Functional adaptation of the infant craniofacial system to mechanical loadings arising from masticatory forces.

The morphology and biomechanics of infant crania undergo significant changes between the pre- and post-weaning phases due to increasing loading of the masticatory system. The aims of this study were to characterize the changes in muscle forces, bite forces and the pattern of mechanical strain and stress arising from the aforementioned forces across crania in the first 48 months of life using imaging and finite element methods. A total of 51 head computed tomography scans of normal individuals were collected and analysed from a larger database of 217 individuals. The estimated mean muscle forces of temporalis, masseter and medial pterygoid increase from 30.9 to 87.0 N, 25.6 to 69.6 N and 23.1 to 58.9 N, respectively (0-48 months). Maximum bite force increases from 90.5 to 184.2 N (3-48 months). There is a change in the pattern of strain and stress from the calvaria to the face during postnatal development. Overall, this study highlights the changes in the mechanics of the craniofacial system during normal development. It further raises questions as to how and what level of changes in the mechanical forces during the development can alter the morphology of the craniofacial system.

Biallelic truncating variants in VGLL2 cause syngnathia in humans.

BACKGROUND: Syngnathia is an ultrarare craniofacial malformation characterised by an inability to open the mouth due to congenital fusion of the upper and lower jaws. The genetic causes of isolated bony syngnathia are unknown. METHODS: We used whole exome and Sanger sequencing and microsatellite analysis in six patients (from four families) presenting with syngnathia. We used CRISPR/Cas9 genome editing to generate vgll2a and vgll4l germline mutant zebrafish, and performed craniofacial cartilage analysis in homozygous mutants. RESULTS: We identified homozygous truncating variants in vestigial-like family member 2 (VGLL2) in all six patients. Two alleles were identified: one in families of Turkish origin and the other in families of Moroccan origin, suggesting a founder effect for each. A shared haplotype was confirmed for the Turkish patients. The VGLL family of genes encode cofactors of TEAD transcriptional regulators. Vgll2 is regionally expressed in the pharyngeal arches of model vertebrate embryos, and morpholino-based knockdown of vgll2a in zebrafish has been reported to cause defects in development of pharyngeal arch cartilages. However, we did not observe craniofacial anomalies in vgll2a or vgll4l homozygous mutant zebrafish nor in fish with double knockout of vgll2a and vgll4l. In Vgll2 -/- mice, which are known to present a skeletal muscle phenotype, we did not identify defects of the craniofacial skeleton. CONCLUSION: Our results suggest that although loss of VGLL2 leads to a striking jaw phenotype in humans, other vertebrates may have the capacity to compensate for its absence during craniofacial development.

An automatic facial landmarking for children with rare diseases.

Two to three thousand syndromes modify facial features: their screening requires the eye of an expert in dysmorphology. A widely used tool in shape characterization is geometric morphometrics based on landmarks, which are precise and reproducible anatomical points. Landmark positioning is user dependent and time consuming. Many automatic landmarking tools are currently available but do not work for children, because they have mainly been trained using photographic databases of healthy adults. Here, we developed a method for building an automatic landmarking pipeline for frontal and lateral facial photographs as well as photographs of external ears. We evaluated the algorithm on patients diagnosed with Treacher Collins (TC) syndrome as it is the most frequent mandibulofacial dysostosis in humans and is clinically recognizable although highly variable in severity. We extracted photographs from the photographic database of the maxillofacial surgery and plastic surgery department of Hôpital Necker-Enfants Malades in Paris, France with the diagnosis of TC syndrome. The control group was built from children admitted for craniofacial trauma or skin lesions. After testing two methods of object detection by bounding boxes, a Haar Cascade-based tool and a Faster Region-based Convolutional Neural Network (Faster R-CNN)-based tool, we evaluated three different automatic annotation algorithms: the patch-based active appearance model (AAM), the holistic AAM, and the constrained local model (CLM). The final error corresponding to the distance between the points placed by automatic annotation and those placed by manual annotation was reported. We included, respectively, 1664, 2044, and 1375 manually annotated frontal, profile, and ear photographs. Object recognition was optimized with the Faster R-CNN-based detector. The best annotation model was the patch-based AAM (p < 0.001 for frontal faces, p = 0.082 for profile faces and p < 0.001 for ears). This automatic annotation model resulted in the same classification performance as manually annotated data. Pretraining on public photographs did not improve the performance of the model. We defined a pipeline to create automatic annotation models adapted to faces with congenital anomalies, an essential prerequisite for research in dysmorphology.

Parental and Child Diagnosis Storytelling and Self-Image in French Children With Cleft lip With or Without Cleft Palate.

OBJECTIVE: Psychosocial adjustment can be challenging for children with cleft lip with or without a cleft palate (CL ± P). Previous studies have linked social integration with self-acceptance and highlighted the impact of the parents' stress on self-acceptance. Teasing can be linked to children having difficulties explaining their diagnosis to others. This prospective research aimed to gain a better understanding of family communication about cleft, children's oral storytelling about their cleft, and explore their self-image and perceived familial acceptance. PARTICIPANTS: Parents and their children with CL ± P (N = 54; average age: 5.6 years). DESIGN: Semistructured interviews with parents and structured interviews with children were conducted regarding their oral storytelling focusing on scars from cleft lip surgery. Children completed a projective test to explore their self-image and perceptions of familial acceptance. Language screening was completed with the French Wechsler Preschool Primary Scale of Intelligence-Fourth Edition. RESULTS: Only 30% of children explained their cleft in a way appropriate for peers, including presence at birth, having had surgery, and scar location. Children's ability to explain their cleft was not related to language performance, which was in the average range of 84%. Children's cleft explanations were dependent on parents' narratives and education methods, including the use of verbal explanations and preoperative photographs. Children's storytelling was related to their self-image and perceived parental acceptance. CONCLUSION: Cleft teams should assist families in building their cleft story based on a complete explanation with photographs and a positive and accepting approach.

A Case of Complex Facial Reconstruction Illuminates Paul Tessier's Surgical State of Mind.

ABSTRACT: Successful head and neck reconstructions tackle both morphological and functional issues within treatment plans involving multiple coordinated steps. Nowadays, biomaterials, computer-assisted surgery, and free tissue transfers have greatly increased the potentialities of craniofacial surgeons. In the 1970s, when Paul Tessier, one of the founders of modern plastic surgery, was at the peak of his career, complex reconstructions had little technology to rely on. Here we report a case of facial reconstruction after gunshot trauma performed by Paul Tessier based on his "craniofacial autarchy" principle, that is using solely local flaps and grafts harvested in the head and neck area. This case involved 30 procedures on the mandible, maxilla, chin, lips, and nose. Based on data from the archives from the "Association Française des Chirurgiens de la Face" (Amiens, France) we provide details on Tessier's approach to surgical planning and on his global conception of treatment plans in reconstructive surgery.

Improvement of Periorbital Appearance in Apert Syndrome After Subcranial Le Fort III With Bipartition and Distraction.

AIM AND SCOPE: Children with Apert syndrome have a characteristic inversion of the orientation of the palpebral fissures, an increase of the inter-orbital distance, telecanthus, and exorbitism. Here, Le Fort III osteotomy with subcranial bipartition and distraction osteogenesis was evaluated as a tool to improve the position of the palpebral fissures in Apert syndrome. MATERIAL AND METHODS: All patients with Apert syndrome who underwent Le Fort 3 osteotomy with subcranial bipartition and distraction osteogenesis using an external device, with canthopexy, between 2009 and 2014, with available preoperative and postoperative frontal photographs, were included into the study. Palpebral fissure inclination was measured. Ratios of the intercanthal distance (ICD) to the outer-canthal distance (OCD) and the interpupillary distance to the OCD were computed. Preoperative and postoperative values were compared using the Wilcoxon signed-ranks test. RESULTS: The authors included 15 patients with Apert syndrome. The mean age at surgery was 10 ±â€Š3.4 years and the average follow-up was 7.3 ±â€Š2.9 years. We found normalization of the negative inclination of the palpebral fissures (right eye: 10.7 ±â€Š2.4 degrees preoperatively versus 7.0 ±â€Š3.1 degrees postoperatively, P < 0.001; left eye: 12.4 ±â€Š3.9 degrees preoperatively versus 8.7 ±â€Š4.1 degrees postoperatively, P = 0.01) and a significant reduction of the inter-pupillary distance: OCD ratio (0.717 ±â€Š0.027 preoperatively versus 0.699 ±â€Š0.030 postoperatively, P = 0.03). These modifications were stable on the long term. There was no significant change of the inter-canthal distance:OCD ratio. CONCLUSIONS: Le Fort III facial advancement with subcranial bipartition and distraction improves the position and orientation of the orbital region in children with Apert syndrome.

Orbital shape in intentional skull deformations and adult sagittal craniosynostoses.

Intentional cranial deformations are the result of external mechanical forces exerted on the skull vault that modify the morphology of various craniofacial structures such as the skull base, the orbits and the zygoma. In this controlled study, we investigated the 3D shape of the orbital inner mould and the orbital volume in various types of intentional deformations and in adult non-operated scaphocephaly - the most common type of craniosynostosis - using dedicated morphometric methods. CT scans were performed on 32 adult skulls with intentional deformations, 21 adult skull with scaphocephaly and 17 non-deformed adult skulls from the collections of the Muséum national d'Histoire naturelle in Paris, France. The intentional deformations group included six skulls with Toulouse deformations, eight skulls with circumferential deformations and 18 skulls with antero-posterior deformations. Mean shape models were generated based on a semi-automatic segmentation technique. Orbits were then aligned and compared qualitatively and quantitatively using colour-coded distance maps and by computing the mean absolute distance, the Hausdorff distance, and the Dice similarity coefficient. Orbital symmetry was assessed after mirroring, superimposition and Dice similarity coefficient computation. We showed that orbital shapes were significantly and symmetrically modified in intentional deformations and scaphocephaly compared with non-deformed control skulls. Antero-posterior and circumferential deformations demonstrated a similar and severe orbital deformation pattern resulting in significant smaller orbital volumes. Scaphocephaly and Toulouse deformations had similar deformation patterns but had no effect on orbital volumes. This study showed that intentional deformations and scaphocephaly significantly interact with orbital growth. Our approach was nevertheless not sufficient to identify specific modifications caused by the different types of skull deformations or by scaphocephaly.

Bilateral Dislocation of the Temporomandibular Joint in Children.

PURPOSE: Bilateral nontraumatic temporomandibular joint (TMJ) dislocation is an acute situation that can lead to a chronic and recurrent condition. Few pediatric cases have been reported in the literature and no standardized care protocol has been established to date. MATERIALS AND METHODS: Two cases of chronic bilateral dislocation of the TMJ in young children are reported and their medical management is discussed based on data from the literature. RESULTS: A 26 months-old child and a 19-months old child were included. Both had chronic bilateral TMJ dislocation managed using a combination of reduction under nitrous oxide sedation, reduction under general anesthesia, chin-to-vertex bandage and orthodontic headgear. CONCLUSION: TMJ dislocations in children raise specific concerns such as the need for screening for underlying congenital disorders of connective tissues. Furthermore, surgical options in children are very limited. The authors propose a standardized management protocol for recurrent joint dislocation in pediatric populations based on 2 new cases and data from the literature.

Three Skulls Dating from the French Revolutionary Years Diagnosed with Tinea Capitis: A Paleopathologic Approach.

The Musée Dupuytren was a Parisian pathology museum established in 1835. This museum hosted 3 skulls with severe craniofacial lesions initially tagged as aggressive forms of tinea capitis. The aim of this study was to investigate these specimens and discuss the initial diagnosis. Historical investigations were conducted based on the biographic data from the tags of the 3 skulls and entries on the catalog of the museum. Age was determined using dentition and the patency of cranial base synchondroses. The computed tomography scans were performed using standard medical devices. The 3 skulls were from the late 18th to early 19th century. Skull № 1 was a 5-year-old child and presented with microcephaly and extensive vault osteolysis compatible with an aggressive benign lesion, a malignant tumor, or a chronic infection. Skull № 2 was a 12- to 18-year-old teenager and presented with symmetrical porotic hyperostosis compatible with undernutrition and various hematologic conditions causing prolonged anemia, but also with chronic inflammation and/or infection. Skull № 3 was also from a 12- to 18-year-old teenager and presented with focal temporal osteolysis compatible with an aggressive benign or a low-grade malignant temporal soft-tissue lesion or with chronic infection. These skulls contribute to the understanding of the concept of tinea in the 19th century. They are furthermore windows on the sanitary and social conditions in Paris in the years following the French revolution and during the Napoleonian wars.

Magnetic resonance sialography of bilateral Stafne bone cavities.

Stafne bone cavities (SBCs) are mandibular radiolucent lesions with challenging differential diagnoses. Many radiologic methods have been proposed to visualize the presence of salivary gland tissues inside the cavities. This report describes a case of bilateral angular mandibular radiolucent cavities located below the mandibular nerve canal. Magnetic resonance (MR) imaging showed continuity between the submandibular glands and the tissue herniated into the cavities. The ductal system of the 2 submandibular glands was evaluated using MR sialography. MR sialography depicted opacification of the glandular ductal system distinct from the contents of the cavities up to its primary branches, confirming the diagnosis of SBC. MR sialography visualized the submandibular gland ducts and the presence of salivary gland tissue inside the mandibular cavities with precise topographic information. This technique does not involve cannulation or injection of contrast agents and does not expose a patient to radiation. MR sialography is a valuable addition to the common imaging procedures used in the investigation of SBCs.

Three-dimensional reconstructions from computed tomographic scans on smartphones and tablets: a simple tutorial for the ward and operating room using public domain software.

Handling 3-dimensional reconstructions of computed tomographic scans on portable devices is problematic because of the size of the Digital Imaging and Communications in Medicine (DICOM) stacks. The authors provide a user-friendly method allowing the production, transfer, and sharing of good-quality 3-dimensional reconstructions on smartphones and tablets.

Humanitarian Facial Recognition for Rare Craniofacial Malformations.

Children with congenital disorders are unfortunate collateral victims of wars and natural disasters. Improved diagnosis could help organize targeted medical support campaigns. Patient identification is a key issue in the management of life-threatening conditions in extreme situations, such as in oncology or for diabetes, and can be challenging when diagnosis requires biological or radiological investigations. Dysmorphology is a central element of diagnosis for craniofacial malformations, with high sensibility and specificity. Massive amounts of public data, including facial pictures circulate daily on news channels and social media, offering unique possibilities for automatic diagnosis based on facial recognition. Furthermore, AI-based algorithms assessing facial features are currently being developed to decrease diagnostic delays. Here, as a case study, we used a facial recognition algorithm trained on a large photographic database to assess an online picture of a family of refugees. Our aim was to evaluate the relevance of using an academic tool on a journalistic picture and discuss its potential application to large-scale screening in humanitarian perspectives. This group picture featured one child with signs of Apert syndrome, a rare condition with risks of severe complications in cases of delayed management. We report the successful automatic screening of Apert syndrome on this low-resolution picture, suggesting that AI-based facial recognition could be used on public data in crisis conditions to localize at-risk patients.

Distractor position and distraction amplitude in fronto-facial monobloc advancement : A case series.

Fronto-facial monobloc advancement with internal distraction (FFMBA) is a central procedure in the management of faciocraniosynostoses. In techniques with internal distraction, two sets of devices are generally positioned: bilateral fronto-orbital and temporo-zygomatic distractors, using a temporal tongue and groove osteotomy design. It is believed that distractors must be positioned as parallel as possible in the horizontal and sagittal planes to avoid mechanical conflicts between the sliding bone fragments of the tongue and groove during distraction, and thus optimize the advancement amplitude. Several approaches involving surgical planification and guides for distractor positioning have thus been proposed to monitor distractor placement. To explore the need for surgical planification in distractor placement, the parallelism of the position of the 4 distractors was assessed in 19 FFMBA procedures and we correlated a set of 10 distractor angles with the degree of advancement. We report that the horizontal cut of the tongue and groove can be used as a landmark for the positioning of the lower, temporo-zygomatic, distractor in fronto-facial monobloc advancement. Other parameters (relative position of the two homolateral and the two contralateral distractors and the orientations of the vertical and horizontal cuts of the tongue and groove) do not interfere with distraction, other things being equal. Our results indicate that distractor orientation is not a critical issue in fronto-facial monobloc advancement when devices are positioned as parallel as possible based on visual monitoring.

Genetic determinism and hemispheric influence in hair whorl formation.

BACKGROUND: The mechanisms determining the laterality and the rotation direction of hair whorls are unknown. Here we report observations on twins investigating the genetic bases of whorl pattern formation. Knowing that vortex phenomena may depend on geographic effects, we also provide comparative data on whorls from children born in the Northern hemisphere (France) versus children born in the Southern hemisphere (Chile). MATERIAL AND METHODS: We retrospectively included children from three populations: (1) Northern hemisphere general population, (2) Southern hemisphere general population, and (3) same-sex Northern hemisphere twins. We recorded whorl rotation direction (clockwise, counterclockwise), whorl position (left, right, central) and twinning type. Univariate logistic models were used to screen for associations between rotation direction and whorl position. For twins, the variable of interest was binary, i.e. same rotation direction (reference class) or opposite directions for each twin pair. For controls, all single combinations were included as virtual twins, and compared to real twins. Odds ratios (OR) were compared for both hemispheres, for real twins and virtual (control) twins. RESULTS: Seventy-four (37 pairs) twins and 50 children from the general population of each hemisphere were included. The OR for opposite rotation directions between two twins was ≠1 (p = 0.017), meaning that whorls rotated preferentially in the same direction in twins. ORs were <1 for Northern and Southern hemispheres, meaning that whorls rotated preferentially in the same direction in simulated twins. OR for the Northern hemisphere (0.04 [0.03; 0.05]) was less than the OR for the Southern hemisphere (0.28 [0.24; 0.32]) with no confidence interval superimposition, indicating than counterclockwise whorls were more frequent in the Southern hemisphere (p < 0.001). CONCLUSIONS: We suggest that hair whorl formation is a genetically determined developmental process that can be influenced by extrinsic environmental factors. Our results furthermore underline the general importance of studies focused on limit phenomena that can provide insights on general developmental mechanisms. We plead for large-scale epidemiological assessments of hair whorls in several Northern and Southern hemisphere populations to confirm these surprising findings suggesting significant modulations of craniofacial development by geographic effects.

Anatomy and mobility in the adult cadaveric craniocervical junction.

Genetic diseases with craniofacial malformations can be associated with anomalies of the craniocervical joint (CCJ). The functions of the CCJ are thus impaired, as mobility may be either limited by abnormal bone fusion causing headaches, or exaggerated in the case of hypermobility, which may cause irreparable damage to the spinal cord. Restoring the balance between mobility and stability requires surgical correction in children. The anatomy and biomechanics of the CCJ are quite unique, yet have been overlooked in the past decades. Pediatric evidence is so scarce, that investigating the adult CCJ is our best shot to disentangle the form-function relationships of this anatomical region. The motivation of the present study was to understand the morphological and functional basis of motion in the CCJ, in the hope to find morphological features accessible from medical imaging able to predict mobility. To do so, we have quantified the in-vitro kinematics of the CCJ in nine cadaveric asymptomatic adults, and estimated a wide range of mobility variables covering the complexity of spinal motion. We compared these variables with the shape of the occipital, the atlas and the axis, obtained using a dense geometric morphometric approach. Morphological joint congruence was also quantified. Our results suggest a strong relationship between bone shape and motion, with the overall geometry predicting best the primary movements, and the joint facets predicting best the secondary movements. We propose a functional hypothesis stating that the musculoligamental system determines movements of great amplitude, while the shape and congruence of joint facets determine the secondary and coupled movements, especially by varying the geometry of bone stops and the way ligaments are tensioned. We believe this work will provide valuable insights in understanding the biomechanics of the CCJ. Furthermore, it should help surgeons treating CCJ anomalies by enabling them to translate objectives of functional and clinical outcome into clear objectives of morphological outcome.

New diagnostic criteria for metopic ridges and trigonocephaly: a 3D geometric approach.

BACKGROUND: Trigonocephaly occurs due to the premature fusion of the metopic suture, leading to a triangular forehead and hypotelorism. This condition often requires surgical correction for morphological and functional indications. Metopic ridges also originate from premature metopic closure but are only associated with mid-frontal bulging; their surgical correction is rarely required. Differential diagnosis between these two conditions can be challenging, especially in minor trigonocephaly. METHODS: Two hundred seven scans of patients with trigonocephaly (90), metopic rigdes (27), and controls (90) were collected. Geometric morphometrics were used to quantify skull and orbital morphology as well as the interfrontal angle and the cephalic index. An innovative method was developed to automatically compute the frontal curvature along the metopic suture. Different machine-learning algorithms were tested to assess the predictive power of morphological data in terms of classification. RESULTS: We showed that control patients, trigonocephaly and metopic rigdes have distinctive skull and orbital shapes. The 3D frontal curvature enabled a clear discrimination between groups (sensitivity and specificity > 92%). Furthermore, we reached an accuracy of 100% in group discrimination when combining 6 univariate measures. CONCLUSION: Two diagnostic tools were proposed and demonstrated to be successful in assisting differential diagnosis for patients with trigonocephaly or metopic ridges. Further clinical assessments are required to validate the practical clinical relevance of these tools.

Facial dog bites in children: A public health problem highlighted by COVID-19 lockdown.

BACKGROUND: Stay-at-home injunction during COVID-19 pandemic led to new dynamics in households and increased the risk of domestic accidents involving pets. The aim of the study was to demonstrate an increase of facial dog bites in children during first lockdown period in France, compared to the same period in 2018 and 2019. Secondary objective was to investigate the demographics and circumstances in which dog bites occurred. METHODS: A retrospective multicentric study was conducted nationwide. Patients under 18 years old managed in fifteen oral and maxillofacial surgery departments for a dog bite were included. RESULTS: Eighty-seven patients were included. A significant increase of the number of children managed for facial dog bite was noticed in 2020 (p=0.0005). The male-to-female ratio was significantly reversed in 2020 with more bites in girls than boys (p=0.02). In 2020, children were mostly bitten to cheeks (28.6 %), lips-and-chin region (26.2 %), and eyelids (23.8 %). Severe bites increased in 2020, in comparison with 2018 and 2019. Dog bites occurring while petting or playing significantly increased in 2020 (31 %) (p=0.03). CONCLUSION: The process leading to bites is highly dependent on the balance of dog-owner relationship. This was strongly disrupted during COVID-19 pandemic, resulting in the increase of dog bites in households. Regarding dog bites, face is the most vulnerable area in children. Its injury has lots of esthetic and functional consequences and maxillofacial surgeons have a key role to play in their prevention. Reminders of some of these management and prevention strategies are presented in this article.

Effects of distraction osteogenesis with Le Fort osteotomies on upper airway volumes: a systematic review and meta-analyses.

OBJECTIVE: Distraction osteogenesis is one of the treatment options in patients with severe maxillomandibular abnormalities to treat morphological and respiratory problems (obstructive sleep apnea syndrome). The study aimed to evaluate the effect of Le Fort I, II and III distraction osteogenesis (DO) on upper airway dimensions and respiratory function. METHODS: Electronic search was performed in PubMed, Scopus, Embase, Google Scholar and Cochrane databases. Studies that only involved two dimensional analyses were excluded. Besides, studies that performed DO in conjunction with orthognathic surgery were not considered. NIH quality assessment tool was used to evaluate the risk of bias. Meta-analyses were performed to assess sleep apnea indices and the mean differences in the airway dimensions before and after DO. Gradings of Recommendations, Assessment, Development and Evaluation were used to analyze the evidence level. RESULTS: Among the 114 studies that went under full-text analyses, 11 articles met the inclusion criteria. Results of the quantitative analyses showed that maxillary Le Fort III DO significantly increased the amounts of oropharyngeal, pharyngeal and upper airway volumes. However, apnea-hypopnea index (AHI) showed a non-significant improvement after this procedure. Besides, the dimensions of the airways increased with Le Fort I and II DO, according to a qualitative analysis. Considering the design of the included studies, our results had a low level of evidence. CONCLUSION: Maxillary Le Fort DO does not significantly impact AHI, while it significantly increases the airway dimensions. Meanwhile, multicentric studies with standardized evaluation are still required to confirm the effects of maxillary Le Fort DO on airway obstruction.

Craniofacial growth and function in achondroplasia: a multimodal 3D study on 15 patients.

BACKGROUND: Achondroplasia is the most frequent FGFR3-related chondrodysplasia, leading to rhizomelic dwarfism, craniofacial anomalies, stenosis of the foramen magnum, and sleep apnea. Craniofacial growth and its correlation with obstructive sleep apnea syndrome has not been assessed in achondroplasia. In this study, we provide a multimodal analysis of craniofacial growth and anatomo-functional correlations between craniofacial features and the severity of obstructive sleep apnea syndrome. METHODS: A multimodal study was performed based on a paediatric cohort of 15 achondroplasia patients (mean age, 7.8 ± 3.3 years), including clinical and sleep study data, 2D cephalometrics, and 3D geometric morphometry analyses, based on CT-scans (mean age at CT-scan: patients, 4.9 ± 4.9 years; controls, 3.7 ± 4.2 years). RESULTS: Craniofacial phenotype was characterized by maxillo-zygomatic retrusion, deep nasal root, and prominent forehead. 2D cephalometric studies showed constant maxillo-mandibular retrusion, with excessive vertical dimensions of the lower third of the face, and modifications of cranial base angles. All patients with available CT-scan had premature fusion of skull base synchondroses. 3D morphometric analyses showed more severe craniofacial phenotypes associated with increasing patient age, predominantly regarding the midface-with increased maxillary retrusion in older patients-and the skull base-with closure of the spheno-occipital angle. At the mandibular level, both the corpus and ramus showed shape modifications with age, with shortened anteroposterior mandibular length, as well as ramus and condylar region lengths. We report a significant correlation between the severity of maxillo-mandibular retrusion and obstructive sleep apnea syndrome (p < 0.01). CONCLUSIONS: Our study shows more severe craniofacial phenotypes at older ages, with increased maxillomandibular retrusion, and demonstrates a significant anatomo-functional correlation between the severity of midface and mandible craniofacial features and obstructive sleep apnea syndrome.

Mobility Assessment Using Multi-Positional MRI in Children with Cranio-Vertebral Junction Anomalies.

OBJECTIVE: This study aimed to assess the relevance of using multi-positional MRI (mMRI) to identify cranio-vertebral junction (CVJ) instability in pediatric patients with CVJ anomalies while determining objective mMRI criteria to detect this condition. MATERIAL AND METHODS: Data from children with CVJ anomalies who underwent a mMRI between 2017 and 2021 were retrospectively reviewed. Mobility assessment using mMRI involved: (1) morphometric analysis using hierarchical clustering on principal component analysis (HCPCA) to identify clusters of patients by considering their mobility similarities, assessed through delta (Δ) values of occipito-cervical parameters measured on mMRI; and (2) morphological analysis based on dynamic geometric CVJ models and analysis of displacement vectors between flexion and extension. Receiver operating characteristics (ROC) curves were generated for occipito-cervical parameters to establish instability cut-off values. (3) Additionally, an anatomical qualitative analysis of the CVJ was performed to identify morphological criteria of instability. RESULTS: Forty-seven patients with CVJ anomalies were included (26 females, 21 males; mean age: 10.2 years [3-18]). HCPCA identified 2 clusters: cluster №1 (stable patients, n = 39) and cluster №2 (unstable patients, n = 8). ΔpB-C2 (pB-C2 line delta) at ≥2.5 mm (AUC 0.98) and ΔBAI (Basion-axis Interval delta) ≥ 3 mm (AUC 0.97) predicted instability with 88% sensibility and 95% specificity and 88% sensitivity and 85% specificity, respectively. Geometric CVJ shape analysis differentiated patients along a continuum, from a low to a high CVJ motion that was characterized by a subluxation of C1 in the anterior direction. Qualitative analysis found correlations between instability and C2 anomalies, including fusions with C3 (body p = 0.032; posterior arch p = 0.045; inferior articular facets p = 0.012; lateral mass p = 0.029). CONCLUSIONS: We identified a cluster of pediatric patients with CVJ instability among a cohort of CVJ anomalies that were characterized by morphometric parameters with corresponding cut-off values that could serve as objective mMRI criteria. These findings warrant further validation through prospective case-control studies.