A safe and minimally invasive implantable stimulation device has received most praise from neurosurgeons, and some experts say it represents a “paradigm shift” in the treatment of mechanical low back pain.
The results of a multinational study show that the ReActiv8 device (Mainstay Medical Limited) is effective, improving function and reducing pain in patients with back pain caused by loss of multifidus muscle function for up to 2 years.
Chris Gilligan, MD, director of the Pain Medicine Department at Brigham and Women’s Hospital in Boston, Massachusetts, said: “We really got a muscle that won’t irritate anymore.” Medscape Medical News.
Gilligan said this intervention represents the first restorative nerve stimulation for back pain. He pointed out that traditional spinal cord devices stimulate sensory nerves and only mask the pain.
“This is not to cover up pain. It is to restore the function of the most powerful stable muscle of the lumbar spine, and in this way restore neuromuscular control and stability, thereby improving the patient’s pain,” Gilligan said.
The results of the study were discussed at the American Association of Neurosurgeons (AANS) 2021 annual meeting, which was held online.
“Like a pleasant massage”
Patients with chronic neuropathic low back pain may be suitable for surgery, such as fusion or decompression. However, these do not apply to more individuals with nociceptive mechanical pain, many of whom suffer from multifidus dysfunction.
The current study included 204 relatively young patients (average age 47 years) who were enrolled in 26 locations around the world, including 16 locations in the United States. The baseline score of the visual analog scale for low back pain (VAS) was 7.3 cm, and the baseline score of the Oswestry Disability Index (ODI) was 39 points.
Participants had suffered from low back pain for about 14 years and had experienced pain 97% of the days in the previous year. Almost 100% of people have received physical therapy before but did not succeed.
For all patients, pain medications failed: 37% of patients took opioids at the beginning of the study, and 52% failed interventional pain treatments such as steroid injections.
Participants were randomly assigned to the treatment stimulation group or the sham stimulation group.
During the stimulation, the surgeon placed the wire next to the medial branch nerves, which provide motor nerve innervation to the multifidus muscles on both sides of the back. Then, they connected the lead to a pulse generator implanted in the upper part of the hip.
In this treatment, the patient turns on the stimulator twice a day for 30 minutes each time. When it opens, it alternates between multifidus contraction for 10 seconds and rest for 20 seconds.
“Many patients describe this as a pleasant massage,” Gilligan said. “They can feel the muscles contracting, but it’s not an unpleasant feeling.”
Researchers followed study participants for 120 days in an unknowing manner.
Severe to mild pain
The results showed that compared with sham operation, the average group difference in the improvement of VAS in the treatment group was significant (23.3 vs. 22.4, phosphorus = .03). Active intervention was also significantly better in terms of ODI and EQ-5D health-related quality of life questionnaire scores and the percentage of pain relief.
The secondary results of resolving low back pain did not reach significant significance.
“Frankly, after 14 years of pain, we don’t want them to resolve their back pain in 120 days,” Gilligan said.
The positive results from the patient satisfaction questionnaire and the physician’s overall clinical change impression score are of great significance to treatment stimulation.
After 120 days, participants in the sham treatment group switched to active treatment. The patient was followed up for 1 year, then 2 years.
When discussing the 1-year results of 176 participants, Gilligan said that the average VAS score was 3 cm, a 59% drop from the baseline. “From severe pain to mild pain,” he said.
Gilligan reports that the average ODI score is 19, and “anything below 20 is mildly disabled”.
Almost half (48%) of those taking opioids at baseline voluntarily stopped using them, and 28% reduced their intake.
Based on these results, the U.S. Food and Drug Administration (FDA) approved the device last year and reportedly Medscape Medical News then.
Gilligan said that for the 156 patients, their condition continued to improve after 2 years. “The longer you treat, the greater the benefits,” he said.
Some patients find that they need less and less stimulation, so that the implant is removed. Others continue to use stimulators regularly. Gilligan reports that a patient in Australia has been ill for 7 years.
During a sponsored conference featuring research, Dr. Robert M. Levy, President of the International Society for Neurostimulation, said that stimulators should “make a big impact” because neurosurgeons rarely recommend them to patients who are not suitable for back pain. Spine surgery.
“This is the first time that a minimally invasive, safe and efficient operation has been provided for these patients,” Levy said.
Other conference speakers agreed that the device represents a “paradigm shift” in treating such patients.
Loss of primary endpoint
However, another expert is not so enthusiastic about the device.
Medscape Medical News Michael Hooten, M.D., professor of anesthesiology at the Mayo Clinic Pain Medicine Department in Rochester, Minnesota, is asked to comment on studies being considered for approval by the FDA.The results of the study were published earlier this year in pain.
Hooten, who did not participate in the AANS virtual meeting, said the study was a “well-designed” randomized, sham-controlled trial.
However, he pointed out that the primary endpoint of the study was that the difference in the proportion of participants achieving pain relief of 30% or greater was not statistically significant at 120 days (57.1% vs. 46.6%, phosphorus = .138).
“The primary endpoint is still inconclusive in terms of treatment advantages,” the researchers wrote in the article.
However, Hooten stated that the discovery was “unambiguous” and “not even close.” phosphorus The value of 0.138.
“They did not reach the end point the study was designed to achieve,” he pointed out.In view of this, Hu Teng said he was a little surprised pain Published this research.
The research was funded by Mainstay Medical. Gilligan reported that Mainstay Medical paid part of his salary directly to his department. The meeting team members and Hooten report no relevant financial relationships.
American Association of Neurosurgeons (AANS) 2021 Annual Meeting. Lunch and study session, August 23, 2021.
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