Witjes Bart, Baillet Sylvain, Roy Mathieu, Oostenveld Robert, Huygen Frank J P M, de Vos Cecile C
Center for Pain Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada.
Neuromodulation. 2023 Jul;26(5):950-960. doi: 10.1016/j.neurom.2022.12.005. Epub 2023 Jan 9.
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).
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.
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.
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.
对脊髓刺激（SCS）的皮质效应的理解仍然有限。多项研究调查了SCS在静息态脑电图中的作用。然而，由于报告结果差异很大，我们旨在使用脑磁图（MEG）描述两种类型的SCS之间以及反应者和无反应者之间不同的皮质反应。
我们对25例慢性疼痛患者进行了5分钟的静息态MEG记录，在三个阶段进行，每个阶段在接受一周的强直性、爆发性或假刺激SCS后进行。我们从测量的神经生理信号中提取了六个频谱特征：α峰值频率；α功率比（7 - 9Hz功率/9 - 11Hz功率）；以及θ（4 - 7.5Hz）、α（8 - 12.5Hz）、β（13 - 30Hz）和低γ（30.5 - 60Hz）频段的平均功率。我们比较了这些特征（使用非参数置换t检验）在不同刺激模式下、报告低疼痛评分（<5，反应者）与高疼痛评分（≥5，无反应者）的参与者之间以及三名代表性参与者的MEG传感器和皮质图谱效应。
我们发现，与强直性和假刺激SCS相比，爆发性SCS引起的MEG传感器信号功率在3Hz以下有统计学显著增加（p < 0.05，经错误发现率校正）。我们未发现反应者和无反应者的功率谱之间存在统计学显著差异（所有p > 0.05）。我们的数据未显示三种刺激模式之间或反应者与无反应者之间在感兴趣的频谱特征上存在统计学显著差异。这些结果通过MEG皮质图谱得到证实。然而，我们确实在所有比较和几个特征的MEG源图谱中确定了某些趋势，不同参与者之间存在很大差异。
对各种SCS治疗方案的皮质反应差异很大，这就需要进行样本量大于该领域通常报告的研究，并制定更个性化的治疗方案。需要对反应者和无反应者进行更精细分层的研究，以推进对SCS治疗效果的认识。
