Witjes Bart, Ottenheym Lucas A, Huygen Frank J P M, de Vos Cecile C
Department of Anesthesiology, Center for Pain Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
Joint Degree Technical Medicine, Leiden University Medical Center, Delft University of Technology and Erasmus University Medical Center, Rotterdam, The Netherlands.
Neuromodulation. 2023 Jan;26(1):35-42. doi: 10.1016/j.neurom.2022.04.036. Epub 2022 May 10.
Spinal cord stimulation (SCS) is an effective therapy for patients with refractory chronic pain syndromes. Although studies have shown that SCS has both spinal and supraspinal effects, the current understanding of cortical effects is still limited. Neuroimaging techniques, such as magnetoencephalography (MEG) and electroencephalography (EEG), combined here as M/EEG, can reveal modulations in ongoing resting-state cortical activity. We aim to provide an overview of available literature on resting-state M/EEG in patients with chronic pain who have been treated with SCS.
We searched multiple online data bases for studies on SCS, chronic pain, and resting-state M/EEG. Primary outcome measures were changes in spectral features, combined with brain regions in which these changes occurred.
We included eight studies reporting various SCS paradigms (tonic, burst, high-dose, and high-frequency stimulation) and revealing heterogeneity in outcome parameters. We summarized changes in cortical activity in various frequency bands: theta (4-7 Hz), alpha (7-12 Hz), beta (13-30 Hz), and gamma (30-44 Hz). In multiple studies, the somatosensory cortex showed modulation of cortical activity under tonic, burst, and high-frequency stimulation. Changes in connectivity were found in the dorsal anterior cingulate cortex, dorsolateral prefrontal cortex, and parahippocampus.
The large heterogeneity observed in outcome measures is probably caused by the large variety in study designs, stimulation paradigms, and spectral features studied. Paresthesia-free paradigms have been compared with tonic stimulation in multiple studies. These studies suggest modulation of medial, lateral, and descending pathways for paresthesia-free stimulation, whereas tonic stimulation predominantly modulates lateral and descending pathways. Moreover, multiple studies have reported an increased alpha peak frequency, increased alpha power, and/or decreased theta power when SCS was compared with baseline, indicating modulation of thalamocortical pathways. Further studies with well-defined groups of responders and nonresponders to SCS are recommended to independently study the cortical effects of pain relief and SCS.
脊髓刺激（SCS）是治疗难治性慢性疼痛综合征患者的一种有效疗法。尽管研究表明SCS具有脊髓和脊髓上的作用，但目前对其皮质效应的了解仍然有限。神经成像技术，如脑磁图（MEG）和脑电图（EEG），在此合并为M/EEG，可揭示静息状态下持续的皮质活动的调制情况。我们旨在概述有关接受SCS治疗的慢性疼痛患者静息状态M/EEG的现有文献。
我们在多个在线数据库中搜索有关SCS、慢性疼痛和静息状态M/EEG的研究。主要结局指标是频谱特征的变化，以及这些变化发生的脑区。
我们纳入了八项研究，这些研究报告了各种SCS模式（持续性、爆发性、高剂量和高频刺激），并揭示了结局参数的异质性。我们总结了不同频段（θ波（4 - 7Hz）、α波（7 - 12Hz）、β波（13 - 30Hz）和γ波（30 - 44Hz））皮质活动的变化。在多项研究中，体感皮层在持续性、爆发性和高频刺激下显示出皮质活动的调制。在前扣带回背侧皮质、背外侧前额叶皮质和海马旁回发现了连接性的变化。
在结局指标中观察到的巨大异质性可能是由研究设计、刺激模式和所研究的频谱特征的多样性所致。在多项研究中，已将无感觉异常模式与持续性刺激进行了比较。这些研究表明，无感觉异常刺激对内侧、外侧和下行通路有调制作用，而持续性刺激主要调制外侧和下行通路。此外，多项研究报告称，与基线相比，SCS时α波峰值频率增加、α波功率增加和/或θ波功率降低，表明丘脑皮质通路受到调制。建议对SCS有明确反应者和无反应者群体进行进一步研究，以独立研究疼痛缓解和SCS的皮质效应。
