Jul-11

New Guidelines Assess Modalities For Painful Diabetic Neuropathy

By Brian McCurdy, Senior Editor

New evidence-based guidelines for painful diabetic neuropathy, recently published in Neurology, examine the efficacy of various types of modalities to relieve the pain of diabetic neuropathy. The authors note that pregabalin (Lyrica, Pfizer) is effective for Level A neuropathy while venlafaxine (Effexor, Pfizer), duloxetine (Cymbalta, Eli Lilly), amitriptyline (Elavil, Merck), gabapentin (Neurontin, Pfizer), valproate (Depacon, Abbott Laboratories), opioids and capsaicin are effective for Level B neuropathy.

Neurology examine the efficacy of different modalities for painful diabetic neuropathy.">

   Stephen Barrett, DPM, cites lectures about the pharmacologic management of peripheral neuropathy by Ian Carroll, MD, at the recent Association of Extremity Nerve Surgeons Meetings. Dr. Carroll says duloxetine is weight neutral and Dr. Barrett says this is a limiting factor for some patients, mostly women who are taking gabapentin or pregabalin. Dr. Barrett notes that duloxetine also treats comorbid depression.

    “We have found that in patients with nerve pathology, the patient without depression is rare,” says Dr. Barrett, an Adjunct Professor at the Arizona Podiatric Medical Program at Midwestern University College of Health Sciences. “Very simply, nerve pain sustained over a period of time will change central nervous system neurotransmitters, resulting in depression, and duloxetine treats this as well.”

   For short-term intervention in patients with diabetic neuropathy, Mackie Walker Jr., DPM, uses pregabalin and duloxetine for painful symptoms. He employs analgesic medicines in patients with more severe pain. In the long term, Dr. Walker will use Metanx (Pamlab) bid. Generally, he will reduce the use of pregabalin and/or duloxetine two to three months after starting Metanx and adjust the dosage of pain medication according to the patient’s clinical response.

   Dr. Barrett was surprised by the guidelines’ conclusion that pregabalin is better than gabapentin. He notes no difference between gabapentin and pregabalin in his patients, except that gabapentin is less expensive. Dr. Barrett notes the conclusion may be due to dosage and the specific articles the authors reviewed. He cites positive results for gabapentin after implementing Dr. Carroll’s dosing schedules, which slowly titrate the drug over the first month with a sub-therapeutic dose. Dr. Barrett notes these patients require education before they receive the prescription as their previous experience could have simply been due to bad implementation of the drug rather than the drug being bad.

Pertinent Insights On Other Modalities

In regard to non-pharmacologic interventions, Dr. Walker cites success with using capsaicin cream, Biofreeze (Biofreeze) and topicals with various compounded combinations of ketamine, gabapentin, clonidine and lidocaine. He will also use transcutaneous electrical nerve stimulation (TENS), Anodyne infrared therapy and nerve stimulation.

   However, Dr. Walker notes those treatments have limited availability and insurance coverage. Some patients have benefited from spinal cord stimulation although this treatment is a “last resort,” notes Dr. Walker, who practices in the Podiatry Division at Carolina Musculoskeletal Institute in Aiken, S.C.

   When it comes to neuropathic patients with severe pain, Dr. Barrett has found the single best treatment to be surgical decompression if the preoperative findings (Tinel’s sign, provocation sign) indicate that the patient has a superimposed nerve entrapment. He says various studies have shown that peripheral nerve decompression has high success rates for the reduction of pain (about 90 percent) and restoration of sensation (80 to 85 percent).

Study: Non-Operative Treatment Effective For Adult-Acquired Flatfoot

By Brian McCurdy, Senior Editor

Most patients with adult-acquired flatfoot can be successfully treated with non-surgical methods, according to a new study in the Journal of Foot and Ankle Surgery.

   The retrospective study focused on 64 consecutive patients who had received non-operative treatment for adult-acquired flatfoot. This therapy consisted of bracing, physical therapy and anti-inflammatory medications. Over the 27-month observation period, authors found non-operative therapy to be successful in 87.5 percent of patients.

   Both Michelle Butterworth, DPM, and Doug Richie Jr., DPM, have found non-operative therapy to be more successful in patients with flatfoot deformities that are more flexible. If the pain and deformity is chronic or longstanding, Dr. Butterworth says non-surgical therapies do not work as well. Dr. Richie adds that non-operative treatments will not work as well in patients over 70, those who are extremely overweight and those with MRI evidence of complete rupture of the posterior tibial tendon.

   Ensuring proper offloading can be particularly challenging, according to Dr. Butterworth, a Fellow and President-Elect of the American College of Foot and Ankle Surgeons. “The hardest thing for patients to do is rest and stay off their feet,” notes Dr. Butterworth. “That is usually the best treatment and the hardest thing to do.”

   To help facilitate offloading, Dr. Butterworth will temporarily immobilize patients in a controlled ankle motion (CAM) boot or CAM walker. Patients generally tolerate the CAM boot but some of her older patients will find the boot too heavy and the weight may cause problems in patients’ knees or back. Dr. Richie has found that his patients do not tolerate rigid walking boots or casts.

   Dr. Butterworth, who is in private practice in Kingstree, S.C., also frequently uses orthotics for adult-acquired flatfoot. She notes that patients with more rigid deformities may not tolerate orthoses so she will use more flexible devices.

   In his experience, patients seem to tolerate articulated ankle foot orthoses (AFOs), according to Dr. Richie, an Adjunct Associate Professor in the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt University. He adds that the only obstacle is getting patients to wear proper footwear with AFOs. He has found patients tolerate physical therapy well.

   At what point do podiatrists determine that conservative therapy has failed and shift toward considering surgical intervention? Dr. Butterworth considers factors like the severity of the deformity, its progression and whether the patient is in pain. Dr. Richie suggests implementing non-operative care for at least three months, noting that it often takes up to 12 months to be successful.

Study Finds No Connection Between Diabetic Neuropathy And Limited Joint Mobility

By Brian McCurdy, Senior Editor

A recent study in the Journal of the American Podiatric Medical Association asserts there is no link between diabetic neuropathy, limited joint mobility and deformities.

   Researchers studied 281 patients with diabetes, performing mobility studies and assessing deformities and hyperkeratosis. Comparing patients with and without diabetic neuropathy, authors noted no substantial differences between the two groups in regard to joint mobility range. The study notes neuropathy was only a risk factor in the passive range of motion (ROM) in the first metatarsophalangeal joint. In addition, researchers note patients without neuropathy had a higher incidence of foot deformities like hallux abductus valgus and hammertoes, as well as more calluses.

   Khurram Khan, DPM, has seen changes in joint mobility in patients with diabetic neuropathy compared to those with non-neuropathic diabetes. Mostly, he says patients with elevated HgA1c have a decrease in ROM compared to age matched non-diabetics.

   Dr. Khan has seen increased deformity in patients with diabetic neuropathy, saying most of the ulcerations occur in patients with limited ROM. He notes that elevated glucose levels and their byproducts during breakdown change joint ROM. Dr. Khan says diabetic patients with neuropathy may not have changes to the structural components of their musculature, especially at the early onset of diabetes.

    “Patients with diabetes for a greater number of years will start to see the structural changes based on the level of glycemic control, which may or may not correlate with neuropathy,” notes Dr. Khan, an Assistant Professor in the Division of Medical Sciences at the New York College of Podiatric Medicine.

   Dr. Khan also points out that the study did not look at any parameters (such as stride length, cadence, propulsion and gait) that might reasonably be linked to neuropathy.

Clarification

The photo caption on page 62 of the May 2011 issue (see “Understanding And Managing Equinus Deformities”) should have noted that the patient was prone during the procedure.