Leading Authors Criticize Surgical Decompression For Diabetic Neuropathy

Author(s): 
By Brian McCurdy, Senior Editor

While some have touted surgical decompression as a possible treatment option for diabetic sensorimotor polyneuropathy (DPN), authors of a recent Diabetes Care commentary have challenged the validity of this procedure, calling it an unproven modality based on flawed hypotheses.    The authors of the commentary note that the use of surgical decompression for DPN is based on several hypotheses including: signs and symptoms being caused by multiple nerve entrapments; that such entrapments can be diagnosed solely with the Tinel sign; that surgical release of the nerves corrects DPN; and that specialized training is required in order to identify these patients and perform surgical decompression procedures.    Let me state very clearly that there is no evidence whatsoever from any randomized trials that (surgical decompression) is a treatment that should be suggested for DPN,” emphasizes Andrew J.M. Boulton, MD, FRCP, a co-author of the Diabetes Care commentary and a Professor of Medicine at the University of Manchester in the United Kingdom.    In the commentary, the authors say the aforementioned hypotheses may have “spawned an entire industry” but are fundamentally flawed. In regard to distal neuropathy, the commentary authors say it is due to progressive axonal loss and entrapment cannot explain sensory or motor symptoms above the anatomic levels of the “entrapped” nerves. They also note that people with diabetes have a small incidence of peripheral nerve entrapment.    As for the Tinel sign, the authors say it is not well standardized and lacks specificity and sensitivity. They also note that the Tinel sign was originally discussed within the realm of nerve regeneration, not nerve entrapment, and is more of a subjective test as opposed to electrodiagnostic studies, an objective diagnostic tool for assessing nerve function.

Assessing The Current Literature And The Need For Further Research

The commentary also notes that in the American Academy of Neurology’s review of evidence-based literature on surgical decompression for DPN, it found only one prospective trial. Accordingly, the Academy rated surgical decompression as an “unproven” treatment based on the current evidence, according to the commentary authors.    “Only well-controlled, randomized, double-masked, sham-procedure, controlled clinical trials will allow us to know whether these surgeries are safe and effective for this indication. (This is) the same standard any drug for diabetic peripheral neuropathy would have to meet,” argue the authors of the Diabetes Care commentary.    Dr. Boulton notes that randomized control trials have supported various treatments for relieving the pain associated with diabetic neuropathy. These treatments include pregabalin (Lyrica, Pfizer), gabapentin (Neurontin, Pfizer) and duloxetine (Cymbalta, Eli Lilly). However, Dr. Boulton says optimal glycemic control is the only prevention that might affect the natural history of DPN.    “As stated in this article and in the previous technical review published in 2004, there are no proven pathogenetic treatments that influence the natural history of diabetic neuropathy aside from tight glycemic control,” maintains Dr. Boulton, a Visiting Professor of Medicine within the Division of Endocrinology, Diabetes and Metabolism at the University of Miami School of Medicine.    Where should future research lead? The commentary notes that researchers should conduct pilot trials to determine whether there is justification to conduct phase 3 studies. The commentary authors believe the Centers for Medicare and Medicaid Services (CMS) should conduct such trials due to the “widespread application of these unproven surgical procedures among Medicare patients.” The commentary authors also support further research into the causes of DPN. For related articles, check out the archives at www.podiatrytoday.com.

Study Validates IDSA Diabetic Foot Infection Guidelines

By Brian McCurdy, Senior Editor While the Infectious Disease Society of America (IDSA) initially presented its diabetic foot infection classification system in 2004, a recent study in Clinical Infectious Diseases validated the system, finding it helpful in grading the severity of these foot infections.    The longitudinal study focused on 1,666 patients with diabetes and found a significant correlation between increasing infection severity and an increased risk for amputation, higher-level amputation and lower extremity-related hospitalization. The IDSA ranks diabetic foot infections in four groups: uninfected, mild, moderate and severe. The International Working Group on the Diabetic Foot developed similar guidelines, ranking infection with grades from 1 to 4.    Benjamin Lipsky, MD, a co-author of the study and a Professor of Medicine at the University of Washington School of Medicine, says classification systems strive to be simple and easy to remember but without sacrificing thoroughness and accuracy.    “The IDSA guidelines took the simple route and I think that was the right way to go,” notes Dr. Lipsky. “The fact that our study validated the ability of the classification system to predict important outcomes in patients with diabetic foot infections was very gratifying.”    Lawrence Lavery, DPM, another co-author of the study, says the system cannot be used in a vacuum. “It cannot replace clinical examination and assessment,” adds Dr. Lavery, a Professor in the Department of Surgery at the Texas A&M Health Science Center College of Medicine.    Study co-author David G. Armstrong, DPM, PhD, concurs. He says the infection classification is highly useful when combined with a treatment-based wound classification system. At the Center for Lower Extremity Ambulatory Research and Scholl Foot and Ankle Clinics, Dr. Armstrong combines the IDSA classification with the University of Texas diabetic wound classification system.    “The combination of the two is highly predictive and helps further increase precision and communication with our patients when they ask, ‘Doc, is my foot going to be amputated?’” notes Dr. Armstrong, a Professor of Surgery, Chair of Research and Associate Dean at the William M. Scholl College of Podiatric Medicine at Rosalind Franklin University of Medicine and Science.

Understanding The Benefits And Limitations Of Classification Systems

Dr. Lipsky does note some caveats about infection classification systems, warning that clinicians may put too much emphasis on the terms selected for the system. As he explains, an infection that appears to be mild may be hiding a more severe infection that further investigation could later uncover. He also points out that the term “moderate” covers a wide spectrum of infections, ranging from a wound with a few centimeters of cellulitis to a large wound involving tendons or bone.    There also should be more information on the validity of the definition of “severe” infections and if other findings, such as critical limb ischemia, should be included in the definition, says Dr. Lipsky, the Director of the Primary Care Clinic and Head of the Antibiotic Research Clinic of VA Puget Sound in Seattle.    Dr. Armstrong agrees and notes that understanding the purpose behind the classification system is more important than memorizing the classification itself.    Classifications must be concise and practical, says Dr. Lavery, who notes that if a system includes a lot of other variables, it becomes unmanageable. For example, while one should consider the possibility of bone infection when evaluating diabetic foot infections, Dr. Lavery says bone infection is not appropriate within the IDSA diabetic foot infection guidelines.    Dr. Lavery says he would be interested in seeing if outcomes improve if physicians use the IDSA classification. Dr. Lipsky would like to see the Clinical Infectious Diseases study replicated in a large prospective trial.

Can A Soft TCC Provide Effective Offloading?

By Brian McCurdy, Senior Editor While a number of different devices have emerged in recent years to help facilitate offloading of lower extremity wounds, the total contact cast (TCC) has been widely regarded as the gold standard. However, one DPM proposes the use of a soft TCC in an abstract that will be presented at the Symposium on Advanced Wound Care at the end of April.    The soft TCC consists of lamb’s wool, cast padding, an ABD pad, an Unna boot and Coban, with an optional 1/4-inch or 1/2-inch of adhesive felt cut-out padding, according to Desmond P. Bell Jr., DPM, CWS, the abstract’s author. The soft TCC has borrowed elements of the traditional TCC and he says clinicians can use the soft TCC for patients who require uninterrupted offloading and patients for whom stability, daily living activities and compliance are concerns.    “Offloading 24/7 is one of the constant challenges we encounter in treating foot ulcers,” says Dr. Bell. “This method has proven to be a viable and simple method to effectively increase compliance and improve rates of healing.”    Dr. Bell says the soft TCC is an effective offloading modality, is not time intensive, does not require costly materials and patients tolerate it well. The casts have been used with various dressings, bilayered living skin substitutes and negative pressure wound therapy, according to the abstract. Dr. Bell notes contraindications to the soft TCC are infected or ischemic wounds.    Jeffrey Jensen, DPM, has seen dozens of different TCC devices around the country while teaching doctors, nurses and physical therapists how to do total contact casting. As he says, the basic tenet of TCCs is reducing ground forces by redistributing pressure from the forefoot and midfoot to the rearfoot and lower leg. To do so requires a rigid device to form the “cone within a cone” weight distribution, according to Dr. Jensen, an Associate Professor at the University of Colorado Health Sciences Center.    Dr. Jensen also notes that locking the ankle joint is a major requisite for offloading the forefoot, where 80 percent of diabetic foot ulcers occur. With the soft TCC, he says one must ask questions that include whether the ankle locks, if the cast reduces shear and if the cast takes weight in the lower leg away from the foot.    The Symposium on Advanced Wound Care will be held from April 28 to May 1 at the Tampa Convention Center in Tampa, Fla. For more info, go to www.sawc.net.

PODIATRY IN PRACTICE: Practice’s Good Reputation Bolsters Referrals

By Brian McCurdy, Senior Editor John McCord, DPM, and his partner Mike Dujela, DPM, have a conservative philosophy in their practice. “If it is not something we would recommend for our wives or mothers, we will not recommend it for our patients,” says Dr. McCord. Dr. McCord says that thinking has helped his practice, the Centralia Medical Center in Centralia, Wash., remain free of malpractice suits for 32 years.    Dr. McCord says his practice has no trouble getting referrals. The orthopedists in his area have their hands full with joint replacement surgeries and he says they are “quite happy to leave the feet and ankles to us.”    He notes that he and Dr. Dujela are not troubled by questions of acceptance and parity with doctors in other professions. Dr. Dujela is the President of the local county medical society and Dr. McCord serves as Chairman of the Board at Providence Centralia Hospital.    Dr. McCord, a Diplomate of the American Board of Podiatric Surgery, says the caseload in his practice ranges from routine foot care to complex limb salvage. The practice also handles two or three new ankle fracture cases a week. Dr. McCord says the practice has no economic issues and overhead is low.    “We do not market our services. We do not have to. Our patients and the local physicians know that we are good and ethical,” explains Dr. McCord.    As for the future, Dr. McCord faces a challenge with his retirement in two years. He must find a replacement, a young DPM who loves people, loves the job and has a broad range of podiatric skills. He notes that the new doctor must be on-call half the time since the local emergency room calls his practice first for foot and ankle trauma, and now he and his partner take turns with the call schedule.    “The reality is we need three DPMs to cover our practice,” says Dr. McCord. Clarification    In the February issue, the Commercial Desk Reference listing for the Federation of Podiatric Medical Boards should have read as follows: Federation of Podiatric Medical Boards Larry Shane, Executive Director 6551 Malta Drive Boynton Beach, FL 33437 Phone: (561) 752-3735 fpmb@fpmb.org In addition, the Web site for Ocean Aid Products should have been listed as www.oceanaidproducts.com. We regret the errors.

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