DENVER – Electrocutaneous direct nerve stimulation via a device that scrambles "pain" and "no pain" signals reduced pain scores in preliminary studies involving patients with refractory chemotherapy-induced peripheral neuropathy, post-herpetic neuralgia, and other forms of chronic, disabling neuropathic pain.
"What I saw in our pilot study in patients with chemotherapy-induced peripheral neuropathy was about a 60% reduction in pain, and you knew right away – within the first 3 days – whether it was going to work," said Dr. Thomas J. Smith, professor of oncology and director of palliative care at Johns Hopkins University, Baltimore.
The device, known as the MC5-A Calmare Scrambler, received Food and Drug Administration clearance in February 2009 and has a Medicare payment code. The Scrambler has been used worldwide to treat more than 4,000 patients with no reported serious side effects. Yet few American physicians have heard of the therapy because Medicare fixed the payment so low (at $44) that there is little financial incentive to adopt it, according to Dr. Smith.
"There’s not much you can do in the hospital outpatient setting for $44. That barely covers the cost of the electrodes and maybe a technician’s time," he said at the annual meeting of the American Academy of Hospice and Palliative Care Medicine. "They set the reimbursement so low that it’s almost guaranteed not to be accepted by physicians until we get more evidence. But there are a significant number of studies in the works."
Chemotherapy-induced peripheral neuropathy affects up to 30%-40% of treated cancer patients. Dr. Smith’s pilot study involved 16 patients with refractory chemotherapy-induced peripheral neuropathy that lasted from 3 months to 8 years. The most common drugs involved were taxanes, platinum-based agents, and bortezomib (Velcade). Patients received hour-long Scrambler sessions daily on 10 consecutive working days.
Pain scores fell from a mean baseline score of 5.8 on a 10-point scale to 2.4 at the end of 10 days. Four patients had a pain score of 0, and 15 of the 16 patients had at least a 20% reduction in their pain score on day 10. There was no toxicity (J. Pain Symptom Manage. 2010;40:883-91).
"When you see that sort of effect size, you can’t believe it’s real," Dr. Smith observed. "That’s in fact what the first reviewer said of the article. He said, ‘I’ve never heard of this therapy, and I don’t believe it.’ I volunteered to give him the case reports."
Neuropathic pain reductions in the 60% range are what are seen with permanent implanted spinal cord stimulation devices, a therapy that runs about $40,000, he added.
Dr. Smith’s Scrambler pilot study results were confirmed in an Italian study involving 40 patients with refractory cancer and 33 with non–cancer-related pain. Their mean pretreatment pain scale score was 6.2, plunging to 1.6 after the 10th day of treatment, and rebounding to 2.9 at follow-up 2 weeks after the final treatment session. Again, there were no side effects (Support Care Cancer. 2012;20:405-12).
Separately, a group led by the Scrambler’s inventor, Giuseppe Marineo, Ph.D., of the University of Rome Tor Vergata, reported on a randomized but unblinded trial involving 52 patients with chronic failed back syndrome, post-herpetic neuralgia, or spinal cord stenosis. Subjects assigned to the control arm received pharmacotherapy according to European Federation of Neurological Societies guidelines (Eur. J. Neurol. 2010;17:1113-e88), while the intervention arm received 10 daily Scrambler sessions.
The pretreatment mean visual analog pain score fell in 1 month from 8.1 in a control group and 8.0 in a group treated with the Scrambler to 5.8 in controls and to 0.7 in the Scrambler group. At 2 and 3 months of follow-up, the mean pain scores were 1.4 and 2.0 points, respectively, in the Scrambler group but were still 5.7 and 5.9 points in controls. A marked and persistent reduction in allodynia was also documented in response to Scrambler therapy (J. Pain Symptom Manage. 2012;43:87-95).
With regard to post-herpetic neuralgia, Dr. Smith presented a series of 10 treated patients. Their mean pain scores dropped from 8 at baseline to less than 1 at 1 month, holding steady with a score of 2 at 2 and 3 months’ follow-up.
The Scrambler entails application of 16 ECG-like electrode pads placed along the dermatome above and below the site of pain. The Scrambler machine is designed to feed 16 different nerve potentials in rapid sequence, essentially in order to confuse a firing nerve. The electrical charge is individually adjusted to patient tolerance. It feels like a bee sting, according to Dr. Smith. The mechanism of benefit isn’t well defined as yet.