Supraspinal Correlates of Patients with Chronic Pain Under Burst Spinal Cord Stimulation: A Proof-of-Concept...

Chronic pain is associated with central pain network-associated alterations. Functional MRI (fMRI) provides a powerful, non-invasive imaging technique to visualize such alterations. This feasibility study attempted to investigate the impact of BurstDR spinal cord stimulation (SCS) on fMRI correlates in patients with chronic pain.

This proof-of-concept study included 11 patients (8 m/3 f; mean age 69.1 ± 11.2 years) with chronic back and/or leg pain with BurstDR SCS. Clinical outcomes were assessed at baseline and after 3 months BurstDR SCS (Numeric Rating Scale (NRS), Pittsburgh Sleep Quality Index (PSQI), Beck Depression Inventory (BDI), Oswestry Disability Index (ODI)). fMRI (1.5 T) was obtained using a classic block-design motor with task and rest with single-subject and group analyses.

Pain decreased at follow-up (NRS: 7.3 ± 1.7 vs. 4.4 ± 1.5; p < 0.001) with improved functional capacity (PSQI: 10.2 ± 3.6 vs. 8.1 ± 2.7; p = 0.009; BDI: 16.9 ± 8.2 vs. 11.9 ± 6.3; p = 0.027; ODI: 56.5 ± 18.3 vs. 45.2 ± 16.4; p = 0.001). In the fMRI analyses, ten patients were included. Movement of the left foot led to significant activation in the medial region of the right precentral gyrus (Z > 3.1, p < 0.05). No differences at the predefined threshold for the entire brain were detected, although the uncorrected voxel-wise analysis showed several regions with increased activation post BurstDR SCS (bilateral middle temporal gyri (left: Z = 3.56, uncorrected p < 0.001; right: Z = 4.48, uncorrected p < 0.0001)). Functional connectivity analyses in 9 patients revealed no significant differences in task-modulated functional connectivity.

BurstDR SCS reduced pain intensity and improved functional status associated with task-related activation of the motor cortex, which was reproducible across the entire cohort. Further randomized controlled studies are warranted to validate these findings and to elucidate the underlying mechanisms.

German Clinical Trials Register (DRKS ID: DRKS00035826).