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美国临床神经生理学会临床脑电图指南2:小儿脑电图最低技术标准

小儿临床脑电图指南应与指南l(临床脑电图操作的最低技术要求)联合使用。尽管指南1中概括的临床脑电图基本原则也适用于小儿,但我们将在下面讨论一些有关小儿脑电图记录的原则。指南2中括号内的数字特指指南1中应修改的部分,而指南2中未涉及的部分,指南1仍然适用并可供参考。

 

由于大龄儿童、青少年的脑电图记录与成人差别不大,我们将在指南2中更加强调新生儿、婴儿和幼儿的脑电图。由于新生儿脑电图记录还有很多特殊的问题,故指南2把儿童与新生儿的脑电图分成两部分来讨论。

 

l 儿童

 

1.1 (MTR 2.1)由于儿童,特别是小龄儿童在记录中活动较多,需要更耐心地放置电极。根据不同实验室的偏好,电极可以用固定胶或火棉胶来固定,但在整个记录过程中应仔细观察其位置和阻抗。最好使用银一氯化银盘状电极(带有可注入电解液的小孔),没有必要也不应该使用针电极

 

1.2 (MTR 2.3)大多数情况下应该使用国际10-20系统(Jasper HH,1958)中的21个电极。适用于成人的标准导联组合也同样适用于儿童。

 

1.3 (MTR 3.2)住院的小儿脑电图记录前,特别是对一些处于危险状况以致必须行床边脑电图检查的小儿而言,技术员应向护士详细了解患儿的情况和记录过程中的任何限制。

 

1.4 (MTR 3.4)由于小儿的脑电活动波幅较大龄儿童和成人高,应适当降低灵敏度(至10μV/mm或15μV/mm)。然而,为了足够显示低波幅的快活动,至少记录的一部分要使用高灵敏度(如7μV/mm)。否则,对于除婴儿之外的患者来说,可以在同一实验室采用与成人一样的设置。

 

1.5 (MTR 3.9)对合适的患儿可以在清醒期使用频率范围为1~20 Hz的闪光刺激

 

1.6 (MTR 3.10)记录时应尽可能包括睁眼和闭眼阶段。对于超过3个月的婴儿而言,被动闭眼(技术员将手遮盖住患儿眼睛)一般都能成功地产生后头部的优势节律,类似于大人用双手遮住自己的脸,把脸一隐一现和婴儿玩捉迷藏的游戏。

 

1.7 (MTR 3.12)应尽可能地记录睡眠脑电图,但并不排斥清醒脑电图。患儿思睡期、睡眠开始时和觉醒期脑电的记录都有重要意义。能自然入睡最好,但如果要使用药物催眠,有必要在记录结束时使用各种方法将患儿唤醒以便能记录到觉醒期的脑电。

 

1.8 (MTR 3.13)记录开始时就应该标明患儿的状态。对小龄的患儿来说,技术员对患儿的持续观察并将其活动标注在脑电图记录上显得尤为重要。

 

 

2 新生儿与小婴儿脑电图(足月产后4 ~ 8周)


2.1 (MTR 1.1)必须使用至少有16个信号通道的仪器。通常要使用2个或更多的信道记录非脑电的“多形性”变异波,如心电和呼吸。16个或更多的通道可灵活变通。


由于新生儿清醒一睡眠周期的脑电图模式不如成人和年长儿童那么确切,为了准确评价患儿在记录时的状态,通常我们也同步记录(非脑电)的多形联组合,为了给脑电图工作室之间提供标准化的参考性变异波,它们有助于鉴别生理伪差;例如显著的单形性δ活动常常可能是呼吸伪差,因为婴儿的呼吸频率可达100次/min以上。此外一些“非脑电”的变异也可能直接与患儿的临床问题相关。例如在发作性窒息患儿中,记录呼吸和心率的改变对诊断更有意义。


在婴儿,最常与脑电一起要监测的参数通常包括:呼吸、眼动、心跳。通过颏下肌电图(EMG)或运动传感器记录肌肉的电活动常也很有意义。

 

呼吸电图可由以下方法来记录:(1)腹部和(或)胸腔应变仪;(2)胸廓电极间的阻抗变化(呼吸阻抗图);(3)气道热敏电阻或热电偶。如果婴儿有呼吸问题,最好能再用3或4个信道以便同时监测腹部和胸部运动及上呼吸道气流。对于没有呼吸问题的婴儿来说,一个用于记录腹部或胸部呼吸电图的信道就足够了。


为了记录眼动,可以将一个电极放置在一只眼睛上方0.5 cm、稍微靠近一侧外眦处,另一个电极放置在另一只眼睛下方0.5 cm、稍微靠近该侧外眦处。分别命名为E1和E2。可以通过连接眼至耳极的电极监测到水平和垂直性眼动。E1与A1相连,E2与A1相连(或E1—A2,E2一A2)。


尤其发现患儿有心脏、呼吸问题或发现节律性的伪差时,应常规记录心电图。


2.2 (MTR 2.1)电极可用火棉胶或固定胶来固定。最好使用银一氯化银盘状电极(带有可注入电解液的小孔)。对新生儿来说,丙酮和乙醚都不能使用,附有电解液的盘状电极最好。不要使用针型电极


2.3 (MTR 2.3)是否减少电极阵列通常对新生儿来说是个体化的选择。一些脑电图医生偏好使用10~20系统,而另一些则偏好使用减少了的电极阵列。一般认为对于头部较小的早产几或在新生儿重症监护室内,由于时间或其他环境不允许使用全部电极阵列的时候,可以接受减少的电极阵列。然而如果能有20个信道的话,使用16信道的成人标准导联组合再加上其他记录非脑电的信道还是可行的。


以下是最少的电极阵列建议:Fp1、Fp2、C3、Cz、C4、T7(T3)、T8(T4)、O1、O2、A1和A2。如果患儿的耳垂太小,可以用乳突电极代替,并命名为M1和M2。前额电极(Fp1和Fp2)也可以用Fp3和Fp4替代。Fp3位于Fp1和F3之间的中点,Fp4位于Fp2和F4之间的中点(注意:由于Fp3和Fp4电极的使用会导致头皮电极间的间隔不完全相等)。

 

对于婴儿和儿童来说,通过测量来确定电极放置的位置与成人一样重要。只有在不可能或临床上不允许对患儿的头部进行测量的情况下才能违反这一原则。如果由于静脉通道、测压螺栓、头皮血肿或其他类似的原因而必须调整电极位置的话,对侧相应位置的电极也必须做同样的调整。如果没有进行测量的话,技术员必须在记录中予以说明。


2.4 (MTR 2.4)电极阻抗常规要小于5 kΩ,但为了避免过分操作或过度磨损娇嫩的皮肤,也允许使用更高的阻抗。最重要的是要避免电极间阻抗有明显的不同

 

2.5 (MTR 3.1) 在新生儿,必须要使用2个或更多的信道用来记录非脑电的多形性变异波,推荐采用以下几种导联组合:

 

 

这些导联组合的设置是基于使用有16个信道设备的基础上,其中4个信道用于记录非脑电的多种不同的生理活动波,剩下12个信道用于记录脑电。A和B是10-20系统完整的导联组合;而C是减少了的导联组合。在导联组合B和C中可以用Fp3和Fp4替代Fp1和Fp2,用M1和M2替代A1和A2。A和B是10-20系统完整的导联组合;而C是减少了的导联组合。在导联组合B和C中可以用Fp3和Fp4替代Fp1和Fp2,用M1和M2替代A1和A2。

 

虽然以上导联组合方式并不意味着是唯一可以使用的导联组合方式,但它被视为是一种标准的导联组合,为了给脑电图工作室之间提供标准化的参考,在所有工作室中应至少采用其中一个标准化的导联组合方式,作为新生儿脑电图记录中的一部分。导联组合C包括了中线电极,它对早产儿的记录特别有帮助。在所有情况下Cz均应包括在内,因为正相的“rolando”尖波(一个常见的病理现象)可能仅出现在这一人群的Cz部位。也可为特殊目的设计其他不同的导联组合,甚至参考电极与头皮——头皮电极相连的导联组合对新生儿来说也是可以接受的。

 

在新生儿的脑电记录中仅使用单一的导联组合通常是足够的,许多实验室都是这样做的,然而这并不意味着单一的导联组合就完全足够了,甚至在偏好单一导联组合的实验室中,必要时,如为了更好的描述单病灶的异常也应增加额外的导联组合。为了记录多形性变异波,建议使用以下的电极:(1)记录眼动(EOG):用E1-A1和E2-A1,或E2-A1。和E2-A2;(2)记录下颏肌电(EMG):在下颏中线的两边1~2 cm处放置两个电极;(3)记录心电图(ECG):导联1(右上肢一左上肢)是最佳的。如果正在记录下颏肌电的同时仅对心率感兴趣,可以省略ECG信道,因为R波经常出现在肌电信道上。

 

2.6 (MTR 3.2) 住院的小儿脑电图记录前,特别是对一些处于危险状况以致必须行床边脑电图检查的小儿而言,技术员应向护士详细了解患儿的情况和记录过程中的任何限制。

 

婴儿出生时的妊娠龄和孕龄(出生时的妊娠龄加上出生后的时间)对脑电图的解释至关重要,所以必须在给脑电图医生提供的信息中包括按时间计算的出生后年龄,它以周数来表示。其他相关的临床信息(包括血气分析、血电解质、目前的治疗)也应该提供给脑电图医生参考。

 

2.7 (MTR 3.4) 在小婴儿中,最合适的灵敏度是7μV/mm,但比年长的患儿更需要经常调整。至少要有部分记录以合适的灵敏度来显示低幅快活动。低频滤波一般采用0.3 Hz或0.6 Hz(-3 dB)(相当于时间常数0.27 s或0.53 s),而不是通常使用的1Hz(0.16 s)。

 

通常建议使用与相应脑电图一致的灵敏度和时间常数(7μV/mm)来记录眼动(EOG)。对于呼吸电图来说,应该调整放大器到能产生一个明确可见的垂直偏转,其低频滤波也应设置在0.3 Hz或0.6 Hz,但不要使用直流电。对于下颏肌电(EMG)的记录,推荐采用3μV/mm的灵敏度,低频滤波设置在5Hz(相当于时间常数0.03 s),高频滤波设置在70Hz

 

2.8 (MTR 3.9,3.12) 如果有可能的话,最好安排在喂养期间行脑电图检查,已经安装完电极后开始喂养患儿,在患儿喂养完毕,想睡觉时开始记录。

 

对于新生儿来说,需要记录更长的时间,这是因为患儿在清醒时有大量的活动和其他生理伪差而导致记录时间的丢失,为了有足够量的记录去评价睡眠——觉醒周期和其他状态,经常需要增加额外的记录时间。

 

除非脑电图是极不正常的,否则20~30 min的脑电记录时间通常是不够的。对于脑电图表现恒定的新生儿来说,可能至少需要60min的记录时间来证实脑电图记录没有变化,其余的患儿要充分记录到两种主要的睡眠状态。新生儿初始睡眠期通常是主动睡眠,可能持续时问非常短或持续数分钟。

 

充分的睡眠记录应当包括整个安静的睡眠。对新生儿而言,我们绝无必要和尝试使用镇静药物来获得睡眠脑电记录。即使可行,重复闪光刺激也很少用于临床新生儿的脑电检查,不推荐使用。

 

2.9 (MTR 3.13) 在每一种导联组合开始记录时,都应标明患儿的状态,包括头和眼睑的位置。对于新生儿而言,技术员对患儿的持续观察和频繁的标记尤为重要。

 

对于昏迷、昏睡和脑电表现为任何一种固定模式的患儿来说,应在记录中给予系统的视觉、听觉、躯体感觉刺激,但最好应在记录的末期实施,以免干扰正常的睡眠周期或产生不期望的觉醒伪差而使此后的描记难以阅读。应该在最接近刺激的时点尽可能记录患儿对刺激的临床反应。

 

 

Introduction

 

These guidelines for clinical pediatric EEG should be considered in conjunction with the more general Guideline 1: Minimum Technical Requirements for Performing ClinicalElectroencephalography (MTR).

 

The basic principles of clinical EEG outlined in the MTR also apply to the very young and are reaffirmed. However, special considerations are pertinent to pediatric recordings and are discussed below. The numbers in parentheses in this Guideline refer specifically to sections of the MTR that must be modified in these special situations. Where a subject is not covered here,the recommendations of Guideline 1 remain appropriate and should be consulted.

 

Emphasis here will be on EEG in neonates, infants, and young children, since recording the EEGs of older children and adolescents differs little from recording the EEGs of adults. Because EEG recording in the newborn presents a number of special problems, this Guideline is divided into two parts setting forth recommendations for children and for neonates separately.

 

1. Children

 

1.1 (MTR 2.1) Because children, especially young children, have a tendency to move a good deal during recording, electrode application should be performed with great care. Electrodes may be applied with paste or collodion, according to the preference of the laboratory, but their positions and impedances should be monitored carefully throughout the study. The inverted saucer-shaped silver-silver chloride electrode with a small hole for the injection of electrolyte solution is best. Needle electrodes are not needed and should not be used.

 

1.2 (MTR 2.3) All 21 electrodes of the International 10-20 System (Jasper HH, 1958) should be used for most purposes. The standard montages used for adults should be used for children.

 

1.3 (MTR 3.2) Before recording the EEGs of young inpatients, especially those in so precarious a condition that the recordings must be done at bedside, the technician should consult with the nursing staff concerning the patient’s condition and any limitations on recording

procedures.

 

1.4 (MTR 3.4) The voltage of EEG activity in many young children is higher than that of older children and adults, and appropriate reduction of sensitivity (to 10 μV/mm or even 15μV/mm) should be used. However, at least a portion of the record should be run at a sensitivity (such as 7 μV/mm) adequate to display low-voltage fast activity. Otherwise, for patients beyond infancy, the same instrument control settings can be used as for adults in the same laboratory.

 

1.5 (MTR 3.9) Photic stimulation over the frequency range of at least 1—20 flashes/s should be used during wakefulness in appropriate patients.

 

1.6 (MTR 3.10) Whenever possible, recordings should include periods when the eyes are open and when they are closed. In infants over 3 months of age, passive eye closure(by placing the technician’s hand over the patient’s eyes) is often successful in producing the dominant posterior rhythm, as is the playing of game such as peek-a-boo.

 

1.7 (MTR 3.12) Sleep recordings should be obtained whenever possible, but not to the exclusion of the awake record. The recording of the patient during drowsiness,initiation of sleep,and arousal is important. Natural sleep is preferred, but if the use of sedation is necessary, all efforts should still be made to record arousal at the end of the recording.

 

1.8 (MTR 3.13) The patient’s condition should be clearly indicated at the beginning of the recording from every montage. Continuous observation by the technician, with frequent notations on the recording, is particularly important when recording young patients.

 

2. Neonates and Young Infants (Up to 4-8 Weeks Post-Term)

 

2.1 (MTR 1.1) Instruments with at least 16 channels should be used. Two, and often more,channels must be devoted to recording non-EEG “polygraphic” variables, such as EKG and respiration. Sixteen or more channels allow the necessary flexibility.


Because EEG patterns seen in the neonate are not as clearly related to stages of the wake-sleep cycle as are those of adults and older children, it is usually necessary to record polygraphic (non-EEG) variables along with the EEG in order to assess accurately the baby’s state during the recording. Polygraphic recording is also helpful in identifying physiologic artifacts; for example,apparent monomorphic delta activity often turns out to be respiration artifact, since babies may have respiratory rates of up to 100/min. Moreover, variables other than the EEG may be directly pertinent to the patient’s problems. For example, in those experiencing apneic episodes,breathing and heart rate changes are most relevant.


The parameters most frequently monitored along with EEG in infants are respirations, eye movements, and heartbeats. A recording of muscle movements, by submental electromyography (EMG) or movement transducer, also can be quite helpful.


Respirogram can be recorded by any of the following means: (1) abdominal and/or thoracic strain gauges,(2) changes in impedance between thoracic electrodes (impedance pneumogram), or (3) airway thermistors/thermocouples. In infants with respiratory problems, it is necessary to devote three or four channels to respiration in order to monitor both abdominal and thoracic movements, plus airflow in the upper airway. In infants without respiratory problems, one channel of abdominal or thoracic respirogram may be sufficient.


For recording eye movements, one electrode should be placed 0.5 cm above and slightly lateral to the outer canthus of one eye and another 0.5 cm below and slightly lateral to the outer canthus of the other eye. These can be designated E1 and E2. Both lateral and vertical eye movements can be detected by linking (referring) eye movement to auricular electrodes: E1 to A1 and E2 to A1 (or E1-A2, E2-A2).


EKG should be recorded routinely, and is particularly needed when there are cardiac or respiratory problems or when rhythmic artifacts occur.


2.2 (MTR 2.1) Electrodes may be applied with either collodion or paste. The inverted saucershaped silver-silver chloride electrode with a small hole for the injection of electrolyte solution is best. For neonates, the fumes of acetone and ether may not be acceptable, and disk electrodes with electrolyte paste are preferable. Needle electrodes should never be used.


2.3 (MTR 2.3) It is a matter of individual preference whether or not a reduced array is routinely acceptable for neonates. Some electroencephalographers prefer the full 10—20 array; others prefer a reduced array. It is generally agreed that a reduced array is acceptable in cipremature infants with small heads or where, as in neonatal intensive care units, time or otherrcumstances may not allow application of the full array. However, if 20 channels are available,it is possible to use standard adult 16-channel montages plus polygraphic variables.
 

The following electrodes are suggested as a minimum reduced array: Fp1, Fp2, C3, Cz, C4, T7(T3), T8 (T4), O1, O2, Al, and A2. If a baby’s earlobes are too small, mastoid leads may be substituted and can be designated Ml and M2. Acceptable alternative frontal placements in the reduced array are Fp3 and Fp4 instead of Fp1 and Fp2. Fp3 and Fp4 are halfway between the Fp1 and F3, and the Fp2 and F4 positions, respectively. (Note that the use of Fp3 and Fp4 makes for unequal interelectrode distances in scalp-scalp montages.)


Determining electrode sites by measurement is just as important in infants and children as in adults. Deviation from this principle is permissible only in circumstances in which it is impossible or clinically undesirable to manipulate the child’s head to make the measurements. If an electrode placement must be modified due to intravenous lines, pressure bolts, scalp hematomas, and the like, the homologous contralateral electrode placement should be similarly modified. If no measurements are made, the technologist should note this on the recording.


2.4 (MTR 2.4) Electrode impedances of less than 5 KOhms can be obtained regularly,although higher impedances may be allowed in order to avoid excessive manipulation or excessive abrasion of tender skin. It is most important that marked differences in impedances among electrodes be avoided.

 

2.5 (MTR 3.1) In neonates in whom two or more channels must be devoted to polygraphic variables, the following montages are recommended:

These are based on the assumption that a 16-channel instrument is used with 4 channels devoted to polygraphic variables, leaving 12 channels for EEG. Montages A and B are for full 10-20 System electrode arrays: Montage C for the reduced array. In Montages B and C, Fp3 and Fp4 may be substituted for Fp1 and Fp2 and M1 and M2 may be substituted for A1 and A2.

 

It is not implied that the above montages are the only ones that can be used. Rather, they should be considered standard montages, and at least one of them should be used for at least a portion of a neonate’s EEG recording in all laboratories, to provide some standardization among laboratories. Since Montage C includes the midline, it can be particularly helpful when recording premature infants. In any case, Cz should always be included because positive “rolandic” sharp waves (a common pathologic finding) may occur only in Cz in this population. Various other montages can be devised for special purposes. Even a montage combining referential and scalp-scalp derivations is acceptable for neonatal EEGs.

 

The use of a single montage throughout a recording of a neonate may be, and often is, sufficient, and is preferred in many laboratories. It is not implied, however, that a single montage is always adequate. Even in laboratories preferring single montages, additional montages should be used when the need arises; for example, to better delineate unifocal abnormalities.

 

For recording polygraphic variables, the following derivations are recommended: (1) For eye movements (EOG): use E1-A1 and E2-A1 or E2-A1 and E1-A2. (2) For submental EMG: two electrodes under the chin, each 1-2 cm. on either side of the midline. (3) For EKG, lead 1 (right arm-left arm) is preferred. If submental EMG is being recorded and if only heart rate is of interest, the EKG channel can often by omitted because the R wave is usually visible in the EMG channel.

 

2.6 (MTR 3.2) Before recording the EEGs of inpatients, especially those in so precarious a condition that the recording must be done at bedside, the technician should consult with the nursing staff concerning the patient’s condition and any limitations on recording procedures.

 

The baby’s gestational age at birth and conceptional age (gestational age at birth plus time since birth) on the day of recording, stated in weeks, are absolutely essential to interpretation and must be included,together with chronological age since birth in the information available to the electroencephalographer.

 

All other available relevant clinical information (including concentration of blood gases, serum electrolyte values, and current medications) should be noted for the electroencephalographer’s use.

 

2.7 (MTR 3.4). In young infants’ EEGs, the most appropriate sensitivity is usually 7 μV/mm, but adjustments up or down are more often needed than in the case of older patients. At least a portion of the recording should be run at a sensitivity adequate to display low-voltage fast activity. The low-frequency filter setting should be between 0.3 and 0.6 Hz (-3 dB) (time constants of 0.27-0.53 s), not the commonly used 1 Hz (0.16 s).

 

For EOG, a sensitivity of 7 μV/mm and the same time constant as for the concomitantly recorded EEG derivations are recommended. For respirogram, amplification should be adjusted to yield a clearly visible

vertical deflection, and a low-frequency filter setting of 0.3-0.6 Hz, but not direct current (DC), should be used. For the submental EMG recording, a sensitivity of 3 uV/mm, a low-frequency filter setting of about 5 Hz (time constant of about 0.03 s), and a high-frequency filter setting of 70 Hz should be employed.

 

2.8 (MTR 3.9, 3.12). If possible, it is advantageous to schedule the EEG at feeding time and arrange to feed the child after the electrodes have been applied, but before beginning the recording, as babies tend to sleep after feedings.

 

Allow for extra recording time for the EEGs of neonates. Time is commonly lost due to a greater number of movement and other physiologic artifacts during wakefulness, and extra time is usually needed in order to obtain sufficient recording to permit evaluation of stages of the wake-sleep cycle and other states.

 

Except when the EEG is grossly abnormal, 20- or 30-min. recordings are usually insufficient. In those neonates in whom patterns appear to be invariant, it may be necessary to obtain at least 60 min. of recording to demonstrate that the tracings are not likely to change. In the rest, adequate sampling of both major sleep states is important. The initial sleep state in the neonate is usually active sleep, which may last a very short time or continue for many minutes. An adequate sleep tracing must include a full episode of quiet sleep.

 

It is never necessary or desirable to use sedation to obtain a sleep recording in a neonate.

 

Repetitive photic stimulation is rarely, if ever, clinically useful in neonates, and is not recommended.

 

2.9 (MTR 3.13) The child’s condition, including head and eyelid position, should be clearly indicated at the beginning of every montage. Continuous observations by the technologist, with frequent notations on the recording, are particularly important when recording from neonates.

 

In stuporous or comatose patients and in those showing invariant EEG patterns of any kind,visual, auditory, and somatosensory stimuli should be applied systematically during recording,but only toward the end of the recording period, lest normal sleep cycles be disrupted or unexpected arousal-produced artifact render the tracings unreadable thereafter. The stimuli and the patient’s clinical responses or failure to respond should be noted on the recording as near as possible to their point of occurrence.