Craniosynostosis: Mayo's individualized approach
Craniosynostosis is a common congenital condition, occurring in 1 in 2,500 births. Most of these cases involve the fusion of a single skull suture. Complex or syndromic craniosynostosis involves the fusion of multiple sutures. Although neurological damage can occur in severe cases, most children can have normal cognitive development and achieve good cosmetic results after surgery. Early diagnosis and treatment are key.
At Mayo Clinic in Rochester, Minn., specialists in the Cleft and Craniofacial Clinic treat craniosynostosis ranging from severe syndromes to simple fusions. Every child treated for craniosynostosis is seen by a pediatric neurosurgeon, plastic surgeon and medical geneticist. For patients with syndromic craniosynostosis, oral surgeons, otorhinolaryngologic surgeons, orthodontists, speech pathologists, social workers and psychologists may be consulted.
"We have a very large and comprehensive craniofacial team," says Nicholas M. Wetjen, M.D., a pediatric neurosurgeon at Mayo in Minnesota. "Not every patient needs all parts of the clinic, but all parts are available."
Advantages of early referral
Most of the cases seen at Mayo are sagittal craniosynostosis, the most prevalent type. Patients are generally referred by pediatricians after a well-child visit. Although there is no upper age limit for referral, the optimal time is between 1 and 2 months of age. Up to age 6 months, patients with all types of single-suture craniosynostosis — sagittal, metopic, coronal and lambdoid — may be candidates for endoscopic surgery. After that, however, open surgery is generally required.
"Early diagnosis and treatment facilitate the brain's normal growth and reshaping of the head into the appropriate configuration," Dr. Wetjen says. "With referral we also can offer the option of endoscopic surgery and make sure patients are receiving care tailored to their needs."
Both endoscopic and open procedures generally produce very good cosmetic results with low risk of complications. However, compared with an open procedure, endoscopic surgery has a lower rate of complications, requires only a one-night hospital stay and has a patient-transfusion rate of just 10 percent. After endoscopic surgery, children must wear a series of two to three helmets for up to a year. "Each helmet has a significant cost, but the overall cost of endoscopic surgery is still less than open surgery," Dr. Wetjen notes.
Open surgery lasts two to three hours and requires a three- or four-day hospital stay. Transfusion also is necessary in all open cases, although no helmet is required afterward. "In open surgery, we fix the skull in position with plates and screws that are absorbable. It's a one-time procedure that requires less follow-up than endoscopic surgery," Dr. Wetjen says.
For parents whose children qualify for either endoscopic or open surgery, Mayo specialists outline the pros and cons and let the parents decide. "We try to present a balanced view because when the patient presents at a young age, either endoscopic or open surgery can be appropriate," Dr. Wetjen says.
Virtual surgical planning
Mayo is one of the few centers in the world that offers virtual surgical planning for treatment of craniosynostosis. In virtual surgical planning, high-definition 3-D CT scans of the patient's skull are sent to a device manufacturer. Engineers at the company consult via Web conference with Dr. Wetjen and Samir Mardini, M.D., a plastic surgeon in Mayo's Cleft and Craniofacial Clinic.
During the meeting the CT data are used to construct a computer-simulated, individualized surgical plan. Based on that virtual surgical plan, patient-specific templates are constructed to guide the Mayo surgeons during the procedure. "In the past, there has been a standard surgical procedure for sagittal craniosynostosis. These templates allow us to customize the procedure to the individual patient, with a high degree of detail," Dr. Wetjen says.
Complex or syndromic craniosynostosis
Only 6 percent of craniosynostosis cases involve multiple sutures or are related to a hereditary syndrome. As a major pediatric neurology center, Mayo has experience with these complex and syndromic cases. Multiple surgeries are often required to correct the patient's head shape.
Treatment for complex or syndromic craniosynostosis often involves the use of a distractor — a device placed in the skull for a period of three to four months. The distractor is widened a millimeter a day to separate the skull bones. Over time, new bone grows across the gap. Cosmetic results are generally very good.
Considerable progress has been made in understanding the genetic causes of syndromic craniosynostosis. But the etiology of about 85 percent of nonsyndromic cases remains unknown. Mayo researchers are analyzing bone removed during craniosynostosis surgery in a genome-wide search for novel genes for the condition.
In a study published in the Feb. 22, 2013, issue of The Journal of Biological Chemistry, Mayo researchers showed that the molecular and functional interplay between the RUNX2 and AXIN2 genes controls the rate of cranial suture closure in laboratory animals. The research identifies a key mechanistic pathway for regulating bone development within the skull and thus suggests a potential means of preventing premature cranial suture closure. Other research at Mayo involves the use of MRI rather than CT scan for diagnosis and treatment of craniosynostosis, strategies for minimizing blood transfusion during surgery, and the use of magnetic resonance elastography as a noninvasive way to measure intracranial pressure.
Dr. Wetjen stresses that the risk of intracranial pressure from simple craniosynostosis is small. "As long as the suture and head shape are fixed, the child's IQ is likely to end up being just like any other child's," he says. As Dr. Wetjen sometimes tells parents, "You can have craniosynostosis and grow up to be a brain surgeon."
For more information
Mardini S, et al. Three-dimensional preoperative virtual planning and template use for surgical correction of craniosynostosis. Journal of Plastic, Reconstructive and Aesthetic Surgery. 2014;67:336.
McGee-Lawrence ME, et al. Runx2 protein represses Axin2 expression in osteoblasts and is required for craniosynostosis in Axin2-deficient mice. The Journal of Biological Chemistry. 2013;288:5291.
Feb. 28, 2014