Diabetic neuropathy: medical and surgical approaches

Decompressive Surgery for Diabetic Neuropathy: Waiting for Incontrovertible Proof

: Triple decompression surgery has been advocated as a treatment for diabetic peripheral neuropathy (DPN). A practice advisory published in 2006 by the American Academy of Neurology concluded that "this treatment alternative should be considered unproven." Since then, multiple cohort studies involving several thousands of patients and 1 nonblind, randomized, controlled trial have been published, suggesting that surgical treatment of DPN has become commonplace in many centers globally. The results of these observational studies suggest that decompressive surgery could result in a substantial reduction of pain and the restoration of sensation in patients with DPN. However, as these studies are all observational in design, the utility of surgery remains unproven. Furthermore, the selection of patients for surgery is based on the incorrect assumption that the presence of a Tinel sign at sites of potential entrapment indicates nerve compression. The utility of surgery could be determined through a randomized, double-blind, sham-controlled trial in which 1 leg is treated with surgical decompression and the other with sham surgery. This design would eliminate a large number of possible confounders and would therefore require only a small number of patients. Such a trial is currently being performed at the University of Texas. The true beneficiaries will be patients with DPN: either decompressive surgery will be established as an evidence-based treatment for millions of patients or they will be spared from potentially harmful surgery with no significant benefit.

ABBREVIATION

DPN, diabetic peripheral neuropathy.

Rationale, Science, and Economics of Surgical Nerve Decompression for Diabetic Neuropathy Foot Complications

Nerve decompression is effective and safe for dealing with the pain and numbness symptoms of the frequent nerve compression entrapments in diabetic symmetric peripheral neuropathy (DSPN). Evidence has accumulated of balance and stability improvements and protection against diabetic foot ulceration, recurrence and its complication cascade. Nerve decompression proffers significant benefit versus the large socioeconomic costs of DSPN complications. Advancing understanding of the mechanism of nerve compression and altered axonal activity in diabetes clarifies the basis of clinical benefit. Clinicians should seek out and recognize nerve entrapments and consider advising nerve decompression for relief of DSPN symptoms and prevention of complications.

Illustration of Cost Saving Implications of Lower Extremity Nerve Decompression to Prevent Recurrence of Diabetic Foot Ulceration

The US diabetic foot ulcer (DFU) incidence is 3-4% of 22.3 million diagnosed diabetes cases plus 6.3 million undiagnosed, 858 000 cases total. Risk of recurrence after healing is 30% annually. Lower extremity multiple nerve decompression (ND) surgery reduces neuropathic DFU (nDFU) recurrence risk by >80%. Cost effectiveness of hypothetical ND implementation to minimize nDFU recurrence is compared to the current $6.171 billion annual nDFU expense. A literature review identified best estimates of annual incidence, recurrence risk, medical management expense, and noneconomic costs for DFU. Illustrative cost/benefit calculations were performed assuming widespread application of bilateral ND after wound healing to the nDFU problem, using Center for Medicare Services mean expense data of $1143/case for unilateral lower extremity ND. Calculations use conservative, evidence-based cost figures, which are contemporary (2012) or adjusted for inflation. Widespread adoption of ND after nDFU healing could reduce annual DFU occurrences by at least 21% in the third year and 24% by year 5, representing calculated cost savings of $1.296 billion (year 3) to $1.481 billion (year 5). This scenario proffers significant expense reduction and societal benefit, and represents a minimum 1.9× return on the investment cost for surgical treatment. Further large cost savings would require reductions in initial DFU incidence, which ND might achieve by selective application to advanced diabetic sensorimotor polyneuropathy (DSPN). By minimizing the contribution of recurrences to yearly nDFU incidence, ND has potential to reduce by nearly $1 billion the annual cost of DFU treatment in the United States.

Multiple locations of nerve compression: an unusual cause of persistent lower limb paresthesia

A paucity of appreciation exists that the "double crush" phenomenon can account for persistent leg symptoms even after spinal neural decompression surgery. We present an unusual case of multiple locations of nerve compression causing persistent lower limb paresthesia in a 40-year old male patient. The patient's lower limb paresthesia was persistent after an initial spinal surgery to treat spinal lateral recess stenosis thought to be responsible for the symptoms. It was later discovered that he had peroneal muscle herniations that had caused superficial peroneal nerve entrapments at 2 separate locations. The patient obtained much symptomatic relief after decompression of the peripheral nerve. The "double crush" phenomenon and multiple levels of nerve compression should be considered when evaluating lower limb neurogenic symptoms, especially after spinal nerve root surgery.

Electrical stimulation improves peripheral nerve regeneration in streptozotocin-induced diabetic rats

We discuss if percutaneous electrical stimulation (ES) at 1 mA and 2 Hz after peripheral nerve transection could enhance axonal regeneration and functional recovery in diabetic animals.

METHODS

Four groups of adult rats (group A: normal rats; group B: normal rats with ES; group C: streptozotocin- induced diabetic rats; and group D: streptozotocin-induced diabetic rats with ES) were subjected to sciatic nerve section followed by repair using silicone rubber conduits across a 10-mm gap. Rats in groups B and D received ES for 15 minutes every other day for three weeks. The groups A and C received no ES.

RESULTS

At four weeks after surgery in groups B and D, immunohistochemical staining showed that lamina I and II regions in the dorsal horn ipsilateral to the injury were significantly calcitonin gene-related peptide-immunolabeled, and a significantly higher number of macrophages were recruited in the distal sciatic nerve compared with group C. In groups A, B, and D, electrophysiological results showed higher levels of reinnervation with significantly shorter latencies and faster nerve conductive velocities, and the histologic evaluations showed relatively larger mean values of myelinated axon densities and endoneurial areas compared with group C.

CONCLUSIONS

Thus, the ES may improve the recovery of a severe peripheral nerve injury in diabetic animals, which could be considered as a supplementary treatment in diabetic neurotrauma.

Revisional peripheral nerve surgery

Peripheral nerve disorders are difficult to manage. In the surgical treatment of patients with peripheral nerve pathology, there are a multitude of factors that may alter the outcome of the patient's recovery and lead to incomplete recovery or possibly worsening of symptoms. The anatomy and function of the peripheral nerve is unique and the evaluation and management of these disorders must be approached in a manner different from musculoskeletal disorders. Many anatomic areas can tolerate scar tissue and adhesions, but in peripheral nerves, loss of the gliding functional and adherence to surrounding soft tissue structures is a common complication from over-zealous dissection and repeat peripheral nerve surgery without modification of technique. The approach to each patient must be thorough and individualized to treat their specific condition, and the surgeon must be aware that at times, the most appropriate treatment for the patient may not be medical but surgical management of the chronic pain condition.