Pediatric Syndromic Craniosynostosis
Pediatric Syndromic Craniosynostosis
What is Pediatric Syndromic Craniosynostosis?
Patients with syndromic craniosynostosis have more complicated needs than those with isolated (non-syndromic) craniosynostosis. There are several reasons for this. The first is that these patients have globally impaired growth of the skull and facial bones that makes it harder to achieve a lasting correction of the appearance and maintain adequate space in the skull for the growing brain. A patient may need several operations during childhood to “catch up” to where they should be if their skulls and face were growing normally. Patients with these syndromes frequently have significant additional problems with breathing, hearing, speech and eating. They may also be born with deformed hands and feet which present additional functional and surgical challenges. Patients with so many complex problems require a team of specialists with expertise in each of the child’s problem areas and experience in caring for children with syndromic craniosynostosis.
These syndromes are usually genetic in nature. The problem may occur when a gene mutates, or may be genetically inherited. At a busy craniofacial center like ours, we see even the most rare syndromes, but on this webpage, we will cover only the more common craniosynostosis syndromes.
What are the types of Pediatric Syndromic Craniosynostosis?
Craniosynostosis syndromes are usually named after the person who first described it. There are at least 70 conditions that can cause syndromic craniosynostosis. The most common of syndromes include:
These may share some common features. For Crouzon, Apert and Pfeiffer syndromes the patient’s eyes may look abnormally large or prominent. The eyes are actually of a normal size, but the eye sockets are more shallow than normal because of abnormal growth of the bones. This causes the eyes to bulge and appear large, and when this is severe it can become difficult for the eyelids to close which can dry the eyes severely. These patients also have flatness in the middle of the face caused by poor growth of the upper jaw. The hands and feet may also have deformities.
The brain more than doubles in size in the first year of life, reaching two-thirds of its adult size by age 1. It continues to grow rapidly until age two years. After age two the brain grows more slowly and reaches adult size between 6 to 10 years of age. The growing brain is what drives skull growth. The growth causes bone production at the cranial sutures. The biggest concern with craniosynostosis in an infant is the potential for the skull to not grow fast enough to keep up with the rapidly growing brain. If the skull grows too slowly because one or more sutures are closed prematurely, it may result in raised pressure inside the skull that is harmful to the brain. This is called elevated intracranial pressure.
Increased Pressure in the Skull
The risk of increased pressure in the skull rises greatly with each closed cranial suture. This is because it makes the open sutures work much harder to make bone. Also, patients with syndromic craniosynostosis may have other problems related to the added pressure in the skull. They have a higher risk of:
- Problems in flow of blood from the brain back to the heart
- Problem in draining the fluid that surrounds the brain (hydrocephalus)
- Obstructed upper airways (for example, sleep apnea)
Waiting too long for surgery while elevated pressure is present can cause blindness and learning delays. This makes diagnosis and prevention of elevated pressure in the skull a priority in treating patients with craniosynostosis. It can be difficult to know if a child has high pressure in his or her skull. Signs may be subtle including low activity or alertness, as well as learning delays. This can be a challenge to diagnose in the very young child. The absolute best way to measure the pressure is to do so directly. This requires going into the hospital to put a pressure monitor through a small hole in the skull. Because this is invasive, we use this test only in cases where we are not sure if pressure is present in the skull and the treatment plan will change depending on the presence of elevated pressure.
How is Pediatric Syndromic Craniosynostosis treated?
What kind of surgery and when to do it depends on each patient’s needs. We perform a limited skull surgery to remove closed cranial sutures if skull pressure is high before 6 months of age. This allows the brain to grow without alleviate pressure and the skull bones to thicken so a definitive open cranial vault expansion can be performed.
Patients with syndromic craniosynostosis have a much greater risk for developing elevated pressure in the skull than non-syndromic craniosynostosis patients. These patients sometimes require an average of 3 or more skull surgeries. The major risk in young patients is blood loss because of their small size and small circulating blood volume. During most surgeries, these patients need blood transfusions.
At Children’s Health, we typically treat syndromic craniosynostosis patients with their first surgery between 6 months and 1 year of age. We operate earlier if there are multiple sutures causing elevated pressure on the brain.
Cranial vault remodeling
The goal of early surgery is to protect the brain, and to protect the airway and the eyes. Usually, the first surgery is to reshape the skull and to increase the space inside to give the brain room to grow into. Open cranial vault procedures require the removal of the skull bones from the outer covering of the brain (dura). This allows the bones to be reshaped and repositioned. The main goal of cranial vault remodeling is to over-correct the skull to treat or to reduce the risk of developing increased pressure in the skull. This allows the brain to grow and improves head shape. While the ultimate goal is to normalize the head shape and overall appearance, these patients have permanent impairments in growth of the skull and facial bones. So even if we overcorrect the position of the skull bones the patients will often outgrow the repair and require another skull expansion. The amount of overcorrection we can achieve is limited by the amount that the scalp will allow.
Cranio vault distraction
The limitations of the scalp in over expanding the skull can be overcome using cranial vault distraction procedures. Distraction osteogenesis is a process where new bone is generated between cut bone edges through the use of a special device (distractor) that slowly moves the bone edges away from one another. This process also stretches the scalp as the bones are moved. Distraction procedures are better for global changes in the size and shape of the skull. While distraction can not be used in all cases, when applicable it can produce more than twice the expansion and change of head shape produced with open cranial vault procedures. It is most commonly used for expansion of the back of the skull, or the forehead together with the middle portion of the face (monobloc). At our institution this is usually the first surgery we perform in patients with syndromic craniosynostosis.
Fronto-orbital advancement (FOA)
This is one of the longest standing procedures used to treat craniosynostosis. This surgery is used to correct the position of the forehead and upper portion of the eye sockets. The longer that we safely can wait to perform the fronto-orbital advancement, the better the chance of the patient having better skull growth and a normal appearance. For this reason, we will perform a posterior cranial distraction as a first procedure and wait for the skull to be close to fully grown before performing the FOA. Sometimes the patient’s eye sockets may be so shallow that the eyelids cannot close enough to protect the eye. If this is not corrected early the patient can have permanent scarring to the eye. If the risk for sight loss is very high, we will either partially close the eyelids with suturing techniques (tarsorrhaphy) or perform a fronto-orbital advancement as out first cranial vault procedure to put the eyelids in a better position to protect the eyes.