Combating chronic pain in a safer manner
August 1, 2022 | View PDF
Dissolving implant to replace drugs
For the first time, researchers have come up with a dissolving implantable device that relieves pain without drugs. The new device has the potential to provide an alternative to opioids and other highly addictive drugs.
Researchers in Chicago, Illinois, have developed a small, soft, flexible implant that relieves pain on demand and without the use of drugs. The biocompatible, water-soluble device works by softly wrapping around nerves to deliver precise, targeted cooling, which numbs nerves and blocks pain signals to the brain. An external pump enables the user to remotely activate the device and then increase or decrease its intensity. After the device is no longer needed, it naturally absorbs into the body, bypassing the need for surgical extraction.
The researchers believe the device has the potential to greatly benefit patients who undergo routine surgeries or even amputations that commonly require postoperative medications. Surgeons could implant the device during the procedure to help manage the patient’s postoperative pain.
“Although opioids are extremely effective, they also are extremely addictive,” said lead device developer John A. Rogers, who is a professor of Materials Science and Engineering, Biomedical Engineering and Neurological Surgery at Northwestern University Feinberg School of Medicine. “As engineers, we are motivated by the idea of treating pain without drugs, in ways that can be turned on and off instantly with user control over the intensity of relief. The technology reported here exploits mechanisms that have some similarities to those that cause your fingers to feel numb when cold. Our implant allows that effect to be produced in a programmable way, directly and locally to targeted nerves, even those deep within surrounding soft tissues.”
Although the new device might sound like science fiction, it leverages a simple, common concept that everyone knows: evaporation. Similar to how evaporating sweat cools the body, the device contains a liquid coolant that is induced to evaporate at the specific location of a sensory nerve.
“As you cool down a nerve, the signals that travel through the nerve become slower and slower, eventually stopping completely,” said study co-author Dr. Matthew MacEwan of Washington University School of Medicine in St. Louis, Missouri. “We are specifically targeting peripheral nerves, which connect your brain and your spinal cord to the rest of your body. These are the nerves that communicate sensory stimuli, including pain. By delivering a cooling effect to just one or two targeted nerves, we can effectively modulate pain signals in one specific region of the body.”
Many older adults are living with chronic pain
A new large study has found that 50.2 million (20.5%) U.S. adults experience chronic pain resulting in an estimated total loss of productivity of nearly $300 billion annually. The findings suggest that older patients with chronic pain may need to reexamine their treatment regimens.
The authors found that respondents with chronic pain reported missing significantly more work days compared to those without chronic pain (10.3 days versus 2.8). They used these figures to quantify the total economic impact of chronic pain on Americans, which they estimated to be $79.9 billion in lost wages. Those with chronic pain also reported more limitations to their engagement in social activities and activities of daily living. Back, hip, knee and foot pain were the most common sources of pain reported, and physical therapy and massage therapy were most commonly sought as treatments.
Chronic pain is associated with substantial disability from reduced mobility, avoidance of activity, falls, depression and anxiety, sleep impairment, and isolation. The authors note that pain medicine is relatively young as a field, and it encompasses specialties including emergency medicine, anesthesia, psychiatry, neurology, psychiatry and radiology. However, there are now promising new techniques for providing pain relief without the usual side effects.
“I don’t want to take any more pills”
Researchers at Lund University in Sweden have developed a completely new stimulation method that relieves pain in a much more painless way. It uses ultra-thin microelectrodes to combat severe pain. This provides effective and personalized pain relief without the common side effects from pain relief drugs.
“The electrodes are very soft and extremely gentle on the brain. They are used to specifically activate the brain’s pain control centers without simultaneously activating the nerve cell circuits that produce side effects,” said lead researcher Jens Schouenborg, a professor of neurophysiology at Lund University.
The method involves implanting a cluster of the ultra-thin electrodes and then selecting a sub-group of the electrodes that provide pure pain relief, but no side effects. This procedure enables extremely precise and personalized stimulation treatment. The pain is blocked by activating the brain’s pain control centers, and these in turn block only the signal transfer in the pain pathways to the cerebral cortex.
“We have achieved an almost total blockade of pain without affecting any other sensory system or motor skill, which is a major breakthrough in pain research. Our results show that it is actually possible to develop powerful and side effect-free pain relief, something that has been a major challenge up to now,” said first study author Matilde Forni, who is with Lund University.
According to the researchers, the new technique should work for all sorts of pain that are conveyed by the spinal cord.
“In principle, the method can be tailored to all parts of the brain, so we believe that it could also be used in the treatment of degenerative brain diseases such as Parkinson’s disease as well as in depression, epilepsy and probably stroke as well. The electrode technique also has applications in diagnostics and not least in research on how the mysterious brain works,” said Schouenborg.
It is currently recommended that all older adults with chronic pain undergo a comprehensive geriatric pain assessment. A comprehensive assessment can guide selection of treatments most likely to combat the pain safely and effectively. A multimodal approach that includes both drug and non-drug modalities for pain is recommended.