Current And Emerging Insights On Treating Diabetic Peripheral Neuropathy

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

   Furthermore, genetic inheritance can predispose a patient with diabetes to increased sensitivity to compression. This is also the case in hereditary neuropathy with liability to pressure palsy although this is rare. There is also the theory that there is an increased risk of endoneurial hypoxia secondary to a decrease in endoneurial capillary density. Of course, there are other factors, both environmental and biomechanical, that can predispose someone to tarsal tunnel syndrome and other entrapments.

   This leads us to patients who come in with complaints of pain in the distal forefoot or cramping in the legs. They may have burning pain and describe temperature abnormalities and interruption of sleep. They often have to wear multiple pairs of socks, even in warmer climates. Getting in the shower is often painful as the hot water can cause allodynia. Some may even describe restless leg syndrome.

   In the patient with diabetes, first and foremost you need to make sure that there is optimum glycemic control. It is also important that patients maintain kidney function as well because edema in the leg or foot is a contraindication to surgical intervention. In our practice and in most AENS trained surgeons’ offices, we do not rely on EMG/NCV studies to tell us whether the patient has a nerve entrapment. In fact, it is even more difficult to isolate a nerve entrapment in a patient with diabetes using EMG/NCV studies.

Pertinent Insights On Diagnosing And Treating Nerve Entrapment

Accordingly, we rely on clinical judgment.

   Dellon found a statistically significant correlation between a positive Tinel’s sign and entrapment of the tibial nerve in the foot.14 After ascertaining the patient history, perform a methodical neurologic exam, which involves testing all of the muscles and reflexes in the entire lower limb. This takes only a few minutes. Then use a disc discriminator to check two point discrimination on the foot. Then start percussing areas of possible entrapment in the leg. This includes the following nerves and entrapment sites from proximal to distal:

• the common fibular nerve in the fibular tunnel;
• the superficial fibular nerve in the distal aspect of the anterior/lateral leg;
• the deep peroneal nerve in the foot near the base of the second metatarsal;
• the tarsal tunnel at the ankle and distally in the porta pedis; and
• the medial calcaneal nerve in the medial posterior heel region.

   After finding an entrapment site, perform a diagnostic block with lidocaine and Decadron to help confirm the diagnosis. If an entrapment is present, as indicated by a positive Tinel’s sign and/or a positive provocation sign, one can pursue conservative treatment with neural modulation techniques. This includes sending the patient to a therapist knowledgeable in the art of neural gliding and flossing.

   If this is unsuccessful at curing the patient, which is usually the case, then we plan surgery. We almost always perform this surgery on an outpatient basis with the patient having general or spinal anesthesia, or a straight local anesthesia if needed for medical reasons. Surgery involves decompression or external neurolysis of the peripheral nerve(s) in question. These techniques have been honed and improved over the years by our group in the AENS.

   The goal is to resect the compressing anatomy that is surrounding the nerve without damaging the nerve itself.

   It is important to realize that the underlying anatomy of the peripheral nerves in the legs is quite variable but predictable. It is important to tell the patient that he or she might need further surgery if desired pain relief does not occur. It is imperative that you receive proper training before attempting to perform peripheral nerve surgery. The AENS offers a course once or twice a year.

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