Short‐ and long‐term effects of conventional spinal cord stimulation on chronic pain and health perceptions: A longitudinal controlled trial

Abstract

Background The effectiveness and long‐term outcomes of spinal cord stimulation (SCS) are not fully established, especially considering that data from patients who withdrew from the trial are rarely analysed, which may lead to overestimation of SCS efficacy. We evaluated short‐ and long‐term effects of SCS on chronic pain and perceived health, beyond natural variability in these outcomes. Methods In a prospective design, 176 chronic pain patients referred to SCS were evaluated five times (baseline; retest ~6 weeks later; post‐SCS trial; 8 and 28 weeks post‐permanent implantation). Patients whose SCS trial failed (Temp group) were followed up and compared to those who underwent permanent SCS (Perm group). Results Analyses revealed a non‐linear (U‐shaped) trend significantly different between the two groups. In the Perm group, a significant improvement occurred post‐SCS implantation in pain severity, pain interference, health‐related quality of life and self‐rated health, which was followed by gradual worsening and return to baseline values at end of follow‐up. In the Temp group, only minor changes occurred in these outcomes over time. On average, baseline and end of follow‐up values in the Perm and Temp groups were similar: ~40% in each group exhibited an increase in pain severity over time and 38% and 33%, respectively, exhibited reductions in pain severity over time. Conclusions Since the greatest improvement in the outcome measures occurred from baseline to post‐SCS trial (T1–T3) followed by a gradual decline in the effect, it appears that SCS may not be effective for the majority of chronic pain patients. Significance This longitudinal study evaluated short and long term effects of spinal cord stimulation (SCS) on chronic pain outcome measures, beyond their natural variation in time. Despite significant short term improvements, by the end of the seven months' follow‐up, the outcomes in the treatment group (people who received the permanent implantation) were similar to those of the control group (people whose SCS trial failed and did not continue to permanent implantation) suggesting SCS may not be cost‐effective for chronic pain patients.

Neuromodulation and Habituation: A Literature Review and Conceptional Analysis of Sustaining Therapeutic Efficacy and Mitigating Habituation

“…Occasionally, patients report uncomfortable paresthesia or unpleasant stimulation associated with changes in posture [25,26]. With regard to the duration of pain relief, several studies have reported that cSCS provides analgesia in patients with low back and leg pain for six months [15,22] to one year [27]. Similarly, a systematic review published in 1995 reported that 62% of patients had pain relief for upwards of one year after implantation.…”

“…Although there has been tremendous growth in this field, there is a dearth of studies analyzing the long-term efficacy of SCS. Specifically, patients have reported diminished analgesic effects over time, which is also notably the most common reason for device explantation [15][16][17]. This phenomenon is known as habituation (or tolerance), defined as the development of inadequate pain despite a good initial response and having ruled out hardware-related issues or changes in stimulation coverage [18].…”

Spinal Cord Stimulation in Chronic Low Back Pain Syndrome: Mechanisms of Modulation, Technical Features and Clinical Application

“…Settings of the stimulator (including amplitude, pulse width, frequency, stimulation configuration) are regulated to overlap the painful area with paresthesia [ 34 ]. For this reason, conventional SCS is also called paresthesia-based SCS [ 35 ].…”

Independent research on long‐term spinal cord stimulation outcomes: Comment on “Short‐and long‐term effects of conventional spinal cord stimulation on chronic pain and health perceptions: A longitudinal controlled trial” by Brill and colleagues

“…Brill and colleagues presented results from a longitudinal study of 176 patients eligible for spinal cord stimulation (SCS) with all patients included in the study undergoing an SCS trial, and 113 patients undergoing permanent implant (Brill et al, 2022). The patients who did not proceed to permanent implant (n = 63) served as a control group.…”