Craniometric and Volumetric Analyses of Cranial Base and Cranial Vault Differences in Patients With Nonsyndromic Single-Suture Sagittal Craniosynostosis

Determination of Novel, Cranium-Based Relationships for Construct Placement in Microtia Reconstruction for Hemifacial Microsomia Patients

OBJECTIVE

Determine if the ideal location of the construct in microtia reconstruction for hemifacial microsomia (HFM) can be more accurately derived from measurements on the cranium.

DESIGN

High-resolution computerized tomography (CT) images were analyzed through craniometric linear relationships.

SETTING

Our tertiary care institution from 2000 to 2021.

PATIENTS/PARTICIPANTS

Patients diagnosed with HFM and microtia, who had high-resolution craniofacial CT scans, yielding 36 patients accounting for 44 CT scans.

MAIN OUTCOME MEASURE(S)

First, the integrity of the posterior cranial vault among HFM patients was determined. If proven to be unaffected, it could be used as a reference in the placement of the construct. Second, the position of the ear in relation to the cranium was assessed in healthy age-matched controls. Third, if proven to be useful, the concordance of these cranium-based relationships could be validated among our HFM cohort.

RESULTS

The posterior cranial vault is unaffected in HFM (P > .001). Further, craniometric relationships between the tragus and the Foramen Magnum, as well as between the tragus and the posterior cranium, have been shown to be highly similar and equally precise in predicting tragus position in healthy controls (P > .001). These relationships held true across all age groups (P > .001), and importantly among HFM patients, where the mean absolute difference in predicted tragus position never surpassed 1.5 mm.

CONCLUSIONS

Relationships between the tragus and the cranium may be used as an alternative to distorted facial anatomy or surgeon's experience to assist in pre-operative planning of construct placement in microtia reconstruction for HFM patients.

A New Measure of Posterior Morphology in Sagittal Craniosynostosis: The Occipital Bullet Index

INTRODUCTION

Sagittal craniosynostosis (SC) is associated with scaphocephaly, an elongated narrow head shape. Assessment of regional severity in the scaphocephalic head is limited by the use of serial computed tomographic (CT) imaging or complex computer programing. Three-dimensional measurements of cranial surface morphology provide a radiation-free alternative for assessing cranial shape. This study describes the creation of an occipital bulleting index (OBI), a novel tool using surface morphology to assess the regional severity in patients with SC.

METHODS

Surface imaging from CT scans or 3D photographs of 360 individuals with SC and 221 normocephalic individuals were compared to identify differences in morphology. Cartesian grids were created on each individual's surface mesh using equidistant axial and sagittal planes. Area under the curve (AUC) analyses were performed to identify trends in regional morphology and create measures capturing population differences.

RESULTS

The largest differences were located in the medial regions posteriorly. Using these population trends, a measure was created to maximize AUC. The OBI has an AUC of 0.72 with a sensitivity of 74% and a specificity of 61%. When the frontal bossing index is applied in tandem, the two have a sensitivity of 94.7% and a specificity of 93.1%. Correlation between the two scores in individuals with SC was found to be negligible with an intraclass correlation coefficient of 0.018. Severity was found to be independent of age under 24 months, sex, and imaging modality.

CONCLUSIONS

This index creates a tool for differentiating control head shapes from those with SC and has the potential to allow for objective evaluation of the regional severity, outcomes of different surgical techniques, and tracking shape changes in individuals over time, without the need for radiation.

Spring forces and calvarial thickness predict cephalic index changes following spring-mediated cranioplasty for sagittal craniosynostosis

BACKGROUND

Variables interacting to predict outcomes following spring-mediated cranioplasty (SMC) for non-syndromic craniosynostosis, including spring parameters and calvarial thickness, are poorly understood. This study assessed interactions between spring parameters and calvarial thickness to predict changes in cephalic index (CI) following SMC.

METHODS

Patients undergoing SMC for non-syndromic sagittal craniosynostosis at our institution between 2014 and 2021 were included. Calvarial thickness was determined from patient preoperative CTs using Materalise Mimics at 27 points in relation to the sagittal suture. Linear mixed effects models were used to determine interactions between anterior, middle, and posterior calvarial thickness with spring force and length.

RESULTS

Sixty-nine patients undergoing surgery at mean age 3.7 months were included in this study. Stronger posterior spring force interacted with thinner posterior calvarial thickness to predict greater changes in CI at 3 months postoperatively (p = 0.022). When evaluating spring force and calvarial thickness set distances from the sagittal suture, stronger posterior spring force interacted with thinner posterior calvarial thickness 5 mm (p = 0.043) and 10 mm (p = 0.036) from the sagittal suture to predict changes in CI. Interactions between spring parameters and calvarial thickness in the anterior and middle positions did not significantly predict changes in CI.

CONCLUSIONS

Stronger posterior spring force interacted with thinner posterior calvaria to predict greater changes in CI 3 months following SMC for non-syndromic sagittal craniosynostosis. These results suggest dynamic interactions between several variables may impact outcomes following SMC.

Morphologic Differences in Sagittal Synostosis with Age before Surgery

BACKGROUND

It is important to determine whether sagittal synostosis-associated scaphocephaly is static in the presurgical period, or whether there are morphologic differences with time to include in surgical decision-making. The authors' purpose was to perform cross-sectional analysis of cranial morphology before any surgical intervention in children with sagittal synostosis younger than 9 months compared to matched controls.

METHODS

The authors performed morphometric analysis on computed tomographic scans from 111 untreated isolated sagittal synostosis patients younger than 9 months and 37 age-matched normal controls. The authors divided the patients into three age groups and performed statistical comparison between sagittal synostosis and controls for each group.

RESULTS

Sagittal synostosis cephalic indices were stable and lower in patients than in controls across groups. Total cranial volume was equivalent, but sagittal synostosis patients had a greater posterior volume than controls at all ages and a smaller middle fossa volume at older ages. Pterional width was greater in sagittal synostosis patients than in controls for each age group. Frontal bossing vectors were most severe in the youngest age groups and least in the older group. Occipital protuberance was consistent across the age groups.

CONCLUSIONS

Upper parietal narrowing and occipital protuberance were the consistent deformities across age groups, with the most parietal constriction seen in older patients. Frontal bossing was not consistent and was more severe in the younger patients. The authors did not detect significant pterional constriction, and the appearance of constriction is relative to adjacent morphology and not absolute.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Machine Learning-Driven Clinical Image Analysis to Identify Craniosynostosis: A Pilot Study of Telemedicine and Clinic Patients

BACKGROUND

The authors have developed pretrained machine learning (ML) models to evaluate neonatal head shape deformities using top-down and facial orthogonal photographs of the patient's head. In previous preliminary analysis, this approach was tested with images from an open-source data bank.

OBJECTIVE

To determine the accuracy of pretrained ML models in identifying craniosynostosis among patients seen in our outpatient neurosurgery clinic.

METHODS

We retrospectively reviewed top-down and facial orthogonal images of each patient's head and provider clinical diagnosis from the same encounters. Head shape classifications generated from 3 pretrained ML models (random forest, classification and regression tree, and linear discriminant analysis) were applied to each patient's photograph data set after craniometric extraction using a predefined image processing algorithm. Diagnoses were codified into a binary scheme of craniosynostosis vs noncraniosynostosis. Sensitivity, specificity, and Matthew correlation coefficient were calculated for software vs provider classifications.

RESULTS

A total of 174 patients seen for abnormal head shape between May 2020 and February 2021 were included in the analysis. One hundred seven patients (61%) were seen in-person and 67 (39%) through telemedicine. Twenty-three patients (13%) were diagnosed with craniosynostosis. The best-performing model identified craniosynostosis with an accuracy of 94.8% (95% CI 90.4-97.6), sensitivity of 87.0% (95% CI 66.4-97.2), specificity of 96.0% (95% CI 91.6-98.5), and Matthew correlation coefficient of 0.788 (95% CI 0.725-0.839).

CONCLUSION

Machine learning-driven image analysis represents a promising strategy for the identification of craniosynostosis in a real-world practice setting. This approach has potential to reduce the need for imaging and facilitate referral by primary care providers.

Single Segment Neo-Bandeau Fronto-Orbital Advancement in Children With Craniosynostosis: Technique Adaptation and Craniometric Analysis

ABSTRACT

Fronto-orbital advancement (FOA) of the anterior skull and orbital bandeau is standard of care for craniosynostosis with anterior morphology. Fronto-orbital retrusion, temporal hollowing, and bony contour irregularities are commonly seen in long-term follow-up. In this study, we report several technical adaptations of a new FOA technique described in Fearon et al that help facilitate adaptation of the single-segment neo-bandeau FOA technique in preparation of use in younger patients, and perform a craniometric analysis of the technique. Five consecutive patients who underwent the single-segment neo-bandeau FOA in 2020 with available pre- and post-operative three-dimensional head computed tomography scans were studied. Using Materialise Mimics (Materialise, Ghent, Belgium), cranial length, cranial height, cranial widths, and intracranial volume were measured. Two (40%) patients were male and all were non-Hispanic White with a median age at surgery of 18.6 months (interquartile range 10.4-45.7). Three patients (60%) had bicoronal or other multi-suture craniosynostosis, and 1 each had metopic and sagittal craniosynostosis. Intraoperatively measured intracranial pressure decreased from 17.8 mmHg (R 13.0-20.0) before craniectomy to 4.8 mmHg (R 2.0-11.0; P = 0.038) after craniectomy. Anterior cranial width increased postoperatively (mean 92.6 mm; R 74.9-111.5 versus 117.6 mm; R 109.8-135.2, P = 0.005). Intracranial volume increased from preoperative (mean 1211 cm3; R 782-1949 cm3) to postoperative (1387 cm3; R 1022-2108 cm3; P = 0.009). The authors find in this small sample that a single-segment neo-bandeau FOA demonstrates volumetric expansion similar to conventional FOA techniques and is feasible in infants under 1 year of age.

Craniometric and Volumetric Analysis of Posterior Vault Distraction Osteogenesis: 10 Year Update

PURPOSE

The purpose of this study is to quantitatively establish the volumetric changes observed with posterior vault distraction osteogenesis in the anterior, middle, and posterior thirds of the cranial vault; characterize change in cranial length, width, and height, correlating these changes to demographic variables that may help identify why younger kids gain more volume; and describe the short-term position of the transport segment.

METHODS

Multisuture craniosynostosis patients who underwent posterior vault distraction osteogenesis were retrospectively reviewed. Pediatric, dose-reduced, thin cut helically acquired head computed tomography scans were analyzed on Materialise Mimics v22 (Materialise, Ghent, Belgium). Pre and post-PVDO and "old" and "young" cohort were compared.

RESULTS

Twenty-one patients met inclusion criteria. The change in cranial length was significantly less at a median of 14.9 mm [Interquartile range (IQR) 11.8, 31.6] compared to the X-ray measured AP distraction distance (30 mm [IQR 24, 33]; P < 0.001) and significantly less than the theoretically calculated distance (23 mm [IQR 19, 31]; P = 0.012). Median anterior cranial height was shorter post PVDO (82.9 mm, [IQR 64.8, 92.6] versus 78.7 mm [IQR 57.0, 88.7]; P = 0.030). The younger cohort saw a greater increase in total intracranial volume (median 335.1 mL [IQR 163.2, 452.3, median 37.1%] versus 144.6 mL [IQR 119.0, 184.8, median 12.0%]; P = 0.011).

CONCLUSIONS

This is the first study to quantify volumetric changes to the anterior, middle, and posterior cranial vaults and demonstrates benefits of preforming PVDO at a younger age to help control turricephaly and produce greater percentage volumetric increases.

Improved cephalic index following early cranial vault remodeling in patients with isolated nonsyndromic sagittal synostosis

OBJECTIVE

Isolated nonsyndromic sagittal synostosis (SS) is the most common form of craniosynostosis in children, accounting for approximately 60% of all craniosynostoses. The typical cranial measurement used to define and follow SS is the cephalic index (CI). Several surgical techniques have been suggested, but agreement on type and timing of surgery is lacking. This study aimed to evaluate the authors' institutional experience of surgically treating SS using a modified subtotal cranial vault remodeling technique in a population-based cohort. Special attention was directed toward the effect of patient age at time of surgery on long-term CI outcome.

METHODS

A retrospective analysis was conducted on all patients with isolated nonsyndromic SS who were surgically treated from 2003 to 2011. Data from electronic medical records were gathered. Eighty-two patients with SS were identified, 77 fulfilled inclusion criteria, and 72 had sufficient follow-up data and were included. CI during follow-up after surgery was investigated with ANOVA and a linear mixed model.

RESULTS

In total, 72 patients were analyzed, consisting of 16 females (22%) and 56 males (78%). The mean ± SD age at surgery was 4.1 ± 3.1 months. Blood transfusions were received by 81% of patients (26% intraoperatively, 64% postoperatively, 9% both). The mean ± SD time in the pediatric ICU was 1.1 ± 0.25 days, and the mean ± SD total hospital length of stay was 4.6 ± 2.0 days. No patient required reoperation. The mean ± SD CI increased from 69 ± 3 to 87 ± 5 for patients who underwent surgery before 45 days of age. Surgery resulted in a larger increase in CI for patients who underwent surgery at a younger age compared with older patients (p < 0.05, Tukey's HSD test). In the comparison of patients who underwent surgery before 45 days of age with patients who underwent surgery at 45-90, 90-180, and more than 180 days of age, the linear mixed model estimated a long-term loss of CI of 3.0, 5.5, and 7.4 points, respectively.

CONCLUSIONS

The modified subtotal cranial vault remodeling technique used in this study significantly improved CI in patients with SS. The best results were achieved when surgery was performed early in life.