Nuffield Department of Surgery, University of Oxford, Oxford, UK.
Exp Neurol. 2010 Jun;223(2):574-81. doi: 10.1016/j.expneurol.2010.02.004. Epub 2010 Feb 21.
The midbrain periaqueductal grey (PAG) area is important for both pain modulation and cardiovascular control via the autonomic nervous system (ANS). While changes in blood pressure dependent upon dorsal or ventral electrode positioning have been described with PAG deep brain stimulation (DBS), little is known mechanistically about the relationships between pain and cardiovascular regulation in humans. Heart rate variability (HRV) is an established measure of cardiovascular regulation, and an index of autonomic function.
16 patients undergoing DBS of the rostral PAG for chronic neuropathic pain were investigated post-operatively to determine whether PAG stimulation would alter HRV, and the subjects' perception of pain. Mean heart rate together with HRV, time and frequency domain measures, low frequency (LF) and high frequency (HF) power components of heart rate and the ratio of LF to HF were calculated before and during DBS. Ventral but not dorsal PAG DBS significantly decreased the ratio of LF to HF power (p<0.05, n=8) with HF power significantly increased. Changes in LF/HF ratio correlated significantly with subjective reporting of analgesic efficacy using a visual analogue score (VAS; gamma(2)=0.36, p=0.01, n=16). Diffusion tensor imaging and probabilistic tractography of 17 normal controls' seeding voxels from the mean ventral and dorsal PAG stimulation sites of the 16 patient cohort revealed significant differences between rostral tract projections and separate, adjacent projections to ipsilateral dorsolateral medulla.
Ventral PAG DBS may increase parasympathetic activity to reduce pain via anatomical connections distinct from dorsal PAG DBS, which may act by sympathetic mechanisms.
中脑导水管周围灰质（PAG）区通过自主神经系统（ANS）在疼痛调节和心血管控制方面都很重要。虽然已经描述了 PAG 深部脑刺激（DBS）中背侧或腹侧电极位置变化与血压的关系，但对于人类疼痛与心血管调节之间的关系，其机制知之甚少。心率变异性（HRV）是心血管调节的一种既定测量方法，也是自主功能的指标。
对 16 名因慢性神经性疼痛而行 PAG 前颅窝 DBS 的患者进行了术后调查，以确定 PAG 刺激是否会改变 HRV 以及患者对疼痛的感知。在 DBS 之前和期间计算平均心率以及 HRV、时间和频域测量、心率的低频（LF）和高频（HF）功率分量以及 LF 与 HF 的比值。腹侧但不是背侧 PAG DBS 显著降低 LF/HF 比值（p<0.05，n=8），HF 功率显著增加。LF/HF 比值的变化与使用视觉模拟评分（VAS）进行的主观镇痛效果报告显著相关（γ(2)=0.36，p=0.01，n=16）。对 16 名患者队列中 17 名正常对照者从平均腹侧和背侧 PAG 刺激部位种子体素进行的弥散张量成像和概率追踪显示，在颅前束投射与同侧背外侧延髓的单独相邻投射之间存在显著差异。
腹侧 PAG DBS 可能通过与背侧 PAG DBS 不同的解剖连接增加副交感神经活动来减轻疼痛，而背侧 PAG DBS 可能通过交感神经机制起作用。
