related neuropathy and compared its ability with that of the electronic neurothesiometer. In this study a 128-Hz tuning fork and a neurothesiometer were used at the bedside. 17 The results of the study showed that vibration perception threshold (VPT) was normal in 1917 individuals and abnormal in about 105 individuals when the tuning fork was used. 17 The participants who had abnormal results were older and also had elevated A1c results. The researchers used the neurothesiometer and the results showed that VPT was 2.5 times higher among patients who had an abnormal tuning fork test. 17 The researchers concluded that the tuning fork had a higher sensitivity and a better predictive value in diagnosing PNP at the bedside. 17 The tuning fork is a reliable instrument in helping to detect PNP in the outpatient setting. It is an appropriate clinical tool that practitioners can utilize either at the bedside or in primary care. Neurometer A double-blinded study by Nather and et al. 18 showed that there were other testing methods that were superior in comparison to the SWMT in detecting PNP. One useful tool was neurometer testing. The neurometer measures readings from rapid current perception threshold (R-CPT) which is derived from the lowest strength of stimulus that the patient could perceive. 18 Three different rates of current signals at levels measuring between 0 and 10 mA were applied by the neurometer to the big toe and ankle. 18 Neurometer testing was found to be highly sensitive as compared to the SWMT. Sensory neuropathy was detected with better accuracy when using the neurometer testing at the big toe and ankle sites in comparison to the SWMT. 18 Studies show that the neurometer is an effective tool that practitioners can use to detect PNP. Temperature guided avoidance therapy Research shows that the best intervention in the prevention of foot ulcers was foot temperature guided avoidance therapy (TGAT). 19 A study by Lavery et al. 20 sought to evaluate the effectiveness of infrared temperature monitoring among individuals at a high risk for diabetes related ulceration and amputations. Patients were placed in a usual therapy group or an enhanced therapy group. 20 The enhanced therapy group had additional tasks such as such as the use of a handheld infrared skin thermometer to measure the temperatures on the bottom of their feet twice a day. 20Participants contacted a nurse if they noted a difference in temperature >4 °F between the left and right foot. 20 The results of the study showed that the enhanced therapy group had notably fewer diabetes related foot complications. 20 The TGAT is an effective method in the detection of PNP where practitioners can assist patients in identifying sensory loss so that foot ulcers and complications can be prevented. Scales for Neuropathy Symptoms The Diabetes Neuropathy Symptom (DNS) score is a valuable tool that can be used to screen for and identify PNP. 21 The scoring is based upon symptoms such as ataxic walking, neuropathic pain, paraesthesia, and/or numbness. The DNS criteria are scored with 1 point each and there is a total of 4 points that can be given. 21 Presence of PNP is present with a score of 1, or more. 21 Similarly, the Diabetic Neuropathy Examination (DNE) is another valuable scoring system that helps to identify PNP. This scoring system consists of a total of eight items: two of the items describe the person’s muscle strength; one item addresses reflexes of the tendon and the other five items address sensation. 21 There is a total of 16 points that can be scored with this system. Any score above 3 points is considered to be abnormal and is PNP. 21 Treatment Educating patients Educational interventions are an important tool in reducing foot ulcers. A randomized controlled trial by Gershater and et al. 22 was designed to investigate the effectiveness of patients learning in groups versus learning on their own with information that is provided to them. The authors sought to understand what types of learning would decrease the incidence of foot ulcers. The study results showed that about 42% of the patients got foot ulcers. 22 Some of the reasons for ulcer development were: stress- related plantar ulcer and trauma. 22 The study showed that education in group sessions among patients who are at increased risk for foot ulcers did not have an effect on whether they would develop ulcers of the foot. 22 It was concluded that sessions conducted within a group educational method may be suitable for patients who have a low risk of getting foot ulcers. The authors of the study suggests that it is important to educate practitioners involved in the patient’s medic al care and also their caregivers regarding improved foot care such as footwear and signs of foot problems. Implications for Practice The conclusive results show the best methods to identify PNP and to prevent foot ulcers was the TGAT, the neurothesiometer and the tuning fork. The TGAT method shows that patients can complete this task at home and alert their practitioner about the results. The TGAT is valuable in showing the results of further neuropathy or damage if patients have a prior history of insensitivity to the SWMT. The SWMT is valuable for practitioners to use in the office setting as this is an inexpensive test. The SWMT is not valid once neuropathy is diagnosed. The practitioner should consider the use of the TGAT at this point and teach the patient how to use an infrared sensitive skin thermometer. The patient should be advised to keep a log book and if the temperature on the designated site is >4 °F, he or she will need to reduce the number of steps taken in the following days and contact their practitioner. The tuning fork was also validated as being highly sensitive in diagnosing PNP and is a goo d test for practitioners to use at the bedside. Certain clinical information about the patient is valuable in predicting future foot ulcers. These predictors were high A1c levels, poor vision, prior history of foot ulcer and/or amputation, monofilament insensitivity, tinea pedis and onychomycosis. The practitioner needs to be aware of these predictors and educate the patient about foot care. Practitioners need to increase monitoring of the patient’s foot at every office visit when these predictors are identified. Education is an important criterion in managing PNP. Patients need to be educated about PNP, foot ulcers, proper fitting shoes and the signs of foot infections. This review of the evidence- based literature revealed that basic SWMT is useful in predicting neuropathy but is not useful in preventing ulcers once neuropathy is diagnosed. There is a common misconception among practitioners that SWMT can be used even when neuropathy is diagnosed. The re-education of practitioners is important with the introduction of new testing methods such as TGAT once neuropathy is already diagnosed. 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