By Ashley Hattle
Chronic neuropathic pain can take a toll on many parts of an individual’s life, and often requires a multidisciplinary approach to treat underlying issues while also managing symptoms. Patients often must undergo a period of trial-and-error with medications and other treatment modalities in an effort to find what works, a challenging process for those who don’t respond to conventional treatments. In recent years, implantable neuromodulation devices have become a core treatment option that offers real hope to people with ongoing or worsening pain caused by nerve damage or injury.
Neuropathic pain affects up to 10% of the general population in the United States. This type of pain can be caused by injuries or as a consequence of other health conditions like diabetes or cancer. The aging demographics of American citizens and the frequency with which these issues hit the elderly mean that the prevalence of these conditions, and their neuropathic pain side effects, is likely to only grow.
Neuromodulation is defined by the International Neuromodulation Society as “the alteration of nerve activity through targeted delivery of a stimulus, such as electrical stimulation or chemical agents, to specific neurological sites in the body.”
Two examples of implantable neuromodulation devices are spinal cord stimulators and dorsal root ganglion stimulators. No surgery or interventional procedure is without risks, and anyone considering an implantable neuromodulation device should thoroughly discuss these possibilities with their health care provider. But many people with neuropathic pain find it worth the risk: These devices have helped many improve their quality of life and, in some cases, have potentially decreased the amount of pain medication needed.
How does implantable neuromodulation work?
“[Neuromodulation uses] a trickle of electricity to shut down pain signaling at the nerves outside the spinal cord before it gets to your spinal cord or to your brain,” says Michael Leong, MD, a pain medicine specialist at Stanford Pain Medicine Center who is board certified in anesthesiology. “What we’re trying to do is not eliminate the sensation of movement or touch but to turn down the volume, like on a radio or cellphone, so the pain just doesn’t bother you as much.”
Implantable neuromodulation devices can provide relief for various root causes of neuropathic pain by zeroing in on the location or root of the problem. Leong recalls that early in his career, these devices would have around a one in two chance of improving one’s condition by 50%. However, the technology has improved immensely over the last two decades, with Leong finding the most success with spinal cord and peripheral nerve stimulation technologies. People with back and leg pain who get a neuromodulation device implanted are now up to 75% more likely to reach at least a 50% pain reduction.
However, the effectiveness of these devices depends on the type of pain condition someone has, the concurrent management of contributing conditions such as diabetes, and choosing the correct neuromodulation device to begin with.
The Gate Control Theory of Pain
“These different devices work to basically wind down or override the body’s symptom of pain, much like when a child bumps their elbow and Mom rubs it to make it feel better,” says Helen Blake, MD, an interventional pain physician who is board certified in anesthesiology and pain management and practices with St. Louis Spine and Orthopedic Surgery Center. “But that process of why it feels better is something called the gate theory.”
The Gate Control Theory of Pain treats the spinal cord as a switch of sorts, with a gate mechanism: when it’s open, it sends pain signals to the brain. Neuromodulation treatment aims to close this gate and restrict signals from traveling to the brain, where they are perceived as pain.
The traditional form of neuromodulation is spinal cord stimulation, which diminishes pain signals using the gate theory. Other stimulators target the dorsal root ganglion, an area in the spinal nerves that control pain signals throughout the body and peripheral nervous system.
A trial period can help you decide
Implantable pain therapy treatment plans often begin with a temporary stimulator, a completely reversible in-office procedure that can show in days whether this technology would benefit the individual living with pain. It often only takes a few days of the trial for the patient to clearly see what benefits they would see from a permanent stimulator.
“How many things can you try before you buy in life?” says Leong.
If the trial is successful, a permanent device is implanted.
These devices can help treat a variety of neuropathic conditions, including complex regional pain syndrome (CRPS), small fiber neuropathy, and diabetic peripheral neuropathy. In fact, a spinal cord stimulator specifically for diabetic neuropathy was recently approved by the FDA.
“We have more people that are living longer, and there’s a larger population now that has this kind of nerve pain or peripheral nerve pain related to diabetes,” says Leong. “We’re very excited about continuing to use neuromodulation for the treatment of chronic nerve pain and other conditions.”
An option when conservative therapies don’t reduce pain
There are three main treatment goals when it comes to using implantable devices: reduce pain, improve overall function, and decrease the need for medication. Candidates for these stimulators typically have not received adequate pain relief from more conservative therapies, such as medications for nerve pain, physical therapy, or chiropractic care. Insurance providers may dictate that the patient try a number of these treatments before surgery for a spinal stimulator can go forward.
Statistics show that people with localized pain in the arm, leg, or back respond well to neuromodulation.
“[Neuromodulation is] one of the most advanced ways that we have in pain management right now to treat pain as an alternative to opioids and pretty much all medicines,” says Leong. “The impact that some of these neuromodulation systems have had recently has been incredible.”
These devices do require maintenance and replacement, with another procedure to replace the neuromodulation generator every seven years. However, battery replacement surgery is less involved and requires less time than the initial procedure, taking about an hour. The leads that deliver the pulses can last a lifetime, unless they move, which is called lead migration. Lead migration tends to occur early on, when the leads haven’t fixed in place yet. Lead migration, bleeding, and infection are the most common side effects of neuromodulation devices.
Deciding to move forward
Pain relief with neuromodulation starts with your doctor. If your pain hasn’t improved and has lasted more than three to six months, Blake recommends finding a physician who uses these devices in their practice and discussing all your stimulator options. In addition to reading the marketing materials each company provides, those considering a stimulator should ask about their doctor’s and other patients’ experiences with different types and brands of these devices.
“I have seen neuromodulation change lives,” Blake says. “I’ve seen patients in their mid-20s with complex regional pain syndrome go back to work and have a gainfully high quality of life. I’ve seen people with walking assistive devices that, during [the] trial, can walk fully. The potential for these therapies to change lives is enormous. There are so many conditions we can apply these stimulators to. The possibilities are endless.”
“What we’re trying to do is not eliminate the sensation of movement or touch but to turn down the volume, like on a radio or cellphone, so the pain just doesn’t bother you as much.”