A 3-hour-old boy is being evaluated in the newborn nursery. The patient was born via spontaneous vaginal delivery to a 25-year-old woman, gravida 2 para 2. The mother had no prenatal care and takes no medications. Head circumference is at the 90th percentile. Weight is at the 25th percentile. Temperature is 37.3 C (99.1 F), pulse is 140/min, and respirations are 32/min. Per the Ballard Score, the patient is at 38 weeks gestation. Head examination shows a full fontanelle. The ears are in the normal position. The oropharynx is clear. Cardiopulmonary examination is unremarkable. The abdomen is soft with no organomegaly. Examination of the back shows a large myelomeningocele. Bilateral lower extremities are flaccid. Head imaging is most likely to reveal which of the following?

Question

A 3-hour-old boy is being evaluated in the newborn nursery.  The patient was born via spontaneous vaginal delivery to a 25-year-old woman, gravida 2 para 2.  The mother had no prenatal care and takes no medications.  Head circumference is at the 90th percentile.  Weight is at the 25th percentile.  Temperature is 37.3 C (99.1 F), pulse is 140/min, and respirations are 32/min.  Per the Ballard Score, the patient is at 38 weeks gestation.  Head examination shows a full fontanelle.  The ears are in the normal position.  The oropharynx is clear.  Cardiopulmonary examination is unremarkable.  The abdomen is soft with no organomegaly.  Examination of the back shows a large myelomeningocele.  Bilateral lower extremities are flaccid.  Head imaging is most likely to reveal which of the following?

Quizplus · Accepted Answer

11ec25c8_d6f1_f227_bc81_f7b7e292609a_MD0003_00 By week 4 of gestation in normal organogenesis, the neural folds fuse to form the neural tube, protecting the meninges, cerebrospinal fluid (CSF), and spinal cord. Closure of the neural tube allows primitive cranial structures to remain appropriately distended with CSF for normal development of the forebrain, midbrain, and hindbrain. Myelomeningocele (spina bifida) is a neural tube defect in which the meninges and spinal cord are exposed due to failure of neural tube closure. Patients have a lumbosacral protrusion consisting of a membranous sac containing meninges, CSF, and the spinal cord. The exposed spinal cord is generally dysplastic, resulting in severe neurologic deficits (eg, paralysis, sensory loss, bowel/bladder incontinence) below the affected level. Myelomeningocele In myelomeningocele, CSF is lost through the open neural tube defect, causing collapse of cranial structures. This collapse results in the development of a small posterior fossa and subsequent inferior displacement (ie, herniation) of the medulla and cerebellum through the foramen magnum, known as a Chiari II malformation. The malformation may also limit CSF flow through the fourth ventricle and/or cerebral aqueduct, causing obstructive hydrocephalus (eg, enlarged head circumference, full fontanelle). Chiari II malformation (Choice A) Arteriovenous malformation at the vein of Galen is a rare, isolated condition that most commonly causes neonatal heart failure due to high-pressure venous blood flow. (Choice B) Choroid plexus papilloma is an overgrowth of the choroid plexus in the lateral ventricles, resulting in excessive CSF production. Myelomeningocele is not associated with this condition. (Choice C) Diffuse leptomeningeal enhancement is seen in meningitis due to increased permeability of the meninges. Although myelomeningocele increases the risk of meningitis due to exposure of the meninges, this complication would be unlikely in the first few hours of life. In addition, this patient's normal temperature makes meningitis less likely. (Choice D) The germinal matrix, a highly vascularized and friable area of the brain, is prone to rupture in premature infants and can lead to ventricular dilation and hydrocephalus. Germinal matrix hemorrhage is unlikely in a term infant and is not associated with myelomeningocele. Educational objective: Myelomeningocele is an open neural tube defect in which the meninges and spinal cord protrude through the skin. It is often associated with a Chiari II malformation (ie, inferior displacement of the medulla and cerebellum through the foramen magnum), as well as obstructive hydrocephalus. References: Myelomeningocele. (http://www.ncbi.nlm.nih.gov/pubmed/31536302) Brain abnormalities in myelomeningocele patients. (http://www.ncbi.nlm.nih.gov/pubmed/31664560)

A 3-Hour-Old Boy Is Being Evaluated in the Newborn Nursery