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Peripheral Neuropathy and the Insensate Foot

More Than Diabetes

Sibbald, R. Gary, MD, MEd, DSc (Hons), FRCPC (Med Derm), FAAD, MAPWCA, JM; Ayello, Elizabeth A., PhD, RN, CWON, ETN, MAPWCA, FAAN

Advances in Skin & Wound Care: April 2019 - Volume 32 - Issue 4 - p 149
doi: 10.1097/01.ASW.0000554390.18232.bd
DEPARTMENTS: EDITORIAL
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R. Gary Sibbald, MD, MEd, DSc (Hons), FRCPC (Med Derm), FAAD, MAPWCA, JM, is the co–Editor-in-Chief of Advances in Skin & Wound Care; Professor, Medicine and Public Health, University of Toronto, Toronto, Ontario, Canada; Director, International Interprofessional Wound Care Course & Masters of Science in Community Health (Prevention & Wound Care), Dalla Lana Faculty of Public Health, University of Toronto; Investigator, Institute for Better Health, Trillium Health Partners; Project Lead, ECHO Ontario, Skin & Wound Care; and President (2008-2012), World Union of Wound Healing Societies.

Elizabeth A. Ayello, PhD, RN, CWON, ETN, MAPWCA, FAAN is the co–Editor-in-Chief of Advances in Skin & Wound Care; Faculty, Excelsior College School of Nursing, Albany, New York; Founder and co–Course Director, WoundPedia Manila; President, World Council of Enterostomal Therapists; President, Ayello Harris & Associates, Inc, Copake, New York; and President (1999), National Pressure Ulcer Advisory Panel.

In our February editorial, we wrote about articles that are published online ahead of print. In this month’s editorial, we want to call attention to one such important article that was published online in January 2019 and now appears in print in this issue: Plantar Ulcers and Neuropathic Arthropathies: Associated Diseases, Polyneuropathy Correlates, and Risk Covariates.1 Most clinicians attribute the insensate foot in persons with diabetes to neuropathy that develops approximately 10 to 15 years after the onset of abnormal serum glucose. Andrews et al1 challenge this belief. They assert that although diabetes mellitus is “one of the most common causes of peripheral neuropathy worldwide, it is not the cause of neuropathy in all patients with diabetes.”1,2 Further, the authors urge clinicians that “other causes should be actively excluded.”1,2

Dr Andrews and her colleagues from the Mayo Clinic retrospectively reviewed 69 patients who had neuropathy over a 3.5-year period. Of 61 adequately assessed patients, they identified 37 (61%) with diabetes, 22 (36%) with no associated disease (ie, chronic idiopathic axonal polyneuropathy), and two patients (3%) with hereditary sensory/autonomic neuropathy.1 Interestingly, the patients with diabetes had similar complications (neurotrophic ulcers, neuropathic arthropathies) to the patients who did not have diabetes. This led the authors to conclude that other factors were responsible for the neuropathy and its complications including older age, obesity, repetitive foot injury, and inadequate foot care. The authors are asking readers to look at peripheral polyarthropathy with new eyes.

Other conditions associated with peripheral neuropathy include infections such as leprosy, syphilis, HIV, and hepatitis C virus. Neuropathy is also associated with alcohol abuse, arsenic poisoning, chemotherapy, and vitamin B12 deficiency. Any spinal cord defect (eg, spina bifida, cerebral palsy, paraplegia) can result in a distal neuropathy. Further, neuropathy is an adverse effect of nerve damage from intra-articular steroid injections.

Clinicians should examine patients with neuropathy for chronic low-grade foot deformities as well as acute changes. Subacute or chronic changes often present insidiously, without patient awareness of pain or the resultant structural foot changes. Acute Charcot joint changes can be identified by a warm, swollen foot that may or may not have associated pain in a previously painless foot and a loss of protective sensation. An infrared thermometer3,4 may detect an 8° F to 15° F temperature increase over the other foot. Affected patients should cease weight bearing and further trauma with a wheelchair or bed rest until the application of a contact or irremovable cast. The consequences of delayed treatment include preventable lower-extremity amputation.

Neuropathic ulcers are most often a result of repetitive trauma; they are associated with a smaller localized temperature increase of 4° F or more. Patient self-monitoring with noncontact infrared thermometers was studied in three randomized controlled studies.3,4 The studies enrolled 483 subjects with diabetes and high-risk feet; results demonstrated that daily patient self-monitoring with noncontact infrared thermometers significantly reduced foot ulcers when localized temperature increases were coupled with decreased ambulation.

So what should we change based on this new information? First, early identification of peripheral neuropathy must include the general population and not only persons with diabetes.5,6 There are 60-second screening tests to identify high-risk feet,5 but feet frequently are not examined in routine care.6 The Andrews article1 heightens the need to screen all feet for chronic idiopathic axonal polyneuropathy and other causes of neuropathy. Further, clinicians must institute preventive foot care for all individuals with neuropathy.5,6 There is a 50% 5-year mortality associated with diabetes-related nontraumatic lower-limb amputations; this prognosis is worse than breast cancer in females, prostate cancer in males, or lymphoma in general!7 Early assessment and risk identification coupled with implementation of appropriate preventive foot care may save a limb—and ultimately save a life.

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R. Gary Sibbald, MD, MEd, DSc (Hons), FRCPC (Med Derm), FAAD, MAPWCA, JM

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Elizabeth A. Ayello, PhD, RN, CWON, ETN, MAPWCA, FAAN

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References

1. Andrews KL, Dyck PJ, Kavros SJ, et al. Plantar ulcers and neuropathic arthropathies: associated diseases, polyneuropathy correlates, and risk covariates [published online ahead of print January 7, 2019]. Adv Skin Wound Care 2019.
2. Kazamel M, Dyck PJ. Sensory manifestations of diabetic neuropathies: anatomic and clinical correlations. Prosthet Orthot Int 2015;39(1):7.
3. Sibbald RG, Mufti A, Armstrong DG. Infrared skin thermometry: an underutilized cost-effective tool for routine wound care practice and patient high-risk diabetic foot self-monitoring. Adv Skin Wound Care 2015;28(1):37–44.
4. Armstrong DG, Lavery LA. Predicting neuropathic ulceration with infrared dermal thermometry. J Am Podiatr Med Assoc 1997;87(7):336–7.
5. Sibbald RG, Ayello EA, Alavi A, et al. Screening for the high-risk diabetic foot: a 60-second tool (2012). Adv Skin Wound Care 2012;25(10):465–76.
6. Persaud R, Coutts PM, Brandon A, Verma L, Elliott JA, Sibbald RG, et al. Validation of the healthy foot screen: a novel assessment tool for common clinical abnormalities. Adv Skin Wound Care 2018;31:154–62.
7. Armstrong DG, Wrobel J, Robbins JM. Guest editorial: are diabetes-related wounds and amputations worse than cancer? Int Wound J 2007;4:286–7.
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