Hansen Tine M, Graversen Carina, Frøkjaer Jens B, Olesen Anne E, Valeriani Massimiliano, Drewes Asbjørn M
Mech-Sense, Department of Radiology, Aalborg University Hospital, Aalborg, Denmark.
Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Aalborg, Denmark.
Br J Clin Pharmacol. 2015 Jun;79(6):926-36. doi: 10.1111/bcp.12579.
The cortical response to nociceptive thermal stimuli recorded as contact heat evoked potentials (CHEPs) may be altered by morphine. However, previous studies have averaged CHEPs over multiple stimuli, which are confounded by jitter between sweeps. Thus, the aim was to assess single-sweep characteristics to identify alterations induced by morphine.
In a crossover study 15 single-sweep CHEPs were analyzed from 62 electroencephalography electrodes in 26 healthy volunteers before and after administration of morphine or placebo. Each sweep was decomposed by a continuous wavelet transform to obtain normalized spectral indices in the delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12-32 Hz) and gamma (32-80 Hz) bands. The average distribution over all sweeps and channels was calculated for the four recordings for each volunteer, and the two recordings before treatments were assessed for reproducibility. Baseline corrected spectral indices after morphine and placebo treatments were compared to identify alterations induced by morphine.
Reproducibility between baseline CHEPs was demonstrated. As compared with placebo, morphine decreased the spectral indices in the delta and theta bands by 13% (P = 0.04) and 9% (P = 0.007), while the beta and gamma bands were increased by 10% (P = 0.006) and 24% (P = 0.04).
The decreases in the delta and theta band are suggested to represent a decrease in the pain specific morphology of the CHEPs, which indicates a diminished pain response after morphine administration. Hence, assessment of spectral indices in single-sweep CHEPs can be used to study cortical mechanisms induced by morphine treatment.
作为接触热诱发电位（CHEPs）记录的皮质对伤害性热刺激的反应可能会被吗啡改变。然而，先前的研究对多个刺激的CHEPs进行了平均，这受到扫描间抖动的混淆。因此，目的是评估单次扫描特征以识别吗啡诱导的改变。
在一项交叉研究中，对26名健康志愿者在给予吗啡或安慰剂之前和之后，从62个脑电图电极分析了15次单次扫描的CHEPs。每次扫描通过连续小波变换进行分解，以获得δ（0.5 - 4Hz）、θ（4 - 8Hz）、α（8 - 12Hz）、β（12 - 32Hz）和γ（32 - 80Hz）频段的归一化频谱指数。计算每个志愿者的四次记录在所有扫描和通道上的平均分布，并评估治疗前的两次记录的可重复性。比较吗啡和安慰剂治疗后的基线校正频谱指数，以识别吗啡诱导的改变。
证明了基线CHEPs之间的可重复性。与安慰剂相比，吗啡使δ和θ频段的频谱指数分别降低了13%（P = 0.04）和9%（P = 0.007），而β和γ频段分别增加了10%（P = 0.006）和24%（P = 0.04）。
δ和θ频段的降低被认为代表了CHEPs疼痛特异性形态的降低，这表明吗啡给药后疼痛反应减弱。因此，单次扫描CHEPs中频谱指数的评估可用于研究吗啡治疗诱导的皮质机制。
