Hallström Y T, Lindblom U, Meyerson B A
Department of Neurology, Karolinska Hospital, Stockholm, Sweden.
Electroencephalogr Clin Neurophysiol. 1991 Mar-Apr;80(2):126-39. doi: 10.1016/0168-5597(91)90150-v.
In 7 awake patients with neuropathic lower extremity pain, spinal somatosensory evoked potentials (SEP) were elicited from the non-painful leg by electrical stimulation of the peroneal nerve and mechanical stimulation of the hallux ball. Recording was made epidurally in the thoraco-lumbar region by means of an electrode temporarily inserted for trial of pain-suppressing stimulation. In response to peroneal nerve stimulation, two major SEP complexes were found. The first complex consisted, as has been described earlier, of an initial positivity (P12), a spike-like negativity (N14), a slow negativity (N16) and a slow positivity (P23). The second complex consisted of a slow biphasic wave, conceivably mediated by a supraspinal loop. Both complexes had a similar longitudinal distribution with amplitude maxima at the T12 vertebral body. The SEP evoked by mechanical hallux ball stimulation had a relatively small amplitude, and there was no significant second complex. The relationship between stimulus intensity and SEP amplitude was negatively accelerating. The longitudinal distribution of spinal SEP was compared with the somatotopic distribution of paresthesiae induced by stimulation through the epidural electrode. It was found that stimulation applied at the level of maximal SEP generally induced paresthesiae in the corresponding peripheral region. Therefore, spinal SEP may be used as a guide for optimal positioning of a spinal electrode for therapeutic stimulation when implanted under general anesthesia. An attempt was made to record the antidromic potential in the peroneal nerve elicited from the dorsal columns by epidural stimulation. The antidromic response was, however, very sensitive to minimal changes of stimulus strength and body position of the patient, and was also contaminated by simultaneously evoked muscular reflex potentials. Thus, peripheral responses evoked by epidural stimulation appeared too unreliable to be useful for the permanent implantation of a spinal electrode for therapeutic stimulation.
在7例患有神经性下肢疼痛的清醒患者中，通过电刺激腓总神经和机械刺激拇趾球部，从无痛侧下肢引出脊髓体感诱发电位（SEP）。通过临时插入的电极在胸腰段硬膜外进行记录，用于试验止痛刺激。对腓总神经刺激的反应中，发现了两个主要的SEP复合波。第一个复合波如先前所述，由一个初始正波（P12）、一个棘状负波（N14）、一个慢负波（N16）和一个慢正波（P23）组成。第二个复合波由一个慢双相波组成，可能由脊髓上环路介导。两个复合波具有相似的纵向分布，在T12椎体处振幅最大。拇趾球部机械刺激诱发的SEP振幅相对较小，且没有明显的第二个复合波。刺激强度与SEP振幅之间的关系呈负加速。将脊髓SEP的纵向分布与通过硬膜外电极刺激诱发的感觉异常的躯体定位分布进行了比较。发现一般在SEP最大处施加刺激会在相应的外周区域诱发感觉异常。因此，脊髓SEP可作为在全身麻醉下植入治疗性刺激脊髓电极时优化电极定位的指导。尝试记录硬膜外刺激从背柱引出的腓总神经的逆向电位。然而，逆向反应对刺激强度和患者体位的微小变化非常敏感，并且还受到同时诱发的肌肉反射电位的干扰。因此，硬膜外刺激诱发的外周反应似乎太不可靠，无法用于治疗性刺激脊髓电极的永久植入。
