Is craniofacial morphology in Apert and Crouzon syndromes the same?

Three-Dimensional Evaluation of Dental Arches in Individuals with Syndromic Craniosynostosis

Objective

Individuals with syndromic craniosynostosis present alterations in the dental arches due to anomalies caused by the early fusion of the craniomaxillary sutures. This study aimed to compare intradental and interdental dimensions between individuals with Apert and Crouzon syndromes and nonsyndromic controls.

Materials and Methods

Digital models were obtained from the archive of a public tertiary care hospital. The sample consisted of 34 patients (Apert n = 18, Crouzon n = 16) and 34 nonsyndromic controls matched for gender and age. Measurements of perimeter, length, intercanine and intermolar distances (upper and lower), overjet, and molar ratio were performed. Statistical comparisons were performed using ANOVA and Tukey tests (p < 0.05).

Results

Patients with Apert and Crouzon syndromes have severely reduced maxillary transverse dimensions, perimeter, and length of the upper arch compared to the control group (p < 0.001). The lower arch is less impacted. Patients with Apert syndrome had an anterior crossbite (p < 0.001), while patients with Crouzon syndrome had an edge-to-edge bite (p <  0.011). Patients with Apert and Crouzon syndromes do not have serious transverse proportion problems when comparing the upper and lower arches.

Conclusions

In this sample, both the Apert and Crouzon groups have severely compromised upper arches compared to the control group. Mild dentoalveolar expansion in the maxilla should be sufficient for the transverse adaptation of the dental arches before frontofacial advancement.

Influence of Nonsyndromic Bicoronal Synostosis and Syndromic Influences on Orbit and Periorbital Malformation

BACKGROUND

Oculoorbital disproportion in patients with craniosynostosis has similarities and dissimilarities between syndromic and nonsyndromic cases. The authors hypothesized that these two conditions have specific individual influences as they relate to development of the orbital and periorbital skeletons.

METHODS

A total of 133 preoperative computed tomography scans (nonsyndromic bicoronal synostosis, n = 38; Apert syndrome bicoronal synostosis subtype, n = 33; Crouzon syndrome bicoronal synostosis subtype, n = 10; controls, n = 52) were included. Craniometric and volumetric analyses related to the orbit and periorbital anatomy were performed.

RESULTS

Orbital cavity volume was mildly restricted in nonsyndromic bicoronal synostosis (7 percent, p = 0.147), but more so in Apert and Crouzon syndromes [17 percent (p = 0.002) and 21 percent (p = 0.005), respectively]. The sphenoid side angle in Apert syndrome was wider than when compared to Crouzon syndrome (p = 0.043). The ethmoid side angle in Apert patients, however, was narrower (p = 0.066) than that in Crouzon patients. Maxilla anteroposterior length was more restricted in Apert syndrome than Crouzon syndrome (21 percent, p = 0.003) and nonsyndromic cases (26 percent, p < 0.001). The posterior nasal spine position was retruded in Crouzon syndrome (39 percent, p < 0.001), yet the anterior nasal spine position was similar in Apert and Crouzon syndromes.

CONCLUSIONS

Orbit and periorbital malformation in syndromic craniosynostosis is likely the combined influence of syndromic influences and premature suture fusion. Apert syndrome expanded the anteriorly contoured lateral orbital wall associated with bicoronal synostosis, whereas Crouzon syndrome had more infraorbital rim retrusion, resulting in more severe exorbitism. Apert syndrome developed maxillary hypoplasia, in addition to the maxillary retrusion, observed in Crouzon syndrome and nonsyndromic bicoronal synostosis patients.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Differential diagnosis of syndromic craniosynostosis: a case series

Purpose

Syndromic craniosynostosis is a rare genetic disease caused by premature fusion of one or multiple cranial sutures combined with malformations of other organs. The aim of this publication is to investigate sonographic signs of different syndromic craniosynostoses and associated malformations to facilitate a precise and early diagnosis.

Methods

We identified in the period of 2000–2019 thirteen cases with a prenatal suspected diagnosis of syndromic craniosynostosis at our department. We analyzed the ultrasound findings, MRI scans, genetic results as well as the mode of delivery, and postnatal procedures.

Results

Eight children were diagnosed with Apert Syndrome, two with Saethre Chotzen syndrome, one with Crouzon syndrome, and one with Greig cephalopolysyndactyly syndrome. One child had a mutation p.(Pro253Leu) in the FGFR2 gene. We identified characteristic changes of the head shape as well as typical associated malformations.

Conclusion

Second trimester diagnosis of syndromic craniosynostosis is feasible based on the identified sonographic signs. In case of a suspected diagnosis a genetic, neonatal as well as surgical counseling is recommended. We also recommend to offer a fetal MRI. The delivery should be planned in a perinatal center.

Craniofacial, oral, and cervical morphological characteristics in Japanese patients with Apert syndrome or Crouzon syndrome

BACKGROUND AND OBJECTIVES

Mutations in the fibroblast growth factor receptor 2 (FGFR2) gene are responsible for both Apert syndrome (AS) and Crouzon syndrome (CS). These diseases share phenotypic characteristics, including midfacial hypoplasia and premature fusion of the calvarial suture(s). Given the extensive range of craniofacial growth and developmental abnormalities, management of these patients requires a multidisciplinary approach. This study aimed to compare craniofacial, oral, and cervical morphological characteristics in Japanese orthodontic patients with AS or CS.

SUBJECTS AND METHODS

Lateral cephalograms, orthopantomograms, dental casts, medical interview records, facial photographs, and intraoral photographs of 7 AS patients and 12 CS patients on initial visits were used in this study. Cephalometric analyses were performed, and standard scores were calculated based on age- and sex-matched Japanese standard values.

RESULTS

Cephalometric analysis revealed that AS patients had significantly more severe maxillary hypoplasia in two dimensions and increased clockwise mandibular rotation. Additionally, cleft of the soft palate, anterior open bite, severe crowding in the maxillary dental arch, and congenitally missing teeth occurred more frequently among AS patients. Multiple fusions between cervical vertebrae C2, C3, C5, and C6 were observed in the AS patients.

LIMITATIONS

Small sample size.

CONCLUSIONS/IMPLICATIONS

Our study shows that AS patients have more severe craniofacial and maxillofacial deformities than CS patients.

Early mandibular morphological differences in patients with FGFR2 and FGFR3-related syndromic craniosynostoses: A 3D comparative study

Syndromic craniosynostoses are defined by the premature fusion of one or more cranial and facial sutures, leading to skull vault deformation, and midfacial retrusion. More recently, mandibular shape modifications have been described in FGFR-related craniosynostoses, which represent almost 75% of the syndromic craniosynostoses. Here, further characterisation of the mandibular phenotype in FGFR-related craniosynostoses is provided in order to confirm mandibular shape modifications, as this could contribute to a better understanding of the involvement of the FGFR pathway in craniofacial development. The aim of our study was to analyse early mandibular morphology in a cohort of patients with FGFR2- (Crouzon and Apert) and FGFR3- (Muenke and Crouzonodermoskeletal) related syndromic craniosynostoses. We used a comparative geometric morphometric approach based on 3D imaging. Thirty-one anatomical landmarks and eleven curves with sliding semi-landmarks were defined to model the shape of the mandible. In total, 40 patients (12 with Crouzon, 12 with Apert, 12 with Muenke and 4 with Crouzonodermoskeletal syndromes) and 40 age and sex-matched controls were included (mean age: 13.7 months ±11.9). Mandibular shape differed significantly between controls and each patient group based on geometric morphometrics. Mandibular shape in FGFR2-craniosynostoses was characterized by open gonial angle, short ramus height, and high and prominent symphysis. Short ramus height appeared more pronounced in Apert than in Crouzon syndrome. Additionally, narrow inter-condylar and inter-gonial distances were observed in Crouzon syndrome. Mandibular shape in FGFR3-craniosynostoses was characterized by high and prominent symphysis and narrow inter-gonial distance. In addition, narrow condylar processes affected patients with Crouzonodermoskeletal syndrome. Statistical analysis of variance showed significant clustering of Apert and Crouzon, Crouzon and Muenke, and Apert and Muenke patients (p < 0.05). Our results confirm distinct mandibular shapes at early ages in FGFR2- (Crouzon and Apert syndromes) and FGFR3-related syndromic craniosynostoses (Muenke and Crouzonodermoskeletal syndromes) and reinforce the hypothesis of genotype-phenotype correspondence concerning mandibular morphology.

Unilateral Coronal Craniosynostosis in an Apert-Like Patient

Background and Significance

Apert syndrome is a congenital disorder of patients who typically present with bilateral coronal craniosynostosis and varying degrees of complex syndactyly of the hands and feet, among other features. We describe a unique presentation of a rare Apert-like patient with unilateral coronal craniosynostosis and complex syndactyly of the hands and feet.

Case Report

A 2-year-old male patient presented to the craniofacial clinic with his mother due to a concerning head shape. The patient also had bilateral syndactyly of the hands and feet and underwent prior surgical release of the third web space. Computerized tomography of the head illustrated a small open anterior fontanelle, a left harlequin orbit, complete left coronal craniosynostosis, and a patent right coronal suture. The patient subsequently underwent fronto-orbital advancement for expansion of the cranial vault and correction of the asymmetric forehead and orbit. The procedure resulted in improvement of his deformity.

Conclusion

This case illustrates a unique presentation of an acrocephalosyndactyly (ACS) syndrome with asymmetric, unilateral coronal craniosynostosis and complete complex syndactyly of the hands and feet that is most consistent with Apert syndrome. Although the majority of patients with ACS can be categorized into known syndromes, other more unusual presentations must still be considered. Such unique cases are exceedingly rare and only through additional reporting and review of unique phenotypes can new subtypes of common ACS syndromes be classified.

Cellular and molecular mechanisms of cleft palate development

Cleft lip and palate are common craniofacial deformities. The etiology underlying these deformities is complex and multifactorial and they can occur as part of one of many chromosomal syndromes, Mendelian single gene disorders, teratogenic effects, and as yet uncharacterized syndromes. Our paper will provide an overview of the multiple genes and molecular pathways that have been implicated in palatal fusion. We believe that understanding the molecular mechanisms of cleft formation can help clinicians anticipate which patients may have difficulties healing and in the future allow them to make surgical and medical treatment decisions based on genetic information.

Crouzon Syndrome: a Comprehensive Review

Crouzon syndrome is a rare genetic disorder with autosomal dominant inheritance. The underlying pathological process is premature synostosis of the cranial sutures with subsequent phenotypic alterations of the affected person. A review of the literature has been conducted in order to resume the overall characteristics of Crouzon syndrome such as craniomaxillofacial malformations, clinical features, dentoalveolar characteristics, aesthetic impairments, and psychological background, as well as, the different therapeutic procedures, which combine surgical and orthodontic interventions. Facial and functional malformations in individuals with Crouzon syndrome could be significantly improved after a series of surgical and orthodontic procedures in almost all cases. A multidisciplinary treatment approach would provide the best outcomes in affected patients.

Genetic Syndromes Associated with Craniosynostosis

Craniosynostosis is defined as the premature fusion of one or more of the cranial sutures. It leads not only to secondary distortion of skull shape but to various complications including neurologic, ophthalmic and respiratory dysfunction. Craniosynostosis is very heterogeneous in terms of its causes, presentation, and management. Both environmental factors and genetic factors are associated with development of craniosynostosis. Nonsyndromic craniosynostosis accounts for more than 70% of all cases. Syndromic craniosynostosis with a certain genetic cause is more likely to involve multiple sutures or bilateral coronal sutures. FGFR2, FGFR3, FGFR1, TWIST1 and EFNB1 genes are major causative genes of genetic syndromes associated with craniosynostosis. Although most of syndromic craniosynostosis show autosomal dominant inheritance, approximately half of patients are de novo cases. Apert syndrome, Pfeiffer syndrome, Crouzon syndrome, and Antley-Bixler syndrome are related to mutations in FGFR family (especially in FGFR2), and mutations in FGFRs can be overlapped between different syndromes. Saethre-Chotzen syndrome, Muenke syndrome, and craniofrontonasal syndrome are representative disorders showing isolated coronal suture involvement. Compared to the other types of craniosynostosis, single gene mutations can be more frequently detected, in one-third of coronal synostosis patients. Molecular diagnosis can be helpful to provide adequate genetic counseling and guidance for patients with syndromic craniosynostosis.

Mandibular Asymmetry in Patients with the Crouzon or Apert Syndrome

The aim of this study was to describe directional and fluctuating mandibular asymmetry over time in children with Crouzon or Apert syndrome. Mandibular asymmetry of children between 7.5 and 14 years of age with Crouzon syndrome (n = 35) and Apert syndrome (n = 24) were compared with controls (n = 327). From panoramic radiographs, mandibular directional and fluctuating asymmetry was determined for the three groups. Multilevel statistical techniques were used to describe mandibular asymmetry changes over time. Patients with Crouzon and Apert syndromes showed statistically significant more fluctuating asymmetry for mandibular measures than did controls. Between the Crouzon and Apert syndromes groups, no statistical differences were found in directional and fluctuating asymmetry. The control group showed statistically significantly more directional asymmetry than did patients with Crouzon or Apert syndrome. The controls showed no change over time for the directional asymmetry of condylar-ramal height; however, the directional asymmetry of the gonial angle increased. Patients with Crouzon syndrome showed side dominance for only condylar-ramal height; whereas, patients with Apert syndrome did not show dominance for any of the measurements. Apert and Crouzon syndromes showed developmental instability, in contrast to the controls. No statistically significant longitudinal differences were found for either the directional or the fluctuating asymmetry between Crouzon and Apert syndromes. Findings for fluctuating and directional asymmetry for both syndromes may indicate an inability to cope with genetic and environmental stress during development and treatment, compared with untreated nonsyndromic individuals.

Bilateral squamosal suture synostosis: A rare form of isolated craniosynostosis in Crouzon syndrome

Craniosynostosis is a pathologic condition which is characterized by the premature fusion of cranial sutures. It may occur alone or in association with other anomalies making up various syndromes. Crouzon syndrome is the most common craniosynostosis syndrome. Bicoronal sutures fusion is most commonly involved in Crouzon syndrome. There have only been a handful of cases of squamosal suture synostosis described in the surgery literature with the few ones described in Crouzon syndrome associated with other types of craniosynostosis. To the best of our knowledge, we are presenting the first case of isolated bilateral squamosal suture synostosis in a patient with Crouzon syndrome in a radiology journal with emphasis on its radiological appearance.

Craniofacial Stability in Patients with Crouzon or Apert Syndrome after Le Fort III Distraction Osteogenesis

Objective

Le Fort III osteotomy with distraction osteogenesis (DO) is used to improve the retruded midface in patients with Crouzon or Apert syndrome. This study aimed to evaluate sagittal and vertical preoperative and postoperative cephalometric changes of DO of the midface in patients with Crouzon or Apert syndrome.

Design

Population-based case-control study.

Patients and Methods

Records of patients with the syndrome of Crouzon (N = 6) or Apert (N = 7) were compared, before and after Le Fort III DO, with a nonsyndromic untreated control group (N = 486).

Main Outcome Measures

Sagittal and vertical cephalometric maxillary landmarks and measurements were used to predict and measure midface advancement and rotation after Le Fort III DO. Cephalograms were taken before surgery (T0), 4 months after surgery at removal of the distraction device (T1), and 1 year after removal of the distraction device (T2).

Analysis

Z scores were performed to compare cephalometric measures of syndromic patients with control subjects.

Results

Cephalograms of 13 patients with Crouzon syndrome (N = 6) or Apert (N = 7) (age range 8.2 to 19.8 years) were evaluated. Treatment changes (T1-T2) showed statistically significant maxillary advancement, with no significant differences between the patients with the Crouzon or Apert syndrome.

Conclusions

DO of the midface in patients with Crouzon or Apert syndrome seems to be stable in the sagittal direction after follow-up. Although Crouzon and Apert differ after DO, anteroposterior craniofacial dimensions were significantly improved and were closer to patterns of normal subjects.

Orthodontic and surgical treatment of a patient with Apert syndrome

The aim of this case report was to present the combined orthodontic and surgical treatment of a patient with Apert syndrome in an adult stage. A 15 years old male patient with Apert syndrome was concerned about the appearance of his face and malocclusion. His profile was concave with a retruded maxilla and prominent lower lip. He had an Angle class I molar relationship with a 9.5 mm anterior open bite. The amount of crowding was 20.4 mm in the maxilla and 6 mm in the mandible. Cephalometric analysis revealed a skeletal Class III relationship due to maxillary hypoplasia with a dolichofacial growth pattern. Orthodontic treatment and orthognathic surgery were planned for the patient. After 45 months of presurgical orthodontics, the patient underwent two surgeries sequentially. The first surgery was performed to advance the maxilla and the second surgery was performed to correct the mandibular rotation and increase the overbite at the time of removing halo device. The amount of maxillary advencement was 8 mm. Mandibula was moved 1.5 mm anteriorly and rotated 1° to 1.5° (SNB and facial depth) in a counterclockwise direction. After a relatively long treatment, an esthetically pleasing and functional occlusion and correction of the skeletal problem was achieved in this adult case.

The role of vertebrate models in understanding craniosynostosis

BACKGROUND

Craniosynostosis (CS), the premature fusion of cranial sutures, is a relatively common pediatric anomaly, occurring in isolation or as part of a syndrome. A growing number of genes with pathologic mutations have been identified for syndromic and nonsyndromic CS. The study of human sutural material obtained post-operatively is not sufficient to understand the etiology of CS, for which animal models are indispensable.

DISCUSSION

The similarity of the human and murine calvarial structure, our knowledge of mouse genetics and biology, and ability to manipulate the mouse genome make the mouse the most valuable model organism for CS research. A variety of mouse mutants are available that model specific human CS mutations or have CS phenotypes. These allow characterization of the biochemical and morphological events, often embryonic, which precede suture fusion. Other vertebrate organisms have less functional genetic utility than mice, but the rat, rabbit, chick, zebrafish, and frog provide alternative systems in which to validate or contrast molecular functions relevant to CS.

Facial growth in patients with apert and crouzon syndromes compared to normal children

OBJECTIVE

To evaluate vertical and sagittal facial growth in children with Apert and Crouzon syndromes and compare it to the growth patterns of a nonsyndromic control group.

DESIGN

Case-control study.

SETTING

Department of Orthodontics, Children's Hospital Erasmus Medical Centre, Sophia, Rotterdam, The Netherlands.

PATIENTS, PARTICIPANTS

Sixty-two patients (37 patients with Crouzon syndrome and 25 patients with Apert syndrome) born between 1971 and 2001 (age range 3.9 to 32 years) and 482 nonsyndromic children as a control group.

INTERVENTIONS

Lateral cephalograms performed prior to any midfacial surgery of 62 patients and 482 nonsyndromic children were traced and horizontal and vertical measurements were digitized.

MAIN OUTCOME MEASURES

Cephalometric measurements of SNA, SNB, ANB, NSMe, and SN/palatal plane angles and lower facial height ratio.

RESULTS

Horizontal measurements for the syndromic groups showed no change in SNA angle during growth. SNA angles were lower in patients with Apert syndrome compared to patients with Crouzon syndrome. The syndromic groups showed smaller values for ANB angles compared to the nonsyndromic group. Vertical measurements showed increased lower facial height ratios for the syndromic groups compared to control subjects. There was an increasing counterclockwise rotation of the palatal plane in relation to the anterior cranial base in syndromic patients. NSMe angles among the three groups were not significantly different.

CONCLUSIONS

Based on the growth differences identified, the sagittal and vertical jaw relationships differ in patients with Crouzon syndrome, patients with Apert syndrome, and control subjects. Syndromic patients show aggravation of midfacial underdevelopment and anterior rotation of the mandible.

The spectrum of Apert syndrome: phenotype, particularities in orthodontic treatment, and characteristics of orthognathic surgery

In the PubMed accessible literature, information on the characteristics of interdisciplinary orthodontic and surgical treatment of patients with Apert syndrome is rare. The aim of the present article is threefold: (1) to show the spectrum of the phenotype, in order (2) to elucidate the scope of hindrances to orthodontic treatment, and (3) to demonstrate the problems of surgery and interdisciplinary approach.

Children and adolescents who were born in 1985 or later, who were diagnosed with Apert syndrome, and who sought consultation or treatment at the Departments of Orthodontics or Craniomaxillofacial Surgery at the Dental School of the University Hospital of Münster (n = 22; 9 male, 13 female) were screened. Exemplarily, three of these patients (2 male, 1 female), seeking interdisciplinary (both orthodontic and surgical treatment) are presented. Orthodontic treatment before surgery was performed by one experienced orthodontist (AH), and orthognathic surgery was performed by one experienced surgeon (UJ), who diagnosed the syndrome according to the criteria listed in OMIM™.

In the sagittal plane, the patients suffered from a mild to a very severe Angle Class III malocclusion, which was sometimes compensated by the inclination of the lower incisors; in the vertical dimension from an open bite; and transversally from a single tooth in crossbite to a circular crossbite. All patients showed dentitio tarda, some impaction, partial eruption, idopathic root resorption, transposition or other aberrations in the position of the tooth germs, and severe crowding, with sometimes parallel molar tooth buds in each quarter of the upper jaw.

Because of the severity of malocclusion, orthodontic treatment needed to be performed with fixed appliances, and mainly with superelastic wires. The therapy was hampered with respect to positioning of bands and brackets because of incomplete tooth eruption, dense gingiva, and mucopolysaccharide ridges. Some teeth did not move, or moved insufficiently (especially with respect to rotations and torque) irrespective of surgical procedures or orthodontic mechanics and materials applied, and without prognostic factors indicating these problems. Establishing occlusal contact of all teeth was difficult. Tooth movement was generally retarded, increasing the duration of orthodontic treatment. Planning of extractions was different from that of patients without this syndrome.

In one patient, the sole surgical procedure after orthodontic treatment with fixed appliances in the maxilla and mandible was a genioplasty. Most patients needed two- jaw surgery (bilateral sagittal split osteotomy [BSSO] with mandibular setback and distraction in the maxilla). During the period of distraction, the orthodontist guided the maxilla into final position by means of bite planes and intermaxillary elastics.

To our knowledge, this is the first article in the PubMed accessible literature describing the problems with respect to interdisciplinary orthodontic and surgical procedures. Although the treatment results are not perfect, patients undergoing these procedures benefit esthetically to a high degree.

Patients need to be informed with respect to the different kinds of extractions that need to be performed, the increased treatment time, and the results, which may be reached using realistic expectations.

Clinical and radiographic presentation and preparation of the prototyping model for pre-surgical planning in Apert's syndrome

Acrocephalosyndactyly, or Apert's syndrome, described nearly a century ago, is a craniofacial dysostosis, an autosomal dominant condition characterized by severe development disturbances of the craniofacial region including bilateral coronal synostosis associated with midface hypoplasia, exophthalmia, hypertelorism, symmetric syndactyly of the hands and feet, cone-shaped calvarium, pharyngeal attenuation and malocclusion. The aim of this study was to assess clinical and computed tomography (CT) imaging patterns of a non-operated patient with Apert's syndrome, correlating the cranium, face and the skull base bone abnormalities. Three-dimensional images were generated from spiral CT scans in order to produce a prototyping model in polyamide material. Clinical examination determined that syndactyly of the hands and feet, pseudocleft in the midline palate and midface hypoplasia were present. The surgical model allowed the analysis of some abnormalities regarding to calvaria morphology, nasal bones and maxilla, improving the criteria for a case diagnosis and surgical plan.

Cranial base in craniofacial development: developmental features, influence on facial growth, anomaly, and molecular basis

The cranial base is of crucial importance in integrated craniofacial development. As distinct from facial bones, it is formed through endochondral ossification. The posterior and anterior cranial bases are derived from distinct embryologic origins and grow independently--the anterior cranial base solely from the neural crest, the posterior cranial base from the paraxial mesoderm. The anterior cranial base has more prolonged and active growth and exerts more influence on facial growth than does the posterior cranial base. Cranial base angulation is a unique feature in modern human beings. Cranial base anomalies have been identified in many genetic and developmental disorders. The molecular basis of cranial base development and growth is being clarified. In this review, these aspects of cranial base are discussed in detail, with a focus on developmental features, roles in craniofacial growth, anomalies, and the genetic basis of development.

Computed tomography assessment of Apert syndrome

Apert syndrome, or acrocephalosyndactyly type I, is a craniofacial dysostosis, an autosomal dominant condition characterized by severe developmental disturbances of the craniofacial region including bilateral coronal synostosis associated with midface hypoplasia, exophthalmia, hypertelorism, and symmetric syndactyly of the hands and feet. The aim of this study is to assess the clinical and computed tomography imaging patterns of non-operated patients with Apert syndrome, correlating the bone abnormalities of the cranium, face and the skull base. The study population consisted of 5 patients with Apert syndrome. As part of the craniofacial assessment of the imaging center's routine, all patients underwent clinical evaluation and CT (computed tomograph) exam. Three-dimensional images were generated from helical CT scans, using an independent workstation, to evaluate the craniofacial abnormalities of the syndrome. Clinical exam determined that syndactyly of the hands and feet, pseudocleft in the midline palate and midface hypoplasia were features observed in all of the Apert patients. 3D-CT showed that some abnormalities such as bilateral coronal synostosis, calvarial midline defect and reduction in the antero-posterior dimension of the anterior, medial and posterior cranial fossae were present in all cases. In conclusion, the correlation of clinical and CT imaging findings can be useful to assess the main features observed in Apert patients, improving the criteria for examining the patient and diagnosing this condition, and contributing to the therapeutic planning and surgical follow-up.

Mandibular form in a rabbit model of familial nonsyndromic coronal suture synostosis

Nonsyndromic coronal suture synostosis produces predictable and well-documented morphologies of the cranial vault with anteroposterior growth restrictions and mediolateral compensatory growth. The potential effects of nonsyndromic coronal suture synostosis on mandibular form are not as clear, however. This study was designed to evaluate whether coronal suture synostosis is associated with alterations in mandibular form by using a familial rabbit model of coronal suture synostosis. To assess this potential relation, the following hypothesis was tested: mandibular form in rabbits with coronal suture synostosis is significantly (P < 0.05) different from that seen in normal rabbits. The cleaned and dried mandibles of 33 adult New Zealand white rabbits were used (12 from normal rabbits, 13 from rabbits with delayed-onset synostosis, and 8 from rabbits with complete coronal suture synostosis). Seven anatomical landmarks on the mandible were located and digitized in three dimensions: anterior molar on the alveolus, posterior molar on the alveolus, coronoid process, anterior pole of the condyle, condylar process, angular process, and mandibular angle. To describe the mandibular condyle, the distance from the anterior pole to the posterior pole of the condyle was measured with digital sliding calipers, as was the distance between the medial and lateral poles. A shape ratio was then created using the dividend of these sums. Statistical analyses of mean form differences between mandibles were executed using Euclidean distance matrix analysis. Statistical analyses of the mandibular condyle linear and shape measurements were analyzed using one-way ANOVA in the three groups. Results showed that complete coronal suture synostosis is associated with significant (P < 0.05) differences in mandibular form compared with that of normal rabbits but that mandibular form in rabbits with delayed-onset synostosis does not differ from that of normal rabbits (P > 0.05). In particular, distances involving the coronoid process in rabbits with coronal suture synostosis were significantly different, paralleling previous work in human patients with coronal synostosis. There are no intrinsic condylar linear or shape differences between any of these groups, however. The form difference noted is most likely secondary to the synostosed coronal suture and may reflect alterations in the cranial base or masticatory musculature in this rabbit model.

The dental health and caries-related microflora in children with craniosynostosis

OBJECTIVE

To compare levels of dental caries, bacterial dental plaque, gingivitis, enamel defects, and caries-related microflora in children with and without craniosynostosis.

STUDY GROUP

Fifty-seven children with craniosynostosis and their matched controls.

OUTCOME MEASURES

The decayed, missing, and filled teeth and surfaces in both the deciduous (dmfs and dmft) and the permanent dentition (DMFS and DMFT). The plaque and gingivitis scores and developmental enamel defects were also recorded. The caries-related microflora was sampled using an alginate swab and the prevalence of Streptococcus mutans and Lactobacillus and Candida species were recorded.

RESULTS

The dmfs (p <.02) and dmft (p <.01) were significantly greater in the control children. The plaque score for the deciduous dentition only (p <.02) and also the gingivitis score for the permanent teeth only (p <.008) in the craniosynostosis group were significantly greater. The total aerobic bacterial count (p <.004), anaerobic count (p <.002), and Candida count (p <.05) were significantly greater in the control group. The proportion of S. mutans both as a percentage of the total anaerobic count (p <.04) and the total streptococcal count (p <.05) was significantly greater in the control group.

Dynamic cranioplasty for brachycephaly in Apert syndrome: long-term follow-up study

Object.Brachycephaly is a characteristic feature of Apert syndrome. Traditional techniques of cranioplasty often fail to produce an acceptable morphological outcome in patients with this condition. In 1996 a new surgical procedure called “dynamic cranioplasty for brachycephaly” (DCB) was reported. The purpose of the present study was to analyze perioperative data and morphological long-term results in patients with the cranial vault deformity of Apert syndrome who were treated with DCB.

Methods.Twelve patients have undergone surgery performed using this technique since its introduction in 1991 (mean duration of follow-up review 60.2 months). Eleven patients had bicoronal synostosis and one had a combined bicoronal—bilambdoid synostosis. Perioperative data and long-term evolution of skull shape visualized on serial cephalometric radiographs were analyzed and compared with normative data. Changes in mean skull proportions were evaluated using a two-tailed paired-samples t-test, with differences being considered significant for probability values less than 0.01.

The mean operative blood transfusion was 136% of estimated red cell mass (ERCM) and the mean postoperative transfusion was 48% of ERCM. The mean operative time was 218 minutes. The duration of stay in the intensive care unit averaged 1.7 days and the mean hospital stay was 11.8 days. There were no incidences of mortality and few complications. An improvement in skull shape was achieved in all cases, with a change in the mean cephalic index from a preoperative value of 90 to a postoperative value of 78 (p = 0.000254).

Conclusions.Dynamic cranioplasty for brachycephaly is a safe procedure, yielding high-quality morphological results in the treatment of brachycephaly in patients with Apert syndrome.

Loss of fibroblast growth factor receptor 2 ligand-binding specificity in Apert syndrome

Craniosynostosis syndromes are autosomal dominant human skeletal diseases that result from various mutations in fibroblast growth factor receptor genes (Fgfrs). Apert syndrome (AS) is one of the most severe craniosynostosis syndromes and is associated with severe syndactyly of the hands and feet and with central nervous system malformations. AS is caused by specific missense mutations in one of two adjacent amino acid residues (S252W or P253R) in the highly conserved region linking Ig-like domains II and III of FGFR2. Here we demonstrate that these mutations break one of the cardinal rules governing ligand specificity of FGFR2. We show that the S252W mutation allows the mesenchymal splice form of FGFR2 (FGFR2c) to bind and to be activated by the mesenchymally expressed ligands FGF7 or FGF10 and the epithelial splice form of FGFR2 (FGFR2b) to be activated by FGF2, FGF6, and FGF9. These data demonstrate loss of ligand specificity of FGFR2 with retained ligand dependence for receptor activation. These data suggest that the severe phenotypes of AS likely result from ectopic ligand-dependent activation of FGFR2.