Heterogeneous Cortical Effects of Spinal Cord Stimulation

Bart Witjes; Sylvain Baillet; Mathieu Roy; Robert Oostenveld; Frank J P M Huygen; Cecile C de Vos

doi:10.1016/j.neurom.2022.12.005

Heterogeneous Cortical Effects of Spinal Cord Stimulation

Neuromodulation. 2023 Jul;26(5):950-960. doi: 10.1016/j.neurom.2022.12.005. Epub 2023 Jan 9.

Authors

Bart Witjes¹, Sylvain Baillet², Mathieu Roy³, Robert Oostenveld⁴, Frank J P M Huygen⁵, Cecile C de Vos⁶

Affiliations

¹ Center for Pain Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands. Electronic address: b.witjes.1@erasmusmc.nl.
² Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada.
³ Department of Psychology, McGill University, Montreal, Canada.
⁴ Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands; NatMEG, Karolinska Institutet, Stockholm, Sweden.
⁵ Center for Pain Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
⁶ Center for Pain Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands; Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada.

PMID: 36631377
DOI: 10.1016/j.neurom.2022.12.005

Abstract

Objectives: The understanding of the cortical effects of spinal cord stimulation (SCS) remains limited. Multiple studies have investigated the effects of SCS in resting-state electroencephalography. However, owing to the large variation in reported outcomes, we aimed to describe the differential cortical responses between two types of SCS and between responders and nonresponders using magnetoencephalography (MEG).

Materials and methods: We conducted 5-minute resting-state MEG recordings in 25 patients with chronic pain with active SCS in three sessions, each after a one-week exposure to tonic, burst, or sham SCS. We extracted six spectral features from the measured neurophysiological signals: the alpha peak frequency; alpha power ratio (power 7-9 Hz/power 9-11 Hz); and average power in the theta (4-7.5 Hz), alpha (8-12.5 Hz), beta (13-30 Hz), and low-gamma (30.5-60 Hz) frequency bands. We compared these features (using nonparametric permutation t-tests) for MEG sensor and cortical map effects across stimulation paradigms, between participants who reported low (< 5, responders) vs high (≥ 5, nonresponders) pain scores, and in three representative participants.

Results: We found statistically significant (p < 0.05, false discovery rate corrected) increased MEG sensor signal power below 3 Hz in response to burst SCS compared with tonic and sham SCS. We did not find statistically significant differences (all p > 0.05) between the power spectra of responders and nonresponders. Our data did not show statistically significant differences in the spectral features of interest among the three stimulation paradigms or between responders and nonresponders. These results were confirmed by the MEG cortical maps. However, we did identify certain trends in the MEG source maps for all comparisons and several features, with substantial variation across participants.

Conclusions: The considerable variation in cortical responses to the various SCS treatment options necessitates studies with sample sizes larger than commonly reported in the field and more personalized treatment plans. Studies with a finer stratification between responders and nonresponders are required to advance the knowledge on SCS treatment effects.

Keywords: Cortical activity; electroencephalography; magnetoencephalography; spectral features; spinal cord stimulation.

MeSH terms

Electroencephalography
Humans
Pain Measurement / methods
Spinal Cord
Spinal Cord Stimulation* / methods