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Pilot Brain Stimulation Study Falls Short of Reducing Back Pain

April 2, 2020
The study of brain stimulation, using tACS, may offer a non-opioid based treatment option for low back pain, but more research is needed.

with David Cosio, PhD, ABPP

The use of non-invasive brain stimulation had no significant impact on respiratory sinus arrhythmia in a randomized, sham-controlled pilot study of adults with chronic low back pain (CLBP). However, measures of autonomic nervous system (ANS) balance did significantly improve in treated patients compared to those who underwent a sham treatment. “Chronic low back pain stems from dynamic interactions between sensory and contextual (ie, cognitive, emotional, and motivational) processes in the brain that are mediated by feed-forward and feedback processes,” according to a paper published by Julianna H. Prim, MD, of the University of North Carolina, Chapel Hill, and colleagues.1 Recent studies have suggested that ANS balance plays a role in chronic pain development, and that respiratory sinus arrhythmia (RSA) may be reduced in patients with chronic LBP, but the potential of using non-invasive brain stimulation to provide relief remains unknown.

In their study, the UNC researchers identified adults ages 18 to 65 years with self-reported clinical diagnoses of lumbosacral region pain for at least six months and no history of psychiatric problems. A total of 41 patients were assessed; 20 patients completed the study. The average age of participants was 43 years; 60% were women.

Participants were randomized to receive either 10 Hz of transcranial alternating current stimulation (tACS) using silicone electrodes applied to the scalp or a sham stimulation. Both the tACS and sham treatment lasted for 40 minutes, but the sham stimulation included only 1 minute of exposure to a current. Patients underwent two sessions with a gap of at least 7 days between each session. Patients in both groups sat comfortably and watched videos of underwater scenes during the process.

Overall, the researchers found no significant effects of the treatment on RSA (P = 0.57) based in part on numeric rating scale scores of pain taken before and after undergoing stimulation. However, they did find a significant effect of condition (though not session or sequence) on the standard deviation of normal intervals of R-peaks (SDNN) in the treatment group compared with the sham group (P = 0.027).

“These findings suggest that tACS modulated total heart rate variability (HRV) (both sympathetic and parasympathetic input) in patients with CLBP,” the researchers wrote in their paper. As for the impact on pain, however, the team found no impact of treatment compared to the sham group on changes in pain measures from baseline. Measures utilized included the Oswestry Disability Index (specific to back pain) and a pressure pain threshold test.

The study of brain stimulation as a treatment option for low back pain is important as a potential alternative to opioids, according to David Cosio, PhD, of the Jesse Brown VA Medical Center in Chicago, and a PPM editorial advisor. However, Dr. Cosio said he was not surprised at the lack of tACS impact on pain in the study. “In my work using cranial electrical stimulation, I have found that it is most effective for conditions such as fibromyalgia and is less effective for low back pain. Past research has shown that cranial electrical stimulation has modest beneficial effects on symptoms of fibromyalgia and does not have an effect on chronic pain associated with spinal cord injury. (Image: iStock),” he explained. “However, cranial electrical stimulation does have a modest beneficial effect on symptoms of anxiety and depression in selected patients,” he noted.

Dr. Cosio commented that next steps for research could include comparison of different types of brain stimulation devices, noting that, “The tACS is not the only type of cranial brain stimulation that is available in the market. It would be interesting to see how the different units available differ in their effectiveness as they all differ slightly in their mechanism.” In addiction, clinicians should consider trialing several tACS sessions to determine effectiveness for any given patient. “When using cranial electrical stimulation, I have noted, anecdotally, that one session is not enough to show effectiveness at times. In my practice, I tend to use three sessions before discontinuing a trial of the treatment,” he said. 

Last updated on: April 2, 2020
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