Ask the Expert: Burning Foot Syndrome
Eight months ago, a patient developed diabetic neuropathy. He is now complaining of a severe burning sensation, pain, and numbness in both lower limbs. He currently is taking pregabalin (Lyrica) at 150 mg bid and duloxetine at 60 mg bid. His glucose level is normal (last HbA1C was 7.2%), and all blood reports were normal. What would you recommend for additional treatment?
I attempt to treat this condition with the standard pharmacologic agents of the day, including antidepressants, anti-inflammatories, and neuropathic agents. I will prescribe opioids, if necessary. I have found gabapentin to be the best neuropathic agent. My favorite topical creams and ointments include lidocaine and compounded versions of morphine, diazepam, and carisoprodol. For non-pharmaceutical options, I particularly like the new electromagnetic therapies that can be used at home. Patients now can obtain small, hand-held infrared, radio wave, and laser instruments to complement their pharmacologic treatments and exercises.
Forest Tennant, MD, DrPH
I assume the patient has been seen by a neurologist and endocrinologist, and has excellent control over his diabetes. Instead of pregabalin, I would prescribe gabapentin/enacarbil (Horizant) off label at the highest recommended dose of 600 mg bid. In my experience with the extended-release formula, I can prescribe a lower dose of the medication and get a similar effect as that of high-dose pregabalin but with less side effects (weight gain and edema), which can be a problem for patients with diabetes.1 I would continue the patient on duloxetine, as prescribed.
Other clinicians might consider dorsal column stimulation. However, a recent article in The Wall Street Journal, raised several issues regarding the treatment.2 The FDA database contains 58 unique reports of paralysis associated with spinal cord stimulators (SCS) in 2013, compared with 48 reported incidences of paralysis in 2012. Researchers at Duke University found that nearly 1 patient in every 100 who received a SCS experienced some degree of spinal cord or spinal nerve root damage.3 This study involved records of more than 12,300 SCS patients. In addition, the complication rates can be between 25% and 35%. Therefore, in this particular patient, I would not recommend dorsal column stimulation; however, I am aware that others would.
As a last resort in patients with intractable neuropathic pain, I would prescribe extended- and immediate-release opioids. In some of these cases, patients need high doses of opioids. Historically, we did not prescribe opioids for neuropathic pain, but the evidence for this has changed because of recently published articles supporting their use. Obviously, if opioids are prescribed, urine drug screens should be conducted as opioid risk tools, and, if there is a concern, a baseline consultation with an addictionologist should be conducted. I also recommend psychotherapy support because the risk of suicide in this type of patient is 2 to 3 times higher than the general public.4 Other options include warm water therapy with physical therapy, a trial of transcutaneous electrical nerve stimulation (TENS), topical gels, lidocaine (Lidoderm) patches, and a podiatry consult.
Joseph Shurman, MD
Jennifer Schneider, MD, PhD
If you want to consider a surgical option, SCS is an option. Though it is not widely used in the US, it is in Europe, where practitioners appreciate the fact that the treatment can open up the small vessels in the feet and offer symptom relief. I would recommend both modalities.
Kern A. Olson, PhD
Because pregabalin is an alpha-2-delta calcium channel agonist, the second choice is to add a sodium channel blocker, such as carbamazepine (Tegretol). But check the patient’s blood work first to rule out hematologic abnormalities at baseline. Duloxetine should be continued.
Finally, the last choice (or addition) is an opioid to help “close the delta” between initial and final pain level (pain level after appropriate anticonvulsant medications have be optimized and you have the duloxetine optimized at 60 mg).
Gary W. Jay, MD