Cath Lab Digest

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.