Neonatal Encephalopathy: Need for Recognition of Multiple Etiologies for Optimal Management

Newborn animal studies and pilot studies in humans suggest that mild hypothermia following peripartum hypoxia-ischaemia in newborn infants may reduce neurological sequelae without adverse effects. To determine the effect of therapeutic hypothermia in encephalopathic asphyxiated newborn infants on mortality, long-term neurodevelopmental disability and clinically important side effects. We used the standard search strategy of the Cochrane Neonatal Review Group as outlined in The Cochrane Library (Issue 2, 2007). Randomised controlled trials evaluating therapeutic hypothermia in term and late preterm newborns with hypoxic ischaemic encephalopathy were identified by searching the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2007, Issue 2), MEDLINE (1966 to June 2007), previous reviews including cross-references, abstracts, conferences, symposia proceedings, expert informants and journal handsearching. We updated this search in May 2012. We included randomised controlled trials comparing the use of therapeutic hypothermia with standard care in encephalopathic term or late preterm infants with evidence of peripartum asphyxia and without recognisable major congenital anomalies. The primary outcome measure was death or long-term major neurodevelopmental disability. Other outcomes included adverse effects of cooling and 'early' indicators of neurodevelopmental outcome. Four review authors independently selected, assessed the quality of and extracted data from the included studies. Study authors were contacted for further information. Meta-analyses were performed using risk ratios (RR) and risk differences (RD) for dichotomous data, and weighted mean difference for continuous data with 95% confidence intervals (CI). We included 11 randomised controlled trials in this updated review, comprising 1505 term and late preterm infants with moderate/severe encephalopathy and evidence of intrapartum asphyxia. Therapeutic hypothermia resulted in a statistically significant and clinically important reduction in the combined outcome of mortality or major neurodevelopmental disability to 18 months of age (typical RR 0.75 (95% CI 0.68 to 0.83); typical RD -0.15, 95% CI -0.20 to -0.10); number needed to treat for an additional beneficial outcome (NNTB) 7 (95% CI 5 to 10) (8 studies, 1344 infants). Cooling also resulted in statistically significant reductions in mortality (typical RR 0.75 (95% CI 0.64 to 0.88), typical RD -0.09 (95% CI -0.13 to -0.04); NNTB 11 (95% CI 8 to 25) (11 studies, 1468 infants) and in neurodevelopmental disability in survivors (typical RR 0.77 (95% CI 0.63 to 0.94), typical RD -0.13 (95% CI -0.19 to -0.07); NNTB 8 (95% CI 5 to 14) (8 studies, 917 infants). Some adverse effects of hypothermia included an increase sinus bradycardia and a significant increase in thrombocytopenia. There is evidence from the 11 randomised controlled trials included in this systematic review (N = 1505 infants) that therapeutic hypothermia is beneficial in term and late preterm newborns with hypoxic ischaemic encephalopathy. Cooling reduces mortality without increasing major disability in survivors. The benefits of cooling on survival and neurodevelopment outweigh the short-term adverse effects. Hypothermia should be instituted in term and late preterm infants with moderate-to-severe hypoxic ischaemic encephalopathy if identified before six hours of age. Further trials to determine the appropriate techniques of cooling, including refinement of patient selection, duration of cooling and method of providing therapeutic hypothermia, will refine our understanding of this intervention.

This Point of View article addresses neonatal encephalopathy (NE) presumably caused by hypoxia-ischemia and the terminology currently in wide use for this disorder. The nonspecific term NE is commonly utilized for those infants with the clinical and imaging characteristics of neonatal hypoxic-ischemic encephalopathy (HIE). Multiple magnetic resonance imaging studies of term infants with the clinical setting of presumed hypoxia-ischemia near the time of delivery have delineated a topography of lesions highly correlated with that defined by human neuropathology and by animal models, including primate models, of hypoxia-ischemia. These imaging findings, coupled with clinical features consistent with perinatal hypoxic-ischemic insult(s), warrant the specific designation of neonatal HIE. Copyright © 2012 American Neurological Association.

We studied (1) the pattern of brain injury in term neonates with encephalopathy with evidence of a preceding hypoxic sentinel event, (2) prenatal and perinatal risk factors, and (3) the correlation between neuroimaging findings and developmental outcomes. We identified, among 500 term neonates with encephalopathy who were studied with MRI between 1992 and 2005, 48 infants with evidence of a preceding acute hypoxic event, and we reviewed their MRI scans retrospectively. Prenatal and perinatal data were compared with those for term normal low-risk infants. Neurodevelopmental outcomes were assessed at a minimum of 12 months. Five patterns of brain injury were identified, as follows: pattern I, basal ganglia and thalami lesions associated with severe white matter damage (n = 6; 14%); pattern II, basal ganglia and thalami lesions with mild or moderate white matter changes (n = 24; 56%); pattern III, isolated thalamic injury (n = 2; 5%); pattern IV, moderate white matter damage only (n = 1; 2%); pattern V, mild white matter changes or normal findings (n = 10; 23%). No scan showed evidence of long-standing injury. The internal capsule was abnormal in 93% of infants with patterns I and II, and 86% of those infants died or developed cerebral palsy. Infants with patterns III and IV had developmental delay and diplegic cerebral palsy, respectively. Pattern V was associated with normal outcomes. Case infants were significantly more often of African descent, born to pluriparous or hypertensive mothers. Uterine rupture followed previous cesarean section in 8 of 11 cases. Cord prolapse accompanied undiagnosed breech presentation in 4 of 9 cases. Basal ganglia and thalami lesions are the imaging signature in term neonates exposed to hypoxic-ischemic sentinel events. Patterns of central gray matter and secondary white matter injury were associated with higher risks of severe morbidity and death. Affected infants did not seem intrinsically different from our low-risk population. These data support the need for anticipating sentinel events and expediting delivery.