Tinazzi M, Fiaschi A, Mauguière F, Manganotti P, Polo A, Bonato C, Zanette G
Department of Neurological and Visual Sciences, Section of Neurology, Verona, Italy.
Neurology. 1998 Jun;50(6):1655-61. doi: 10.1212/wnl.50.6.1655.
We evaluated vertex-parietal P37, N50, and contralateral N37 somatosensory evoked potentials (SEPs) to posterior tibial nerve stimulation during weak (20 to 30%) and strong (80 to 90%) ipsilateral gastrocnemius-soleus contraction. The results were compared with data obtained during full relaxation. P37 and N50 were attenuated significantly during weak contraction and then abolished during strong contraction, whereas the contralateral N37 was not. The N37 potential spreads over the vertex and over the ipsilateral parietal region during strong contraction. The Cz'-F3 montage was not appropriate for detecting these SEP patterns. These findings suggest that thalamic or cortical gating mechanisms affect specific cortical responses. P37 and N50 could reflect the arrival of the afferent volley into the motor areas from thalamic and cortical (subareas 1 and 2 of S1) projections. N37 could be generated in subarea 3b. Differential analysis of N37 and P37 is required in clinical practice, mainly in those conditions that involve the motor system and in those conditions in which tonic muscular activity is increased.
我们评估了在同侧腓肠肌-比目鱼肌轻度（20%至30%）和重度（80%至90%）收缩期间，对胫后神经刺激所产生的顶点-顶叶P37、N50以及对侧N37体感诱发电位（SEPs）。将结果与完全放松时获得的数据进行比较。轻度收缩期间P37和N50显著衰减，重度收缩期间则消失，而对侧N37并非如此。重度收缩期间，N37电位分布于顶点及同侧顶叶区域。Cz'-F3导联组合不适用于检测这些SEP模式。这些发现表明，丘脑或皮层门控机制会影响特定的皮层反应。P37和N50可能反映了传入冲动从丘脑和皮层（初级体感皮层1区和2区）投射到达运动区。N37可能在3b区产生。临床实践中需要对N37和P37进行差异分析，主要是在涉及运动系统的情况以及紧张性肌肉活动增加的情况中。
