Apnea In A Term Neonate: Expanding The Differential Diagnosis

A zero-day old female infant is admitted to the NICU for persistent oxygen desaturations and cyanosis. She was born at a gestational age of 39 weeks to a 31-year-old Gravida 4 Para 4 mother by spontaneous vaginal delivery. The pregnancy was uncomplicated. Maternal blood type was O positive and the remainder of the maternal serologies are unremarkable. Delivery was complicated by the presence of meconium stained fluid and a tight nuchal cord. APGAR scores were six at one minute and eight at five minutes. The infant required administration of CPAP in the delivery room for an oxygen saturation of seventy percent at five minutes of life. Following admission to the NICU, the infant had an escalating oxygen requirement and recurrent apneic events resulting in endotracheal intubation and mechanical ventilation. The infant’s birth weight is 3.310kg (56 percentile on WHO Girls Curve), birth length is 49.5cm (58 percentile on WHO Girls Curve), and FOC is 35.6cm (92 percentile on WHO Girls Curve). Vital signs are significant for an axillary temperature of 36.8 degrees Celsius, heart rate of 132bpm, blood pressure of 88/62, and oxygen saturation of 97% on a fraction of inspired oxygen of 40%. Her physical exam is remarkable for easy respiratory effort on mechanical ventilation with clear breath sounds and equal air entry. Her respiratory rate is slow for a neonate at 20 breaths per minute. She does not have a murmur. Her capillary refill is brisk and she has a normal heart rhythm on the monitor. She has normal muscle tone and patellar reflexes. She did not have any striking dysmorphic craniofacial features and her abdominal, genitourinary, musculoskeletal, and skin exams are grossly normal. She continues to periods of apnea while on mechanical ventilation. A chest radiograph demonstrates clear lung fields and a normal cardiac silhouette. The family history is significant for three older siblings who are healthy and developmentally typical. Initial laboratory studies revealed a glucose of 77, a CBC with a WBC of 13.8, hemoglobin of 19.6, hematocrit of 58, platelet count of 221, with a normal cell differential. Her venous blood gas revealed a pH of 7.22, CO2 of 64, P02 of 41, bicarbonate of 26, and a base deficit of 3.6. Electrolyte and hepatic function panel revealed normal results. A lumbar puncture is performed and CSF analysis is normal. Blood and CSF cultures are negative. Herpes simplex virus studies are negative. A serum ammonia level is 85umol/L, which is within normal range for the hospital laboratory. A meconium drug screen is negative. Her state newborn screen is normal. A karyotype is performed which reveals a normal female chromosome complement, 46, XX. Her head ultrasound reveals no abnormality. A Brain MRI with and without contrast reveals a few punctate foci of restricted diffusion in the right hemisphere, with otherwise