Causes of bulging anterior fontanelle

Fontanelles - bulging Information | Mount Sinai

Soft spot - bulging; Bulging fontanelles

A bulging fontanelle is an outward curving of an infant's soft spot (fontanelle).

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.

A tense or bulging fontanelle occurs when fluid accumulates in the skull cavity or when pressure increases in the brain. Common causes are hydrocephalus or increased intracranial pressure due to illness.

Considerations

The skull is made up of many bones, 8 in the skull itself and 14 in the face area. They join together to form a solid, bony cavity that protects and supports the brain. 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 change shape to help it pass through the birth canal. The sutures get minerals added to them over time and harden, firmly joining the skull bones together.

In an infant, the space where 2 sutures join forms a membrane-covered "soft spot" called a fontanelle (fontanel). The fontanelles allow for growth of the brain and skull during an infant's first year.

There are normally several fontanelles on a newborn's skull. They are located mainly at the top, back, and sides of the head. Like the sutures, fontanelles harden over time and become closed, solid bony areas.

• The fontanelle in the back of the head (posterior fontanelle) most often closes by the time an infant is 1 to 2 months old.
• The fontanelle at the top of the head (anterior fontanelle) most often closes between 7 to 19 months.

The fontanelles should feel firm and very slightly curved inward to the touch. A tense or bulging fontanelle occurs when fluid builds up in the brain or the brain swells, causing increased pressure inside the skull.

When the infant is crying, lying down, or vomiting, the fontanelles may look like they are bulging. However, they should return to normal when the infant is in a calm, head-up position.

Causes

Reasons a child may have bulging fontanelles include:

• Encephalitis. Swelling (inflammation) of the brain, most often due to infections.
• Hydrocephalus. A buildup of fluid inside the skull.
• Increased intracranial pressure.
• Meningitis. Infection of the membranes covering the brain.

Home Care

If the fontanelle returns to normal appearance when the child is calm and head-up, it is not a truly bulging fontanelle.

When to Contact a Medical Professional

Immediate, emergency care is needed for any infant who has a truly bulging fontanelle, especially if it occurs along with fever or excess drowsiness.

What to Expect at Your Office Visit

The health care provider will perform a physical exam and ask questions about the child's medical history, such as:

• 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 present (such as fever, irritability, or lethargy)?

Diagnostic tests that may be done are:

• CT scan of the head
• MRI scan of the head
• Spinal tap (lumbar puncture)

Goyal NK. The newborn infant. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 113.

Rosenberg GA. Brain edema and disorders of cerebrospinal fluid circulation. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 88.

Somand DM, Meurer WJ. Central nervous system infections. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 99.

Last reviewed on: 2/2/2021

Reviewed by: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

Bulging Fontanels: Causes, Diagnosis, and Prevention

What is a bulging fontanel?

A fontanel, also called fontanelle, is more commonly known as a soft spot. When a baby’s born, they typically have several fontanels where bones of their skull haven’t fused yet. A newborn has fontanels on the top, back, and sides of their head.

Usually, only the anterior fontanel, which is on the top of the head toward the front, can be seen and felt. This is the one called the soft spot. In some babies, the posterior fontanel, which is found toward the back of the head, can also be felt, though it’s much smaller.

It’s important for new parents to understand what a fontanel looks and feels like. A baby’s soft spot should feel relatively soft and curve inward very slightly.

Changes in texture or appearance can be a sign of serious health issues. Parents should watch for soft spots that are curved outward on their baby’s head and feel very firm. This is known as a bulging fontanel and may be a sign of brain swelling or fluid buildup in the brain.

A bulging fontanel is an emergency. It can be a sign of pressure rising inside the skull which may result in damage to the baby’s developing brain. If your child is experiencing this symptom, seek medical attention immediately.

What are the causes of a bulging fontanel?

Some of the most common causes of a bulging fontanel are:

• encephalitis, which is a brain inflammation caused by a viral or bacterial infection
• hydrocephalus, which is excess brain fluid that’s present at birth or occurs from injury or infection
• meningitis, which is inflammation of the brain and spinal cord tissue that results from a viral or bacterial infection
• hypoxic-ischemic encephalopathy, which is brain swelling and damage that occurs when your baby’s brain is deprived of oxygen for a long period
• intracranial hemorrhaging, which is bleeding in the brain
• head trauma

Other Causes

A bulging fontanel may be attributed to additional conditions, along with numerous others, as possible causes:

• a brain tumor or abscess
• Lyme disease, which is a bacterial infection you get from an infected tick
• Addison’s disease, which is a condition in which your adrenal glands don’t make enough hormones for your body to function properly
• congestive heart failure, which is when blood and fluid buildup in parts of your body because your heart can’t pump enough blood
• leukemia, which is cancer of the white blood cells
• an electrolyte disturbance, which is when your blood’s levels of certain chemicals, such as sodium and potassium, are out of balance
• hyperthyroidism, which is when your thyroid makes more hormones than you need
• maple syrup urine disease, which occurs when your body can’t properly break down proteins
• anemia, which is a condition in which your blood doesn’t contain enough oxygen

In most cases of these conditions, a baby would have other symptoms in addition to a bulging fontanel and would most likely be sick.

Also, it would be very uncommon, if not rare, for any of these — except brain tumor or abscess — to cause a bulging fontanel, either because the condition is rare in infancy or because the condition happens in infancy, but rarely causes a bulging fontanel.

When should I seek medical care?

There are several factors that can make a soft spot appear to be bulging when in reality there’s no danger. Common things babies do such as lying down, vomiting, or crying can be mistaken for your baby having a bulging fontanel.

To determine whether your infant actually has a bulging fontanel, first try to calm them down, and then position them so their head is upright. If you succeed in doing this and the soft spot still appears to be bulging, seek medical attention for your child immediately.

Don’t wait to make a doctor’s appointment. Go to the nearest emergency room. This is especially crucial if your baby has a fever or seems extremely sleepy.

If you don’t already have a pediatrician, the Healthline FindCare tool can help you find one in your area.

What can happen if a bulging fontanel is not treated?

A bulging soft spot can be a sign of several very serious conditions that can even be life-threatening. For instance, encephalitis, a common cause of bulging fontanels, can lead to permanent brain damage or even death in severe cases.

What to expect at the hospital

Because there can be many explanations for these symptoms, your doctor will collect as much information as possible about your child’s condition.

Your doctor will perform a physical examination of your infant and will likely ask:

• about your baby’s medical history and any medications
• whether the bulge is constant or appears normal at times
• when you first noticed the abnormal appearance of the soft spot

Be sure to tell your doctor about any other symptoms you’ve observed, including:

• marked drowsiness
• an elevated temperature
• irritability beyond what’s normal for your child

Depending on the answers you provide and other symptoms that may be present, your doctor may order one or more tests, such as an MRI or CT scan, to make a diagnosis.

Lumbar puncture, or a spinal tap, may also be performed. This involves taking a sample of cerebrospinal fluid from your baby’s lower spine to check for disease and infection in their nervous system.

Treatment will depend on the underlying cause of your baby’s symptoms.

Is there any way to prevent a bulging fontanel?

There’s no definite way to prevent fontanels from bulging. This is mostly because the symptom has so many potential causes.

With available information, parents and other caregivers can better understand this symptom. For example, it can help them distinguish between a soft spot that temporarily appears to be bulging and one that’s protruding.

However, though information is available, it’s important for parents and other caregivers to contact their child’s doctor if they have questions or concerns about bulging fontanel.

Takeaway

A bulging fontanel is a medical emergency that requires a hospital visit. Once there, your doctor can determine the potential causes as well as appropriate treatment measures.

While a bulging fontanel has specific characteristics, call your child’s pediatrician if you have any doubts.

Six fontanelles of the baby. Why does the fontanel sink or bulge? The size of the fontanel by month. What to do if a child has a convex fontanel

A newborn has several areas on the head that are not covered by the bones of the skull. Is it dangerous?

Anatomy lesson - the skull and fontanelles of a newborn

The human skull is not a monolithic "construction", but a collection of several bones that are grouped into two sections: the brain - the skull - and the facial. The first consists of flat bones, the junctions of which are called sutures. In newborns, the skull is the same in number and composition of bones as in adults. But if in "large" the brain section is only twice as large as the front, then in babies it is eight times. And the seams are not yet formed. In places where several flat bones (three or more) "join", there are holes covered with a fibrous membrane - a dense and durable fibrous connective tissue. nine0005

These are fontanelles. They got their name due to the association with springs of water spouting from the ground: if you put your fingers on the fontanel, you can feel the pulsation of blood vessels. An infant has six fontanelles: anterior (or large), posterior, two mastoid and two wedge-shaped. Mastoid and wedge-shaped are located symmetrically on the sides of the cranium. They are very small and hard to spot. But the anterior and posterior, which are located on the midline of the skull, are easy to detect by stroking the baby on the head. nine0005

Gradually, the connective tissue ossifies, and the fontanelles "close". Small ones overgrow within a few weeks. The large, or anterior, fontanel lasts longer than the others. Its standard size at birth is approximately 30 x 30 mm. He finally disappears at about the age of one and a half years.

Why does a child need fontanelles on his head

From the point of view of physiology, fontanelles play a very important role - first of all, they help the baby to pass through the birth canal. If you look closely at the head of a newborn, you will notice that it is, as it were, slightly flattened on the sides. This is explained by the fact that the anterior and posterior fontanelles allowed the bones to go behind each other. Literally after 4-5 days, the baby's head acquires a normal shape. nine0005

The fontanelle is also involved in the process of thermoregulation of the body, which is extremely important in infancy. When the child's body temperature rises above 38 °C, the membrane of the large fontanel helps to remove excess heat from the meninges.

Size of the large fontanel by months

Parental fears are usually associated with the size and speed of closing of the main fontanel. There are average statistical norms, which are given in the table. However, they are not a dogma, everything happens individually. The mere fact of "deviation from the schedule" does not mean anything. nine0005

Dimensions of the large fontanel

Indeed, in some diseases, the fontanel behaves "unusually". But each of these diseases, which are very rare and are caused by genetic factors, has other symptoms that are more obvious and attract attention. Therefore, a mother should not try to independently make difficult diagnoses for her child, based solely on the state of the fontanel.

What to do if the fontanel is sunken or bulging

Worry is justified only in two situations. nine0116 Sunken fontanel. This indicates dehydration. You should try to restore the fluid balance with plenty of fluids and visit a pediatrician as soon as possible. In cases where dehydration occurs due to a disorder of the gastrointestinal tract - the child has diarrhea, vomiting - call an ambulance.

The fontanel protrudes from the cranium. Serious reason to see a doctor. A bulging fontanel, especially for a long time, can be a sign of serious diseases such as meningitis and encephalitis. nine0005

If you are worried about your child's fontanel, be sure to share your concerns with your pediatrician. Do not be afraid to seem suspicious - a mother feels the state of her child best of all. If all is well, the doctor will explain to you why the worries are in vain.

What determines the rate of overgrowth of the fontanel? Typical fears of parents

Fear No. 1. The skin in the place of the fontanelle can tear even from careless movement of the comb. And if the baby, God forbid, falls, then a serious injury is guaranteed. nine0005

Actually. You can absolutely calmly comb your child's hair, kiss him on the crown and crown, put on hats and cut his hair. Fibrous tissue has sufficient strength, because nature conceived it as a means of protecting the brain of a newborn. When falling, the fontanel is also "responsible for the safety" of the baby's head. It is thanks to the large open fontanel that the skull remains elastic to a certain extent and can absorb shock.

Fear No. 2. In order for everything to be fine, I must take special care of the fontanel, carefully monitor its condition and measure it regularly.

Actually. The fontanel does not require special care and control. During a scheduled examination, the doctor will definitely measure anthropometric parameters and examine the fontanel. If he notices something wrong, he will give appropriate recommendations. You may have to track the dynamics of fontanel closure yourself. The easiest way to do this is with an ordinary tracing paper and a soft felt-tip pen. Put the tracing paper on the baby's head and circle the edges of the fontanel with a felt-tip pen. Next to the received line, put the date. Several of these measurements will help the doctor identify abnormalities and prescribe therapy if necessary. nine0005

Fear No. 3. If the fontanelle quickly closes, this means that the growth of the skull bones has ended. This means that the brain no longer increases in size. The child is doomed to physical and mental disability.

Actually. The closure of the fontanel does not affect the development of the skull and brain. First of all, the sutures between the flat bones of the skull grow and lengthen. Don't get nervous for no particular reason.

Fear No. 4. His fontanel is too large, probably a sign of rickets. nine0005

Actually. The size of the fontanelle and the rate of its overgrowth do not directly indicate the presence of rickets. This disease has other very striking symptoms: sleep disturbance, irritability, poor appetite, sweating and itching. An accurate diagnosis can be made after a biochemical blood test.

Fear No. 5. The fontanel is very small, and the doctor prescribed vitamin D and calcium gluconate. Does this accelerate the overgrowth of the fontanel?

Actually. nine0004 Vitamin D is "responsible" for the regulation of calcium and phosphorus metabolism in the body, promotes the proper formation of bone tissue and teeth. Subject to the dosage and dosage regimen, the rate of overgrowth of the fontanel will not increase.