SPR Therapeutics’ Neuromodulation System Treats Phantom-Limb Pain

Before that, the side effects from his medications for pain were so significant that he was ready to undergo surgery on the nerve that was sending the pain signals.

“Since my treatment, I haven’t taken a pain medication once, which to me is amazing,” Schlicht said. “The area on my leg still isn’t 100% like it was before I had this problem. … I may feel a twinge, or a different sensation. But it’s not painful.”

Applying mild electric current directly to the nerves is a long-standing way of treating many forms of pain, as well as other conditions like epilepsy. It doesn’t work for everyone, and researchers at the companies that make neuromodulation devices still lack a definitive explanation for the biological mechanism of action behind neuromodulation therapy.

Mark Stultz, who once worked in Medtronic’s neuromodulation division, is senior vice president of market development at SPR. He said SPR’s peripheral nerve stimulation seems to work by interrupting pain signals from the affected nerve and changing how the brain processes the information. Whether the diseased nerve has been sending too much information to the brain, or just not enough healthy information, the result is that the pain has become “centralized” — and the SPR therapy disrupts that.

The difference between SPR’s treatment and other neuromodulation techniques used to treat pain may lie in the location of the treatment. Instead of stimulating at the spinal cord or in related nerve cells, Sprint therapy is applied near the peripheral nerves, closer to the source of the pain signals. The most common uses of the Sprint system are to treat pain in the shoulder, back or knee, or nerve pain.

“There is something about being in the periphery that is allowing us to treat pain syndromes that haven’t otherwise been well-treated by these other more-invasive permanent technologies. And there’s something about stimulating the periphery that is allowing us to have a durable effect, when every other therapy requires the implant to be permanent,” Stultz said.

The stimulation is also applied about a half-inch from the nerve, as opposed to directly on the nerve, which may also increase the treatment effect.

The past success rate of neuromodulation therapies has been such that patients often try out a temporary system to see if it will work, before undergoing a permanent implant.

Originally, SPR’s system was designed to be the same. But Stultz said the company found in clinical trials that its temporary system was creating lasting results, so it decided to design a device intended to be implanted for up to 60 days.

“There’s always an expectation that you need to have something permanently implanted to have an effect,” he said. “And what we are seeing is that we’re able to introduce this tiny lead adjacent to peripheral nerve, placed under image guidance — sometimes ultrasound, sometimes fluoroscopy — and the majority of our patients are getting sustained effect.”