Spinal Cord Stimulation Tolerance and Treatment by Waveform Conversion Using Externalized Trialing: A Retrospective...

Spinal cord stimulation is utilized in the management of a variety of pain states. Commonly, implanted stimulator systems lose their efficacy, resulting in explantation of the devices. Strategies beyond repositioning the leads have evolved in recent years. Replacing generators to deliver a new electrical signaling is known as "salvage" or "rescue" therapy.

To assess the impact of testing multiple pulse generator systems during a salvage trial on clinical outcomes and cost-effectiveness in patients with failed primary SCS devices.

Retrospective chart review.

An academic health care institution.

We retrospectively reviewed the charts of patients who were treated from 2016 to 2019, had previously been implanted with spinal cord stimulation (SCS) systems, and had subsequently undergone a salvage trial in the operating room. In all cases, the original SCS generator was explanted while the existing epidural lead array was preserved and connected to percutaneous extension leads. Those leads were externalized and attached to an alternative stimulation system. Patients underwent a one-week externalized trial with individualized parameter optimization. They then returned to the operating room for either permanent implantation or system removal. Data on changes in visual analog scale (VAS) scores, percent coverage, potential morphine equivalent daily dose (PMEDD), and trial outcomes were collected.

We reviewed 20 serially treated patients who had been previously implanted with SCS systems and subsequently undergone a salvage trial in the operating room. The present investigation found, in a subgroup analysis of patients, that gender may play a role in the complexity of waveform selection. Average age was slightly higher in the multiple trial group (55.4 years versus 49.6 years), and both groups had comparable BMI values (32.6 versus 32.16). Patients in the multiple-trial group tended to proceed to salvage therapy sooner (3.5 years versus 4.9 years, P < 0.001). In summary, proprietary electrical signaling platform cycling seems to be an effective strategy for SCS salvage. Pre-trialing may improve implantation outcomes, and larger studies are warranted to develop best practice strategies for these chronic pain patients.

Limitations include a small sample size, variability in follow-up timing, inconsistent reporting of clinical data, and the absence of standardized functional and quality-of-life outcome measures.

Emerging stimulation paradigms such as burst and high-frequency stimulation present promising alternatives for patients with ineffective SCS systems. In cases wherein the existing device cannot support these modalities, an IPG externalization trial may serve as a low-risk strategy to potentially rescue and optimize therapy.