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Difficulty: Very hardPediatric Neurologic Disorders

Parents bring their 16-week-old male infant to the pediatric evaluation center due to persistent, forceful vomiting and extreme fussiness that has worsened over the past two days. The mother notes that the baby's eyes appear to be constantly looking downward, which she describes as a 'setting sun' appearance. Pregnancy and spontaneous vaginal delivery at 39 weeks of gestation were unremarkable. Vital signs show a temperature of 37.2°C (99.0°F), a heart rate of 115/min, and blood pressure of 105/65 mmHg.

On examination, the infant has a noticeably enlarged head with a tense, protruding anterior fontanelle and engorged scalp veins. The sagittal suture is palpably diastatic. Neurologic assessment confirms an upward gaze palsy with light-near dissociation. Lower extremity tone is mildly hypertonic. Dermatologic exam notes a scattering of small, erythematous papules with central pustules confined to the bilateral cheeks. The parents are anxious, mentioning he hasn't learned to roll from his back to his tummy yet, and they are upset with their primary pediatrician for not taking action when his head circumference crossed two major percentile lines a month ago.

A point-of-care cranial ultrasound indicates marked expansion of the lateral and third ventricles, while the fourth ventricle appears normal.

Which of the following interventions represent the most appropriate immediate steps in the management of this patient? (Select 2)

  1. Performance of magnetic resonance imaging of the brainAnswer
  2. Urgent consultation for cerebrospinal fluid diversionAnswer
  3. C
    Referral to physical therapy for gross motor developmental delay
  4. D
    Initiation of punitive disciplinary measures against the primary care provider
  5. E
    Administration of intravenous acyclovir for the facial skin eruption

Answer

The correct steps are the performance of magnetic resonance imaging of the brain and an urgent consultation for cerebrospinal fluid diversion.
The infant's clinical presentation—featuring a rapidly enlarging head circumference, a tense fontanelle, prominent scalp veins, and Parinaud syndrome (upward gaze palsy with a 'setting sun' appearance)—is highly specific for severe hydrocephalus with acutely increased intracranial pressure. The point-of-care cranial ultrasound confirms non-communicating (obstructive) hydrocephalus by demonstrating dilation of the lateral and third ventricles while sparing the fourth ventricle, which localizes the obstruction to the cerebral aqueduct. The most appropriate immediate steps are to obtain an MRI of the brain to delineate the precise anatomy and evaluate for potential anatomical lesions (such as a pineal mass), and to urgently consult neurosurgery for definitive cerebrospinal fluid diversion (e.g., via an endoscopic third ventriculostomy or a ventriculoperitoneal shunt).

Step-by-Step Solution

1
Analyze the physical exam findings and diagnostic imaging.
The infant exhibits classical signs of elevated intracranial pressure (tense fontanelle, diastatic sutures, setting sun sign/Parinaud syndrome) alongside an ultrasound demonstrating enlarged lateral and third ventricles with a normal fourth ventricle.
This establishes the primary diagnosis of non-communicating (obstructive) hydrocephalus, likely localized at the cerebral aqueduct.
2
Determine the necessary diagnostic follow-up for the neurologic condition.
Magnetic resonance imaging (MRI) of the brain is identified as the optimal modality.
MRI provides the high-resolution anatomical detail required to pinpoint the exact etiology, such as aqueductal stenosis or a pineal mass causing the obstruction.
3
Identify the required therapeutic intervention.
Neurosurgical consultation is mandated.
Obstructive hydrocephalus presenting with acute signs of elevated intracranial pressure requires urgent cerebrospinal fluid diversion to prevent permanent brain injury or herniation.
4
Evaluate the secondary parental concerns regarding development, medical error, and skin findings.
The motor development is normal for age (4 months), the medical error requires a systems-based approach rather than punishment, and the facial rash is benign neonatal cephalic pustulosis.
Recognizing these allows the physician to avoid unnecessary interventions like physical therapy referrals, inappropriate punitive legal measures, or unwarranted antiviral medications.

Key Concept

Diagnosis and management of non-communicating hydrocephalus in infants, including the differentiation of acute pathologic neurologic signs from normal developmental and physiologic variants.
Estimated Time:1m 30s
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Topics

Pediatric Neurologic Disorders

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