Leading Authors Criticize Surgical Decompression For Diabetic Neuropathy

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.

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