Clinical Considerations Clinical Recognition Neonatal encephalopathy manifests as an acute change in mental status and/or seizures In its most profound presentation, the infant will show depressed level of consciousness (as in stupor or coma) with global hypotonia, and autonomic disturbances that include apnea, respiratory failure, or abnormal cardiac rhythms Moderate encephalopathy may manifest as a variable change in alertness, with alternating periods of decreased arousal, or hypervigilance, tremors, jitteriness, and irritability The timing and pattern of changes in degree of encephalopathy may help distinguish etiology; in acute hypoxia–ischemia, there may be a period of “normalization” of the neurologic examination 12 to 24 hours after the event or trauma Acute intoxication or IEM are more likely to present with progressive encephalopathy and typically not demonstrate this period of “pseudonormalization.” Triage Considerations The lethargic infant with decreased levels of alertness should be triaged emergently, as these infants can quickly develop autonomic instability and cardiorespiratory collapse Additionally, if born outside a medical setting and presenting within hours of life, time-sensitive therapies are available that offer neuroprotection Clinical Assessment The clinical assessment requires detailed history regarding the timing and onset of symptoms—initial symptoms may include decreased arousal, increased lethargy, decreasing oral intake, and increasing irritability History may also reveal potential asphyxial events or trauma Unexplained intracranial hemorrhage should also warrant an evaluation for nonaccidental trauma once the infant is stabilized Given the risk of either autonomic deterioration or a global asphyxial event that could result in multisystem dysfunction, clinical assessment should include detailed cardiopulmonary evaluation, including monitoring for apnea Serum toxicology screen should be sent, as well blood gas, BMP, liver function panel, ammonia level, and plasma amino acids Urine should be collected and sent for toxicology, urinalysis for ketones, and urine for organic acids Acute bilirubin encephalopathy (kernicterus) is a rare cause of brain injury, but should be suspected if the infant also presents with jaundice Infants should also be evaluated for infection, including bacterial and/or viral meningoencephalitis IEM presenting with neonatal encephalopathy are summarized in Table 96.5 Other causes of neonatal hypotonia and weakness are presented in Table 96.6