Kenneth F. Casey, MD

Medical Advisory Board Member

For decades, technology has enabled medicine to evolve and change. In our lifetimes, we have seen breakthroughs in surgical devices used to operate on patients, developments in implants used to replace joints, and cutting-edge wearable technology that has shown promise in the management of chronic pain.

Lately, we have heard a lot about wearable technology. According to Grand View Research, “the global wearable technology market size was valued at USD 61.30 billion in 2022 and is expected to expand at a compound annual growth rate (CAGR) of 14.6% from 2023 to 2030.” We can track our steps, heart rate, and sleep.

In 1965, researchers Patrick Wall and Ronald Melzack proposed the gate control theory. It suggests that a pain pathway can be “distracted” by another stimulus, reducing or blocking the pain perception and response, controlled by the patient. Several forms of “wearable technology” do just that through nerve stimulation, remodulation of perceived pain and light that can affect tissue changes.

But what can wearable health technology do for chronic pain?

In this article, we are going to look at a few different therapies that can be worn and controlled by the patient. We will also look at other non-incisional options. This can provide a feasible alternative to surgery or medication or can be used to supplement medication.

Transcutaneous Nerve Stimulation (TENS or tDCS)

Transcutaneous electrical nerve stimulation employs an electric current to activate peripheral nerves for pain relief. The TENS unit, a compact, often battery-powered device, can easily fit into a pocket.

Research suggests that placing a spinal cord stimulator in the neck may relieve facial pain. TENS on the face has also shown promise, although it is still being debated by experts as to whether it is an effective option. While there is a learning curve for proper electrode pad placement, these methods have helped some individuals with trigeminal pain and dental pain. Preliminary results for trigeminal neuralgia (TN) are promising, showing reduced pain.

The pads are typically placed by “bracketing” the area of pain. It’s believed that placing the pads directly on the nerve paths is not as effective as placing them at the edges. For trigeminal pain in the second or third division, we position them at the jaw angle, chin, and temple. Placing the pads too close together can limit the therapy to the area between the pads. The settings typically range from 2-10 hertz, but some studies use settings as high as 50 hertz. It’s a good idea to test TNS on your arm or leg to get a sense of the sensation and determine the best settings for you. There is no commercial model that stands out as more beneficial than another.

An emerging area of study is the use of vagal nerve stimulation for chronic pain relief. This method has been used to relieve migraines by affecting the transmission of trigeminal nerve pain. Vagal nerve stimulation (VNS) has been clinically utilized for suppressing seizures for the past twenty years. The vagus nerve (VN) connects to various brain regions involved in pain processing, making it possible for VNS to have an impact. In addition to its neural regulation effects, VNS also exhibits antiinflammatory properties, which may contribute to its ability to inhibit pain. Both invasive and noninvasive VNS devices have been developed, with noninvasive options including transcutaneous stimulation of the vagus nerve in the ear (auricular VN) or in the neck (carotid VN). These noninvasive devices are undergoing various clinical trials for the treatment of chronic pain. Research on the use of VNS for facial pain patients is limited, but stimulation of the eyebrow area (supra-orbital branch) did not activate pain in those studies.

Scrambler Therapy is used as a different approach to the Wall-Melzack concepts. Where TENS aims at deeper pain receptors (alpha fibers) ST looks to quiet the surface skin receptors (C fibers). It produces sensory deceptions due to the production of painless information that is a result of the stimulation of tactile C-fibers, thereby remodulating the perceived pain. This painless information is at times perceived as pleasant sensations in some patients akin to massage. When you rub your nose to stop from sneezing, you are combining the two stimuli — deep and surface fibers. A Scrambler Therapy unit consists of five electrical stimulation channels that replace the body’s pain signals with synthetic “non pain” or “normal” signals through the same pain pathways to the brain. This technology can be particularly helpful for patients experiencing triggered pain. The inventor of the system, Marineo, compares it to using surface creams to alleviate itching or sunburn pain by reducing the response of pain receptors. Clinical trials have shown its effectiveness in treating cancer pain, back pain, and especially post-herpetic neuralgia, which is known to be very challenging to address. The therapy is typically administered in a clinical setting and its effectiveness can be gauged after a few sessions. Many users report experiencing some degree of relief early on, allowing them to determine if the treatment is beneficial for them.

Low-level Laser Therapy (LLLT)

“Low-level laser therapy is a treatment strategy that uses a single-wavelength light source. Laser radiation and monochromatic light may alter cell and tissue function. Many authors have reported significant pain reduction in a number of conditions such as rheumatoid arthritis, fibromyalgia, post operative pain, headache, nervous system diseases, myofascial pain syndrome, chronic neck pain, and low back pain as a result of laser application” (Falaki, et.al.). The literature noted again that the post herpetic pain groups did quite well, with statistically improved, sustained relief. Several types of lasers are in use (He-Ne, GaAlAs, and CO2 laser), but there does not seem be more benefit to one form versus another. Lasers used to treat pain are either Class 3 or Class 4 lasers. Class 3 lasers are also called “cold lasers,” “LLLT,” “low level light therapy,” or “low level laser therapy.” Recent work suggests Class 4 lasers have earlier, better outcomes for neuropathic pain. In this study, a Neodymium YAG laser was used for twenty patients with refractory TN pain. 75% of patients reported partial to full relief after two sessions XLR8 lasers are FDA approved for chronic pain use. This is a class four laser for home use. Disclosure — I do not have any connection or stock.

This is mirrored in the published studies. Laser therapy uses single-wavelength light, monochromatic, to affect tissue changes. The wavelengths appear to be most effective in the 660 to 850 nanometer range. Photobiomodulation therapy applied in the form of low-intensity Light Amplification by Stimulated Emission of Radiation (LASER) and light-emitting diode (LED) has been shown to reduce inflammation and swelling, promote healing, and reduce pain for an array of musculoskeletal conditions. There is evidence that photobiomodulation therapy reduces pain intensity in non-specific knee pain, osteoarthritis pain, post-total hip arthroplasty, fibromyalgia, temporomandibular diseases, neck pain, and low back pain. Red laser is indicated for superficial injuries regarding its weak penetration and therefore greater absorption while passing through the tissues.

Infrared laser, on the other hand, is indicated for causing instant and impermanent analgesic effects, following from its deeper penetration through biological membranes. It interacts with the polarity alterations and induces analgesia by causing hyperpolarization on cell membrane (light-cell biological interaction) which is known to be a photophysical mechanism (Ash, et. al.; Haghighat, et. al.). This therapy is usually clinic-based. The home devices using “red” light and generated laser light have not been studied yet.

Repetitive transcranial magnetic stimulation (rTMS)

The newest wearable technology uses magnetic stimulation to affect brain pathways and relief. Patients did report some relief, but sporadically. Applying magnetic energy to the brain has been in use since 1985 when Barker and his group created the first external device. It is a non-invasive treatment technique used to treat various psychiatric and neurological disorders. It is in widespread use for various types of depression. It involves the stimulation of specific deep brain regions by the production of high and low-intensity magnetic fields which modulate the cortical excitability. A surface magnetic coil is placed over the brain target area, and a series of on/off pulses of energy are used. In the case of refractory face pain, the target is like that for motor cortex stimulation.

The evidence from 14 randomized, placebo-controlled trials involving approximately 750 patients indicates that high-frequency motor cortex rTMS has a significant analgesic effect on neuropathic pain. When compared to direct transcutaneous electrical stimulation (TNS), it seems that the pathways and targets of stimulation are similar. However, both rTMS and Transcranial Direct-Current Stimulation (tDCS) specifically target abnormal hyperexcitable states of pain, rather than acute or experimental pain. For both techniques, M1 (motor-sensory cortex) seems to provide the best target for chronic pain relief, and achieving clinically significant benefits may require repeated sessions over relatively long periods of time.

Patients who respond to tDCS may differ from those who benefit from rTMS. One advantage of tDCS is its potential for home use and cost-effectiveness. Both therapies may require some trial and error to determine the best stimulation parameters, and neither has been associated with increased pain. Currently, several other non-surgical treatment modalities exist for the management of chronic pain, These include physical therapy, pharmacologic therapy, behavioral medicine. The next steps are neuromodulation (DBS, MCS), minimally invasive interventions, Cryo-rhizolysis, Glycerol, and open surgery. It is important to do research and consult your medical team to establish if there is an option that shows positive effects in the treatment of facial pain, and which one might be best for you.