What is Craniosynostosis?
Craniosynostosis (kray-nee-o-sin-os-TOE-sis) is a condition in which one or more of the joints between the bones of your baby’s skull close prematurely. The skull consists of seven bones that are separated by joints, which are called sutures. As the infant grows these bones expand to accomodate normal brain development. Premature closure of the sutures can potentially cause problems with brain and skull growth and cause the head shape to become asymmetrical in appearance. There are different types of craniosynostosis depending on which suture is involved, and each type yields a distinctive head shape.
Signs of Craniosynostosis
- Abnormal skull shape
- Slow head growth (This is one of the reasons that pediatricians routinely measure head circumference at well-child visits.)
- Palpable, hard ridge along one of the sutures
- Increased pressure within the skull (intra-cranial pressure), child may complain of headaches
It is important for parents and physicians to keep in mind that this condition exists on a spectrum in which the findings at times can be subtle and other times obvious. Also, as the skull continues to grow, the effect of the craniosynostosis may increase over time. For this reason an early evaluation by an experienced craniofacial surgeon is important. A misshapen skull does not necessarily mean that craniosynostosis exists and could be the result of prolonged pressure on one part of the skull.
Etiology of craniosynostosis
It occurs in approximately 1 in 5,000 live births, and is categorized into nonsyndromic or syndromic, depending on whether the condition occurs in the context of additional findings. The exact cause of nonsyndromic craniosynostosis is generally unknown, and recent research points to various factors. Syndromic craniosynostosis, such as Aperts or Crouzons, is largely genetic in origin and occurs when a baby inherits a gene from a parent or has a fresh mutation in a specific gene.
How is craniosynostosis diagnosed?
If parents are concerned about their child’s abnormal head shape, they should contact their pediatrician for a referral or make an appointment with a craniofacial surgeon. The diagnosis is made by a thorough physical exam and confirmed by diagnostic testing. Diagnostic tests for craniosynostosis may include one or two of the following:
- Skull x-rays of the head – a diagnostic test that produces images of bones of the head
- CT Scan of the head- an imaging study that shows images of the bones and the structures of the brain. CT scans are more detailed than skull x-rays.
- MRI of the head- a procedure used to get details about the structures within the brain
Types of Craniosynostosis
Metopic synostosis (Trigonocephaly)
The metopic suture extends from the central upper forehead toward the nose. When it fuses prematurely, the head shape will appear to be pointed in the front and the eyes appear closer together. There will be a ridge in the middle of the forehead.
Metopic synostosis is less common than sagittal and coronal synostosis but is frequently managed by experienced craniofacial surgeons.
Sagittal synostosis (Scaphocephaly)
The sagittal suture extends from the back of the head to the top of the head. When premature fusion occurs, the head shape will be narrow and longer than normal.
The sagittal suture is the most common single suture involved in craniosynostosis.
The incidence of sagittal synostosis in the population is approximately 1 in 4,200 births. Males are affected about three times as often as females.
Treatments for Craniosynostosis
Regardless of the type of craniosynostosis, varying degrees of severity exist. Some cases are mild and only entail a ridge along the skull that can be felt through the skin. These can be managed with serial exams to ensure normal neurological development and overall skull growth. In other cases, if a child’s skull has begun to grow abnormally or pressure on the brain exists, the child will often require surgical treatment. The key to a good outcome is to remove the fused suture and to reshape any abnormally-shaped bone. This allows for correction of the deformity and provides expansion of the skull to relieve any excess pressure on the brain. The new shape of the bone is held in place by absorbable plates and screws. These will dissolve into the bone after 9-12 months.
Timing of Surgery
Surgery is often performed in the first 3-24 months of life. Optimal timing depends on which sutures are involved and on the degree of severity. Surgery usually consists of a single operation, though occasionally a staged, two-operation approach is required for specific forms of craniosynostosis. We will discuss these factors in depth on a case-by-case basis, depending on your child’s specific situation.
A newer procedure called strip craniectomy for sagittal suture fusion can be done at an early age starting at 3-4 months. This can eliminate the need for a second operation with less time in the operating room and an earlier discharge. We release the fused suture through a smaller insicion on the head. Then, a postoperative helmet is applied within 10 days of surgery to help mold and reshape the head. It is worn for up to 3 months.