Craniosynostosis

All infants are born with a portion of their skull still soft, allowing the brain to expand and grow until the segments of the skull join and become fused together and hardened. When the joints of the skull meet and harden too early in cases of craniosynostosis, the continuing growth of the brain will alter the shape of the head and face and cause deformities. The pressure inside the skull can then press upon the brain, leading to a number of problems including: vision problems, difficulty eating, developmental delays and intellectual disability, and sleep problems.

Definition & Facts

Craniosystonosis is a medical term derived from Greek origins that refers to a condition in which the bones (-ostosis) of the skull (cranio-) join together (-syn) and fuse too early. Craniosynostosis occurs in approximately one out of every 2,000 to 2,500 births globally. Doctors classify craniosynostosis with different categories based on which skull sections are prematurely fused and the resulting deformities of the child's head.

Symptoms & Complaints

• Headaches
• Vomiting
• An increase of intracranial pressure
• Bulging eyes
• Developmental delays (mental)
• Wide-set eyes
• Facial asymmetry
• Beaked nose
• Flat face
• Fused or webbed fingers and/or toes
• Very long, thin fingers
• Hearing problems
• Sleep apnea
• A cleft palate or split uvula

Causes

Most incidences of craniosynostosis are classified as non-syndromic in which the craniosynostosis occurs in isolation. Currently, it has not been established what exactly causes nonsyndromic craniosynostosis. Recent research in the fields of genetics and studies on animals have identified that changes in the dura mater (the thick material that encases the brain) may be responsible for triggering craniosynostosis.

There are also indications that various environmental factors, like the mother smoking during pregnancy, exposure to valproic acid, and medications that contain amine may play a role in increasing the risk of giving birth to a child with craniosynostosis.

In addition to nonsyndromic craniosynostosis, there are over 70 genetic disorders that cause syndromic cases of craniosynostosis. These disorders include Apert syndrome, Crouzon syndrome, and Pfeiffer syndrome. Carpenter syndrome and Baller-Gerold are additional conditions associated with craniosynostosis. The latter involves mental retardation. In cases of syndromic craniosynostosis, skull deformities exist alongside other issues, including deformities of the hands and feet, heart problems, and dental abnormalities.

Genetic mutations cause these cases of syndromic craniosynostosis. Mutations have been discovered in the fibroblast growth factor receptor genes among those with craniosynostosis, and mutations in the interleukin 11 receptor alpha subunit have also been linked to craniosynostosis.

Diagnosis & Tests

Currently, cases of craniosynostosis are identified by medical professionals through a physical examination of the child. As the condition is caused by one or more instances of premature fusion of the skull, the presence of craniosynostosis is usually self-evident when conducting an external exam. Further diagnostic information can be gained by performing an X-ray.

Some researchers have conducted MRI scans on pregnant mothers in order to identify if craniosynostosis has occurred, but some studies have suggested that the magnetic fields produced by such a scan may contribute to the development of the condition.

As a number of other conditions can result in increased intracranial pressure and mimic the symptoms of craniosynostosis, pediatricians may attempt to rule out other disorders and conditions such as plagiocephaly (flat head syndrome) and microcephaly (the child is born with a head that is smaller than normal).

The pediatrician may also test for a number of rare conditions like Apert syndrome, Crouzonodermoskeletal syndrome, Crouzon syndrome, Jackson-Weiss syndrome, Loeys-Dietz syndrome, Muenke syndrome, Pfeiffer syndrome, Saethe-Chotzen syndrome, and Shprintzen-Goldberg syndrome, as these may be the primary cause for the child developing craniosynostosis.

Treatment & Therapy

Treatment for this condition is almost always surgical intervention in order to allow the brain to expand and grow normally. When possible, the surgeon will undo the premature suture in order to allow the skull to expand. If necessary, surgery will be performed to reshape the skull in order to correct any deformities. If the skull bones are still soft enough to be shaped, the surgeon will effectively fracture (break) the bone and then allow it to heal naturally.

Other surgical techniques for treating craniosynostosis involve separating the prematurely fused sections and then using a special bony filler to plug any gaps once the rest of the skull has naturally hardened (around 1 year of age).

The prevailing consensus amongst pediatric surgeons today is that the ideal time to perform corrective surgery is when the child is between 6 and 12 months old, although successful corrective surgeries have been performed on teenagers. Surgeries on children younger than 6 months old are generally not recommended due to risks of bleeding.

Prevention & Prophylaxis

Genetic testing of the parents can identify additional risk factors. Autosomal recessive disorders are linked to craniosynostosis, while autosomal dominant disorders are the most common indicators of craniosynostosis. In the latter case, there is a 50% chance of the child inheriting craniosynostosis syndromes if one parent has the condition, though many cases of craniosynostosis are completely sporadic and have no known association with genetic mutations.