Distinguishing Craniomorphometric Characteristics And Severity In 100 Metopic Synostosis Patients
Kitae E. Park, BA, Ludmila Chandler, BS, Navid Pourtaheri, MD, PhD, Omar Allam, BS, Mohammad Ali Mozaffari, MD, Sumun Khetpal, BS, BA, John Smetona, MD, John A. Persing, MD, Michael Alperovich, MD, MSc.
Yale School of Medicine, New Haven, CT, USA.
PURPOSE: Metopic craniosynostosis is the second most common form of single suture synostosis. Controversy persists regarding the most accurate method for assessing severity in trigonocephaly. This study aimed to develop a robust diagnostic measurement system for reproducible severity assessment in trigonocephaly. In addition, it aimed to identify a severity scale to distinguish between mild, moderate, and severe metopic patients.
METHODS: Morphometric analysis using Materialise Mimics was performed on preoperative CT scans of infants with metopic craniosynostosis. Assessed indices of trigonocephaly were endocranial bifrontal angle, frontal angle, posterior angle of the anterior cranial fossa, brow ridge to eurion ratio, horizontal orbital cone angle, temporal depression angle, orbital rim angle, and interdacryon distance. Inter- and intra-rater reliability were established with two independent reviewers per patient. Results were analyzed using a Pearsonís correlation coefficient. Furthermore, age-based sub group analysis was performed between <6 months (group 1) and >6 months (group 2) using an unpaired T-test.
RESULTS: One hundred patients with metopic craniosynostosis were included in the analysis. The majority were male (82%) with a mean age of 6.6 months. The endocranial bifrontal angle ranged from 112.9 to 148.0 with a mean of 127.0. The frontal angle ranged from 83.2 to 109.3 with a mean of 98.3. Strong correlations existed between the frontal angle, posterior angle of anterior cranial fossa, horizontal cone angle, orbital rim angle, metopic index (bitemporal distance/biparietal distance), and upper orbital width (Pearson coefficient > 0.3 for all). Additionally, the posterior angle of anterior cranial fossa strongly correlated with zygomaticofrontal suture distance, interdacryon distance, and lateral orbital width. Changes in the endocranial bifrontal angle were associated with changes in the lateral orbital width, but there were no other correlations found between the endocranial bifrontal angle and the other measurements. Age-based subgroup analysis showed that there was no significant difference between measurements of severity between group 1 and group 2.
CONCLUSION: In the largest radiographic series of metopic synostosis patients to date, concordance of measures was identified between the frontal angle, posterior angle of anterior cranial fossa, horizontal cone angle, orbital rim angle, metopic index, and upper orbital width. These measurements represent reliable measures for trigonocephaly assessment. Furthermore, we found that there is no significant difference in severity based on age.
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