Unità Operativa di Neurofisiopatologia, CTO, Via S. Nemesio 21, 00145 Rome, Italy.
Clin Neurophysiol. 2010 Jun;121(6):921-9. doi: 10.1016/j.clinph.2010.01.006. Epub 2010 Feb 12.
To investigate the effect of the voluntary movement on the amplitude of the somatosensory evoked potentials (SEPs) recorded by an epidural electrode at level of the dorsal column nuclei (DCN).
Five patients, suffering from chronic pain resistant to pharmacological treatment, underwent an epidural electrode implant at high cervical spinal cord level (C2) for neuromodulation. After tibial nerve stimulation, SEPs were recorded from the epidural electrode contacts, from a Cz lead, and from two electrodes placed over the 12th dorsal vertebra and 4th lumbar vertebra, respectively. SEPs were recorded at rest and during a voluntary flexo-extension movement of the stimulated foot. Beyond the low-frequency SEPs, also the high-frequency oscillations (HFOs), obtained by filtering the recorded traces by means of a 1000-2000 Hz bandpass offline, were analysed.
The epidural electrode contacts recorded a triphasic potential (P1-N1-P2), whose negative peak showed a latency similar to that of the P30 far-field response obtained from the scalp. The epidural potential amplitude was significantly decreased by the voluntary movement, as compared to the rest (p<0.01). A main HFO peak, identifiable at around 1200 Hz, was significantly lower in amplitude during movement than at rest (p=0.008).
Our findings suggest that the epidural C2 triphasic wave is a potential arising from DCN. The low-frequency epidural SEP component is subtended by a 1200 Hz HFO, probably generated by post-synaptic events.
The amplitude reduction of the DCN response during movement is possibly due to decreased excitability of the DCN neurons receiving the somatosensory ascending input.
研究在硬脊膜外电极记录背柱核（DCN）水平体感诱发电位（SEP）时，自主运动对其振幅的影响。
5 例慢性疼痛患者，经药物治疗无效，行颈髓高位（C2）硬脊膜外电极植入以进行神经调节。在刺激胫神经后，从硬脊膜外电极触点、Cz 导联以及分别放置在第 12 胸椎和第 4 腰椎的两个电极记录 SEP。SEP 在休息和受刺激脚的自主屈伸运动时记录。除低频 SEP 外，还通过在线滤波获得的高频振荡（HFO）进行分析，滤波范围为 1000-2000Hz。
硬脊膜外电极触点记录到三相电位（P1-N1-P2），其负峰潜伏期与头皮记录的远场 P30 反应相似。与休息时相比，自主运动时硬脊膜外电位幅度明显降低（p<0.01）。运动时幅度明显低于休息时的主要 HFO 峰值，约 1200Hz（p=0.008）。
我们的研究结果表明，C2 硬脊膜外三相波可能是 DCN 产生的电位。低频硬脊膜外 SEP 成分由 1200Hz 的 HFO 组成，可能由突触后事件产生。
运动时 DCN 反应幅度减小可能是由于接收体感传入的 DCN 神经元兴奋性降低所致。
