Craniosynostosis refers to a skull deformity associated with the premature closure of one or more cranial sutures. An infant skull is comprised of multiple flat bones separated by non-boney sutures. Growth of these bones occurs at these sutures in response to outward pressure created by the developing brain. This growth is most rapid during the first year of life. Craniosynostosis can occur isolated or as part of a syndrome.
Non-syndromic synostosis affects approximately 1 in 2000 children born in the United States. Because brain growth occurs most rapidly at a very young age, early correction is critical to provide adequate room for this growth to occur. There are different types of craniosynostosis which occur depending on which suture or sutures are involved. Definitive surgical treatment varies based on the specific abnormality of each patient. The following are the most common types of craniosynostosis and their associated shape description in parentheses):
- Sagittal synostosis (scaphocephaly)
- Metopic synostosis (trigonocephaly)
- Unilateral coronal synostosis (anterior plagiocephaly)
- Lambdoid synostosis (posterior plagiocephaly)
- Bilateral coronal synostosis (brachycephaly)
This group of syndromes consists of genetic disorders that include most commonly sporadic and autosomal dominant modes of inheritance. Several genes have been implicated but the most common include the fibroblast growth factor receptor and TWIST genes. These patients often have more than one suture involved or multi-suture synostosis. They can also develop late-presenting or “progressive” synostosis. Carpenter syndrome is the most rare and the only one that is autosomal recessive. These syndromes are very rare and result in a wide range of characteristics.
- Apert: 1 in 100,000 live births. midface hypoplasia and syndactyly
- Crouzon: 1-2/100,000 live births. Midface hypoplasi, no syndactyly or hand abnormalities.
- Pfeiffer: 1 in 100,000. Midface hypoplasia, broad thumbs or great toes. A spectrum of severity.
- Saethre-Chotzen: 1 in 100,000. Short forehead, beaked nose, ptosis, incomplete syndactyly.
- Carpenter’s: <1 in 100,000. polydactyly/extra fingers and toes.