Spinal cord stimulation (SCS) as a medical treatment has been around for the past 50 years. In all that time, the fundamental underlying technology has not changed: tonic nerve stimulation provides pain relief. The only parameters that can be altered in current stimulation technology are the pulse width, frequency, and amplitude.

More recently, in the past decade, Boston Scientific increa-sed the flexibility of these devices by allowing each channel in the stimulator to have different stimulation settings.1 Nonetheless, this stimulation fell short of properly simulating all aspects of the body's pain perception machinery. A new device from St. Jude Medical seems to come closer to true physiological mimicry. The company's Prodigy stimulation system uses both tonic and burst stimulation to provide pain relief, and it represents a potential next generation in SCS.1

The Prodigy system from St. Jude relies on using both low-level tonic stimulation and brief periods of high-frequency burst stimulation. Given that the brain possesses neurons using both of these patterns, pain modulation should be enhanced when using both types of stimulation. This system possesses the unique ability to provide stimulation using either paradigm.

Several working mechanisms have been proposed to explain why the Prodigy system seems to provide superior results. One theory as to how the burst stimulation works is rooted in differences in spinal pain pathway activation. Compared with tonic stimulation, which is capable of activating the lateral pain pathway, burst stimulation is capable of activating both the lateral and medial pain pathways. This allows modulation of discriminatory components of pain (lateral) and pain vigilance and awareness (medial).

However, several other theories exist as to how the system works, including frequency-dependent opioid release from the dorsal horn, and selective A[beta] fiber effects.1

Regardless, most of these hypotheses revolve around the same principle: burst stimulation is better at using physiological machinery already present in our nervous system. Therefore, these systems should be more effective than traditional tonic stimulation.

Indeed, several preliminary studies exist suggesting the superior efficacy of burst stimulation. A study from De Ridder et al2 demonstrated that back and overall pain were consistently 20% better using burst stimulation compared with tonic stimulation.

Another such study from Courtney et al3 demonstrated a 46% reduction in visual analog scale pain scores during burst stimulation compared with tonic stimulation in 22 patients with tonic SCS during a 2-week period. Moreover, 96% of patients in the study reported a reduction or elimination of paresthesia. Lastly, Van Havenbergh et al4 demonstrated that increasing the burst stimulation frequency to 1 kHz had no additional pain modification effects compared with 500-Hz burst stimulation. As such, preliminary data suggest burst stimulation represents the likely future platform of SCS.

Despite these supporting studies, the Prodigy system is not yet approved for use in the United States. The SUNBURST trial is targeted at accomplishing this goal, and it is the largest US clinical trial of burst stimulation to date. Preliminary data were shared by one of the principal investigators at the North American Neuromodulator Society (NANS) 2015 annual conference. The data presented were consistent with the results of previous studies that suggested burst stimulation reduced paresthesia and was equally or more effective than tonic stimulation alone.

Timothy Deer, MD, DABPM, chair of the study, was quoted in BusinessWire saying, "We are excited to report the positive results of the SUNBURST study, which shows burst stimulation can provide patients additional options to effectively manage their chronic pain."5 Deer also is president and chief executive officer of the Center for Pain Relief in Charleston, West Virginia.

The study was scheduled to be completed in April 2016, after which the Prodigy system could be approved for use by the FDA.6

Physiatrist Jason Siefferman, MD, of New York University, commented: "The recent findings by St. Jude Medical that intermittent bursts of stimulation are potentially more effective than traditional tonic stimulation come as no surprise. We've known from studies of TENS [transcutaneous electrical nerve stimulation] that the body habituates to a steady frequency of electricity and that modulating settings are more effective. It is nice, however, to have evidence to pave the way for new technology."

As such, the Prodigy system could be an effective treatment for patients with chronic pain. If approved, physicians may want to consider this platform when recommending possible interventions to reduce the patient's pain, provided the final results are consistent with what was presented at NANS.

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