Doctors then inject an outer sheath of insulation around the newly formed electrode, and use the same gel to craft a wire running from the injectrode to the surface of the skin.
“You now have a direct connection to stimulate a deep nerve from the surface of the skin, without affecting any nerves on the surface of the skin,” Ludwig said. “We’re trying to get this to the point where it’s like getting a tattoo, in terms of invasiveness.”
The use of electrical pulses to alter nerve activity, a technique called neuromodulation, has been shown to effectively treat chronic nerve pain, Ludwig said.
“When you feel pain, those nerves are sending an electrical signal that goes to your brain and tells you that you’re feeling pain,” Ludwig said. “This interrupts that signal.”
However, neuromodulation hasn’t been a viable means of treating nerve pain because it requires invasive and expensive surgery to place what amounts to a tiny, electrically charged computer inside a person, Ludwig said.
Because the neuromodulation procedure is so costly, patients often have to show that opioid drugs and other therapies aren’t effective in treating their pain before insurance will cover the cost of an implant, Ludwig said. By then, the person may be addicted.
“If we can make this procedure less invasive, then you can start doing it not just for patients who have failed all drug therapies first. You can start doing it before the drugs or at least with the drugs,” Ludwig said.
Spinal cord stimulators have some of the worst safety records among all implants, causing more than 500 deaths and 80,000 injuries since 2008, according to a 2018 report by investigative journalists.
These implants malfunction and either shock or burn people in part because the devices and wires aren’t able to stretch and flex with the human body. The injectrode gel is mechanically more akin to human tissue, which hopefully will make the injectable implants long-lasting and reliable, the study authors said.
The researchers are proceeding to human safety trials, which they hope to conclude by the end of 2021, Ludwig said.
Dr. Griffin Baum is an assistant professor of neurosurgery with Lenox Hill Hospital in New York City.
The injectrode technology being investigated “is another great step forward towards focused therapy for pain coming from the peripheral nervous system,” Baum said, referring to nerves outside the brain and spinal cord.
“For those patients with chronic pain unexplained by a structural spine or anatomical problem, there are few promising therapies that can offer durable pain relief for many years and decades,” Baum said. “This research and this type of electrode can not only help many patients in the short term but will hopefully provide the foundation for further research that can help to address the future tsunami of patients with chronic pain.”