Making Room For Nerve Decompression In The Diabetic Limb Salvage Armamentarium

I read with interest the recent article on diabetic limb salvage (“How To Form A Diabetic Limb Salvage Team” in the June 2010 issue). Over the last 14 years, I have been significantly involved with wound care and limb salvage in the diabetic patient population. In 1998, I was asked to join the staff of a multidisciplinary wound center associated with two local hospitals as a podiatric surgeon and wound specialist.

   As most who read your periodical can attest, there have been significant advances and changes regarding the treatment of wounds in the diabetic patient. Yet loss of protective sensation, a neurologic complication of diabetes, continues to wreak havoc in our diabetic patient populations. Despite the advancements of medicine and technology, the catastrophic trend of the natural course of the diabetic wound continues.

   Specifically, the patient with diabetes who develops wounds would enter the clinic. Once the patient was in the wound clinic, he or she would undergo triage and treatment, and be seen by one or more specialists (podiatry/ orthopedics/ infectious disease/ vascular/ endocrinology/ nutritionist/ plastics, etc). The wound (ideally) healed and the limb was salvaged. The treating physician would subsequently discharge the patient with appropriate shoe gear, educational material and appropriate rehabilitation.

   Then, despite the tremendous investment of time, resources, energy, education and active precautions, these patients consistently tended to re-ulcerate, re-infect and remain at high risk for amputation. The number one indicator of a patient with diabetes developing a wound in the future is a history of a previous wound.

   This may be good for the wound center’s business but it is bad for patients.

Reviewing The Double Crush Phenomena

Around 1998, I became familiar with nerve decompressions as an option for reversing the symptoms of neurologic complications of diabetes. When one ensures a thorough clinical exam, proper diagnostic testing and appropriate patient selection, surgical decompression of the nerves of the affected extremities is advocated.

   The purpose of the surgery is to increase nerve function by releasing nerves at known sites of anatomic narrowing and compression at the level of the fibular neck, the dorsal first interspace, tarsal tunnel and associated plantar foot nerves.

   The rationale behind the surgical procedure involves the concept of the double crush phenomena. The first insult is metabolic in nature and is suffered by the patient because of the metabolic changes occurring to the diabetic nerve. The hypothesis of the double crush phenomena states simply that the disease of diabetes is not enough in and of itself to cause the symptoms of loss of protective sensation (as well as other neurologic symptoms) in all of the patients with diabetes who suffer from these symptoms.

   A second insult is needed to explain the progressive neurologic symptoms. This second insult to the nerve develops with time. The diabetic nerve begins to increase in diameter because of the increase in sorbitol within the nerve in comparison to the extraneural environment. An osmotic potential develops because of this increased sorbitol concentration, water crosses into the nerve and the diameter of the nerve then may increase by as much as 50 percent. This increased diameter of the nerve causes a nerve entrapment syndrome to develop because the anatomic funnels that these nerves pass through do not increase correspondingly. Time passes and the double crush insult to the nerve begins to rob the patient with diabetes of protective sensation.

Emphasizing The Potential Impact Of Nerve Decompression In Preventing Ulcer Recurrence

Over the last 12 years, I have incorporated the nerve decompression surgery into a wound salvage protocol. My intent with this procedure was to decrease the recurrence of wound formations in the diabetic patient population. While I did not initially anticipate pain relief, it was a side effect that proved to be an adjunctive benefit.

   The success we had with the nerve decompressions in regard to the prevention of recurrence was insidiously dramatic. The wound clinic suffered initially because we stopped the cycle of wound formation and subsequent need for recurrent wound treatment. The clinic itself began to empty as the patients who healed stayed healed. The clinic’s “repeat business” was gone.

   As the clinic studied its census report, we realized why the clinic was struggling. It was not due to a failure to heal. It was not due to a failure to restore protective sensation. Rather, the clinic struggled under the weight of its success and the unintended consequences that went with it.

   Organizationally, the wound clinic had to develop a new marketing strategy to continue to bring in a flow of new patients. The name of the wound clinic changed to the “Wound Healing and Prevention Institute” to edify a goal of not only healing wounds but to offer the patient a chance to prophylactically intervene prior to the formation of a wound in high-risk patients. This would give the body a way to protect itself and, for all intents and purposes, stop the neuropathic wound before it starts.

   The pros and cons of this type of surgery are being passionately debated among people whom I respect a great deal within medicine and surgery. This is as it should be. Anecdotal experiences are the weakest component of any argument in medicine. That being said and acknowledged, I feel that over the course of the last 12 years and having performed decompressions on over 650 limbs in the diabetic patient population, it bears mention that I have only had two patients develop or redevelop wounds of the lower extremity.

   This surgery is not a panacea. The patient continues to suffer the metabolic insult to the nerve from diabetes. However, removing the second insult from the nerve via a decompression has consistently allowed for the restoration of a level protective sensation that has kept our patients from re-ulcerating and re-infecting, and reduced the chance of amputation risk tremendously.

   As a podiatric surgeon and wound specialist, I have not come across a similar intervention that has altered the natural course of the disease of diabetes so fundamentally from a wound development/prevention standpoint.

   I encourage any wound clinic physicians to leave themselves open to the possibility of utilizing this surgery as an adjunct to a comprehensive limb salvage team.

— Michael A. Wood, DPM
Foot Health Institute
Chicago

Remaining ‘Technologically Polygamous’

We greatly appreciate the note from Dr. Wood. We particularly appreciate his plea to keep one’s mind open to all possible treatments and technologies. We call ourselves “technologically polygamous.” This mandates going into the treatment room with an open mind.

   However, it also mandates that we continually ask ourselves about who and what we are treating. We can never be so protective of our own armamentarium that we cannot risk calling it all into question. Arguably, it is that moment when we are willing to throw it all away that we are closest to our best practice possible.

— David G. Armstrong, DPM, MD, PhD
Professor of Surgery and Director
Southern Arizona Limb Salvage Alliance (SALSA)
University of Arizona College of Medicine
Tucson, Ariz.