Theuvenet Peter J, van Dijk Bob W, Peters Maria J, van Ree Jan M, Lopes da Silva Fernando L, Chen Andrew C N
Department of Anesthesiology, Alkmaar Medical Center, pranjelaan 61, 1815 JR Alkmaar, The Netherlands.
Brain Topogr. 2006 Winter;19(1-2):29-42. doi: 10.1007/s10548-006-0010-1.
Contralateral somatosensory evoked fields (SEF) by whole head MEG after unilateral median and ulnar nerve stimulation of both hands were studied in 10 healthy right-handed subjects. Major parameters describing cortical activity were examined to discriminate median and ulnar nerve evoked responses. Somatic sensitivity showed high similarity in the 4 study conditions for both hand and nerve. The brain SEFs consisted of 7-8 major peak stages with consistent responses in all subjects at M20, M30, M70 and M90. Comparable inter-hemispheric waveform profile but high inter-subject variability was found. Median nerve induced significantly shorter latencies in the early activities than those of the ulnar nerve. The 3D cortical maps in the post stimulus 450 ms timeframe showed for both nerves two polarity reversals, an early and a late one which is a new finding. Dipole characteristics showed differential sites for the M20 and M30 in the respective nerve. Higher dipole moments evoked by the median nerve were noticed when compared to the ulnar. Furthermore, the results of the dipole distances between both nerves for M20 were calculated to be at 11.17 mm +/- 4.93 (LH) and 16.73 mm +/- 5.66 (RH), respectively after right hand versus left hand stimulation. This study showed substantial differences in the cortical responses between median and ulnar nerve. Especially the dipole distance between median and ulnar nerve on the cortex was computed accurately for the first time in MEG. Little is known however of the cortical responses in chronic pain patients and the parameter(s) that may change in an individual patient or a group. These results provide precise basis for further evaluating cortical changes in functional disorders and disease sequelae related to median and ulnar nerves.
对10名健康右利手受试者进行研究，通过全头磁脑图（MEG）记录双手单侧正中神经和尺神经刺激后的对侧体感诱发电场（SEF）。研究描述皮质活动的主要参数以区分正中神经和尺神经诱发反应。在双手和神经的4种研究条件下，躯体感觉表现出高度相似性。脑SEF由7 - 8个主要峰值阶段组成，所有受试者在M20、M30、M70和M90处反应一致。发现半球间波形轮廓具有可比性，但个体间差异较大。正中神经在早期活动中诱发的潜伏期明显短于尺神经。刺激后450毫秒时间范围内的三维皮质图显示，两条神经均有两个极性反转，一个早期反转和一个晚期反转，这是一个新发现。偶极特征显示，各神经在M20和M30处的位点不同。与尺神经相比，正中神经诱发的偶极矩更高。此外，右手与左手刺激后，计算出两条神经M20处偶极距离分别为11.17毫米±4.93（左侧半球）和16.73毫米±5.66（右侧半球）。本研究显示正中神经和尺神经的皮质反应存在显著差异。特别是在MEG中首次精确计算了皮质上正中神经和尺神经之间的偶极距离。然而，对于慢性疼痛患者的皮质反应以及个体患者或群体中可能发生变化的参数知之甚少。这些结果为进一步评估与正中神经和尺神经相关的功能障碍和疾病后遗症中的皮质变化提供了精确依据。
