Around 100 million Americans experience chronic back pain, including 20 million who have high-impact pain that limits their ability to work most or all days over a six-month period.
Medical management is typically the first step in treating chronic back pain. Radiofrequency ablation and epidural injections may be used in patients who don’t respond to oral or topical medications. Despite these interventions, many patients continue to experience pain.
Spinal cord stimulation (SCS), in which an implanted device sends low levels of electricity directly to the spinal cord to block the transmission of pain signals, is frequently used as a next step for patients who do not achieve sufficient pain relief from non-surgical approaches or who continue to experience pain after spine surgery.
An evolving landscape for spinal cord stimulation in the treatment of chronic back pain
Initial SCS devices targeted neuronal cells and replaced the feeling of pain with a tingling sensation.
While initial and next-generation SCS systems targeted neuronal cells within the spinal cord, it has been known for more than 20 years that there are many (about 12x) times more glial cells than neuronal cells in the spinal cord, and a growing body of research has explored the role that glial cells play in the development and maintenance of pain.
Recent evidence shows that chronic pain occurs when neuro-glial interactions act out of sync.
Recent advances in SCS technology build upon the understanding of the role that glial cells play in pain. This approach, known as Differential Target Multiplexed™ Spinal Cord Stimulation (DTM™SCS), targets different areas of the spinal cord (Differential Target) with different signals or frequencies (Multiplexed).
In preclinical studies, the DTM waveform best modulates glial and neuronal gene expression back toward the non-pain state.
Perhaps more importantly, DTM™ SCS has also demonstrated benefits compared with conventional SCS in a robust, randomized controlled trial (RCT).
In the RCT, 94 patients with chronic back or leg pain were randomised and implanted with either DTM™ SCS or conventional SCS which was delivered using the Intellis™ platform (Medtronic).
Data from 79 patients evaluable at 12 months demonstrated an 84 per cent responder rate (≥ 50 per cent improvement) in the DTM™ SCS arm, which was significantly better than the SCS arm (p=0.0005), and higher than rates reported at 12 months in comparable RCTs*.
Additionally, 69 per cent of patients in the DTM™ SCS arm were profound back pain responders (≥ 80 per cent improvement) at 12 months, compared with only 35 per cent with conventional SCS.
Patients in the DTM™ SCS arm also had greater reductions in back pain scores as assessed by the Visual Analog Scale (VAS) compared with patients in the conventional SCS arm (75 per cent vs. 50 per cent).
Similar differences were observed between the DTM™ SCS and conventional SCS arms with respect to mean VAS score reductions for back and leg pain at 12 months (1.74 vs. 3.71, respectively for back pain and 1.45 vs. 2.25 for leg pain).
These results indicate that this RCT met its primary endpoint of noninferiority compared with conventional SCS.
A pre-specified secondary statistical test for superiority showed the difference between DTM™ SCS and conventional SCS as highly significant.
In the DTM™ SCS group, multiple secondary endpoints showed significant changes at 12 months compared with baseline, including sustained improvements in the degree of disability, quality of life, and satisfaction with treatment.
An evolving landscape for treating patients with chronic back pain
The RCT data support the potential for DTM™ SCS to provide durable and more effective pain relief compared with conventional SCS and demonstrate the clinical value of continued innovation across the pain therapy landscape.
However, the promise of innovative technologies can only be realised when they are implemented in clinical practice and broadly available to patients.
Given that the care of patients with chronic back pain is often managed by multi-disciplinary teams that may comprise orthopedic/neurosurgery, pain management, and physical therapy specialists as well as primary care providers, ensuring that patients who may benefit from DTM™ SCS receive it requires close coordination and communication.
It is incumbent upon all of us who treat these patients to understand how to integrate emerging technologies into evolving treatment paradigms to enable optimum patient outcomes.
The RCT data provide a compelling rationale for making DTM™ SCS standard of care for patients with intractable chronic back or leg pain.
Establishing or accessing referral networks to connect these patients with providers who can provide DTM™ SCS is essential for improving access to this cutting-edge therapy.
*Descriptive comparison including studies with similar design (RCT; randomisation >100 subjects; comparing 2 SCS therapies; with at least 12-months follow-up) and patient populations (inclusion/exclusion criteria; baseline demographics) with back pain responder rates reported. This is not based on a statistical analysis of outcomes between studies.
Author
Leonardo Kapural, MD, PhD, is a pain physician at the Carolinas Pain Institute and The Center for Clinical Research.
He is also a clinical adjunct faculty of anesthesiology at Wake Forest University, School of Medicine.
Dr. Kapural is a consultant for Medtronic, which provided Medtronic technical support for, and reviewed the contents of this article prior to publication.
