The occipitofrontal circumference: reliable prediction of the intracranial volume in children with syndromic and complex craniosynostosis

Abstract

<jats:sec> <jats:title>OBJECT</jats:title> <jats:p>Patients with syndromic and complex craniosynostosis are characterized by the premature fusion of one or more cranial sutures. These patients are at risk for developing elevated intracranial pressure (ICP). There are several factors known to contribute to elevated ICP in these patients, including craniocerebral disproportion, hydrocephalus, venous hypertension, and obstructive sleep apnea. However, the causal mechanism is unknown, and patients develop elevated ICP even after skull surgery. In clinical practice, the occipitofrontal circumference (OFC) is used as an indirect measure for intracranial volume (ICV), to evaluate skull growth. However, it remains unknown whether OFC is a reliable predictor of ICV in patients with a severe skull deformity. Therefore, in this study the authors evaluated the relation between ICV and OFC.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Eighty-four CT scans obtained in 69 patients with syndromic and complex craniosynostosis treated at the Erasmus University Medical Center-Sophia Children’s Hospital were included. The ICV was calculated based on CT scans by using autosegmentation with an HU threshold &lt; 150. The OFC was collected from electronic patient files. The CT scans and OFC measurements were matched based on a maximum amount of the time that was allowed between these examinations, which was dependent on age. A Pearson correlation coefficient was calculated to evaluate the correlations between OFC and ICV. The predictive value of OFC, age, and sex on ICV was then further evaluated using a univariate linear mixed model. The significant factors in the univariate analysis were subsequently entered in a multivariate mixed model.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>The correlations found between OFC and ICV were r = 0.908 for the total group (p &lt; 0.001), r = 0.981 for Apert (p &lt; 0.001), r = 0.867 for Crouzon-Pfeiffer (p &lt; 0.001), r = 0.989 for Muenke (p &lt; 0.001), r = 0.858 for Saethre- Chotzen syndrome (p = 0.001), and r = 0.917 for complex craniosynostosis (p &lt; 0.001). Age and OFC were significant predictors of ICV in the univariate linear mixed model (p &lt; 0.001 for both factors). The OFC was the only predictor that remained significant in the multivariate analysis (p &lt; 0.001).</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>The OFC is a significant predictor of ICV in patients with syndromic and complex craniosynostosis. Therefore, measuring the OFC during clinical practice is very useful in determining which patients are at risk for impaired skull growth.</jats:p></jats:sec>

Intracranial Volume and Head Circumference in Children with Unoperated Syndromic Craniosynostosis

“…Having access to craniofacial growth curves offers the clinician an opportunity to directly compare clinical findings to published normal data. In the clinic, one can quickly assess whether a patient's growth curve is deflecting from the norm (an OFC not changing or showing growth of <0.5 SD within 2 years is a risk factor for developing papilloedema) 17 , and therefore have a higher level of suspicion for raised intracranial…”

“…For easier comparison, patients were further subdivided into 6 age ranges: 0 -1y, 1 -2y, 2 -4y, 4 -8y, 8 -12y, 12 -18y. 17 (Table 1).…”

First Vault Expansion in Apert and Crouzon-Pfeiffer Syndromes

“…5,28 The advancement/expansion achieved by vault expansion is greatest for the springs method, followed by conventional occipital expansion, and then by fronto-orbital advancement. The significantly greater increase in occipitofrontal head circumference after occipital expansion compared with fronto-orbital advancement indicates that, given the strong relationship between occipitofrontal head circumference and intracranial volume, 12 the resulting greater increase in intracranial volume leads to lower incidences of tonsillar herniation and papilledema. An additional advantage is that the frontal-orbital area remains untouched, thereby facilitating a monobloc or facial bipartition procedure later in life.…”

Head circumference - a useful single parameter for skull volume development in cranial growth analysis?

“…Further, early on Buda et al [ 37 ] pointed out that the HC in children with non-normally shaped skulls is not a valid indicator of cranial volume [ 37 ]. Skull morphology appears too complex to be represented via any single parameter, according to Marcus et al [ 21 ], in contrast to Rijken [ 40 ]. Our own examinations of healthy children showed invalidity in the relation between HC and cranial volume (Fig.…”