Early predictors of outcome in infants treated with hypothermia for hypoxic–ischaemic encephalopathy

Abstract

Hypoxic–ischaemic encephalopathy (HIE) is a leading cause of acquired neonatal brain injury. Assessment of the severity of cerebral injury and likely neurological outcome in infants with HIE is important for determining management and prognosis, for counselling parents, and for selection for neuroprotective trials. The condition of the infant at birth, the severity of HIE, neurophysiological tests, including amplitude‐integrated electroencephalography (aEEG), biochemical markers, and neuroimaging have been used to assess prognosis and predict long‐term outcome. The predictive accuracy of these indicators in the early postnatal period is modest. Neurophysiological assessment seems to be most helpful during the first 24 to 48 hours after birth whilst magnetic resonance imaging (MRI) seems most informative later. Several biochemical markers, including serum S100β and neuron‐specific enolase (NSE), are also associated with HIE but their levels depend on the timing of sampling and their prognostic value is uncertain. Comprehensive neurophysiological assessment and neuroimaging may be limited to specialist centres. Therapeutic hypothermia is now standard care in infants with moderate to severe HIE so it is important to examine the influence of hypothermia on the assessment of prognosis in these infants.

Management and investigation of neonatal encephalopathy: 2017 update

“…In severe HIE there is increased echogenicity in the thalamus and basal ganglia. However CrUSS is a poor prognostic indicator, with only a 79% (95% CI 37% to 97%) sensitivity and 55% (95% CI 35% to 70%) specificity for abnormal outcome 40. Cerebral flow velocity can also be measured using Doppler studies.…”

“…A current review of the prognostic value of clinical assessment and various investigations in HIE is available. 40 Neurophysiology EEG and aEEG are important tools for assessment of severity of HIE, monitoring improvement over time and for recognition of seizures. Both have advantages and disadvantages.…”

“…However CrUSS is a poor prognostic indicator, with only a 79% (95% CI 37% to 97%) sensitivity and 55% (95% CI 35% to 70%) specificity for abnormal outcome. 40 Cerebral flow velocity can also be measured using Doppler studies. In healthy term infants in the first 24 hours, the average resistance index (RI) is 0.726 (SD 0.057).…”

“…Diffusion weighted imaging and the apparent diffusion coefficient may demonstrate abnormalities earlier than conventional MRI, but they are of less prognostic value (sensitivity 58% (95% CI 24% to 84%), specificity 89% (95% CI 62% to 98%); and sensitivity 79% (95% CI 50% to 93%), specificity 85% (95% CI 75 to 91) respectively). 40 MRS is increasingly used as a quantitative tool both for clinical and research prognostication. 1 H MRS can be used to measure peaks of N-acetylasparate (NAA), choline, creatine, lactate and the relative ratios of each in the thalamus and basal ganglia.…”

Blood biomarkers for evaluation of perinatal encephalopathy: state of the art

“…The presence of meconium, non-reassuring fetal heart rate tracing, Apgar scores, umbilical artery blood gases, and physical exam, are tools currently used to identify brain injury in the fetus and neonate but they all both separately and collectively lack precision. Amplitude integrated EEG can detect early changes associated with brain injury and has been used to determine prognosis and predict long term outcomes, (Merchant and Azzopardi, 2015) however, interference from hypothermic environments can reduce the prediction of HIE prognosis, and amplitude integrated EEG cannot determine the time of injury (Thoresen et al, 2010).…”