Prestor B, Gnidovec B, Golob P
Department of Neurosurgery, University Hospital Centre, Ljubljana, Slovenia.
Electroencephalogr Clin Neurophysiol. 1997 Nov;104(6):470-9. doi: 10.1016/s0168-5597(97)00040-3.
Low amplitude high frequency waves (LHW) were investigated in normal and patient cervical somatosensory evoked potentials after median nerve stimulation (CSEP) in parallel to normal and patient conducted somatosensory evoked potentials (SEP) after tibial nerve stimulation. Normal recordings were obtained in five subjects undergoing dorsal root entry zone (DREZ) coagulation for pain relief. Patient recordings were obtained in 11 subjects suffering from either syringomyelia, spinal cord tumour, or both. All recordings were made intraoperatively from the dorsal spinal cord surface using the subpial recording technique. Normal CSEP showed typical triphasic potential starting with an initial P9, followed by N13 and a final positivity, P1. Numerous LHW were superimposed on slow triphasic potential. To improve the visibility of LHW, slow triphasic potential was removed from the original CSEP. Potentials thus obtained contained only high frequency components of CSEP, i.e. LHW. They were compared with conducted SEP after tibial nerve stimulation. Comparison revealed similarities in high frequency, low amplitude and general wave form, LHW thus showing characteristics of conducted potential. Duration was found to be significantly shorter than normal duration in both patient LHW (Student's t-test, P < 0.0005) and patient conducted SEP (Student's t-test, P = 0.064). A shorter duration was associated with worsening of configuration in patient LHW and patient conducted SEP. These changes of LHW could not be connected with distortion of N13 seen in patient CSEP. A shorter duration and worsening of configuration in patient LHW were most prominent in cases with a loss of vibration and posture senses, but were also observed in cases where only pain and temperature senses were affected. We therefore concluded that cuneate fascicle is the most likely generator of LHW, although the participation of other cervical long sensory tracts, e.g. spinothalamic tract, cannot be ruled out.
在正中神经刺激后的正常和患者颈段体感诱发电位（CSEP）中研究了低幅高频波（LHW），同时也对胫神经刺激后的正常和患者体感诱发电位（SEP）进行了研究。对5名接受后根入髓区（DREZ）凝固术以缓解疼痛的受试者进行了正常记录。对11名患有脊髓空洞症、脊髓肿瘤或两者皆有的受试者进行了患者记录。所有记录均在术中使用软膜下记录技术从脊髓背表面进行。正常CSEP显示典型的三相电位，起始为初始P9，随后是N13，最后为正向波P1。许多LHW叠加在缓慢的三相电位上。为了提高LHW的可见性，从原始CSEP中去除了缓慢的三相电位。由此获得的电位仅包含CSEP的高频成分，即LHW。将它们与胫神经刺激后的体感诱发电位进行了比较。比较发现高频、低幅和总体波形相似，LHW因此显示出诱发电位的特征。发现患者LHW的持续时间（学生t检验，P < 0.0005）和患者体感诱发电位的持续时间（学生t检验，P = 0.064）均显著短于正常持续时间。较短的持续时间与患者LHW和患者体感诱发电位的波形恶化有关。LHW的这些变化与患者CSEP中所见的N13畸变无关。患者LHW中较短的持续时间和波形恶化在振动觉和姿势觉丧失的病例中最为明显，但在仅痛觉和温度觉受影响的病例中也观察到了。因此，我们得出结论，楔束是LHW最可能的起源部位，尽管不能排除其他颈段长感觉束，如脊髓丘脑束的参与。
