F245 Arch Dis Child Fetal Neonatal Ed: first published as 10.1136/adc.2004.064964 on 21 April 2005. Downloaded from ORIGINAL ARTICLE Recovery of amplitude integrated electroencephalographic background patterns within 24 hours of perinatal asphyxia L G M van Rooij, M C Toet, D Osredkar, A C van Huffelen, F Groenendaal, L S de Vries ............................................................................................................................... Arch Dis Child Fetal Neonatal Ed 2005;90:F245–F251. doi: 10.1136/adc.2004.064964 Objective: To assess the time course of recovery of severely abnormal initial amplitude integrated electroencephalographic (aEEG) patterns (flat trace (FT), continuous low voltage (CLV), or burst suppression (BS)) in full term asphyxiated neonates, in relation to other neurophysiological and neuroimaging findings and neurodevelopmental outcome. Methods: A total of 190 aEEGs of full term infants were reviewed. The neonates were admitted within See end of article for 6 hours of birth to the neonatal intensive care unit because of perinatal asphyxia, and aEEG recording was authors’ affiliations started immediately. In all, 160 infants were included; 65 of these had an initial FT or CLV pattern and 25 ....................... an initial BS pattern. Neurodevelopmental outcome was assessed using a full neurological examination Correspondence to: and the Griffiths’ mental developmental scale. Dr de Vries, Department of Results: In the FT/CLV group, the background pattern recovered to continuous normal voltage within Neonatology, Wilhelmina 24 hours in six of the 65 infants (9%). All six infants survived the neonatal period; one had a severe Children’s Hospital, KE 04. disability, and five were normal at follow up. In the BS group, the background pattern improved to normal 123.1, PO Box 85090, 3508 AB Utrecht, the voltage in 12 of the 25 infants (48%) within 24 hours. Of these infants, one died, five survived with Netherlands; l.devries@ moderate to severe disability, two with mild disability, and four were normal. The patients who did not wkz.azu.nl recover within 24 hours either died in the neonatal period or survived with a severe disability. Accepted Conclusion: In this study there was a small group of infants who presented with a severely abnormal aEEG 2 December 2004 background pattern within six hours of birth, but who achieved recovery to a continuous normal background ....................... pattern within the first 24 hours. Sixty one percent of these infants survived without, or with a mild, disability. copyright. uring recent years the clinical use of amplitude N arterial cord blood pH ,7.10 integrated electroencephalography (aEEG) in the neo- N delayed onset of spontaneous respiration natal intensive care unit has increased. The aEEG D N Apgar score of (5 at five minutes background pattern correlates well with the standard EEG, and the method has been noted to have very good predictive N multiorgan failure. value for neurodevelopmental outcome in term neonates For aEEG recording, the CFM 4640 (Lectromed, after perinatal asphyxia, especially in the first hours after Letchworth, Hertfordshire, UK) was used. The CFM records birth.1–7 This early assessment has been used for selection of a single channel EEG from bilateral parietal electrodes. The infants who might benefit from neuroprotective therapy.89It filtered signal is rectified, smoothed, and amplitude inte- is also used for informing the parents about the likely grated before it is printed out at slow speed (6 cm/h) at the prognosis and provides additional information for use in the cot side.45 For pattern recognition, we used the following decision to continue or withdraw intensive care in a severely http://fn.bmj.com/ criteria4512: asphyxiated infant. It is known that the background pattern can change during the first 24–48 hours after birth, especially N FT: very low voltage, mainly inactive (isoelectric) tracing 51011 in infants with a burst suppression pattern. Spontaneous with activity below 5 mV; recovery in aEEG background patterns after perinatal asphyxia has not yet been described in detail. N CLV: continuous background pattern of very low voltage The aim of this study was to assess the recovery of aEEG (around or below 5 mV); patterns in full term asphyxiated neonates who present with N BS: discontinuous background pattern periods of very low on September 30, 2021 by guest. Protected a severely abnormal initial aEEG (flat trace (FT), continuous voltage (inactivity) intermixed with bursts of higher low voltage (CLV), or a burst suppression (BS) pattern). We amplitude; hypothesised that children in whom an abnormal back- N discontinuous normal voltage (DNV): discontinuous trace, ground pattern rapidly recovered would have a chance of a where the voltage is predominantly above 5 mV; normal neurodevelopmental outcome. N continuous normal voltage (CNV): continuous activity with voltage 10–25 (250) mV (fig 1). METHODS Between 1992 and 2002, all full term neonates with perinatal We retrospectively reviewed the medical records of 190 asphyxia, who were admitted to the neonatal intensive care infants in whom the aEEG recording was started within the unit at Wilhelmina Children’s Hospital (a tertiary referral first 6 hours of birth. Infants with congenital malformations centre) had an aEEG recorded for at least 24 hours (range or chromosomal abnormalities were excluded, and one 24 hours to 7 days). Asphyxia was diagnosed if they met at patient had to be excluded because he was lost to follow least three of the following criteria: Abbreviations: aEEG, amplitude integrated electroencephalography; N signs of intrauterine asphyxia, as indicated by late BS, burst suppression; CLV, continuous low voltage; CNV, continuous decelerations on fetal monitoring or meconium stained normal voltage; DNV, discontinuous normal voltage; FT, flat trace; MRI, liquor magnetic resonance imaging www.archdischild.com F246 Rooij, Toet, Osredkar, et al Arch Dis Child Fetal Neonatal Ed: first published as 10.1136/adc.2004.064964 on 21 April 2005. Downloaded from Hypoxic-ischaemic encephalopathy grade 2 100 uV 100 uV 50 50 25 25 Phenobarbital4 h 1 Phenytoin 2 Clonazepam 100 uV 100 uV 50 50 25 25 9 h 3 100 uV 100 uV 50 50 25 25 14 h Lidocaine 4 Figure 1 Example of an amplitude integrated electroencephalographic pattern, which shows recovery within 24 hours. The different background patterns are: 1, flat trace; 2, burst suppression; 3, discontinuous normal voltage; 4, continuous normal voltage. up. Thus 160 full term asphyxiated infants were eligible for to stand and take steps holding on to furniture; (c) cannot this study. The aEEG tracings were reviewed by two clinicians sit—is unable to maintain anti-gravity head and trunk who were blinded to the outcome. The tracings were analysed control in prone and sitting positions. copyright. for the background pattern during the first 6 hours after Most of the infants had a magnetic resonance imaging birth. If a depressed background pattern (BS/CLV/FT) was (MRI) scan during the first 2 weeks of birth (median age present, we followed the recovery. First we noted the time of 9 days, range 5–15; up until 1999 only conventional images; recovery to a DNV pattern, as this pattern tends to be since 1999 diffusion weighted images also). Abnormal associated with a normal neurodevelopmental outcome.5 We findings in cortex, basal ganglia, thalamus, white matter, subsequently noted the time of recovery to a CNV pattern. and posterior limb of the internal capsule seen after a Administration of anti-epileptic drugs was also noted. hypoxic-ischaemic insult were assessed.17–19 Seventy neonates had a normal aEEG (CNV/DNV) pattern A statistical analysis was performed using SPSS for at the onset (fig 2). For this study, we focused on a group of windows version 11.5. For group comparison, the Mann- 65 neonates who had an initial FT or CLV pattern, and 25 Whitney U test was used for continuous variables and Fisher neonates with an initial BS pattern within 6 hours of birth. exact or x2 tests for categorical variables. Sensitivity, The mean gestational age of the FT/CLV group was 40 weeks specificity, and positive and negative predictive values of http://fn.bmj.com/ (range 37–42) and mean birth weight 3440 g (range 2170– the test were calculated. p,0.05 was regarded as significant. 4885). In the BS group, the mean gestational age was also 40 weeks (range 37–42), and the mean birth weight 3480 (range 2580–5140). All had a moderate to severe encephalo- 13 pathy, grade 2 and 3 according to Sarnat and Sarnat. None n = 160 of the patients were involved in an early intervention study. Full term infants on September 30, 2021 by guest. Protected All survivors were seen in our outpatient clinic. recorded within 6 hours Neurodevelopmental outcome was assessed using the of birth Griffiths mental developmental scale at postnatal ages of at least 24 months.14 The maximum age at follow up was 10 years. Neuromotor assessment was performed by a paediatric n = 70 n = 90 physiotherapist, who was blinded to the aEEG and other CNV/DNV pattern FT/CLV/BS pattern neonatal data. Cerebral palsy was classified according to the criteria of 15 Hagberg et al. Adverse outcome was defined as death in the n = 6 n = 64 n = 79 n = 11 neonatal period, cerebral palsy, or a developmental quotient Moderate/ Normal Died or Normal ,85 on the Griffiths scale at 2 years of age. Maximal severe moderate/ locomotor function of those with cerebral palsy was graded handicap severe according to a simplified version of the classification handicap suggested by Palisano et al.16 At 2 years, a distinction was made between: (a) walking independently without restric- Figure 2 Flow diagram of 160 study patients. BS, Burst suppression; tions—can take more than 10 steps without any help; (b) sits CLV, continuous low voltage; CNV, continuous normal voltage; DNV, independently—infant maintains floor sitting and may pull discontinuous normal voltage; FT, flat trace.