What is the role of neonatal EEG as a diagnostic and prognostic tool?

Updated: Oct 03, 2019
  • Author: Rosalia C Silvestri-Hobson, MD; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Although most neonatal EEG patterns are nonspecific and cannot provide the diagnosis when used alone, it is conversely true that they should cue the clinician to order neuroimaging tests. This is especially true for interhemispheric or regional asymmetries; specific EEG features may suggest infectious causes or deep matter necrosis, genetic brain malformations, or an inborn error of metabolism.

EEG is also an excellent tool to help diagnose subclinical seizures or to avoid a misdiagnosis of seizures in the presence of atypical nonictal neonatal behaviors. When used selectively through serial recordings, neonatal EEG's greatest value is its potential for prediction of short- and long-term prognosis.

Video-polysomnography (PSG) in preterm infants weighing less than 1800 g is indicated to rule out sleep-related respiratory disorders that may endanger the baby once he or she is discharged from the neonatal unit. The most common indication for video-PSG in these babies is the observed presence of apneas and oxygen desaturations. The most frequently associated conditions is hyaline membrane disease, [26] cardiorespiratory impairment being detected in 65% with a 32% rate of immature EEG activity and 13% of abnormal patterns. The authors underline that based on their study, a requirement for home monitoring was alerted in 69% of babies, with a quarter of them needing oxygen at home.

In premature infants younger than 30 weeks gestational age, "dysmature" and "disorganized" are the EEG patterns mostly and persistently found over serial recordings in newborns with severe or moderate sequelae as for cognition and cerebral palsy, with a sensitivity for psychomotor outcome of 83.3%, a specificity of 88%, and a positive predictive value of 90%. [27]

In particular in preterm babies to detect periventricular leukomalacia (PVL), EEG recordings are recommended within 48 hours from birth to detect acute-stage abnormalities and in the first 2 weeks of life to assess chronic-stage abnormalities. In fact, the latter are observed most frequently and most severe between days 5 and 14 and resolved in all survivors, persisting longer only in babies with extensive cystic PVLs. [28]

The EEG background, static abnormalities, and EEG maturational indices are the best prognostic factors. EEG may reflect the severity of brain injury in neonatal asphyxia, the degree of abnormalities usually being consistent with the clinical grading of HIE. [29] Therefore, in neonatal asphyxia, EEG background pattern especially is a valuable predictor of future neurologic outcome in combination with clinical data such as gestational age, birth weight, imaging, and HIE severity. Low birth weight amplitude of brain electrical activity, duration of interburst intervals, and sleep-wake cycle disturbance were among the most significant indexes of a poor long-term prognosis. [30]

In newborn infants undergoing cardiac surgery for congenital heart disease, amplitude-integrated EEG (aEEG) prior to surgery, during surgery, and 72 hours postoperatively, reviewed for seizure activity and background pattern to correlate with neurodevelopmental outcome at 2 years, indicate that perioperative seizures are common (30%), often subclinical, in this group and do not affect neurodevelopmental outcome. Instead, delayed recovery in aEEG background continuity was associated with increased risk of early mortality and worse neurodevelopment. [31]

In children with neonatal seizures, the presence of severely abnormal background EEG activity (odds ratio [OR], 9.5) and status epilepticus (OR, 6.1) were found to be predictors of postneonatal epilepsy in association with partial or no response to anticonvulsant therapy (OR, 16.7 and 47, respectively) and severely abnormal ultras and scan alterations (OR, 5.4), even if only the former seemed to be an independent predictor for subsequent epilepsy. [32]

To assess early markers of risk for neurobehavioral compromise in congenital heart disease (CHD) survivors, fetuses younger than 24 weeks gestational age have been enrolled in a pilot study performing serial Doppler assessment of the middle cerebral and umbilical arteries. The cerebral-to-placental resistance ratio (LPR) and middle cerebral artery pulsatility were correlated with postnatal high-density EEG and beta-frequency band EEG power, showing that abnormal cerebrovascular resistance in hypoplastic left-sided heart syndrome, transposition of great arteries, and tetralogy of Fallot predicted decreased neonatal EEG left frontal beta power and lower cognitive development scores at 18 months. [33]

A numerical score of background EEG, [34] with higher numerical scores reflecting greater abnormality, has recently shown reliability to improve the prognosis of neurodevelopmental impairment cerebral palsy and epilepsy, especially if correlated with neuroimaging abnormalities. Quantitative EEG [35] and prolonged bed-side amplitude-integrated EEG [36] have increased the prognostic accuracy for babies at risk of HIE after perinatal asphyxia.

Also, limited-channel EEG technology may be seen as a useful and economic alternative for longitudinal bedside monitoring in neonatal units when prolonged video-EEG monitoring is not obtainable.

Although some ictal discharges may have specific significance, a normal interictal EEG indicates the greatest chance of favorable outcome, even in the case of early, recurrent seizures. Several studies have demonstrated the prognostic role of EEG in different diseases, ranging from neonatal seizures to asphyxia and hemorrhage. [37, 9, 38] At this early developmental age, the EEG has a greater prognostic potential than any other diagnostic tool available to neonatologists. EEG is clearly preferable to a neurological examination of a neonate who inherently displays a narrow behavioral and clinical profile. Prospectively, EEG can predict in early infancy later developmental patterns such as hypsarrhythmia with infantile spasms.


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