Current And Emerging Insights On Treating Diabetic Peripheral Neuropathy

Author(s): 
Peter Bregman, DPM, FAENS, FACFAS, and Pasquale Cancelliere, DPM

   For any physicians who have not seen the results of these procedures, we would encourage them to explore the large amount of substantive data that is currently available and have an open mind about the possibility for significant improvement for their patients.9,10 Certainly not all patients with diabetes are candidates for the surgery but we think it would be prudent for all medical professionals to be able to identify those patients who are good candidates and refer them to someone who can perform the surgery.

   We feel very comfortable telling our patients that the worst thing that can happen is they just do not see any improvement and it is extremely rare for them to get worse. The lead author notes that probably 85 percent of his patients have improved following surgery, which is consistent with the literature. Along with his other colleagues at AENS, the lead author has personally trained dozens of DPMs to identify and treat patients with peripheral neuropathy.

Why You Should Consider Nerve Decompression

Even with the currently available research on this procedure, there are still people, especially those in academia, who choose not to recognize that patients with diabetes with a superimposed compression(s) in the lower extremity can benefit from decompression. Carpal tunnel is well documented as an early predictor of diabetes but why is that not accepted in the foot?

   It is well documented that a “double crush” syndrome, with diabetes being the first crush and the actual compression being the second crush, exists in the hand and by extension must exist in the ankle and foot.11

   In his landmark article, Dellon found that decompressing the tarsal tunnel in patients with diabetes not only relieved pain by 80 percent but also restored sensitivity/sensation in the foot.7 This led to a significantly decreased incidence of new ulcerations in these patients and a decrease in the rate of amputation.7,12 This has been consistent with our clinical experience.

   This does not mean that every patient with diabetic peripheral neuropathy is a candidate for surgical decompression of the tarsal tunnel. One should reserve this surgery only for those patients who have a diagnosed compression of a peripheral nerve in a site of anatomical narrowing. Electrodiagnostic studies carry a false negative rate of 33 percent in people with symptomatic carpal tunnel.11

   There are no significant systematic reviews of the sensitivity and specificity of nerve conduction velocity (NCV) and electromyography (EMG) in patients with tarsal tunnel syndrome. However, we know we should not rely on these studies to determine whether an entrapment is present as there is a greater than a 50 percent false negative rate with EMG/NCV.13,14 However, research has shown a positive Tinel’s sign to be a positive predictor of successful surgery in the relief of symptoms in 90 percent of patients with diabetic chronic nerve compression and 88 percent of patients with idiopathic nerve entrapment.13,14

   We know the changes occurring to the nerve in the tarsal tunnel or any entrapment site manifest in the surrounding connective tissue. Tenosynovitis with accelerated glycosylation and enhanced lysyl oxidase activity result in increased collagen cross-linking, which in turn causes the tissues to become less compliant and even fibrotic. This will subsequently allow shear forces across the nerve to increase and decrease the volume of tissues surrounding the nerve tunnel.

   We also know that due to direct damage to the nerve, hyperglycemia leads to apoptosis and impaired mitochondrial function with Schwann cell dysfunction. If we add nerve compression on top of this dysfunction, it is even worse and we can see this microscopically.

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