SCS Trial Duration

60-Day PNS Treatment May Improve Identification of Delayed Responders and Delayed Non-Responders to Neurostimulation for Pain Relief

Objective

Conventional neurostimulation typically involves a brief (eg, ≤10-day) trial to assess presumed effectiveness prior to permanent implantation. Low trial conversion rates and high explant rates due to inadequate pain relief highlight the need for improved patient identification strategies. The development of a 60-day percutaneous peripheral nerve stimulation (PNS) system enables evaluation of outcomes following an extended temporary treatment period of up to 60 days, that may obviate or validate the need for permanent implant. The present study provides the first real-world evidence regarding patient response throughout a 60-day PNS treatment period.

Methods

Anonymized data listings were compiled from patients who underwent implantation of temporary percutaneous leads and opted-in to provide real-world data to the device manufacturer during routine interactions with device representatives throughout the 60-day treatment.

Results

Overall, 30% (222/747) of patients were early responders (≥50% pain relief throughout treatment). Another 31% (231/747) of patients initially presented as non-responders but surpassed 50% pain relief by the end of treatment. Conversely, 32% (239/747) of patients were non-responders throughout treatment. An additional 7% (55/747) of patients initially presented as responders but fell below 50% relief by the end of the treatment period.

Conclusion

An extended, 60-day PNS treatment may help identify delayed responders, providing the opportunity for sustained relief and improving access to effective PNS treatment. Compared to a conventionally short trial of ≤10 days, a longer 60-day PNS treatment may also help reduce explant rates by identifying delayed non-responders unlikely to benefit long-term. These scenarios support the importance of an extended 60-day temporary PNS stimulation period to help inform stepwise treatment strategies that may optimize outcomes and cost-effectiveness.

Redefining Spinal Cord Stimulation "Trials": A Randomized Controlled Trial Using Single-Stage Wireless Permanent Implantable Devices

BACKGROUND

"Traditional" spinal cord stimulation (SCS) trials with percutaneous electrodes externalized to a pulse generator (PG) are typically limited in duration due to risk of infection. Newer miniaturized wireless SCS technology eliminates the percutaneous extension (as well as PGs implanted for chronic use), thus facilitating a single-stage implantation after which the device can remain indefinitely.

OBJECTIVE

To evaluate fully implanted wireless SCS devices during a 30-day screening trial in subjects with chronic low back pain and leg pain and a history of lumbosacral spine surgery.

METHODS

In a randomized controlled trial of single-stage wireless SCS using a wireless percutaneous system, 99 subjects received either 10 kHz high frequency stimulation (HFS) or lower frequency stimulation (LFS) below 1500 Hz (Bolash R, Creamer M, Rauck R, et al. Wireless high frequency spinal cord stimulation (10 kHz) compared to multi-waveform low frequency spinal cord stimulation in the management of chronic pain in failed back surgery syndrome subjects: preliminary results of a multicenter, prospective, randomized controlled study. Pain Med 2019, https://doi.org/10.1093/pm/pnz019). In this report, we assess the 30-day trial success rate (≥50% pain relief from baseline) and complications.

RESULTS

The overall trial success rate was 88% (87/99): 92% (46/50) for HFS and 84% (41/49) for LFS (NS). The trial success rate in the 64 subjects with predominant low back pain was 92% (59/64) vs. 80% (28/35) in those with leg pain ≥ low back pain (NS). During the screening trial, one infection occurred (1%) and one subject withdrew and was explanted (1%). Electrode migrations were seen on routine follow-up x-rays in 10 cases (10%).

CONCLUSION

Using wireless SCS devices that allow for an extended trial period and evaluation of various waveforms, we observed a high rate trial success rate with both HFS and LFS waveforms, with minimal incidence of infection. Long-term follow-up will address the cost-effectiveness and morbidity associated with this technology, which facilitates single-stage treatment.

Impact of the National Institute for Health and Care Excellence (NICE) guidance on medical technology uptake: analysis of the uptake of spinal cord stimulation in England 2008-2012

BACKGROUND

The National Institute for Health and Care Excellence (NICE) Technology Appraisal Guidance on spinal cord stimulation (SCS) was published in 2008 and updated in 2012 with no change. This guidance recommends SCS as a cost-effective treatment for patients with neuropathic pain.

OBJECTIVE

To assess the impact of NICE guidance by comparing SCS uptake in England pre-NICE (2008-2009) and post-NICE (2009-2012) guidance. We also compared the English SCS uptake rate with that of Belgium, the Netherlands, France and Germany.

DESIGN

SCS implant data for England was obtained from the Hospital Episode Statistics (HES) database and compared with other European countries where comparable data were available.

RESULTS

The HES data showed small increases in SCS implantation and replacement/revision procedures, and a large increase in SCS trials between 2008 and 2012. The increase in the total number of SCS procedures per million of population in England is driven primarily by revision/replacements and increased trial activity. Marked variability in SCS uptake at both health regions and primary care trust level was observed.

CONCLUSIONS

Despite the positive NICE recommendation for the routine use of SCS, we found no evidence of a significant impact on SCS uptake in England. Rates of SCS implantation in England are lower than many other European countries.

Successful long-term outcomes of spinal cord stimulation despite limited pain relief during temporary trialing

Objectives.  In spinal cord stimulation (SCS) therapy, limited pain relief during the temporary trial period is generally considered to be predictive of poor long-term benefit. To validate or refute this perception, the long-term outcomes of subjects who reported less than 50% pain relief during a temporary SCS trial were examined. Materials and Methods.  Twelve subjects with intractable pain underwent implantation of trial SCS systems. After a trial period in which they reported less than 50% pain relief, they each received a permanent SCS implant. Pain ratings and complications were tracked for 6-18 months. Results.  At the end of the temporary trial period, the average pain relief was 21%; no subject reported 50% or better pain relief. More favorable outcomes were reported after activation of the permanent system, however. At all follow-up time points, at least a third of the subjects reported better than 50% pain relief, and the average pain relief varied over time between 44% and 83%. All complications were readily resolved and no subjects withdrew from the study. Conclusions.  Although SCS provided limited pain relief during the trial period, efficacy was more satisfactory after permanent implantation. Several subjects went on to experience nearly complete pain relief for up to 18 months (the maximum follow-up visit for study purposes), and no subject chose to discontinue SCS therapy. SCS appears to be a viable treatment option for patients who fail trials, raising some doubt as to the predictive sensitivity and specificity of the trial period. Thus, although outcome of a temporary trial period may be suggestive of later efficacy with SCS, it may not be the sole predictor of success. Alternatively, the arbitrary benchmark of 50% pain relief that is typically used to define the success of a temporary trial may be too stringent and unreliable.