PPM ACCESS
Access to the PPM Journal and newsletters is FREE for clinicians.
4 Articles in this Series
Introduction
Chronic Pain and Its Companions
Opioids & The Taper Talk
Painful Diabetic Neuropathy: Could SCS Replace Pharmacologic Management?
The Links Among Peripheral Arterial Disease, Lumbar Stenosis, and Claudication

Painful Diabetic Neuropathy: Could SCS Replace Pharmacologic Management?

A PAINWeek 2020 Virtual Meeting Highlight with Erika Petersen, MD, Neel Mehta, MD, and Sean Li, MD

Painful diabetic neuropathy (PDN) is common, with up to 26% of people with diabetes experiencing PDN, said Neel Mehta, MD, medical director of pain medicine at Weill-Cornell Pain Medicine Center and New York-Presbyterian Hospital at PAINWeek’s virtual 2020 meeting. With more than 30 million patients diagnosed with diabetes,1 “We estimate that there are about 7 million with intractable, painful diabetic neuropathy.”

In their talk, Dr. Mehta and co-presenter, Erika Petersen, MD,  professor of neurosurgery at the University of Arkansas for Medical Sciences, focused on diabetic neuropathy and distal symmetrical polyneuropathy (DSPN), sharing results of their recent investigation into the use of SCS as a potential treatment.

DSPN Symptoms and Prevalence

DSPN is defined as the presence of symptoms and/or signs of peripheral nerve dysfunction in people with diabetes after excluding other causes.2 It is present in at least 20% of people with diabetes mellitus type 1 after 20 years of disease duration, in up to 15% of newly diagnosed patients with diabetes mellitus type 2, and up to half after 10 years of disease duration.

Symptoms vary according to the class of sensory fibers involved, that is, small or large fiber. Most commonly, early symptoms are induced by the involvement of the small fibers and include pain and dysesthesias, explained Dr. Mehta. With small fiber involvement, pain amplification and hyperalgesia occur, with a loss of sensitivity later on. With large fiber involvement, sensory and/or motor nerves may be affected, with the feet usually impacted first. Patients with large fiber involvement may report a deep-seated, gnawing pain.

DSPN has been linked to glycemia, smoking, blood pressure, weight, and lipids. Symptoms can become severe enough to interfere with daily activities and lead to psychosocial impairments. Pain intensifies at night, interfering with sleep, and has been linked to depression as well.

Foot examinationInvestigators aimed to provide level 1 evidence for the use of SCS in diabetic neuropathy patients. (Image: iStock)

DSPN: Which Treatments to Try, Which to Avoid

While glycemic control has been suggested, Dr. Mehta pointed out that, “No compelling evidence exists in support of glycemic control or lifestyle management as therapies for neuropathic pain in diabetes or prediabetes, which leaves only pharmaceutical interventions.” Instead, he recommends the following medication management:

  • Initially, consider pregabalin or the SNRI duloxetine.
  • Gabapentin may be used as an initial approach, too, but take into account the patient's socioeconomic status, comorbidities, and potential interaction with their existing medications.
  • Tricyclic antidepressants should be used with caution due to the higher risk of serious side effects, especially in older adults.
  • Opioids, including tapentadol or tramadol, are not recommended as first-or second-line agents. Use only as a “last resort.”

The ADA Algorithm

Citing the American Diabetes Association (ADA) position statement on diabetic neuropathy, including DSPN,3 Dr. Mehta demonstrated how their algorithm for managing DSPN works.

Is the pain confirmed due to DSPN? If a clinician is unsure, or if this is not confirmed, referring to a neurologist or pain clinic is advised. If it is confirmed, an assessment of comorbidities, risks, and drug interactions needs to be assessed. Then, a clinician may choose from three options:

  • pregabalin or gabapentin
  • SNRIs
  • tricyclic antidepressants.

If there is still no meaningful effect, the patient may be switched to another agent from the list. If that fails as well, the clinician may try combining or adding tramadol or tapentadol to the regimen.

SCS as an Emerging Treatment Trend for PDN

Dr. Mehta then moved on to his and Dr. Petersen's work trialing the use of SCS for PDN. He shared some stats on the suboptimal treatment of PDN and relative prescription frequency statistics, noting that gabapentin and pregabalin are most used, at 67%; followed by antidepressants (17%), opioids (13%), and topical agents such as lidocaine and capsaicin (3%).4 He called the “fair amount” of opioid prescribing “somewhat concerning.”

Medication regimens leave many patients with inadequate pain relief, however, and can have significant side effects, he explained. For better relief, Dr. Mehta suggested that spinal cord stimulation (SCS) may be a better avenue.

He and Dr. Petersen (the principal investigator) summarized their 3-month study results of a Nevro-funded study on SCS (presented as a poster at PAINWeek 2020). The study was conducted at 18 US centers, randomizing 216 subjects 1:1. The researchers compared conventional medical management (CCM) alone with CCM plus 10kHz SCS utilizing Nevro’s SENZA system.

This device is FDA-approved to treat the pain of the trunk or limbs, which can include DSPN. However, if it is used for the diagnosis of DSPN, coverage is limited by insurance companies, Dr. Mehta told PPM. “The study [was] an attempt to provide level 1 evidence.”

At 3 months, they assessed pain, quality of life, and neurological function, including a diabetic foot exam. The mean age in both groups was 60; patients were primarily white. Most had type 2 diabetes, on average for 7 years. Their average A1C was about 7.4%.

Looking at the primary endpoint of a 50% or higher pain relief, the researchers found just 5.3% of the CMM group but 75% of the CMM plus SCS group met that primary endpoint. While the CMM alone group reported a 5% average pain relief, the CMM with the SCS group reported 77% average pain relief. The combination group did better in the 6-minute walk test, averaged 336.4 meters compared to 296.2 for the CMM group.

Only 2% of those in the CMM group thought their quality of life was ''a great deal” better, compared to 67% of those in the combination group. The clinicians' impressions were similar. Dr. Petersen concluded her talk, noting that, “10kHZ SCS is a safe and effective treatment for PDN patients with symptoms refractory to CMM.”

“There were a small number of adverse events,” shared Dr. Petersen. Specifically: 16 AEs in the combination arm; none in the CMM only arm. Only 1 AE was rated as serious. Wound dehiscence, infection, discomfort around the incision, irritation from the surgical dressing were most common.

 

Practical Takeaways

After their presentation, Drs. Petersen and Mehta shared their impressions of the outlook for the treatment of DSPN using SCS in particular with PPM.  “We estimate that about 7 million with painful diabetic neuropathy have intractable pain,” Dr. Petersen said. “Medications work, then don't work. There are real limits to how to help these folks.”

Agreed Dr. Mehta,” These folks have no other options.” He estimated that at least 2 to 3 million people would be candidates for the treatment.

While SCS has been looked at in the past, these kinds of results are worth noting, and continuing to study, added Dr. Peterson. “I had a patient with a [pain sore of] 9 down to a 1. And I have a few down to 0.”

The results, they noted, are better in many ways than with medication. It is one of the first time researchers have looked at sensory change, using SCS for DPN, and with 72% reporting improvement there, that is “'very big news,” said Dr. Petersen. Better sensation means patients can feel and better protect tissues.

Sean Li, MD, regional medical director of Premier Pain Centers, in Shrewsbury, NJ, and adjunct clinical associate professor at Rutgers New Jersey Medical School, Newark, was involved in a pilot study of the SCS SENZA approach for DPN but not in the RCT described herein. He consults for several neuromodulator companies, including Nevro.  For appropriate patients, he said, such as those who have failed on treatment and are left with nothing or opioids, SCS could definitely help. With the device not yet approved for diabetic neuropathy, he estimates the ''out the door” cost without insurance at about $40,000.

Other companies, such as Medtronic, offer SCS for PDN.

 

Disclosures: Dr. Mehta reports grant and research support as well as honoraria from Nevro, which m manufactures the SENZA SCS system. Dr. Petersen is a consultant and independent contractor for Abbott/St. Jude Medical, Medtronic Neuromodulation, and Nevro. She has grant or research support from Nevro, Neuros Medical, ReNeuron, and Medtronic Neuromodulation. She is on the advisory board of, and a stock shareholder of, Synerfuse. Dr. Li consults for several neuromodulator companies, including Nevro.

 

Sources

  1. CDC. National Diabetes Statistics Report. 2020. Available at: www.cdc.gov/diabetes/pdfs/data/statistics/national-diabetes-statistics-report.Pdf. Accessed Sep. 15, 2020.
  2. Kasznick J. Advances in the diagnosis and management of diabetic distal symmetric polyneuropathy. Arch Med Sci.2014;10(2):345–354.
  3. Pop-Busui R, Boulton AJM, et al. Diabetic Neuropathy: A Position Statement by the American Diabetes Association. Diabetes Care. 2017;40(1): 136-154.
  4. Yang M, Qian C, Liu Y. Suboptimal Treatment of Diabetic Peripheral Neuropathic Pain in the United States. Pain Med. 2015;16(11):2075-2083.
Next summary: The Links Among Peripheral Arterial Disease, Lumbar Stenosis, and Claudication
close X
SHOW MAIN MENU
SHOW SUB MENU