TweetWhile much larger studies are needed, this neuromodulation therapy shows promising results for the future
Transcranial direct-current stimulation (tDCS) may improve pain-related mood symptoms in patients suffering from chronic lower back pain (LBP), according to the results of a new study. A team of researchers, led by Timothy Mariano, MD from Harvard Medical School, presented their findings at the 2018 annual meeting of the American Society of Clinical Psychopharmacology in Miami.1
“[T]his is the first double-blinded, placebo-controlled randomized controlled trial of multiple tDCS sessions targeting left dorsal anterior cingulate cortex to modulate the affective component of chronic LBP,” the authors wrote in their abstract.1
Pain as a Complex Phenomenon
Pain is comprised of both sensory and affective components;2most therapies focus on managing the sensory component of pain. Current treatment options, including acetaminophen, non-steroidal anti-inflammatory drugs, muscle relaxants, antidepressants, anticonvulsants, and opioids, are not without their side effects, and in fact, the long-term use of opioids for pain management may have serious repercussions.3
“There are few treatments that adequately address the affective symptoms associated with chronic LBP,” Dr. Mariano told Practical Pain Management. However, according to Dr. Mariano and his co-investigators, “chronic LBP’s affective symptoms are significant drivers of disability and psychiatric comorbidity.”
A non-invasive neuromodulation technique, tDCS may be used to alter neuronal activity in selected brain regions4 where the anterior cingulate cortex is a key region of the brain involved in processing pain.2
A Closer Look at the Study Design
Twenty-one patients suffering from chronic LBP for at least 6 months participated in this study, recruited from the Providence Veterans Administration Medical Center and Butler Hospital in Providence, Rhode Island.
Patients were diagnosed using the Defense and Veterans Pain Rating Scale (DVPRS). All patients had been administered pharmacotherapy at least once during the course of their illness. Pain assessment measures used in the study included the West Haven-Yale Multidimensional Pain Inventory (WHY-MPI), assessing impact on daily life; the Roland Morris Disability Questionnaire (RMDQ), assessing degree of pain-related disability; the Patient Health Questionnaire (PHQ-9), assessing depressive symptoms; and the Credibility/Expectancy Questionnaire (CEQ).
Patients were assigned to either an active- or sham-treatment group. For patients in the active arm, tDCS treatments targeting the dorsal anterior cingulate cortex (dACC) were administered once per day, 20 minutes per session, for 10 consecutive weekdays. The sham group received fake treatment within the same regimen, briefly adjusting electric currents to reproduce the transient sensations (eg skin tingling) associated with active tDCS to enhance blinding.
Patients Report Benefits
Significant improvement across all pain measurement scales was shown in patients treated with tDCS. By day 10 of treatment, CEQ, WHY-MPI, and RMDQ scores were p= .038, p = .037, and p = .028 respectively.
At the 6-week follow-up, patients in the active-treatment arm continued to demonstrate significant improvement in low back pain relief when assessed with the WHY-MPI, RMDQ, and PHQ-9 scores (p= .002, p= .001, and p= .003 respectively), compared to those in the sham arm.
“We were interested to find that the pain interference, pain disability, and depression symptoms were significantly reduced in the active tDCS group at the follow-up visit six weeks after completing tDCS,” said Dr. Mariano. “One might expect to see the changes during the acute treatment phase, but there is, in fact, a growing body of literature suggesting that the cumulative effect of multiple tDCS sessions may be delayed.”
A Promising Direction for Future Research
“I’m glad to see progress being made in this arena as there are a great many patients who could benefit from this therapy,” Corey Hunter, MD, board committee member of the North American Neuromodulation Society and assistant clinical professor at Mount Sinai Hospital in New York, told Practical Pain Management. “tDCS is as non-invasive as it gets, and if it is effective as promised, it could help us win the war against opioids.”
But some challenges still stand in the way of this novel approach, as noted by Timothy Deer, MD, president of the International Neuromodulation Society: “The impact is uncertain since the main issue of this type of therapy is the ability to use it in an ongoing mode to allow continuous therapy. That remains the difficult part of noninvasive neuromodulation.” Dr. Deer also serves as chairman of the American Society of Pain and Neuroscience, and is a clinical professor at the West Virginia University School of Medicine.
Drs. Deer, Hunter and Mariano all agreed on the need for additional research in this area of study. “Our study was quite small for an RCT,” explained Dr. Mariano. “Much larger replication studies are needed before tDCS could be considered as a possible clinical treatment for chronic low back pain and its affective symptoms.”
Added Dr. Hunter, “Many people, physicians included, will be skeptical about this therapy. Many will think it is too good to be true, while others will not be able to comprehend how applying energy to the brain could eliminate pain and change one’s moods. There needs to be an emphasis on demystifying the mechanism of action and a push to get the data in the hands of those in a position to prescribe this therapy.”
When asked to place the use of tDCS in a larger context, Dr. Deer stated, “[T]he public and referring physicians should know that the use of neuromodulation is not only for pain and that the use of bioelectric medicine will continue to change the field of medicine and result in fewer drugs, improved function, and mitigation of side effects.
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