Predicting the future for term infants experiencing an acute neonatal encephalopathy: electroencephalogram, magnetic resonance imaging, or crystal ball?

Magnetic resonance biomarkers of neuroprotective effects in infants with hypoxic ischemic encephalopathy

Evaluation of infants with hypoxic ischemic encephalopathy by magnetic resonance spectroscopy and imaging is useful to direct clinical care, and may assist the evaluation of candidate neuroprotective therapies. Cerebral metabolites measured by magnetic resonance spectroscopy, and visual analysis of magnetic resonance images during the first 30 days after birth accurately predict later neurological outcome and are valid biomarkers of the key physiological processes underlying brain injury in neonatal hypoxic ischemic encephalopathy. Visual assessment of magnetic resonance images may also be a suitable surrogate outcome in studies of neuroprotective therapies but current magnetic resonance methods are relatively inefficient for use in early phase, first in human infant studies of novel neuroprotective therapies. However, diffusion tensor imaging and analysis of fractional anisotropy with tract-based spatial statistics promises to be a highly efficient biomarker and surrogate outcome for rapid preliminary evaluation of promising therapies for neonatal hypoxic ischemic injury. Standardisation of scanning protocols and data analysis between different scanners is essential.

Predicting outcome in term neonates with hypoxic-ischaemic encephalopathy using simplified MR criteria

BACKGROUND

MRI is an established investigation in the evaluation of neonates with suspected hypoxic-ischaemic encephalopathy (HIE). However, its role as a predictor of neurodevelopmental outcome remains complex.

OBJECTIVE

To establish reproducible simplified MR criteria and evaluate their role in predicting neurodevelopmental outcome in term neonates with HIE.

MATERIALS AND METHODS

Term neonates with suspected HIE had MRI at 7-10 days of age. MR scans were interpreted according to new simplified criteria by two radiologists blinded to the clinical course and outcome. The new simplified criteria allocated grade 1 to cases with no central and less than 10% peripheral change, grade 2 to those with less than 30% central and/or 10-30% peripheral area change, and grade 3 to those with more than 30% central or peripheral change. MRI changes were compared with clinical neurodevelopmental outcome evaluated prospectively at 1 year of age. Neurodevelopmental outcome was based upon the DQ score (revised Griffith's) and cerebral palsy on neurological assessment.

RESULTS

Of 20 subjects, all those showing severe (grade 3) MR changes (35%) died or had poor neurodevelopmental outcome. Subjects with a normal MR scan or with scans showing only mild (grade 1) MR changes (55%) had normal outcomes. One subject showing moderate (grade 2) changes on MRI had a moderate outcome (5%), while another had an atypical pattern of MR changes with a normal outcome (5%).

CONCLUSIONS

Assessment of full-term neonates with suspected HIE using the simplified MR criteria is highly predictive of neurodevelopmental outcome.

Dopamine for prevention of morbidity and mortality in term newborn infants with suspected perinatal asphyxia

BACKGROUND

Perinatal asphyxia remains an important condition with significant mortality and long-term morbidity. Multisystem involvement including hypotension and low cardiac output is common in infants with perinatal asphyxia. Dopamine is commonly used for infants with hypotension of any etiology, with the goal of improving cardiac output and preventing its detrimental consequences.

OBJECTIVES

To determine if dopamine, compared to placebo, no treatment, volume or another inotrope reduces morbidity and mortality in term newborn infants with suspected perinatal asphyxia.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group was used. Searches were conducted of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register (The Cochrane Library, Issue 1, 2002), MEDLINE (1966 to March 2002), previous reviews including cross references, abstracts and conference proceedings (Perinatal Society of Australia and New Zealand 1998-2002 and Pediatric Academic Societies meetings 1998-2001).

SELECTION CRITERIA

Randomised controlled trials comparing dopamine with placebo, no treatment, other inotropic agents, or volume in infants greater than 36 weeks gestation. Perinatal asphyxia could be suspected on the basis of a cord blood pH < 7.0, cord blood base excess < -16 mEq/L or 5 minute Apgar score < 6.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Neonatal Review Group with use of relative risk (RR), risk difference (RD) and weighted mean difference (WMD). The fixed effects model using RevMan 4.1 was used for meta-analysis. Data from individual studies were only eligible for inclusion if at least 75% of participants were followed up.

MAIN RESULTS

Only one study (DiSessa 1981) was eligible. This study compared low dose dopamine at 2.5 mcg/kg/min with placebo (dextrose in water). This study enrolled 14 term infants with a 5 minute Apgar <6 and a systolic BP >=50 mmHg at a mean of 10 hours age. Seven infants only were randomised to treatment with dopamine and seven to receive placebo. No significant differences between these two groups were found for mortality or long term neurodevelopmental outcome. Length of hospitalisation was not significantly different between the two groups. No study was found that examined the effect of dopamine in infants with evidence of cardiovascular compromise, nor were any studies identified in which dopamine was compared to other inotropic agents for term infants with suspected asphyxia.

REVIEWER'S CONCLUSIONS

There is currently insufficient evidence from randomised controlled trials that the use of dopamine in term infants with suspected perinatal asphyxia improves mortality or long-term neurodevelopmental outcome. The question of whether dopamine improves outcome for term infants with suspected perinatal asphyxia has not been answered. Further research is required to determine whether or not the use of dopamine improves mortality and long-term morbidity for these infants and if so, issues such as which infants, at what dose and with what co-interventions should be addressed.