We found a statistically significant reduction in the VAS scores for both low back and leg pain at six months compared to the baseline. This reduction was also observed at 12 months, indicating a sustained effect.

In all studies, VAS scores were improved for low back pain after 6 and 12 months. A different observation was for the VAS scores for the leg pain. While all studies showed improvement in leg pain after 6 and 12, only one study, Rigoard [19], showed improvement without statistical significance (MD, 0.58; 95% CI, -0.84 to 2.00). Despite the lower sample of patients, it was sufficient to show a significant improvement in VAS scores for back pain. Regarding this, the authors also mentioned that they could not exclude the possibility of a potential loss of efficacy over time. This could necessitate the identification of new spatial targets of stimulation located under deliberately inactive contacts of the initially implanted SCS lead. Therefore, long-term follow-up would be necessary to determine any potential loss of efficacy over time. It is essential to highlight that most of the studies included in this research (Table 1) also reported improvements in quality-of-life measures and functional outcomes observed in the m-SCS intervention group. These findings underscore m-SCS as an effective treatment option for FBSS patients, offering them sustained pain relief and potentially enhancing their quality of life.

A previous meta-analysis on SCS in FBSS conducted by Kurt et al. [20] incorporated two studies [21, 22]. The authors observed a significant reduction in low back pain at 3, 6, and 12 months compared to the baseline, with weighted mean differences (WMD) of 3.52 (95% CI, 3.10–3.94, p < 0.01), 2.25 (95% CI, 0.40–4.11, p = 0.02), and 3.16 (95% CI, 1.58–4.75, p < 0.01), respectively. Similarly, for leg pain, there was a significant decrease at 3, 6, and 12 months compared to the baseline, with WMDs of 4.40 (95% CI, 3.97–4.82, p < 0.01), 3.25 (95% CI, 1.70–4.80, p < 0.01), and 4.01 (95% CI, 3.68–4.34, p < 0.01), respectively.

In addition, a comprehensive meta-analysis conducted by Taylor et al. [7] (n = 3025) evaluated the effectiveness of SCS and FBSS in alleviating chronic back and leg pain, considering their combined effects. The average pain relief reported across studies was 58% (95% CI: 53% to 64%, random effects) at a mean follow-up duration of 24 months. The study suggested that SCS successfully mitigated pain, regardless of the location of chronic back and leg pain. This review endorses SCS as an efficacious treatment for chronic back and leg pain, predominantly leg pain, irrespective of whether the patient has undergone back surgery previously. Notably, they discovered that the duration of pain is the only predictor of the level of pain relief following SCS [7].

A mixed method analysis conducted by Witkam et al. [23] included qualitative data from 13 patients who had SCS implants for FBSS, with a duration ranging from 3 to 20 years. Follow-up interviews conducted 25 to 35 months post-implantation revealed that 11 of these 13 patients reported reduced pain intensities, and all 11 were satisfied with the outcome of SCS. Prior to the operation, all participants anticipated a decrease in pain intensity. Quantitative analysis showed that the median baseline pain intensity score was 8.0 (6.0–9.0), and the median expected post-SCS pain intensity score was 5.0 (1.0–10.0). Despite the absence of precise pain data, patients experienced a statistically significant improvement in activity and mobility, with p-values of 0.009 for walking and 0.004 for daily activities.

The findings from this systematic review and meta-analysis have significant clinical implications for the treatment of FBSS using m-SCS. Our results demonstrate a substantial reduction in both back and leg pain, as indicated by the changes in VAS scores at six and twelve months. These outcomes suggest that m-SCS could be considered more proactively in the treatment algorithm for patients with FBSS who have not responded to conventional therapies, including single-column SCS. Furthermore, the ability of m-SCS to target specific pain territories more effectively might lead to more personalized pain management strategies, potentially reducing the need for pharmacological interventions and their associated side effects. This could encourage a shift in clinical practice guidelines towards earlier consideration of m-SCS in the treatment pathway. Additionally, the sustained pain relief observed suggests that m-SCS may also help improve the overall quality of life and functional capabilities of patients, underscoring its value as a long-term treatment option. Adoption of m-SCS based on these findings could ultimately lead to better patient management and resource utilization in healthcare systems dealing with chronic pain conditions.

We provide up-to-date evidence of the beneficial impact of SCS on back and leg pain relief in patients with FBSS. Still, there are some limitations. First, the number of studies is small despite including studies from various designs. Second, it is essential to highlight that even though there was observed heterogeneity, previous studies on the same topic showed high heterogeneity as well as noted in Taylor et al. research substantial statistical heterogeneity (P < 0.0001) [7]. Still, we performed a sensitivity analysis, and the results were consistent.