Surgeons and centers vary widely on surgical approaches for sagittal craniosynostosis, including some who consider minimally invasive options like strip craniectomy inferior to open cranial vault remodeling.
A retrospective study evaluated outcomes of three minimally invasive techniques and found that all three achieved a satisfactory head shape, defined as a cranial index score of 75 or above, at 3 to 5 years after surgery. The technique with the highest median score was wide-strip craniectomy with subsequent helmet therapy at 79.4.
This is the first study to evaluate head-shape changes over an extended time period, as well as the first to use 3D morphometrics to measure those changes. Investigators at Children’s HealthSM led the study in collaboration with two other centers, using custom imaging solutions developed at the Analytical Imaging and Modeling (AIM) Center at Children’s Medical Center Dallas.
“The data shows that minimally invasive surgery for sagittal craniosynostosis is a viable path to a clinically normal head shape. Surgeons can perform any of these three procedures with confidence,” says Alex Kane, M.D., Plastic and Craniofacial Surgeon at Children’s Health and Professor at UT Southwestern who co-led the study.
Centers practice different techniques for different reasons
The three techniques included in the study were:
Spring-assisted cranioplasty
Narrow-strip craniectomy followed by helmet therapy
Wide-strip craniectomy followed by helmet therapy
Surgeons who opt for a minimally invasive approach often prefer one technique over others, based on personal familiarity and assessment of trade-offs. For example, spring-assisted cranioplasty requires an additional procedure to remove the springs. Strip procedures do not, but they do require the patient to wear an orthotic helmet for a year or so afterward. Wide-strip craniectomy removes more bone than narrow-strip, which some believe takes longer to heal and increases the risk of complications.
Each center in the study practiced a different technique, with roughly 50-90 patients in each cohort. Patients at Children’s Health received wide-strip craniectomy.
“Part of our motivation for this study was to challenge our own practice. Should we change techniques?” says Paymon Sanati-Mehrizy, M.D., Craniofacial Surgeon at Children’s Health and Assistant Professor of Plastic Surgery at UT Southwestern.
All 3 methods reliably achieve typical range
Cranial index, the standard measurement for head-shape analysis, served as the study’s endpoint. It’s a simple calculation based on length and width, with typical range defined as 75 to 90.
All three techniques fell within that range:
Spring-assisted: 75.9 (73.1 to 78.6)
Narrow-strip: 75.9 (75.4 to 78.5)
Wide-strip: 79.4 (76.4 to 81.9)
“Wide-strip, the technique we use in Dallas, resulted in the best cranial index without any evidence of impaired bone reformation,” Dr. Sanati-Mehrizy says.
Overall, the findings align withpublished outcomes of open cranial vault expansion, which reliably achieve clinically normal head shape within 2 years.
3D analysis enables more detailed forecasting
The use of 3D modeling enabled the investigators to evaluate other features, as well. Rami Hallac, Ph.D., Imaging Scientist and Director of the AIM Center at Children's Health and Associate Professor at UT Southwestern, used thousands of data points from 3D photographs to create digital versions of every patient’s head. Custom 3D image-processing pipelines then compared the images and created a composite example for each of the three surgical techniques.
“We also created heat maps that compare each composite head shape with age-matched control patients and highlight the deviations,” says Dr. Hallac.
This analysis revealed that patients receiving wide-strip procedures showed the greatest correction in occipital bulleting (rounding in the back of the head), while spring-assisted cranioplasty showed improvement in frontal bossing (forehead bulging) and skull height.
Findings like these may not be enough to sway surgeons toward or away from individual techniques. But they do give surgeons more detailed information for setting expectations with patients.
“In the past, surgeons would try to describe to families what to expect based on the outcomes of their previous patients. Now, with the generation of composite heat maps based on robust data, we have a visual tool that can give families a much clearer picture,” says Dr. Sanati-Mehrizy.
Why Children’s Health: Continuous pursuit of better approaches and outcomes
The team also conducted a related study evaluating how barrel-stave osteotomies of different lengths affect outcomes for strip-craniectomy patients. Surgeons often remove small, medium or large staves from the side of the patient’s head during strip procedures to enable greater flexibility for the skull to reform. But no one had ever studied how the amount of resected bone influenced the final head shape.
“We found the size of the barrel stave didn’t seem to matter clinically. All sizes had a similar effect,” says Dr. Sanati-Mehrizy.
A randomized prospective study, currently enrolling patients, will investigate the question further and help the team determine which barrel stave size is ideal – and whether they’re necessary at all.
“We’re constantly working to improve our techniques. We get our kids to an excellent outcome, but we can always improve,” Dr. Sanati-Mehrizy says.
Learn more about pediatric craniofacial surgery at Children's Health.
