In the latest Case Record of the Massachusetts General Hospital, a newborn boy was admitted to the hospital because of respiratory distress and hypotension. At delivery, meconium was suctioned from the airway. Respiration and blood pressure improved after intervention, but lethargy and myoclonus developed.
Neonatal brain tumors are often not apparent in utero; only 18% are identified on prenatal ultrasound, even when polyhydramnios and hydrocephalus are present. This is because neonatal brain tumors tend to grow rapidly in the third trimester, after the period when prenatal ultrasonography is performed during uncomplicated pregnancies.
- What is the mortality rate associated with meconium aspiration syndrome?
Meconium is present in 3 to 18% of term deliveries, and in such cases, the meconium aspiration syndrome develops in 2 to 9% of the neonates. The meconium aspiration syndrome accounts for 10% of all neonatal respiratory failure and is associated with a mortality rate of 39%.
- What is the mechanism of lung injury in meconium aspiration syndrome?
Meconium, which is thick and particulate, can physically obstruct the airways, causing a ball-valve phenomenon that then leads to air trapping and hyperinflation. Asymmetric lung inflation, with areas of collapse and hyperinflation, increases the likelihood of pneumothorax and of ventilation-perfusion mismatch. Meconium can cause surfactant inactivation and is also toxic to the type II cells, thereby decreasing production of surfactant. Meconium can also indirectly affect the lung tissue, by inducing inflammatory mediators and apoptosis and by inhibiting lung-fluid resorption.
Morning Report Questions
Q: What lesions are included in the differential diagnosis for congenital brain tumors?:
A: Congenital brain tumors are uncommon, accounting for only 1 to 2% of all brain tumors in pediatric patients (1 to 3 cases per 1 million live births). The differential diagnosis of brain tumors in infants differs from that in older children. Teratomas account for 35 to 45% of all brain tumors in newborns, whereas low-grade astrocytomas comprise the largest proportion of brain tumors affecting older children. Aggressive embryonal tumors — including medulloblastomas, supratentorial primitive neuroectodermal tumors, and atypical teratoid-rhabdoid tumors — account for nearly one quarter of all brain tumors in both infants and older children, with atypical teratoid-rhabdoid tumors occurring most frequently in infants and very young children. Tumors of the central nervous system in older children are more commonly infratentorial, whereas 60 to 70% of tumors of the central nervous system in neonates are supratentorial.
Q: What is the prognosis for an infant with a congenital brain tumor?
A: Given the large size of many neonatal tumors and the limited therapeutic options, the outcome for newborns and infants who receive a diagnosis of a brain tumor other than choroid plexus papilloma is very poor. The prognosis for neonates with a highly aggressive embryonal tumor is particularly poor; less than 20% of affected children survive. Patients who do survive typically have global impairments, including neurocognitive deficits (69% of affected children have a full-scale intelligence quotient of <85, and 54% have a full-scale intelligence quotient of <70, the standard threshold for mental retardation), motor delays (in 85%), visual impairment, hearing deficits and speech delays (in 50%), and feeding problems and endocrine deficits (in 25%).