New method for quantification of the relative severity and (a)symmetry of isolated metopic synostosis

L.N.A. Van Adrichem,O.D.M. Kronig,S.A.J. Kronig,H.A. Vrooman,J.F. Veenland

doi:10.1016/j.ijom.2021.03.003

L.N.A. Van Adrichem, O.D.M. Kronig + Show 3 more

Open Access

https://doi.org/10.1016/j.ijom.2021.03.003

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Abstract

Trigonocephaly is the result of premature fusion of the metopic suture and its severity can vary widely. However, there is no gold standard for quantification of the severity. This study was performed to quantify severity using the Utrecht Cranial Shape Quantifier (UCSQ) and to assess forehead symmetry. Nineteen preoperative non-syndromic trigonocephaly patients (age ≤1 year) were included for the analysis of severity and symmetry. Severity according to the UCSQ was based on the following combined variables: forehead width and relative skull elongation. The UCSQ was compared to the most established quantification methods. A high correlation was found between the UCSQ and visual score (r=0.71). Moderate to negligible correlation was found between the UCSQ and frontal angle, binocular distance, inter-ocular distance, and frontal stenosis. Additionally, correlation between the visual score and these established quantification methods was negligible. Assessment of the frontal peak (a)symmetry (ratio of right to left triangle area in the curve) showed a mean right versus left triangle area ratio of 1.4 (range 0.9–2.4). The results suggest that the UCSQ is appropriate for the quantification of severity based on the high correlation with clinical judgement. Furthermore, a larger triangle area right than left was unexpectedly found, indicating forehead asymmetry.

Highlights

Is the result of premature fusion of the metopic suture and its severity can vary widely
The diagnosis trigonocephaly is based on clinical examination and can be confirmed by computed tomography (CT)
The recent literature has focused on reducing the radiation load of CT scans for children, and several studies have proven that CT examination is not routinely necessary for the accurate diagnosis of trigonocephaly and that the diagnosis can be made by clinical examination alone[7,8,9]

Summary

Introduction

Is the result of premature fusion of the metopic suture and its severity can vary widely. When the metopic suture fuses prematurely, growth of both frontal bones is restricted in width and compensatory growth of the other open sutures and expansion of the skull occurs[3]. Due to these growth patterns, a typical triangular shape of the forehead (trigonocephaly), anterior cranial fossa, anterior cranial base, and orbits can be seen; the forehead is pushed forward due to growth from the coronal sutures. Clinical examination focuses on the classical clinical features, which include straight, narrowed frontal bones, orbital narrowing, biparietal widening, and temporal constriction These and other features are not pathognomonic for trigonocephaly, but can be present as a normal variation in children with different malformations[5,6]. The present study focused on CT scan data, there are emerging trends in preoperative diagnosis and planning without a radiation load, such as three-dimensional (3D) photogrammetry, ultrasound examination, and magnetic resonance imaging (MRI)[10,11,12]

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