MEDICINE-FREE PAIN MANAGEMENT
Migraine relief without drugs? No “digestive issues” due to pain meds after surgery? Better still, no worry about addiction after that appendectomy or hip replacement? Sounds a bit science-fictiony, does it not?
The news reminds us nearly every day of the profound need for pain management without opioids. As you read last week, alternatives to analgesics such as morphine, codeine, or fentanyl exist. But science also takes us beyond medicine: researchers have developed devices that control pain and inflammation electronically. This drug-free approach is called electrostimulation–using low levels of electricity to zap pain.
THE BODY ELECTRIC
How does one feel pain in the first place? Pain, and more pleasant sensations (the taste of chocolate, for instance) come courtesy of the nervous system. This system serves as the wiring that enables the machines of our bodies to move, experience, and interpret the world.
Our nervous system has two main parts that work in tandem: the central and peripheral nervous systems. The central nervous system functions as the “switchboard” that sends and receives information from peripheral nervous system’s local lines. The peripheral nervous system is a vast network of nerves found everywhere in body.
The central nervous system is made up of neurons. These cells send and receive signals electrochemically, through signaling molecules called neurotransmitters. These chemicals are converted into electrical signals in the neuron. Here’s how: when a neurotransmitter reaches one edge of a neuron, the dendrite, it opens ion channels in the cell membrane. These tiny openings allow the positively charged sodium ions to pass through. These positive ions travel down the other side of the neuron through an extension called an axon. When the electrical charge reaches the end of the axon, it signals the release of other neurotransmitters, which then switch on other neurons and the chain of sensation unfurls.
Groups of neurons form nerves outside the central nervous system. Nerves transmit sensory information such as touch, temperature, and pain. Different kinds of nerves respond according to the specific receptor on their surface. Pain receptors detect chemicals that tissue damage releases. The pain signal then zooms along the nerve to the central nervous system for interpretation and response by the brain. Pain can also be caused by direct damage to the nerves themselves (think pinched nerve).
SLAMMING THE GATE ON PAIN
As you no doubt noticed, pain perception is complex. Remember the last time you bashed your knee? Did you rub it? The Gate Theory of Pain says this rubbing action does temporarily reduce pain. In that moment, signals from your non-pain nerves block signals from your pain nerves. In other words, non-pain nerves prevent pain from reaching your brain.
Electrostimulation relies on the body’s ability to run interference on pain. It uses electricity to treat chronic pain by stimulating a patient’s peripheral nerves or spinal cord. In either case, a small pulse generator sends electrical pulses to the nerves or spinal cord, “shutting the gate” on pain.
Several companies already have electrostimulation-based devices on the market, including:
• Medtronic (Fridley, MN). Its Intellis spinal cord neurostimulation system gained FDA approval in September and European Union approval for managing chronic pain earlier this month. This small, implantable neurostimulator communicates wirelessly with a Samsung tablet that a doctor uses to adjust pain relief and monitor patients’ activity. More activity indicates that the patient’s level of pain is lessening.
• Stimwave (Pompano Beach, FL). This company’s latest device, the StimQ Peripheral Nerve Stimulator, was approved in August for chronic pain. Tiny enough to be inserted by needle, it communicates wirelessly with an external transmitter that delivers electrical pulses. The device is also safe to wear in MRI machines. This innovation makes neurostimulation available to people whose treatment requires ongoing imaging.
• Abbott (North Chicago, IL) also offers neurostimulation systems. Their most recent is the BurstDR system. Developed by St. Jude Medical in St. Paul, MN, this proprietary technology delivers bursts of electrical stimulation in a way that mimics the body’s natural response to pain.
THE LATEST BUZZ: NEW APPLICATIONS AND NEW TECH
While neurostimulation can treat chronic pain, the technology may provide other therapies as well. Because nerve signals permeate the entire body, modulating them may work for other medical conditions. For example, neural signaling partially controls inflammation, the body’s response to injury. This suggests that neurostimulation may treat inflammatory disorders such as Crohn’s disease and rheumatoid arthritis.
Federal agencies, large pharmaceutical companies, and small start-ups are taking note. The National Institutes of Health (Bethesda MD) has established the Stimulating Peripheral Activity to Relieve Conditions (SPARC) program to fund the basic exploration of how peripheral nerves’ electrical signals control the function of internal organs. This effort may lay the groundwork for electroceuticals–the next generation of tiny neurostimulation devices.
In the private sphere, GlaxoSmithKline (GSK; Middlesex, U.K.) leads the charge. The corporation is heavily involved in creating a Nerve Atlas to map the nervous system’s role in disease. GSK is also investing in start-ups such as SetPoint Medical (Santa Clarita, CA), which has already produced clinical data supporting the use of electroceuticals on rheumatoid arthritis . Another of GSK’s notable investments in electroceuticals was the launch of Galvani (Stevenage, England) in 2016, in partnership with Verily (San Francisco, CA). Galvani is developing electroceuticals for chronic conditions including Type 2 diabetes, autoimmune, and endocrine disorders.
COCKTAIL FODDER: THE DOWNSIDE OF FEELING NO PAIN
Feeling no pain sounds great, doesn’t it? Yet people born with congenital analgesia suffer greatly from injury and illness, because they never feel the pain associated with them. In a BBC interview, sufferer Steven Pete talked about breaking a limb roller skating as a boy, noticing it only when friends pointed out the bloody wound caused by the bone protruding from his leg! Fortunately, this inherited nervous system disorder is extremely rare, with only 20 or so cases known in the medical literature.
Emily Burke, PhD has worked in biopharma for 20 years, gaining science writing experience at The Scripps Research Institute and Ionis Pharmaceuticals. As a Ph.D. molecular biologist, she is passionate about advancing the public’s understanding of science. In addition to being a self-proclaimed “science geek,” she is regularly asked to speak at international scientific meetings. When not teaching and writing the WEEKLY for Biotech Primer, Dr. Burke swims with her swim club and performs regularly on the improv circuit in San Diego.