Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

INTRODUCTION. Chronic low back pain (cLBP) is a leading cause of disability worldwide, with a socioeconomic impact estimated at $87 billion per year in healthcare spending. Spinal cord stimulation (SCS) is a promising therapeutic intervention with superior patient outcomes compared to more traditional modalities for the treatment of cLBP. To date, SCS in cLBP has been delivered via epidural electrodes, requiring neurosurgical implantation. Transcutaneous SCS (tSCS) is a novel neuromodulation technique in the field of spinal cord injury. Through non-invasive lumbosacral spinal cord excitability potentiation, tSCS enables motor functions, such as postural control, in patients with chronic complete motor paralysis. In this study, we report the preliminary results of the pilot clinical trial on the initial efficacy of 12 tSCS therapy sessions to improve pain and objective sensorimotor outcomes in patients with non-specific cLBP.

METHODS. Individuals with non-specific chronic low back pain (duration > 6 months, intensity on Visual Analogue Scale (VAS) > 5 at enrollment) were eligible for the study. Before initiation of therapy, patients underwent a battery of assessments, including sit-to-stand full-body biomechanics with paraspinal and lower extremity surface electromyography (EMG), resting-state functional magnetic resonance imaging (fMRI), and electroencephalography (EEG) to assess motor and neurophysiological function objectively. Stimulation was administered via 3-4 surface electrodes placed on the spine between vertebral segments (T8, T10, L1, C5) 3 times a week for 30 minutes per session for 12 sessions in the research clinic. Patients were asked to mark painful areas of the body on a schematic body map diagram and rate their pain before and immediately after each tSCS to assess its acute pain-relieving efficacy. Additionally, pain intensity was tracked daily (on both stimulation and non-stimulation days) through VAS surveys over a month it took to complete the study.

RESULTS. To date, 4 out of the target 15 participants have completed the study. All patients reported an immediate reduction in back pain intensity after tSCS (Figure 1). Analysis of the daily VAS scores reported over a month showed that, on average, there was a 56% (42 points) reduction in back pain after tSCS therapy as compared to VAS scores at enrollment; 80% (24 points) reduction in right leg pain (2 out of 4 patients reported R leg pain at baseline); 64% (20 points) reduction in left leg pain (1 out of 4 patients reported L leg pain at baseline) (Figure 2). In an interim analysis, using repeated measures ANOVA with a Greenhouse-Geisser sphericity correction (0.693), we found that VAS was significantly changed over time (p <0.05). We recognize the limitation of the statistical significance of our results so far due to a small sample, therefore, we highlight the preliminary nature of our findings.

DISCUSSION. While the objective sensorimotor outcomes analysis is ongoing, our preliminary results suggest that tSCS shows promising efficacy for acute and longitudinal pain relief based on patient-reported outcomes. A  transcutaneous delivery of SCS could provide a non-invasive mode of safe and effective neuromodulation therapy suitable for low back pain patients.