Bulging Fontanelle: Causes, Treatment & When To See A Doctor

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A bulging fontanelle in infants is characterized by the outward appearance of their soft spot (fontanelle). Under normal conditions, the fontanelle is curved inwards. But when the pressure inside the brain increases or if there is a fluid buildup, the tension within leads to the protrusion and formation of the dome-shaped fontanelle, making the baby’s head appear bulged.

The condition could be accompanied by fever and may require medical care. Read on to know more about the causes of bulging fontanelle, its diagnosis, and treatment.

What Is Fontanelle In Infants?

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The skull consists of several bones, of which eight bones enclose and protect the brain. Each bone meets at a joint called a suture. In adults, the sutures are closed, but in infants, there is a space between the sutures filled with membranous tissue. The space between the sutures is called a fontanelle or soft spot.

The function of fontanelle is to allow the baby’s head to mold during delivery and support the brain’s growth during infancy. The sutures fuse over time due to the addition of minerals, and the soft spot eventually disappears without any distension or bulging.

Since the skull has multiple bones, a baby has multiple fontanelles that close at different stages of infancy and toddlerhood (1). The following are the most notable fontanelles and the age at which they usually close.

• Posterior fontanelle, situated in the back of the head, closes by one to two months of age.

• Anterior fontanelle, on top of the head, closes between seven and 19 months after birth.

Quick fact

A newborn has six fontanelles at the time of birth (2).

Normally the fontanelles feel firm and slightly curved inward to the touch. It is normal for fontanelles to bulge when an infant cries, vomits, or lays down. They return to normal when the infant is calm, in a head-up position. However, bulging fontanelle in other situations can be an indication of a pathology. A tense or bulging fontanelle occurs when fluid builds up in the brain or the brain itself swells – in any condition leading to increased pressure inside the skull.

Causes Of Bulging Fontanelle

It is important to note that bulging fontanelle is not a disease itself but rather a sign of an underlying disease or condition

. An infant may have bulging fontanelle due to the following reasons (2).

• Hydrocephalus, a condition that causes fluid buildup in the skull

A mom of four, Vicky Herbert, shares about her youngest son, Ethan, who was diagnosed with hydrocephalus that led to the bulging of his fontanelle. She writes, “Ethan was born nine weeks early, weighing 3lbs 10oz, and following a traumatic birth, where the umbilical cord was wrapped tightly around his neck, he suffered a bleed on the brain… Hydrocephalus was mentioned during this conversation, more to make us aware than anything else… He was still in the special care baby unit at this time, and one week later, I arrived at the unit and knew instantly that he had developed Hydrocephalus. His fontanelle was full and bulging, making his head appear cone-shaped. I had read a little about Hydrocephalus since it was mentioned last week and immediately recognized the signs (i).”

• High intracranial pressure

• Encephalitis, swelling of the brain tissue commonly due to infections

• Meningitis, an inflammation of the brain membranes

• Intracranial hemorrhage

• Head trauma

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• Hypoxic-ischemic injury due to deprivation of oxygen to the brain

• Congenital hypothyroidism

• Tumors
• Certain genetic syndromes

You may seek medical care to identify and begin treatment of causes since brain anomalies may lead to severe complications.

Be watchful

Several metabolic, hematologic, and cardiovascular disorders can cause bulging fontanelles in newborns (2).

When To See A Doctor?

Prompt medical care is required if your baby has bulging fontanelle. Symptoms such as fever, changes in appetite, persistent vomiting, irritability, and drowsiness, along with the bulging and enlargement of soft spots, may indicate a problem and require emergency care.

Contact the doctor if the fontanelle is protruding, even if the baby remains calm and has no other symptoms.

Diagnosis Of Bulging Fontanelle

Medical history and physical examination may help to identify raised or expanded bulging fontanelle and its causes.

The following tests may be done (3).

• Lumbar puncture or spinal tap

• Blood tests

• CT scan of the head

• MRI scan of the head

Things to know

The physical examination of the fontanelles should be done when the baby is calm and is being supported in supine and upright positions (2).

Image: Shutterstock

Treatment For Bulging Fontanelle

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The treatment options may vary according to the cause and may include the following.

• Brain infections are treated with antibiotics or antivirals, depending on the etiologic agents.

• Surgical procedures may be performed to create shunts to drain excess fluid in case of hydrocephalus in babies

• Surgical removal of tumors is done if present

• Thyroid hormone replacement therapy could help infants with thyroid abnormalities

• Intracranial pressure is managed with medications if present

Regular pediatric check-ups are crucial for tracking an infant’s development and assessing fontanelles. Create a safe environment during your baby’s growth phase to prevent incidents that could lead to head trauma. Stay alert for signs that require immediate medical attention to catch potential issues early and avoid complications.

Infographic: Bulging Fontanelle And Its Causes

Bulging fontanelle may require prompt medical treatment but it is helpful to know its causes. Check this infographic to have a glance at the condition and its causes.

Illustration: Momjunction Design Team

View this incredible video of a cute baby with an extremely bulging fontanelle to understand the significance of this condition and the subsequent procedures to be followed.

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Dr. Pooja ParikhMBBS, DCH, DNB

Dr. Pooja Parikh is a pediatrician with 11 years of experience in the field. Her medical journey has taken her from Rajkot (PDUMC) to Vadodara (SSGH) to Mumbai (Hinduja & Breach Candy Hospital). Currently, she is actively involved in critical, intensive, and general care of 0 to 18-year-olds in the port town of Gandhidham, where she was born and brought up.

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