Based on the experience of implanting over two hundred and fifty paraesthesia-free spinal cord stimulation devices, Stefan Schu (Sana Kliniken GmbH Duisburg, Germany) has revealed that when deciding on which system should be selected for which indication or for which patient, there is no true distinction. He maintains, however, that traditional tonic spinal cord stimulation is no longer “good enough” for most patients.
During a presentation at the Annual Meeting of the Neuromodulation Society of the United Kingdom and Ireland (NSUKI; 6–8 November, London, UK) Schu reported his personal experience using traditional tonic spinal cord stimulation, high frequency (HF10) spinal cord stimulation (with the Senza device from Nevro) and burst spinal cord stimulation (with the St Jude Medical technology) and described what factors impact on his decision-making when it comes to implant.
He maintained that though it is an accepted standard of care in the treatment of chronic pain, traditional tonic spinal cord stimulation has limitations. “This has been a big topic of discussion. Some people say that they can have a wonderful result with just four contact electrodes, and everything is totally fine. To be honest, it is not,” he said.
When it comes to spinal cord stimulation, Schu pointed out that with increasing awareness and quantification, studies now show that 20%–30% of patients are non-responders, with some studies showing even higher rates of failed trials. Further, pain control in patients with nociceptive pain remains ineffective and durability of the therapy is a top criteria for pain management; and finally, there are challenges associated with paraesthesia, especially where patients experience unwanted paraesthesia in areas where there is no pain.
Further, inadequate pain control and a dislike for spinal cord stimulation therapy are the most common reasons for withdrawal after the trial period. He reported that approximately 25% of patients withdraw after the spinal cord stimulation implant trial period; and approximately 69% of withdrawing patients have cited inadequate relief or dislike for spinal cord stimulation therapy. Additionally, in some studies, approximately 15% of patients underwent explantation of spinal cord stimulation systems.
“Paraesthesia is a challenging component of tonic spinal cord stimulation therapy. If you do not cover the pain area, you will not have pain relief. Despite numerous technical improvements, obtaining paraesthesia in the lower back can be challenging; changes in body position can significantly modify intensity of paraesthesia, requiring frequent adjustments; and a substantial majority of patients do not tolerate paraesthesia or prefer not to feel sensation at all,” he explained.
In his personal experience, Schu reported that he has implanted more than 1000 traditional tonic spinal cord stimulation devices, more than 110 high frequency stimulation devices and more than 140 burst stimulation devices.
The long-term follow-up from the 10KHZ randomised controlled trial have demonstrated a 66.4% VAS score decrease at 12-months with high frequency stimulation compared with a 44.7% decrease at 12 months with traditional stimulation.
The other paraesthesia-free stimulation option is burst stimulation. He referred to data from a 2014 study where burst stimulation was used as a salvage system for tonic stimulation non-responders and to improve the response in tonic stimulation responders. The study included 102 patients in two centres. In the study, 23.5% of the patients did not respond to tonic spinal cord stimulation therapy. Once the burst technology was loaded onto the existing systems however, 62.5% of chronic non-responders to tonic stimulation responded to burst stimulation. Additionally, 94.9% of chronic responders to tonic stimulation had further improvement to response rate with burst stimulation.
Despite his experience however, Schu said that there is no clear method to choosing a certain stimulation mode for a specific indication. “If you asked me which system is the best choice for which indication, I cannot give you an answer,” he maintained.
He did reveal though, that tonic stimulation does still have a place in most patients over 60 or 70 years old. “In older patients, it often does not work out. Most of them are not intellectually able to follow the idea. If you put it in, they often say that they do not feel any paraesthesia—they are unable to concentrate on the pain relief because they do not feel the paraesthesia. This results in a lot of drop outs. So my personal experience is that if you can avoid paraesthesia-free stimulation in patients over 60, avoid it,” Schu suggested.
On the other hand, he said, patients below 50 or 40 years of age are now asking for paraesthesia-free stimulation. “Nobody is interested in having paraesthesia in pain relief. In young patients therefore, I always give them the opportunity to use a paraesthesia-free system.”
“So which paraesthesia-free stimulation technology is best for which patient? I cannot tell you any remarkable differences,” Schu added.
Referring to the recharging factor to be considered with high-frequency stimulation, Schu reported that in his experience, there has never been a patient who has complained about recharging their device. “Patients do not really complain about recharging once they have the pain relief,” he said.
In terms of implant procedure Schu noted that experienced implanters should be able to place a lead in 10 or 15 minutes, no matter which device they are using.
An advantage of both forms of paraesthesia-free stimulation, Schu added, is the limited number of patients that require reprogramming. “Since we started using paraesthesia-free stimulation, on reprogramming day the numbers have gone down from an average of 30 patients to three or five patients.”
He warned however, that while paraesthesia-free systems need very few reprogrammings, what they do need, especially in the first year, are close follow-ups.
“Is traditional stimulation always bad? No. We have long-term data for more than 50 years. Is paraesthesia evil? No. Most of the patients do not complain about paraesthesia, but some patients, especially younger ones prefer paraesthesia-free.
“Can paraesthesia-free stimulation help to decrease the number of adverse events related to stimulation? Yes, because we avoid in some cases the unwanted paraesthesia area, which is nicer for the patient. Can we decrease the frequency of reprogramming? Yes we can, but we should not decrease the frequency of check-ups,” Schu concluded.