Neuromodulators provide guidelines for implantation of "digital drugs" to manage chronic pain

Jun 12 2013

Neuromodulators have joined together in the Neuromodulation Appropriateness Consensus Committee (NACC) to provide the first coordinated set of recommendations about patient selection and appropriateness for implantation of "digital drugs" to manage chronic pain.

The guidelines were announced at the 11th World Congress of the International Neuromodulation Society (INS), a six-day international scientific meeting. Sessions today concern research-driven neuromodulation guidelines, patient registries, and development of a multi-site pain index and interactive database on spinal cord stimulation - the most common neuromodulation therapy.

The NACC examined current medical evidence for the family of neuromodulation therapies - including therapies that target the head as well as the body - with an eye to reducing complications and delivering better care to patients who have chronic pain. Introduced more than 40 years ago and in common use since the 1980s, neuromodulation therapies treat the nerves themselves and continue to grow, expand, and advance.

In many cases, adaptation of these methods follows pivotal clinical studies that examine the improvement in care that is possible. For instance, in 2012, patients in Europe gained access to occipital nerve stimulation for refractory migraine with CE mark approval. The marketing clearance followed a 12-week study of 157 patients at 15 U.S. centers published in Cephalalgia in November. The participants experienced a 28 percent reduction in migraine frequency and 42 percent reduction in severity and 53 percent of the patients ranked the relief as good or excellent.

Neuromodulators recognize the importance of carefully designed studies and increasingly value the benefit of reporting any unanticipated complications on a case-by-case basis. This forms a rich knowledge base that can be used to refine delivery of care.

Findings gathered through careful observation and patient follow-up inform the recommendations of the NACC, which will be submitted to Neuromodulation: Technology at the Neural Interface for peer review. The recommendations address the most common form of neurostimulation - spinal cord stimulation - as well as peripheral nerve stimulation such as stimulation of the occipital nerve.

Mechanical complications, such as lead migration, are the foremost issue seen in neurostimulation implants such as spinal cord stimulators, with most reports placing that occurrence between 10 - 25 percent. Lead migration can be resolved by adjusting programming if the displacement was slight, or replacing the lead. A 2011 review by Dr. Robert Levy, co-director of the Shands Jacksonville Neuroscience Institute at the University of Florida College of Medicine in Jacksonville, and colleagues of the incidence of complications from the use of paddle-style spinal cord stimulator leads (that have a flat area for electrical contacts) found the risk of serious neurological injury is real, but rare.

"Procedural safety, careful patient follow-up and management of complications are recommended to minimize that risk," said migraine study investigator Dr. Eric Buchser, head of Anaesthesia and Pain Management Department and Neuromodulation Centre at the EHC-Hôpital de Morges, Switzerland.

Less frequent are biological complications associated with surgical procedures, which include the risk of infection, hemorrhage, skin erosion at the site of the implant, and headache.

Despite the frequency of complications and their costs, spinal cord stimulation has been found to be cost-effective when compared to either conventional medical management or spinal reoperation, noted safety review co-author Dr. Konstantin Slavin, a neurosurgeon with expertise in peripheral nerve stimulation and professor of Stereotactic and Functional Neurosurgery at the University of Illinois at Chicago.

With these issues in mind, the NACC examined risk mitigation recommendations and weighed the appropriateness of these advanced treatments in order to deliver better care to patients who have chronic disease.

"The synthesis of all available evidence based medicine and expert clinical opinion concerning both patient and device selection, implant techniques and complication avoidance and management is critical for practitioners in the rapidly evolving field of neuromodulation," said Levy, also the editor-in-chief of the INS journal Neuromodulation: Technology at the Neural Interface. "Guidelines to improve the safety, efficacy and cost effectiveness of these techniques will help to improve high-quality outcomes and patient access to these important therapies."

It is important to note that in device-based therapies, the experience of the implanter significantly affects the rate of complications. This has been successfully demonstrated in the case of cardiovascular defibrillator and total hip replacement, said Dr. Paul Verrills, co-director of the Metro Spine Clinic in Melbourne.

The self-policing and reflection on best practices with a focus on patient outcomes is evolving in parallel with technology advances, noted Dr. Jason Pope of the Center for Pain Relief in Charleston, W.Va.

As an example, imaging techniques have advanced during the four decades of development of neuromodulation. Due to the potential for metal parts to heat during a magnetic resonance imaging scan, the NACC advises that MRI should not be considered for patients with neurostimulation systems if other potentially safer diagnostic methods, such as CT, X-ray, or ultrasound will provide adequate diagnostic information.

If MRI is required, the advice of a radiologist should be sought and, depending on imaging site and sequencing, imaging may be possible; however, at present, the majority of radiologists would advise against use of MRI with a spinal cord stimulation system in place, said Dr. Allen W. Burton, a renowned cancer pain specialist with the Houston Pain Centers.

In the final analysis, the committee members agree, rather than solely compare cases or incidence data, exercising clinical judgment also includes assessing the relative potential impact from neurostimulation implants of infections, neurological lesions, hemorrhage or equipment failure against the alternative potential posed by long-term painkiller use that can result in allergic reactions, metabolic disturbances, or psychotropic adverse events.

SOURCE International Neuromodulation Society