Clinical Reasoning: An encephalopathic 3-day-old infant

Abstract

A full-term, 3-day-old infant presented to the emergency department with poor feeding, increased work of breathing, and encephalopathy 1 day after having been discharged from the hospital in good health. Pregnancy and labor were uneventful, and birth was by spontaneous vaginal delivery. Apgar scores were 9 and 9 at 1 and 5 minutes, respectively. The infant's nursery course was unremarkable. On the evening after discharge, his parents noted he became sleepy and lost interest in feeding over the next 12 hours. The following morning, they noted his breathing was rapid, so they brought him to the emergency room. His general examination at presentation revealed suprasternal retractions, a flat anterior fontanelle, and an enlarged liver. Neurologic examination was notable for marked encephalopathy; he did not open his eyes or react to stimulation. His suck was weak and poorly coordinated and his gag reflex was absent. He lay in a frog-legged position; however, passive tone was increased in all 4 extremities. There were no spontaneous movements or motor response to noxious stimulation. Deep tendon reflexes were symmetrically brisk without ankle clonus. ### Questions for consideration: 1. What is the differential diagnosis for an infant who is initially well but becomes encephalopathic at several days of life? 2. What are the initial steps to evaluate an encephalopathic neonate? The differential diagnosis for encephalopathy in a previously well 3-day-old full-term neonate includes infection (sepsis, meningitis, encephalitis), a vascular event such as a sinovenous thrombosis, nonaccidental trauma, epilepsy leading to nonconvulsive status, and metabolic disturbances secondary either to inborn errors of metabolism or exogenous causes (such as inaccurate preparation of infant formula). A careful review of the history can help identify infectious risk factors, such as a maternal history of group B streptococcus colonization, prolonged rupture of membranes, or labor complicated by chorioamnionitis. Absence of herpetic lesions does not exclude the …