Evaluation of the distortion of EEG signals caused by a hole in the skull mimicking the fontanel in the skull of human neonates
Evaluation of the distortion of EEG signals caused by a hole in the skull mimicking the fontanel in the skull of human neonates
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DOI：
10.1016/j.clinph.2005.01.007
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发表时间：
2005-05-01
影响因子：
4.7
通讯作者：
Okada, Y
中科院分区：
文献类型：
--
作者：
Flemming, L;Wang, YZ;Okada, Y
目的：新生儿脑电(EEG)信号的解释在某些情况下是困难的，因为颧骨和开放的缝合导致头骨电导率的不均匀。由于脑电信号的失真在围产期的神经学检查中是很重要的，我们通过实验确定了模拟前穹窿的小孔对脑电的影响。方法：实验在10头麻醉的农场猪上进行。颧骨被颅骨上的一个洞(12x12毫米)模仿。洞内填充3种电导率不同的介质(空气，0.017 S/m；蔗糖琼脂，0.017 S/m；盐琼脂，1.28 S/m)。用同心双极电极刺激鼻子的三个位置，以激活靠近洞的中央、边缘和外侧的皮质区域。体感诱发电位(SEP)记录采用4×4电极阵列，栅距4 mm。将其放置在28×28 mm的测量区域的四个象限上，放置在浸泡过盐水的滤纸上，作为人工头皮。结果：孔上的SEP在填充蔗糖或生理盐水琼脂时明显强于空气，但自相矛盾的是，蔗糖或盐水琼脂的漏电电流强于生理盐水琼脂。从孔洞中漏出的电流与活性组织的位置密切相关。对于距洞口边缘6-10 mm的震源，其影响几乎可以忽略不计。每种刺激引起的SEP的三个分量的失真不同，可能表明了源相对于孔的距离的影响。结论：孔/穹窿的存在使EEG发生强烈的失真，这种失真具体取决于孔的电导率和源的位置。意义：与以往研究显示的脑磁图(MEG)信号没有失真相反，EEG的失真是相反的。在用脑电研究大脑发育时，应该准确地模拟婴儿的头部和来源，以便将信号与潜在的活动联系起来。在研究婴儿的大脑功能时，脑磁图可能比脑电图仪更有优势，因为它对头骨缺陷相对不敏感。(C)2005年国际临床神经生理学联合会。爱思唯尔爱尔兰有限公司出版。版权所有。
Objective: Interpretation of Electroencephalography (EEG) signals from newborns is in some cases difficult because the fontanels and open sutures produce inhomogeneity in skull conductivity. We experimentally determined how EEG is influenced by a hole mimicking the anterior fontanel since distortion of EEG signals is important in neurological examinations during the perinatal period.Methods: Experiments were carried out on 10 anesthetized farm swine. The fontanel was mimicked by a hole (12 X 12 mm) in the skull. The hole was filled with 3 types of medium differing in conductivity (air, 0 S/m; sucrose-agar, 0.017 S/m; saline-agar, 1.28 S/m). Three positions of the snout were stimulated with a concentric bipolar electrode to activate cortical areas near the middle, the edge, and the outside of the hole. The somatic-evoked potential (SEP) was recorded by a 4 X 4 electrode array with a 4 mm grid spacing. It was placed on the 4 quadrants of a 28 X 28 mm measurement area on a saline-soaked filter paper over the skull, which served as artificial scalp.Results: The SEP over the hole was clearly stronger when the hole was filled with sucrose- or saline-agar as compared to air, although paradoxically the leakage current was stronger for the sucrose- than saline-agar. The current leaking from the hole was strongly related to position of the active tissue. It was nearly negligible for sources 6-10 mm away from the border of the hole. The distortion was different for 3 components of the SEP elicited by each stimulus, probably indicating effects of source distance relative to the hole.Conclusions: EEG is strongly distorted by the presence of a hole/fontanel with the distortion specifically dependent on both conductivity of the hole and source location.Significance: The distortion of the EEG is in contrast to the lack of distortion of magnetoencephalography (MEG) signals shown by previous studies. In studying brain development with EEG, the infant's head and sources should be modeled accurately in order to relate the signals to the underlying activity. MEG may be particularly advantageous over EEG for studying brain functions in infants since it is relatively insensitive to skull defects. (c) 2005 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.