Bulging Fontanelle

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Fontanelles are fibrous membrane-covered gaps between cranial bones. A newborn has six fontanelles: anterior, posterior, two mastoid, and two sphenoid. The most prominent are the anterior and posterior fontanelles

A bulging fontanelle represents increased intracranial pressure, which may be transient, benign, or malignant. The most commonly considered etiologies include Meningitis, space-occupying lesion, cerebral edema, and hemorrhage (spontaneous, non-accidental, or traumatic). A meticulous history and physical is essential to guide management of these infants.

  • The posterior fontanelle usually closes by 1-2 months of age.
  • The anterior fontanelle usually closes between 7-19 months of age.

Differential Diagnosis


Standard approach:

  1. Head CT followed by Lumbar Puncture if not contraindicated by CT findings
  2. Record opening and closing pressures in children is warranted

for a well appearing, asymptomatic, afebrile child with bulging fontanelle, an observation period may be appropriate. In these stable children, if a subacute condition such as an asymptomatic space-occupying lesion is likely, he may benefit from admission and MRI


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