Testing high-frequency stimulation
The new findings included the 24-month follow-up data from a randomized controlled trial that assessed the effectiveness of high-frequency spinal cord stimulation for painful diabetic neuropathy. The original 216 participants enrolled in the trial had diabetic neuropathy symptoms for at least 12 months and either could no not tolerate or did not respond to medications. Enrollment criteria also included lower-limb pain intensity of at least 5 on a 0-10 visual analogy scale and hemoglobin A1c of no more than 10%.
For the first 6 months of the trial – before crossover was offered – participants were randomly assigned to receive either 10 kHz of spinal cord stimulation along with conventional medical management or to receive conventional medical management alone. The 6-month data from 187 patients, as reported in April 2021 in JAMA Neurology, revealed that 79% of those receiving spinal cord stimulation experienced at least 50% improved pain relief without worsening of their baseline neurologic deficits, compared with only 5% of those receiving only conventional treatments.
Average pain levels increased 2% in the control participants compared with a decrease of 76% in those with the spinal cord stimulation devices. In addition, 62% of the patients receiving spinal cord stimulation demonstration neurologic improvement in reflexes, strength, movement and sensation, compared with 3% of those in the control group. The study’s findings led the FDA to approve the device using 10 kHz.
At 6 months, 93% of control patients crossed over to receiving spinal cord stimulation while none with the devices opted to stop their spinal cord stimulation. The 12-month data revealed that 85% of those receiving spinal cord stimulation experienced at least 50% pain relief, with the average pain relief at 74%. Patients also reported statistically significant improved quality of life as well as less interference with sleep, mood, and daily activities from pain.
Two years after baseline, patients’ pain relief was maintained with average 80% improvement, and 66% of patients showed neurologic improvement since baseline. Though no patients had devices removed because of ineffectiveness, five patients’ devices were removed because of infection while infections in three other patients resolved.
“Being able to offer something that is not a pharmaceutical, without the side effects, that shows an even longer durability to that response is a really important finding at this point,” Dr. Petersen said.
Surgical considerations
Among the estimated 37 million Americans with type 1 or 2 diabetes, approximately one quarter of them experience some level of painful diabetic neuropathy, but medication and other medical management strategies are not always adequate in treating their pain. After a 1-week trial of spinal cord stimulation, the devices are implanted under the skin and rechargeable through the skin for up to 10 years, after which they can be replaced.
An appropriate candidate for spinal cord stimulation would be someone for whom existing non-invasive pain relief options, including medications, are ineffective or intolerable, Dr. Petersen and Dr. Markman both said. An adequate trial of medication is not “one size fits all” and will vary by each patient, added Dr. Markman, who is also interested in whether this study’s participants were able to have a reduction in use of pain relief medications.
“I think there’s a significant number of patients out there who can benefit from this, so I think that’s why it’s promising and exciting,” Dr. Markman said. “I do think it’s important to see if this actually allows them to be on less medication or whether stimulation turns out to be another treatment in addition to their baseline treatments.” The challenge is identifying “which patients are most likely to be benefiting from this and which are most likely to be harmed.”
Aside from infection from implantation, other possible risks include pain at the battery site and, in rare cases, a need for reoperation because of migration of the leads, he said.