Bromm B, Treede R D
Institute of Physiology, University Hospital Eppendorf, Hamburg, F.R.G.
Rev Neurol (Paris). 1991;147(10):625-43.
Heat stimuli, applied to the skin by non-contact radiation pulses emitted by a CO2-laser, activate simultaneously both A-delta (mean conduction velocity 14 m/s) and C-fibres (0.8 m/s), which terminate in the most superficial skin layers. Correspondingly, brief heat stimuli elicit two pain sensations with mean reaction times of about 500 ms and 1400 ms. Similarly, two evoked potential waveforms were observed in the electroencephalogram: the late components N240/P370 and the ultralate components N1050/P1250. The shape of the two components was reproducible in independent samples of healthy volunteers. In patients with dissociated sensory loss, the laser evoked cerebral potentials are affected, depending on the kind of disturbed nerve and tracts. This is shown in patients with syringomyelia, encephalomyelitis disseminata, myelitis, Brown-Sequard syndrome, Wallenberg syndrome. In cases with hereditary motor and sensory neuropathy type I or with neurosyphilis, ultralate potentials are observed as correlates of delayed pain perception in the affected body areas. The laser evoked cerebral potentials reflected the clinical disorder of pain sensitivity in most cases, whereas somatosensory evoked potentials in response to conventional nerve stimuli failed in objectifying the diagnosis. As such, evoked cerebral potentials in response to laser heat stimuli applied to the hairy skin can be used for an overall examination of the functional integrity of peripheral small fibres, anterolateral tracts and thalamocortical projections.
通过二氧化碳激光发出的非接触辐射脉冲作用于皮肤的热刺激，同时激活了Aδ纤维（平均传导速度14米/秒）和C纤维（0.8米/秒），这些纤维终止于最表层的皮肤层。相应地，短暂的热刺激会引发两种疼痛感觉，平均反应时间分别约为500毫秒和1400毫秒。同样，在脑电图中观察到两个诱发电位波形：晚期成分N240/P370和超晚期成分N1050/P1250。这两种成分的形状在健康志愿者的独立样本中是可重复的。在感觉分离性丧失的患者中，激光诱发的脑电位会受到影响，这取决于受干扰的神经和神经束的类型。这在脊髓空洞症、播散性脑脊髓炎、脊髓炎、布朗-塞卡尔综合征、瓦伦贝格综合征患者中得到了体现。在患有I型遗传性运动和感觉神经病或神经梅毒的病例中，观察到超晚期电位是受影响身体部位疼痛感知延迟的相关指标。在大多数情况下，激光诱发的脑电位反映了疼痛敏感性的临床紊乱，而对传统神经刺激的体感诱发电位未能客观地进行诊断。因此，对有毛皮肤施加激光热刺激所诱发的脑电位可用于全面检查外周小纤维、脊髓丘脑束和丘脑皮质投射的功能完整性。
