Painful Diabetic Neuropathy

Charles E. Argoff, MD, lists off useful diagnostic tools for different classifications of painful diabetic neuropathy, a neuropathic pain condition that may afflict more than 15 percent of the 25 million diabetes patients in the United States.

While Argoff notes that there isn’t much of a difference between diabetic neuropathy’s presentation in type 1 and type 2 diabetes, he explains that patients with the condition fall into two main groups: Those who have severe pain, and those who have numbness and a loss of sensation, but no pain.

“There are symptoms associated with diabetic neuropathy that are considered positive symptoms — crawling sensations; tingling; a sense of burning; just sharp, out of nowhere, electrical-like sensations. Then there are the negative symptoms that often drive people with diabetic neuropathy more batty, more crazy than the more positive symptoms — numbness, loss of sensation,” Argoff says. “The numbness can really, really be a terrible thing for people.”

To determine the type of diabetic neuropathy, Argoff says “a good old fashioned physical examination is very, very, very important, so taking a history is important, examining individuals, noting whether or not that person has a presence of reflexes (or) loss of reflexes.” A reflex test with a simple pin prick alone can differentiate between large fiber neuropathy, where larger neurofibers that control reflexes and other aspects of sensation are preserved, and the more common small-fiber neuropathy, where smaller neurofibers that control pain and temperature sensation are lost, Argoff explains.

Argoff cautions that small-fiber neuropathy patients “may have preserved reflexes, but also normal nerve conductions and normal [electromyography (EMG)] findings, which may mean … that they’re being told by someone who doesn’t realize that that small fiber neuropathy will result in such, ‘I’m sorry, your EMG shows that you don’t have a neuropathy’ — which is wrong, and unfortunately, patients are told that, and so they’re wondering what’s wrong with them.”

If EMG and other electrophysiological assessments fail to diagnose patients presumed to have small-fiber neuropathy, Argoff recommends a 3 millimeter skin punch biopsy, “which can be done routinely in the office at the foot, calf, and thigh level … to confirm the abnormalities of small nerve fibers.”