How To Diagnose Diabetic Peripheral Neuropathy

By Kathleen Satterfield, DPM

Diabetic peripheral neuropathy (DPN) is a “diagnosis of exclusion.” Diagnostic challenges are one thing but few practitioners relish that phrase when it comes to DPN. For this condition, the practitioner needs to cast a very wide net of tests and keep an open mind regarding clinical suspicion in order to reach an accurate diagnostic conclusion. How likely is it that there could be another neuropathy-causing disease or medical condition resulting in these same lower extremity symptoms? Does the podiatric physician really need to consider thyroid problems, vitamin B12 deficiencies, nerve entrapments, lupus, kidney failure, nutritional deficiencies and alcoholism among other diagnoses? Noted Mayo Clinic researcher Peter J. Dyck, MD, strongly cautions that the physician diagnosing DPN must first eliminate the presence of other neuropathy-inducing conditions because there is an estimated 10 percent occurrence of other neurologic diagnoses in patients who have concurrent diabetes. To fail to diagnose and treat these other conditions (or make an appropriate referral to other physicians) could be catastrophic for the patient’s outcome.1 That said, it is neither an easy nor inexpensive task to eliminate that 10 percent of outlying cases. The potential list of comparisons is a long one with vague symptoms. Indeed, when you treat patients with diabetes, you likely hear these common comments: • “My feet burn.” • “I feel electric shocks in my toes.” • “My toes are numb at the end of the day.” • “I can’t get to sleep at night because my feet feel like they are on fire.” There was a time when a patient’s complaints of symptomatic or painful neuropathy led to commiseration from the physician but not much else because there were no distinctly good treatments. Now there is much more to offer than just empathy. Emerging treatments include surgical decompression of nerves, anti-seizure medications, antidepressants and even infrared light therapy, just to name a few of the leading proven treatments.2-4 Many of the treatments are not benign. Surgery has the inherent risks associated with anesthesia and potential postoperative complications of infection and scarring. Medical (pharmaceutical) treatments can have adverse effects and drug interactions. Given the fact that there is no completely benign treatment, there is a profound desire to make a definitive diagnosis prior to embarking on a treatment plan. This brings us back to the pivotal question: How does one distinguish between diabetic peripheral neuropathy and the array of other causes of these same symptoms? What The International Consensus Group Recommended While it might seem like there is a circuitous trip in reaching a diagnosis, there is usually a very distinct roadmap leading to the correct diagnosis. At least there is if one agrees with the International Consensus Group, which arose out of suggestions made by Neurodiab, a subgroup of the larger European Association for the Study of Diabetes. The internationally respected members, primarily Europeans, debated and discussed the subject for several years before agreeing on criteria required for a correct diagnosis of DPN.5 The panel of 39 experts from the European countries and Canada also had four representatives from the United States, including Lawrence B. Harkless, DPM, of the University of Texas Health Science Center at San Antonio and Aristidis Veves, MD, of the Beth Israel Deaconess Medical Center and Harvard Medical School. This panel of diabetologists, podiatrists, neurologists, diabetes specialists, nurses and primary care physicians advocated an annual assessment in order to facilitate early diagnosis of neuropathy. Once one has diagnosed the condition, the panel said it is essential to manage it aggressively and/or make appropriate referrals within the multidisciplinary team in order to minimize complications of the condition. The international and multidisciplinary panel was mindful of the limitations of available modalities that might exist in different countries. Accordingly, the panel wanted to develop an easy to follow system that would enable the podiatrist in America to have the ability to reach the same conclusion as the diabetologist in Finland.

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