Department of Neurosurgery, Rhode Island Hospital, Brown Alpert Medical School, Providence, RI 02903, USA Department of Neuroscience, Brown University, Providence, RI 02903, USA.
Pain. 2011 Nov;152(11):2505-2513. doi: 10.1016/j.pain.2011.07.011. Epub 2011 Sep 8.
Chronic neuropathic pain is associated with long-term changes at multiple levels of the neuroaxis, including in the brain, where electrical stimulation has been used to manage severe pain conditions. However, the clinical outcome of deep brain stimulation is often mixed, and the mechanisms are poorly understood. By means of electrophysiologic methods, we sought to characterize the changes in neuronal activity in the ventral posterolateral nucleus of the thalamus (VPL) in a rat model of peripheral neuropathic pain, and to reverse these changes with low-voltage, high-frequency stimulation (HFS) in the VPL. Extracellular single-unit neuronal activity was recorded in naive rats and in those with sciatic chronic constriction injury (CCI). Seven days after CCI, brush- and pinch-evoked firing, as well as spontaneous firing and afterdischarge, were significantly increased compared to naive rats. Spontaneous rhythmic oscillation in neuronal firing was also observed in rats with CCI. HFS decreased neuronal firing rates in rats with CCI up to ~50% except for spontaneous activity, whereas low-frequency stimulation had no effect. Compared to naive rats, burst firing properties (burst events, percentage of spikes in burst, and mean interburst time) were altered in rats with CCI, whereas these changes were reversed to near normal after HFS. Thermal hyperalgesia in rats with CCI was significantly attenuated by HFS. Therefore, this study demonstrates that electrical stimulation within the VPL can effectively modulate some nociceptive phenomena associated with peripheral neuropathic pain.
慢性神经性疼痛与神经轴多个水平的长期变化有关，包括大脑，大脑中已经使用电刺激来治疗严重的疼痛状况。然而，深部脑刺激的临床效果往往参差不齐，其机制也知之甚少。通过电生理方法，我们试图在周围神经性疼痛的大鼠模型中描述 VPL 中神经元活动的变化，并通过 VPL 中的低电压、高频刺激（HFS）来逆转这些变化。在未受伤的大鼠和坐骨神经慢性缩窄性损伤（CCI）大鼠中记录了体外单单位神经元活动。CCI 后 7 天，与未受伤的大鼠相比，触须和捏合诱发的放电以及自发性放电和后放电显著增加。CCI 大鼠也观察到神经元放电的自发性节律性振荡。HFS 可使 CCI 大鼠的神经元放电率降低至约 50%，但自发性活动除外，而低频刺激则没有影响。与未受伤的大鼠相比，CCI 大鼠的爆发放电特性（爆发事件、爆发中尖峰的百分比和平均爆发间隔时间）发生了改变，而这些变化在 HFS 后恢复到接近正常。CCI 大鼠的热痛觉过敏通过 HFS 显著减轻。因此，本研究表明，VPL 内的电刺激可以有效地调节与周围神经性疼痛相关的一些伤害感受现象。
