Pediatric emergency medicine trisk 643

avoiding hyperthermia For neonates encephalopathic immediately after birth, therapeutic hypothermia initiated within hours of life and continued for 72 hours is now an evidence-proven therapy that should be considered Parenteral fluids should be administered to ensure adequate cardiac output Metabolic derangements should be addressed in order to maintain serum sodium close to 140 to avoid exacerbations of cerebral edema, and hypoglycemia should be treated aggressively to avoid secondary neuronal injury Infants with evidence of trauma or increased intracranial pressure may need to have emergent neurosurgical interventions, and coagulation disturbances should be corrected to try and control intracranial hemorrhage Acute intoxication and/or IEM may present with worsening encephalopathy, and in certain circumstances, may require emergent dialysis to clear the offending metabolite CLINICAL PEARLS AND PITFALLS The neonatal neurologic examination can be challenging due to subtle changes in mental status in infants with underdeveloped CNSs Nonetheless, the neurologic examination can identify infants at high risk for brain injury and timely interventions, such as hypothermia, can result in neuroprotection In some circumstances, brainstem herniation can occur without bulging of the anterior fontanelle because of isolated increased pressure in the posterior fossa It is not uncommon for the infant to have waxing and waning of neurologic signs, and careful documentation and serial evaluations are important diagnostic and prognostic clues Perinatal hypoxia–ischemia is a major cause of neonatal encephalopathy, however, additional etiologies for late-onset or progressive encephalopathy must be evaluated Current Evidence Hypoxic–ischemic injury during the perinatal period is the most common identified cause of neonatal encephalopathy The pathophysiology of injury leading to cerebral edema, reperfusion injury, and neuronal cell death can also be applied to any acute asphyxial event in the neonatal period Brain injury in response to such an event continues to evolve over a period of hours to days, and can account for changes seen in the clinical examination 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 Management The infant should be stabilized and if there are signs of respiratory distress, should be supported with assisted ventilation Patients with signs of global asphyxial injury should be supported with fluid boluses or inotropes if there are signs of poor cardiac output For select patients presenting with encephalopathy since birth, the consideration of therapeutic hypothermia should be discussed with a neonatologist A history that is concerning for trauma or asphyxia, or infants with evidence of trauma or increased intracranial pressure, should undergo emergent head imaging (noncontrast head CT) If there is evidence of intracranial hemorrhage, cerebral edema, and/or herniation, pediatric neurosurgery should be consulted In addition, a complete blood count and coagulation studies should be sent and abnormalities should be corrected aggressively with transfusion of blood products to stabilize any hemorrhage Any metabolic derangements should be corrected—particularly hypoglycemia, with the rapid infusion of parenteral dextrose bolus and then an ongoing infusion Tight control of serum sodium should be achieved to decrease the effects of cerebral edema Broad-spectrum antibiotics should be administered once the cultures have been obtained Acute hyperbilirubinemia with encephalopathy is treated with hydration and exchange transfusion Hyperammonemia is treated with scavenger drugs and/or dialysis in conjunction with a pediatric nephrologist Once stabilized, many IEM can be managed by diet in conjunction with a metabolic geneticist Degenerative diseases such as Tay–Sachs, Menkes, Neiman–Pick, Guacher, Crabber, and peroxisomal and mitochondrial disorders have no effective treatments other than supportive care TABLE 96.5 INBORN ERRORS OF METABOLISM PRESENTING WITH ENCEPHALOPATHY Urea cycle defects Maple syrup urine disease Nonketotic hyperglycinemia Organic acid disorders Hypervalinemia Phenylketonuria Lysinuric protein intolerance Vomiting, stupor and seizures Hyperammonemia, acidosis with respiratory alkalosis Stupor, seizures, odor of maple syrup Acidosis, hypoglycemia Stupor, seizures, hiccups Hyperglycinemia in CSF, serum, and urine Absence of acidosis or ketones in urine Stupor, coma, tachypnea, vomiting Metabolic acidosis Stupor and developmental delay Vomiting and musty odor Vomiting and hypotonia ... (noncontrast head CT) If there is evidence of intracranial hemorrhage, cerebral edema, and/or herniation, pediatric neurosurgery should be consulted In addition, a complete blood count and coagulation studies... transfusion Hyperammonemia is treated with scavenger drugs and/or dialysis in conjunction with a pediatric nephrologist Once stabilized, many IEM can be managed by diet in conjunction with a metabolic