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Fontanelles - enlarged

Definition

Enlarged fontanelles are larger than expected soft spots for the age of a baby.

The skull of an infant or young child is made up of bony plates that allow for growth of the skull. The borders at which these plates intersect are called sutures or suture lines. The spaces where these connect, but are not completely joined, are called soft spots or fontanelle (fontanel or fonticulus).

Alternative Names

Soft spot - large

Considerations

Fontanelles allows for growth of the skull during an infant's first year. Slow or incomplete closure of the skull bones is most often the cause of a wide fontanelle.

Common Causes

Larger than normal fontanelles are most commonly caused by:

  • Down syndrome
  • Hydrocephalus
  • Intrauterine growth retardation (IUGR)
  • Premature birth

Rarer causes:

Call your health care provider if

If you think that the fontanelles on your baby's head are larger than they should be, talk to your health care provider. Most of the time, this sign will have been seen during the baby's first medical exam.

What to expect at your health care provider's office

An enlarged large fontanelle is almost always found by the health care provider during a physical exam.

  • The health care provider will examine the child and measure the child's head around the largest area.
  • The doctor may also turn off the lights and shine a bright light over the child's head.
  • Your baby's soft spot will be regularly checked at each well-child visit.

Blood tests and imaging tests of the head may be done.

References

Cohen A. Disorders of the head shape and size. In: Martin RJ, Fanaroff AA, Walsh MC, eds. Fanaroff and Martin’s Neonatal-Perinatal Medicine. 9th ed. St. Louis, Mo: Mosby Elsevier; 2010:chap 40.

Skull of a newborn
The "sutures" or anatomical lines where the bony plates of the skull join together can be easily felt in the newborn infant. The diamond shaped space on the top of the skull and the smaller space further to the back are often referred to as the "soft spot" in young infants.
Fontanelles
Fontanelles are the "soft spots" on an infant's head where the bony plates that make up the skull have not yet come together. It is normal for infants to have these "soft spots", which can be seen and felt on the top and back of the head. Fontanelles that are abnormally large may indicate a medical condition.
Large fontanelles (lateral view)
A wide fontanelle occurs when the fontanelle is larger in size than expected for the age of the baby. Slow or incomplete ossification of the skull bones is most often the cause of a wide fontanelle.
Large fontanelles
The bones of the skull are not joined together firmly at birth. The sutures gradually accumulate minerals and harden (this process is called ossification), firmly joining the skull bones together. In an infant, the spaces where sutures intersect but don't completely touch is called the "soft spot", a membrane covered area also called a fontanelle (fontanel or fonticulus). The fontanelles allow for growth of the skull during an infant's first year. When the spaces of the fontanelles are larger than normal underlying causes such as hydrocephalus may be suspected.

Review Date: 12/4/2013
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.

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