In craniosynostosis syndromes, one or more bones of the skull and face fuse prematurely during fetal development. The skull is composed of multiple bones separated by sutures, or openings. If any of these close too early, the skull will expand in the direction of the open sutures, resulting in an abnormal head shape.
Premature closure of a single suture can be caused by space constraints in the womb, and is seen more often in twins than in a single fetus. Single suture closure usually isn't associated with a syndrome. Premature closure of multiple sutures, however, is often seen in children with a craniosynostosis syndrome.
The most common craniosynostosis syndromes are Crouzon, Pfeiffer and Apert. Pfeiffer syndrome is the most common of the three, affecting about one out of every 25,000 births, and its severity varies. Crouzon syndrome occurs in about one out of every 100,000 births, and its severity also varies considerably. Apert syndrome is less variable from case to case than either Crouzon of Pfeiffer syndrome, and is found in about one out of every 100,000 births.
Children with Apert, Crouzon or Pfeiffer syndrome usually have premature fusion of at least the coronal suture, which extends across the top of the skull, but other sutures may also close. These conditions are caused by genetic mutations in one of the genes known as fibroblast growth factor receptor (FGFR) genes. They are autosomal dominant conditions, meaning a parent with the syndrome has a 50 percent chance of passing it on to each child.
In children with a craniosynostosis syndrome, the fused bones in the skull result in abnormal head shapes. Bones in the face may also be fused together, resulting in a flat midface and protruding eyes. Children with Apert syndrome also have syndactyly, or webbing, of the hands and feet.
A baby with single suture synostosis that's not part of a syndrome usually doesn't have any functional problems, such as difficulty breathing or feeding. Surgical release of the closed suture may be necessary, and if so, would usually be done during the first year of life.
An infant with a craniosynostosis syndrome should be seen immediately after birth by a nurse from the Center for Craniofacial Anomalies to make sure the infant can adequately breathe and feed. Shortly after being discharged from the hospital, the child should be seen for a full team evaluation at the center. The skull abnormalities require early attention, although the timing varies. A surgical procedure to advance the forehead is usually done before the baby is 6 months old.
Reviewed by health care specialists at UCSF Benioff Children's Hospital.
Last updated
June 17, 2010
Craniofacial Anomalies Center
513 Parnassus Avenue, S-747
San Francisco, CA 94143-0570
Phone: (415) 476-2271
Fax: (415) 476-9513
Appointment information