Name: how to obtain reliable visual event-related potentials in newborns
Uploaded: 2019-10-24T14:00:00
Description: Watch this Scientific Journal Video about How to Obtain Reliable Visual Event-related Potentials in Newborns at JoVE.com

Engineer H&#233;ctor Belmont, Dr. M&#243;nica Carlier, Dr. Yuria Cruz and Dr. Mar&#237;a Elena Ju&#225;rez collaborated in data collection. The authors thank Paul Kersey for revising English language use. The project was partially funded by PAPIIT grant IN2009/7 and CONACYT (National Council for Science and Technology, Mexico) grant 4971.

1. Preparation of the Newborns
NOTE: The procedure followed is innocuous and painless, so there are no counter-indications for evaluating full-term and preterm newborns, once they are clinically stable.
<ol>
	<li>Ensure two and half hour fasting and wakefulness before beginning the study, in neonates older than 40 weeks of postconceptional age.</li>
	<li>Make sure that the baby&#39;s head be washed with neutral soap the day before the study. Thus, his/her hair will be clean ...

<ol>
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M., Hirano, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishment+of+normal+values+for+flash+visual+evoked+potentials+(VEPs)+in+preterm+infants:+a+longitudinal+study+with+special+reference+to+two+components+of+the+N1+wave.">Establishment of normal values for flash visual evoked potentials (VEPs) in preterm infants: a longitudinal study with special reference to two components of the N1 wave.</a> Electroencephalography and Clinical Neurophysiology. 96, 291-299 (1995).</li><li>Roy, M. S., Gosselin, J., Hanna, N., Orquin, J., Chemtob, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In&#64258;uence+of+the+state+of+alertness+on+the+pattern+visual+evoked+potentials+(PVEP)+in+very+young+infant.">In&#64258;uence of the state of alertness on the pattern visual evoked potentials (PVEP) in very young infant.</a> Brain &amp; Development. 26, 197-202 (2004).</li><li>Kraemer, M., Abrahamsson, M., Sjostrom, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+neonatal+development+of+the+light+&#64258;ash+visual+evoked+potential.">The neonatal development of the light &#64258;ash visual evoked potential.</a> Documenta Ophthalmologica. 99, 21-39 (1999).</li><li>Apkarian, P., Mirmiran, M., Tijssen, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+Behavioral+State+on+Visual+Processing+in+Neonates.">Effects of Behavioral State on Visual Processing in Neonates.</a> Neuropediatrics. 22, 85-91 (1991).</li><li>Cubero-Rego, L., Corsi-Cabrera, M., Ricardo-Garcell, J., Cruz-Mart&#237;nez, R., Harmony, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visual+evoked+potentials+are+similar+in+polysomnographically+de&#64257;ned+quiet+and+active+sleep+in+healthy+newborns.">Visual evoked potentials are similar in polysomnographically de&#64257;ned quiet and active sleep in healthy newborns.</a> International Journal of Developmental Neuroscience. 68, 26-34 (2018).</li><li>Mizrahi, E. M., Mosh&#233;, S. L., Hrachovy, R. A., Niedermeyer, E., Lopes da Silva, F. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Normal+EEG+and+Sleep:+Preterm+and+Term+Neonates.">Normal EEG and Sleep: Preterm and Term Neonates.</a> Niedermeyer's Electroencephalography: Basic Principles, Clinical Applications, and Related. , 154-163 (2011).</li><li>Grigg-Damberger, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Visual+Scoring+of+Sleep+in+Infants+0+to+2+Months+of+Age.">The Visual Scoring of Sleep in Infants 0 to 2 Months of Age.</a> Journal of Clinical Sleep Medicine. 12 (3), 429-445 (2016).</li><li>Husain, A. M., Niedermeyer, E., Lopes da Silva, F. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evoked+Potentials+in+Children+and+Infants.">Evoked Potentials in Children and Infants.</a> In Niedermeyer's Electroencephalography: Basic Principles, Clinical Applications, and Related Fields. , 1057-1082 (2011).</li><li>Odom, J. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ISCEV+standard+for+clinical+visual+evoked+potentials:+2016+update.">ISCEV standard for clinical visual evoked potentials: 2016 update.</a> Documenta Ophthalmologica. 133 (1), 1-11 (2016).</li><li>Pojda-Wilczek, D., Maruszczyk, W., Sirek, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flash+visual+evoked+potentials+(FVEP)+in+various+stimulation+conditions.">Flash visual evoked potentials (FVEP) in various stimulation conditions.</a> Documenta Ophthalmologica. 138, 35-42 (2019).</li><li>Tsuneishi, S., Casaer, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stepwise+decrease+in+VEP+latencies+and+the+process+of+myelination+in+the+human+visual+pathway.">Stepwise decrease in VEP latencies and the process of myelination in the human visual pathway.</a> Brain &amp; Development. 19, 547-551 (1997).</li></ol>

Three components of visual-evoked responses (NII, PII and NIII) were characterized in healthy, full-term newborns while doing stimulation with LED googles, and recorded during polygraphically-identified sleep states. The VEP morphology observed is consistent with previous results reported for fewer neonates11,15. The characterization of VEP responses was achieved by recording 20 healthy, full-term newborns at similar post-conceptional age16</sup...

Early detection of abnormal development of the central nervous system in at-risk newborns is crucial for successful early interventions1,2. Visual event-related potentials (VEPs) provide a useful means of evaluating visual cortical status because they do not require patient cooperation, which is not possible in the first month of life, are objective, and are sensitive to structural and functional brain damage3,4.
Though, some studies of newborns have shown that normal visual-evoked responses indicate adequate neural maturation of the cerebral cortex4,5, and that this has often been studied in newborns to assess neurodevelopment and identify abnormal development of the visual pathways4,5, the clinical use of VEPs has been limited by the variability observed in their morphology4,5,6,7. Therefore, it is important to obtain better, more reliable characterizations of VEPs in newborns.
One cause of the variability in VEP morphology is that earlier studies have mixed preterm and older babies (over one month)8,9,10. However, the most important source is the lack of attention paid to the infants&#39; behavioral state while recording VEPs; namely, awake, quiet (QS), active (AS), or transitional sleep. QS and AS have either not been analyzed separately5,11,12, or studies have relied exclusively on behavioral observation without using polysomnography to identify states7,8. Trac&#233; alternant, which consists in bursts of high amplitude slow activity alternating with inter-burst intervals of minimal amplitudes is present in QS, but has not been taken into account when averaging VEPs. Some studies with newborns have measured VEPs by recording during wakefulness13,14, but at this stage of development waking periods are brief and newborns are usually crying or moving, which makes it difficult to obtain high quality, reliable recordings.
Few studies have used light-emitting diodes (LEDs) googles6,9 to elicit VEPs, though this light source generates more consistent recordings than the usual strobe flashes of white light11,14,15, which are less reliable. Obtaining replicable VEPs in the same newborn is indispensable for clinical use4, but another cause of variability is the low reproducibility of VEP morphology, likely due to the lack of control of physiological states and of the stimuli used to elicit VEPs. Given these conditions, the high variability of VEP morphology is hardly surprising.
A previous study conducted with 20 healthy full-term newborns that considered several sources of variability: post-conceptional age, polysomnographically-identified sleep states, LED googles to elicit VEPs, and measures of reproducibility between two VEP averages found that a clearer, more reliable VEP morphology can be obtained during active sleep. During this sleep stage all infants generated clear VEPs with higher correlations between two averages than in QS. Also, fewer VEP averages were required to obtain reproducibility16.
Given the clinical usefulness of VEP studies to assess, as early as possible, the integrity of visual pathways, this study proposes a series of methodological steps designed to obtain reliable VEPs in preterm and older newborns, using LED goggles during AS unambiguously defined by simultaneous polysomnography.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Digital Electroencephalograph</td>
			<td>Neuronic Mexicana, SA</td>
			<td>Medicid 3E</td>
			<td>Sleep electroencephalogram record</td>
		</tr>
		<tr>
			<td>Evoked Potentials equipment</td>
			<td>Neuronic Mexicana, SA</td>
			<td>Neuronic PE (N_N-SW-2.0)</td>
			<td>Visual evoked potentials record</td>
		</tr>
		<tr>
			<td>Nuprep Gel</td>
			<td colspan="2">WEAVER and Company</td>
			<td>Skin preparing abrasive gel (114 g)</td>
		</tr>
		<tr>
			<td>Ten20 Conductive Paste</td>
			<td colspan="2">WEAVER and Company</td>
			<td>Neurodiagnostic electrode paste (228 g)</td>
		</tr>
		<tr>
			<td>Tubular elastic mesh bandage</td>
			<td>Le Roy</td>
			<td></td>
			<td>Fixation of cranial surface electrodes, Size 4 or Small</td>
		</tr>
	</tbody>
</table>

how to obtain reliable visual event-related potentials in newborns

The present study discusses the characteristics of visual event-related potentials (VEPs) and outlines methodological steps for obtaining reliable measurements in newborns. Obtaining high-quality, reliable VEPs is crucial for the early detection of abnormal development of the central nervous system in at-risk newborns, and for implementing successful early interventions. Recommendations are based on a previous study which showed that when post-conceptional age, polysomnography-identified sleep stages, and light-emitting diodes (LEDs) googles as the luminous source are controlled, no more than 4 repetitions of VEP averages are required to obtain replicable recordings, variability decreases, and reliable VEPs can be obtained. By controlling for these sources of variability and using statistical analyses, we were able to clearly and reliably identify the amplitude and latency of three main components (NII, PII and NIII) present in 100% of newborns (n = 20) during active sleep. Recording VEPs during awake states, quiet sleep and transitional sleep is not recommended because VEP morphology may differ significantly from one average to the next, leading to the risk of misleading clinical prognoses. Moreover, it is easier to obtain VEPs during active sleep because this state can be clearly and reliably identified at this stage of development, sleep cycles are short enough to allow measurements to be taken in a reasonable time, and the method does not require new o expensive equipment.

To detect adequate maturation in the function of the visual pathway it is essential to obtain the PII component of the VEP, which can be seen in both term and preterm infants. The simultaneous recording of VEPs with polysomnography during AS makes it possible to obtain typical VEPs.
Reliable VEP studies require obtaining reproducible average waveforms that will be indispensable for clinical use. Figure 2</st...

Watch this Scientific Journal Video about How to Obtain Reliable Visual Event-related Potentials in Newborns at JoVE.com

How to Obtain Reliable Visual Event-related Potentials in Newborns

Several important points for obtaining high-quality reliable visual evoked potentials (VEPs) in newborns while minimizing variability and the risk of misleading prognoses are presented.

The present study discusses the characteristics of visual event-related potentials (VEPs) and outlines methodological steps for obtaining reliable ...

Obtaining high quality visual event-related potentials is crucial for the early detection of abnormal development within the central nervous system and is important for successful early intervention implementation in at-risk newborns. VEPs are objective, non-invasive, and sensitive to structural and functional brain damage. Recording during polysomnography-identified active sleep reduces variability allowing reliable VEPs to be obtained.The day before the study, make sure that the baby's head is washed with neutral soap so that the hair is clean and dry. 30 minutes before beginning the study, allow the parent to begin feeding the newborn before burping the baby and wrapping the baby in a sheet so that the baby sleeps easily and spontaneously. Before handling the neonate, wash the hands carefully and put on a sanitary mask.Gently wipe the scalp of the newborn with alcohol to remove any residual dirt and superficial grease before the neonate falls asleep and measure the distance between the nasion and inion and between both preauricular pits. Calculate 10%and 20%to ensure proper placement of the cranial electrodes according to the International 10-20 System of Electrode Placement and cover the newborn's entire head with a tubular elastic mesh for the correct attachment of the EEG and VEP electrodes, leaving the face fully free and exposed. Mark the location of the surface electrodes on the mesh and use a swab to perfectly separate the newborn's hair at the sites at which each electrode will be placed, then lightly rub the skin with abrasive gel for neurophysiological studies.For electrode placement, place an elastic band sensor on the baby's chest to record the thoracic respiratory expansion and locate individual surface disc electrodes for the EEG through the mesh at leads F3, F4, C3, C4, O1, and O2.To record ocular movements, place one electrode through the mesh one centimeter above the external canthus of the left eye and place another electrode one centimeter below the external canthus of the right eye. Fix the electrodes to the skin with medical adhesive tape and attach the electrodes for surface electromyogram recording on both sides of the chin referenced against each other. Place the ground electrode on the right mastoid and set the one channel of the VEP equipment with the Oz versus Cz leads, then set the analysis time for the VEP registration at 600 milliseconds and wait to begin the VEP recording until the impedance values are below 5 kilo ohms.With the newborn sleeping in a hospital crib, prolong the EEG recording for 60 to 90 minutes until active sleep is identified. Begin the EEG recording while carefully observing the characteristics of neonatal sleep to identify the active sleep stage during which the VEPs will be recorded, according to the criteria summarized in the table. When the neonate brings well-defined active sleep, allow one minute of EEG recording before positioning handheld goggles with an LED matrix two centimeters directly above each eye to apply monocular light stimulation.Observe whether the infant's eyes are closed during the VEP registration in active sleep and begin presenting 20 to 40 luminous stimuli. During the recording, check the reproducibility of the recorded averages and identify the PII component as the maximal positive peak between 120 and 300 milliseconds preceded by a negative NII wave and followed by a maximal NIII negativity between 200 and 400 milliseconds. Stop the averaging if the newborn moves excessively, wakes up, or changes to another sleep stage distinct from active sleep.Finish the registration after two averages with reproducible VEP are attained or when six averages occur without a recognizable VEP. At the end of the analysis, evaluate the reproducibility of the VEPs by similar appearance and measurements between the two averaged curves and use the device cursors to measure the absolute latencies of the NII, PII, and NIII waves. Calculate the inter-peak latencies in milliseconds, including the differences between the absolute PII-NII, NII-NIII, and PII-NIII latencies, then measure the peak-to-peak amplitudes in microvolts for the NII-PII and PII-NIII components and compare the latency in amplitude values obtained to the normal or expected values estimated for a population of healthy, similarly aged newborns.In a healthy, full-term newborn, a clear positivity around 200 milliseconds compatible with the PII component can be observed. NII, which corresponds to a preceding negative small potential, is evident at about 130 milliseconds. The NIII component follows PII as a negativity of approximately 300 milliseconds.Here three epochs of sleep EEGs with typical aspects of active sleep, quiet sleep, and trace alternant are shown. In a full-term newborn, typical VEP waveforms demonstrate a clear PII, an immature response observed in pre-term newborns that is normal at this age, and this tracing from a 36-week old preterm newborn with periventricular leukomalacia a non-replicable waveform with waves that do not exactly reproduce the shape of the previous average can be observed, making it impossible to reliably measure the true latency or amplitude of the components. Active sleep must be carefully observed when attempting this procedure.VEP recording during a state change must be avoided and reproducibility must be achieved in at least two average waveforms. Using the appropriate sensory stimulation to obtain somatosensory and auditory middle-long latency evoked responses can provide a sensitive and non-invasive means for evaluating pathological conditions in other sensory pathways.

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