Incidence of Cranial Base Suture Fusion in Infants with Craniosynostosis:

Association of cranial base suture/synchondrosis fusion with severity of increased intracranial pressure in Crouzon syndrome

This study investigated how the fusion states of the cranial base is related to the degree of increased intracranial pressure (ICP) in patients with Crouzon syndrome. This retrospective cohort study enrolled patients who were diagnosed with Crouzon syndrome between May 2007 and April 2022. We categorized the patients into three groups: A, B, and C, according to the severity of increased ICP and the number of cranial vault remodeling procedures for corrective operation. The preoperative fusion states of the cranial base sutures/synchondroses were examined using facial bone computed tomography and compared between groups. Overall, 22 patients were included in Groups A, B, and C, including 8, 7, and 7 patients, respectively. The preoperative average grades of the total cranial base suture/synchondrosis fusion appeared to significantly increase with severity, except for the frontoethmoidal suture, which showed the opposite tendency. In the subgroup analysis, frontosphenoidal, sphenoparietal, sphenosquamosal, parietomastoid, and occipitomastoid suture and petro-occipital synchondrosis were associated with earlier fusion in the more severe group. Premature closure of the cranial base sutures/synchodroses seems to be associated with increased ICP severity in patients with Crouzon syndrome. Precise evaluation of minor sutures/synchondroses at the first visit might help build subsequent operative plans and predict disease prognosis.

Fusion of Lateral Calvarial Sutures on Volume-Rendered Computed Tomography Reconstructions in Patients With Known Craniosynostosis

INTRODUCTION

After treating a child with familial sagittal craniosynostosis, clinocephaly, and bilateral parietomastoid/posterior squamosal suture fusion, the authors wondered if major-suture synostosis and clinocephaly were associated with abnormal fusion of minor lateral calvarial sutures.

METHODS

The authors reviewed all preoperative volume-rendered head computed tomography reconstructions performed for craniosynostosis at their institution from 2010 through 2014 and determined whether the sphenoparietal, squamosal, and parietomastoid sutures were open, partially fused, or fused. The authors determined whether any sutures were abnormally fused based upon a previous study from their center, in which abnormal fusion was defined as either 1 of 3 abnormal fusion patterns or abnormally-early fusion. The authors then determined the rate of abnormal fusion of these sutures and whether abnormal fusion was associated with (1) major-suture craniosynostosis, (2) type of craniosynostosis (sutures involved; single-suture versus multisuture; syndromic versus nonsyndromic), and (3) clinocephaly.

RESULTS

In 97 included children, minor lateral sutures were abnormally fused in 8, or 8.2%, which was significantly higher than in children without craniosynostosis from our earlier study. Abnormal minor lateral suture fusion was not associated with the type of single-suture synostosis or with multisuture synostosis but was associated with syndromic synostosis. Four of 8 children with abnormal minor lateral suture fusion had multisuture synostosis and 6 had syndromic synostosis. Lateral sutures were abnormally fused in 1 of 4 subjects with clinocephaly, which was not significant.

CONCLUSION

Abnormal minor lateral calvarial suture fusion is significantly associated with major-suture craniosynostosis, especially syndromic synostosis.

Management of Minor Suture Craniosynostosis

Although most reported cases of minor suture involvement include multiple sutures, isolated suture involvement has been reported. Morphologic differences such as scaphocephaly and anterior plagiocephaly have been reported. Management should involve proper identification and multidisciplinary treatment. Surgical treatment should involve the expansion of the cranial vault as well as the correction of the deformity.

The 27 Facial Sutures: Timing and Clinical Consequences of Closure

SUMMARY

Facial sutures contribute significantly to postnatal facial development, but their potential role in craniofacial disease is understudied. Since interest in their development and physiology peaked in the mid-twentieth century, facial sutures have not garnered nearly the same clinical research interest as calvarial sutures or cranial base endochondral articulations. In addition to reinforcing the complex structure of the facial skeleton, facial sutures absorb mechanical stress and generally remain patent into and beyond adolescence, as they mediate growth and refine the shape of facial bones. However, premature closure of these sites of postnatal osteogenesis leads to disrupted growth vectors and consequent dysmorphologies. Although abnormality in individual sutures results in isolated facial deformities, we posit that generalized abnormality across multiple sutures may be involved in complex craniofacial conditions such as syndromic craniosynostosis. In this work, the authors comprehensively review 27 key facial sutures, including physiologic maturation and closure, contributions to postnatal facial development, and clinical consequences of premature closure.

Morphology of the Occipital Bones and Foramen Magnum Resulting From Premature Minor Suture Fusion in Crouzon Syndrome

To identify skull-base growth patterns in Crouzon syndrome, we hypothesized premature minor suture fusion restricts occipital bone development, secondarily limiting foramen magnum expansion.

Skull-base suture closure degree and cephalometric measurements were retrospectively studied using preoperative computed tomography (CT) scans and multiple linear regression analysis.

Evaluation of multi-institutional CT images and 3D reconstructions from Wake Forest's Craniofacial Imaging Database (WFCID).

Sixty preoperative patients with Crouzon syndrome under 12 years-old were selected from WFCID. The control group included 60 age- and sex-matched patients without craniosynostosis or prior craniofacial surgery.

None.

2D and 3D cephalometric measurements.

3D volumetric evaluation of the basioccipital, exo-occipital, and supraoccipital bones revealed decreased growth in Crouzon syndrome, attributed solely to premature minor suture fusion. Spheno-occipital (β = -398.75; P < .05) and petrous-occipital (β = -727.5; P < .001) suture fusion reduced growth of the basioccipital bone; lambdoid suture (β = -14 723.1; P < .001) and occipitomastoid synchondrosis (β = -16 419.3; P < .001) fusion reduced growth of the supraoccipital bone; and petrous-occipital suture (β = -673.3; P < .001), anterior intraoccipital synchondrosis (β = -368.47; P < .05), and posterior intraoccipital synchondrosis (β = -6261.42; P < .01) fusion reduced growth of the exo-occipital bone. Foramen magnum morphology is restricted in Crouzon syndrome but not directly caused by early suture fusion.

Premature minor suture fusion restricts the volume of developing occipital bones providing a plausible mechanism for observed foramen magnum anomalies.

Respective Roles of Craniosynostosis and Syndromic Influences on Cranial Fossa Development

BACKGROUND

Little is known about the detailed growth of the cranial fossae, even though they provide an important structural connection between the cranial vault and the facial skeleton. This study details the morphologic development of isolated cranial vault synostosis and associated syndromes on cranial fossa development.

METHODS

A total of 125 computed tomographic scans were included (nonsyndromic bicoronal synostosis, n = 36; Apert syndrome associated with bicoronal synostosis, n = 24; Crouzon syndrome associated with bicoronal synostosis, n = 11; and controls, n = 54). Three-dimensional analyses were produced using Materialise software.

RESULTS

The regional anterior and middle cranial fossae volumes of nonsyndromic bicoronal synostosis are characterized by significant increases of 43 percent (p < 0.001) and 60 percent (p < 0.001), respectively, and normal posterior cranial fossa volume. The cranial fossae depths of nonsyndromic bicoronal synostosis were increased, by 37, 42, and 21 percent (all p < 0.001) for anterior, middle, and posterior cranial fossae, respectively, accompanying the shortened cranial fossae lengths. The volume and morphology of all cranial fossae in Apert syndrome nearly paralleled nonsyndromic bicoronal synostosis. However, Crouzon syndrome had reduced depths of cranial fossae, and more restricted fossa volumes than both Apert syndrome and nonsyndromic bicoronal synostosis.

CONCLUSIONS

Cranial vault suture synostosis is likely to be more influential on cranial fossae development than other associated influences (genetic, morphologic) in Apert and Crouzon syndromes. Isolated Apert syndrome pathogenesis is associated with an elongation of the anterior cranial fossa length in infants, whereas in Crouzon syndrome, there is a tendency to reduce cranial fossa depth, suggesting individual adaptability in cranial fossae development related to vault synostosis.

Bilateral Squamosal Suture Craniosynostosis Presenting with Abducens Nerve Palsy and Severe Papilledema

BACKGROUND

Patients with single-suture or minor suture craniosynostosis are typically asymptomatic at early presentation; intervention is aimed at reducing the risk of elevated intracranial pressure and associated developmental sequelae. Patients may be symptomatic in cases of major multisuture syndromic synostoses or delayed diagnosis. Clinical presentation in this context may include headaches, papilledema, cognitive delay, or behavioral issues. Cranial nerve palsies are atypical symptoms of intracranial hypertension in this patient population.

CASE DESCRIPTION

An 11-month-old, otherwise healthy girl presented with bilateral severe papilledema and left abducens nerve palsy owing to nonsyndromic near-complete bilateral squamosal suture synostosis with associated incomplete sagittal and right lambdoid synostoses. The patient underwent urgent open cranial expansion, with resolution of her papilledema and improvement in eye position and motility.

CONCLUSIONS

Cranial nerve palsies may be presenting symptoms of intracranial hypertension in patients with craniosynostosis. Multidisciplinary evaluation and treatment is paramount for appropriate management.

Role of thyroid hormones in craniofacial development

The development of the craniofacial skeleton relies on complex temporospatial organization of diverse cell types by key signalling molecules. Even minor disruptions to these processes can result in deleterious consequences for the structure and function of the skull. Thyroid hormone deficiency causes delayed craniofacial and tooth development, dysplastic facial features and delayed development of the ossicles in the middle ear. Thyroid hormone excess, by contrast, accelerates development of the skull and, in severe cases, might lead to craniosynostosis with neurological sequelae and facial hypoplasia. The pathogenesis of these important abnormalities remains poorly understood and underinvestigated. The orchestration of craniofacial development and regulation of suture and synchondrosis growth is dependent on several critical signalling pathways. The underlying mechanisms by which these key pathways regulate craniofacial growth and maturation are largely unclear, but studies of single-gene disorders resulting in craniofacial malformations have identified a number of critical signalling molecules and receptors. The craniofacial consequences resulting from gain-of-function and loss-of-function mutations affecting insulin-like growth factor 1, fibroblast growth factor receptor and WNT signalling are similar to the effects of altered thyroid status and mutations affecting thyroid hormone action, suggesting that these critical pathways interact in the regulation of craniofacial development.

A Craniometric Analysis of the Posterior Cranial Base After Posterior Vault Distraction

BACKGROUND

Posterior vault distraction osteogenesis (PVDO) has been demonstrated to effectively increase intracranial volume, treat increased intracranial pressure, and improve head shape in syndromic patients. The purpose of this study is to compare changes along the posterior cranial base before and after distraction.

METHODS

A retrospective review was completed of subjects who underwent PVDO with computed tomography scans at 2 time-points: within 3 months preoperatively and 1 to 6 months postoperatively. Using Mimics software, craniometric landmarks were identified and surface area of the foramen magnum was calculated. A comparison of pre- to postoperative measurements was completed using Wilcoxon matched-paired signed rank tests and linear regression.

RESULTS

A total of 65 PVDO subjects were identified, 12 subjects met inclusion criteria. Mean operative age was 3.0 ± 4.0 years. The cranial vault was distracted on average 25.0 ± 6.0 mm, with those < 12 months of age distracted 29.5 ± 4.9 mm and >12 months of age distracted 22.0 ± 4.9 mm (P = 0.0543). There was a significant increase in pre- to postoperative foramen magnum surface area (52.1 ± 63.2 mm, P = 0.002), length (0.9 ± 1.4 mm, P = 0.050), and width (0.6 ± 1.0 mm, P = 0.050). Similarly, linear distances between nasion and posterior cranial base landmarks such as foramen magnum (3.4 ± 4.2 mm, P = 0.010), and occipital protuberance (9.1 ± 9.6 mm, P = 0.003) were increased. Subjects under 12 months had a greater percentage increases in posterior vault length than those over 12 months.

CONCLUSION

Posterior vault distraction osteogenesis is associated with an increase in size of the foramen magnum, and lengthening of the posterior cranial base, both of which may be beneficial in patients with turribrachycephaly.

Syndromic Craniosynostosis

Management strategies for syndromic craniosynostosis patients require multidisciplinary subspecialty teams to provide optimal care for complex reconstructive approaches. The most common craniosynostosis syndromes include Apert (FGFR2), Crouzon (FGFR2), Muenke (FGFR3), Pfeiffer (FGFR1 and FGFR2), and Saethre-Chotzen (TWIST). Bicoronal craniosynostosis (turribrachycephaly) is most commonly associated with syndromic craniosynostosis. Disease presentation varies from mild sutural involvement to severe pansynostoses, with a spectrum of extracraniofacial dysmorphic manifestations. Understanding the multifaceted syndromic presentations while appreciating the panoply of variable presentations is central to delivering necessary individualized care. Cranial vault remodeling aims to relieve restriction of cranial development and elevated intracranial pressure and restore normal morphology.

Critical Growth Processes for the Midfacial Morphogenesis in the Early Prenatal Period

BACKGROUND

Congenital midfacial hypoplasia often requires intensive treatments and is a typical condition for the Binder phenotype and syndromic craniosynostosis. The growth trait of the midfacial skeleton during the early fetal period has been assumed to be critical for such an anomaly. However, previous embryological studies using 2-dimensional analyses and specimens during the late fetal period have not been sufficient to reveal it.

OBJECTIVE

To understand the morphogenesis of the midfacial skeleton in the early fetal period via 3-dimensional quantification of the growth trait and investigation of the developmental association between the growth centers and midface.

METHODS

Magnetic resonance images were obtained from 60 human fetuses during the early fetal period. Three-dimensional shape changes in the craniofacial skeleton along growth were quantified and visualized using geometric morphometrics. Subsequently, the degree of development was computed. Furthermore, the developmental association between the growth centers and the midfacial skeleton was statistically investigated and visualized.

RESULTS

The zygoma expanded drastically in the anterolateral dimension, and the lateral part of the maxilla developed forward until approximately 13 weeks of gestation. The growth centers such as the nasal septum and anterior portion of the sphenoid were highly associated with the forward growth of the midfacial skeleton (RV = 0.589; P < .001).

CONCLUSIONS

The development of the midface, especially of the zygoma, before 13 weeks of gestation played an essential role in the midfacial development. Moreover, the growth centers had a strong association with midfacial forward growth before birth.