Soft spot - bulging; Bulging fontanelles
A bulging fontanelle is a convex displacement of an infant’s soft spot (fontanelle).
The skull is made up of many bones, 7 in the skull itself and 14 in the facial area. They join together to form a solid, bony cavity protecting the brain and supporting the structures of the head. The areas where the bones join together are called the sutures.
The bones are not joined together firmly at birth. This allows the head to accommodate passage through the birth canal. The sutures gradually accumulate minerals and harden, firmly joining the skull bones together. This process is called ossification.
In an infant, the spaces where two sutures intersect form a membrane-covered “soft spot” called a fontanelle (fontanel). The fontanelles allow for growth of the skull during an infant’s first year.
There are several fontanelles that are normally present on a newborn’s skull, primarily at the top, back, and sides of the head. Like the sutures, fontanelles gradually ossify and become closed, solid bony areas. The posterior fontanelle (in the back of the head) usually closes by the time an infant is 1 or 2 months old. The anterior fontanelle at the top of the head usually closes within the range of 7 - 19 months.
The fontanelles should feel firm and very slightly concave to the touch. A tense or bulging fontanelle occurs when fluid accumulates in the skull cavity or when pressure increases in the brain (increased intracranial pressure).
When the infant is crying, lying down, or vomiting, the fontanelles may look like they are bulging, but they should return to normal when the infant is in a calm, head-up position.
- Increased intracranial pressure (associated with meningitis and other disorders)
If the fontanelle returns to normal appearance when the child is calm and head-up, it is not a truly bulging fontanelle.
Call your health care provider if
An infant with a truly bulging fontanelle, especially if accompanied by fever or lethargy, should be examined promptly by an emergency room physician or pediatrician. THIS IS A MEDICAL EMERGENCY.
What to expect at your health care provider’s office
The medical history will be obtained and a physical examination performed.
Medical history questions documenting bulging fontanelle in detail may include:
- Does the “soft spot” return to normal appearance when the infant is calm or head-up?
- Does it bulge all the time or does it come and go?
- When did you first notice this?
- Which fontanelles bulge (top of the head, back of the head, or other)?
- Are all the fontanelles bulging?
- What other symptoms are also present (such as fever, irritability, lethargy)?
Diagnostic tests that may be performed are:
- Head x-ray
- CT scan of the head
- Possible lumbar puncture
After seeing your health care provider:
You may want to add a diagnosis related to bulging fontanelles to your personal medical record.
by Harutyun Medina, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.