Bulging fontanelle

Pathophysiology

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

• Meningo-encephalitis
• Congestive heart failure
• Space-occupying lesions
• Thyroid disroders
• Intracranial hemorrhage
• Parathyroid disorders
• Brain abscess
• Diabetic ketoacidosis
• Intracranial hemorrhage
• Hypervitaminosis A
• Anemia
• Lead encephalopathy
• Leukemia
• Inborn errors of metabolism
• Uremia
• Trauma
• Roseola
• Vaccinations
• Shigella
• Benign Intracranial hypertension
• Dural sinus thrombosis
• Viral syndromes

Treatment

Standard approach:

• • CT followed by lumbar puncture if not contraindicated by CT findings
  • 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)

Sources

Baqui AH, de Francisco A, Arifeen SE, Siddique AK, Sack RB. Bulging fontanelle after supplementation with 25,000 IU of vitamin A in infancy using immunization contacts. Acta Paediatr. 1995 Aug;84(8):863-6.

Beri S, Hussain N. Bulging fontanelle in febrile infants: lumbar puncture is mandatory. [Letter]. Arch Dis Child. 2011; 96 (1):109.

Biswas AC, Molla MA, Al-Moslem K. A baby with bulging anterior fontanelle. Lancet. 2000; 356(9224):132.

Long SS. Transient bulging fontanelle after immunization. J Pediatr. 2005; 147(5):A3

Opfer K. The bulging fontanelle. Lancet. 1963 Jan 12;1(7272):116.

Silver W, Kuskin L, Goldenberg L. Bulging anterior fontanelle. Sign of congestive heart failure in infants. Clin Pediatr (Phila). 1970 Jan;9(1):42-3.

Shacham S, Kozer E, Bahat H, Mordish Y, Goldman M. Bulging fontanelle in febrile infants: is lumbar puncture mandatory? Arch Dis Child. 2009;94:690–692.