Using a one-millimetre-sized wireless implant to stimulate peripheral nerves from within blood vessels has the potential to treat neuropathic pain that is resistant to traditional medical therapy, according to a team of multi-institutional researchers led by Sunil Sheth (University of Texas Health [UTHealth] Houston, Houston, USA).
Sheth was co-principal investigator of a study published recently in Nature Biomedical Engineering reporting the design and in vivo proof-of-concept testing of an endovascular, wirelessly powered, battery-free millimetric implant for the stimulation of specific peripheral nerves that are difficult to reach via conventional surgeries.
After receiving a grant from the National Institutes of Health (NIH) in 2019, researchers teamed up to create these implantable nerve stimulators for use in place of opioids for pain management. The implants—which are roughly the size of a grain of rice—are small enough to be placed on stents, and delivered within blood vessels adjacent to specific areas of the central and peripheral nervous system.
In Nature Biomedical Engineering, the researchers detail that the device can be delivered through a percutaneous catheter and leverages magnetoelectric materials to receive data and power through tissue via a digitally programmable, 1mm×0.8mm system-on-a-chip. Implantation of the device directly on top of the sciatic nerve in rats, and near a femoral artery in pigs (with a stimulation lead introduced into a blood vessel through a catheter), allowed for wireless stimulation of the animals’ sciatic and femoral nerves, they report.
“We are getting more and more data showing that neuromodulation, or technology that acts directly upon nerves, is effective for a huge range of disorders—depression, migraine, Parkinson’s disease, epilepsy, dementia etc. But, there is a barrier to using these techniques, because of the risks associated with doing surgery to implant the device, such as the risk of infection,” Sheth said. “If you can lower that bar and dramatically reduce those risks by using a wireless, endovascular method, there are a lot of people who could benefit from neuromodulation.”
Previous research has shown electrical stimulation to be an effective treatment for reducing neuropathic pain when doctors target the spinal cord and dorsal root ganglia (DRG). However, as per a UTHealth press release, existing DRG stimulators require open surgery to implant bulky devices, including a battery pack and pulse generator. In addition, traditional pharmacological therapies in this space carry the risk of opioid addiction.
With their newly developed technology, the Texas-based researchers say they have found a way to perform minimally invasive bioelectronic therapy that helps with more precise placement of the implant and enables more predictable outcomes. Ultimately, Sheth hopes to seek regulatory approval of the device from the US Food and Drug Administration (FDA). “We are doing some longer-term studies to ensure this approach is safe and that the device can stay in the body for a long time without causing problems,” he added, also estimating that this process is likely to take “a few years”.
