Pierre Robin sequence: A comprehensive narrative review of the literature over time

Global Research Trends and Focuses on Pierre Robin Sequence From 1992 to 2023: A Bibliometric Analysis of the Past 3 Decades

There is currently a lack of scientific bibliometric analyses in the field of Pierre Robin sequence (PRS). Pierre Robin sequence is known for its clinical triad of micrognathia, glossoptosis, airway obstruction, and possible secondary cleft palate. These defects can lead to upper airway obstruction, sleep apnea, feeding difficulties, affect an individual's growth and development, education level, and in severe cases can be life-threatening. Through analysis of literature retrieved from the Web of Science Core Collection (WoSCC) database using Results Analysis and Citation Report and Citespace software, 933 original articles and reviews were included after manual screening. The overall trend for the number of annual publications and citations was increasing. On the basis of the analysis, airway evaluation and treatment, mandibular distraction osteogenesis (MDO), as well as descriptions of PRS characteristics have been the focus of research in this field. In addition, with advances in new technologies such as gene sequencing and expanding understanding of diseases among researchers, research on genetics and etiology related to PRS has become a growing trend.

Lacrimal drainage anomalies in Pierre Robin sequence

Pierre-Robin sequence consists of a classical triad of micrognathia, glossoptosis, and upper airway obstruction. The common ocular manifestations include congenital glaucoma, high myopia, maculopathy, and retinal detachment. Except for a mention of a nasolacrimal duct obstruction without many details, lacrimal drainage anomalies have not been reported earlier to the best of the authors' knowledge. The present case describes several lacrimal drainage anomalies including supernumerary puncta, canalicular wall hypoplasia, grossly dilated nasolacrimal duct, and complex congenital nasolacrimal duct obstruction in a patient of Pierre Robin sequence. The patient was successfully managed with endoscopic guided probing and marsupialization of the large intranasal cyst resulting in a complete resolution of epiphora.

Overexpression of Fgf18 in cranial neural crest cells recapitulates Pierre Robin sequence in mice

The pivotal role of FGF18 in the regulation of craniofacial and skeletal development has been well established. Previous studies have demonstrated that mice with deficiency in Fgf18 exhibit severe craniofacial dysplasia. Recent clinical reports have revealed that the duplication of chromosome 5q32-35.3, which encompasses the Fgf18 gene, can lead to cranial bone dysplasia and congenital craniosynostosis, implicating the consequence of possible overdosed FGF18 signaling. This study aimed to test the effects of augmented FGF18 signaling by specifically overexpressing the Fgf18 gene in cranial neural crest cells using the Wnt1-Cre;pMes-Fgf18 mouse model. The results showed that overexpression of Fgf18 leads to craniofacial abnormalities in mice similar to the Pierre Robin sequence in humans, including abnormal tongue morphology, micrognathia, and cleft palate. Further examination revealed that elevated levels of Fgf18 activated the Akt and Erk signaling pathways, leading to an increase in the proliferation level of tongue tendon cells and alterations in the contraction pattern of the genioglossus muscle. Additionally, we observed that excessive FGF18 signaling contributed to the reduction in the length of Meckel's cartilage and disrupted the development of condylar cartilage, ultimately resulting in mandibular defects. These anomalies involve changes in several downstream signals, including Runx2, p21, Akt, Erk, p38, Wnt, and Ihh. This study highlights the crucial role of maintaining the balance of endogenous FGF18 signaling for proper craniofacial development and offers insights into potential formation mechanisms of the Pierre Robin sequence.

Mechanical stress can regulate temporomandibular joint cavitation via signalling pathways

The temporomandibular joint (TMJ), composed of temporal fossa, mandibular condyle and a fibrocartilage disc with upper and lower cavities, is the biggest synovial joint and biomechanical hinge of the craniomaxillofacial musculoskeletal system. The initial events that give rise to TMJ cavities across diverse species are not fully understood. Most studies focus on the pivotal role of molecules such as Indian hedgehog (Ihh) and hyaluronic acid (HA) in TMJ cavitation. Although biologists have observed that mechanical stress plays an irreplaceable role in the development of biological tissues and organs, few studies have been concerned with how mechanical stress regulates TMJ cavitation. Based on the evidence from human or other animal embryos today, it is implicated that mechanical stress plays an essential role in TMJ cavitation. In this review, we discuss the relationship between mechanical stress and TMJ cavitation from evo-devo perspectives and review the clinical features and potential pathogenesis of TMJ dysplasia.

Craniofacial disorders and dysplasias: Molecular, clinical, and management perspectives

There is a wide spectrum of craniofacial bone disorders and dysplasias because embryological development of the craniofacial region is complex. Classification of craniofacial bone disorders and dysplasias is also complex because they exhibit complex clinical, pathological, and molecular heterogeneity. Most craniofacial disorders and dysplasias are rare but they present an array of phenotypes that functionally impact the orofacial complex. Management of craniofacial disorders is a multidisciplinary approach that involves the collaborative efforts of multiple professionals. This review provides an overview of the complexity of craniofacial disorders and dysplasias from molecular, clinical, and management perspectives.

Analysis of the cause of retrolingual obstruction in patients with moderate-severe obstructive sleep apnea

PURPOSE

To evaluate the percentage of obstructive sleep apnea (OSA) patients with retrolingual obstruction in all moderate-severe OSA patients and the proportions of different causes in all moderate-severe OSA patients with retrolingual obstruction and to discuss the accuracy of the Friedman tongue position (FTP) and retrolingual cross-sectional area (RCSA) in assessing the retrolingual obstruction.

METHODS

Two hundred and twenty moderate-severe OSA patients were enrolled. After retrolingual obstruction was diagnosed, the percentage of OSA patients with retrolingual obstruction in all moderate-severe OSA patients was calculated. After that, the different causes of retrolingual obstruction were diagnosed based on different diagnostic criteria, and the proportions of different causes in all moderate-severe OSA patients with retrolingual obstruction were calculated. Finally, the correlations between FTP, RCSA, and apnea-hypopnea index after nasopharyngeal tube insertion (NPT-AHI) were analyzed, and the proportions of different causes of retrolingual obstruction based on different FTP and RCSA were observed.

RESULTS

There were 128 patients with retrolingual obstruction, accounting for 58.2% of all moderate-severe OSA patients. In 128 patients with retrolingual obstruction, the proportions of glossoptosis (48.4%), palatal tonsil hypertrophy (28.1%), and lingual hypertrophy (8.6%) were relatively high. Both FTP and RCSA did not correlate with NPT-AHI. The proportion of lingual hypertrophy increased gradually with the increase of FTP and the proportions of glossoptosis in all FTP classifications were high. The patients with RCSA > 180 mm2 were mainly affected by glossoptosis and palatal tonsil hypertrophy, while patients with RCSA ≤ 180 mm2 were mainly affected by lingual hypertrophy.

CONCLUSION

The percentage of patients with retrolingual obstruction in all moderate-severe OSA patients is relatively high, mainly glossoptosis, palatal tonsil hypertrophy, and lingual hypertrophy. FTP classification and RCSA can only reflect the retrolingual anatomical stenosis, but cannot fully reflect the retrolingual functional stenosis, especially the presence of glossoptosis.

The Evolution of Robin Sequence Treatment Based on the Biomimetic Interdisciplinary Approach: A Historical Review

The Robin sequence is a congenital anomaly characterized by a triad of features: micrognathia, glossoptosis, and airway obstruction. This comprehensive historical review maps the evolution of approaches and appliances for its treatment from the past to the current modern possibilities of an interdisciplinary combination of modern engineering, medicine, materials, and computer science combined approach with emphasis on designing appliances inspired by nature and individual human anatomy. Current biomimetic designs are clinically applied, resulting in appliances that are more efficient, comfortable, sustainable, and safer than legacy traditional designs. This review maps the treatment modalities that have been used for patients with a Robin sequence over the years. Early management of the Robin sequence focused primarily on airway maintenance and feeding support, while current management strategies involve both nonsurgical and surgical interventions and biomimetic biocompatible personalized appliances. The goal of this paper was to provide a review of the evolution of management strategies for patients with the Robin sequence that led to the current interdisciplinary biomimetic approaches impacting the future of Robin Sequence treatment with biomimetics at the forefront.

Tri-lobed Tongue: Rare Manifestation Accompany With Pierre Robin Sequence

BACKGROUND

The tongue is an essential organ accounted for proper deglutition and articulation. Surgical repair should be planned soon after diagnosis of any structural abnormality to prevent later speech and swallowing disorders. The lobulated tongue could be isolated (sporadic) or in association with other disorders. Pierre Robin Sequence (PRS) consists of the clinical trial of congenital micrognathia, glossoptosis, and airway obstruction with variable inclusion of a cleft palate. We present the case of a rare congenital tri-lobed tongue with Pierre Robin sequence and its surgical management in our hospital setting.

CASE PRESENTATION

Six-month-old boy presented with severe retrognathia, high arch, complete isolated cleft palate, and a bizarre mass in the oral cavity instead of his tongue that led to disruption of his swallowing. The mass (deformed tongue) check clearly, and the normal shape of the tongue was restored through multiple local randomized flaps. Dramatic improvement in swallowing was noticed 6 months after surgery during postoperative follow-up.

DISCUSSION

We present the case of a patient with a tri-lobed tongue with Pierre Robin sequence characterized by severe retrognathia, high arch, and complete isolated cleft palate. This seems to be the first reported case of this particular craniofacial anomaly.

CONCLUSION

The management of infants with the Pierre Robin sequence is complex, and much still needs to be learned and practiced. Congenital tri-lobed tongue with a cleft as part of the Pierre Robin sequence is a very rare malformation. Early repair of the tongue is important to assist the baby in adapting to speech and swallowing as they grow.

Differences in analysis and treatment of upper airway obstruction in Robin sequence across different countries in Europe

The goal of this study was to explore the availability of diagnostic and treatment options for managing upper airway obstruction (UAO) in infants with Robin Sequence (RS) in Europe. Countries were divided in lower- (LHECs, i.e., PPP per capita < $4000) and higher-health expenditure countries (HHECs, i.e., PPP per capita ≥ $4000). An online survey was sent to European healthcare professionals who treat RS. The survey was designed to determine the availability of diagnostic tools such as arterial blood gas analysis (ABG), pulse oximetry, CO2 analysis, polysomnography (PSG), and sleep questionnaires, as well as to identify the used treatment options in a specific center. Responses were received from professionals of 85 centers, originating from 31 different countries. It was equally challenging to provide care for infants with RS in both LHECs and HHECs (3.67/10 versus 2.65/10, p = 0.45). Furthermore, in the LHECs, there was less access to ABG (85% versus 98%, p = 0.03), CO2 analysis (45% versus 70%, p = 0.03), and PSG (54% versus 93%, p < 0.01). There were no significant differences in the accessibility concerning pulse oximetry, sleep questionnaires, home saturation monitoring, nasopharyngeal tubes, Tuebingen plates, and mandibular distraction.    Conclusion: This study demonstrates a large difference in available care for infants with RS throughout Europe. LHECs have less access to diagnostic tools in RS when compared to HHECs. There is, however, no difference in the availability of treatment modalities between LHECs and HHECs. What is Known: • Patients with Robin sequence (RS) require complex and multidisciplinary care. They can present with moderate to severe upper airway obstruction (UAO). There exists a large variety in the use of diagnostics for both UAO treatment indications and evaluations. In most cases, conservative management of UAO in RS is sufficient. Patients with UAO that persist despite conservative management ultimately need surgical intervention. To determine which intervention is best suitable for the individual RS patient, the level of UAO needs to be determined through diagnostic testing. • There is a substantial variation among institutions across Europe for both diagnostics and treatment options in UAO. A standardized, internationally accepted protocol for the assessment and management of UAO in RS could guide healthcare professionals in the timing of assessment and indications to prevent escalation of UAO. Creating such a protocol might be a challenge, as there are large financial differences between countries in Europe (e.g., health expenditure per capita in purchasing power parity in international dollars ranges from $600 to over $8500). What is New: • There is a substantial variation in the availability of objective diagnostic tools between European countries. Arterial blood gas analysis, CO2 analysis and polysomnography are not equally accessible for lower-healthcare expenditure countries (LHECs) compared to higher-healthcare expenditure countries (HHECs). These differences are not only limited to availability; there is also a difference in quality of these diagnostic tools. Surprisingly, there is no difference in access to treatment tools between LHECs and HHECs. • There is national heterogeneity in access to tools for diagnosis and treatment of RS, which suggests centralization of health care, showing that specialized care is only available in tertiary centers. By centralization of care for RS infants, diagnostics and treatment can be optimized in the best possible way to create a uniform European protocol and ultimately equal care across Europe. Learning what is necessary for adequate monitoring could lead to better allocation of resources, which is especially important in a low-resource setting.

DLX6 and MSX1 from saliva samples as potential predictors of mandibular size: A cross-sectional study

INTRODUCTION

Morphologic features of the mandible are influenced by the genes of each individual. Mandible size is important to orthodontists because the mandible is the mechanism by which the lower face influences facial esthetics and dental function. To date, no biological marker has been identified that indicates eventual mandible size. This study aimed to correlate the expression of DLX5, DLX6, EDN1, HAND2, PRRX1, and MSX1 to mandible size.

METHODS

Fifty-nine orthodontic patients aged >6 years who had available cephalometric radiographs were studied. Patients were classified on the basis of condylion-to-gnathion measurements. Messenger RNA was isolated from saliva and subjected to real-time quantitative polymerase chain reaction.

RESULTS

Threshold cycle values for subjects with small mandibles (>1 standard deviation [SD] from the mean) had the least expression of DLX6 and MSX1. Threshold cycle values for subjects with large mandibles (>1 SD) had less expression of DLX6 and MSX1 than subjects within 1 SD but more than those with small mandibles.

CONCLUSIONS

DLX6 and MSX1 are related to mandible development and size. This finding could be used to improve treatment planning for medical and dental professionals seeking to understand the impact of genetics on bone growth.

Does Frenotomy Modify Upper Airway Collapse in OSA Adult Patients? Case Report and Systematic Review

Ankyloglossia (tongue-tie) is a condition of the oral cavity in which an abnormally short lingual frenulum affects the tongue's mobility. Literature on the correlation between ankyloglossia and obstructive sleep apnea (OSA) is scarce. The main objective of this study was to report our preliminary experience in adult OSA patients before and after ankyloglossia treatment, using drug-induced sleep endoscopy (DISE) to evaluate the upper airway modifications resulting after treatment, and to present a systematic review of the impact of ankyloglossia and its treatment on OSA adults. We found that, after frenotomy, regarding the DISE findings, and according to the VOTE classification, two of the three patients showed an improvement in tongue level, from 2A-P (complete anteroposterior collapse) to 1ap (partial anteroposterior collapse). The third patient showed no changes in his UA after frenotomy, neither worsening nor showing improvement. Thus, the results of this study suggest that frenotomy in OSA patients with ankyloglossia could reduce tongue collapse, probably by allowing the tongue to take into the physiological position in the oral cavity. These patients should undergo speech therapy and oropharyngeal exercises prior to any surgical procedure, in order to avoid glossoptosis and to improve the quality of life and sleep apnea results.

Automation of Measurements for Personalized Medical Appliances by Means of CAD Software-Application in Robin Sequence Orthodontic Appliances

Measuring the dimensions of personalized devices can provide relevant information for the production of future such devices used in various medical specialties. Difficulties with standardizing such measurement and obtaining high accuracy, alongside cost-intensive measuring methodologies, has dampened interest in this practice. This study presents a methodology for automatized measurements of personalized medical appliances of variable shape, in this case an orthodontic appliance known as Tübingen Palatal Plate (TPP). Parameters such as length, width and angle could help to standardize and improve its future use. A semi-automatic and custom-made program, based on Rhinoceros 7 and Grasshopper, was developed to measure the device (via an extraoral scanner digital file). The program has a user interface that allows the import of the desired part, where the user is able to select the necessary landmarks. From there, the program is able to process the digital file, calculate the necessary dimensions automatically and directly export all measurements into a document for further processing. In this way, a solution for reducing the time for measuring multiple dimensions and parts while reducing human error can be achieved.

Qualitative and quantitative assessment of condylar displacement after orthognathic surgery: A voxel-based three-dimensional analysis

PURPOSE

This study aimed to evaluate the morphometric changes in the position of the mandibular condyles before and after orthognathic surgery.

METHODS

A retrospective single-center cohort study was conducted and included patients with a presurgical (T1) and postsurgical (T2) Cone Beam computed tomography (CBCT). The primary predictor variable was the orthognathic surgical treatment. Pre-operative and post-operative CBCT scans were superimposed using voxel-based registration. Semitransparent overlays of the models of condylar regions at T1 and T2 were created for the qualitative analysis. The primary outcome variable was the quantitative displacement of condyles (CoR; CoL) analyzed in X, Y, Z axis and the 3D distances. Descriptive and bivariate statistical analysis was performed, setting α=0.05.

RESULTS

The study sample included 33 patients (mean age: 25.33±2.49 years) affected by skeletal class III malocclusion with or without skeletal asymmetry. The X-axis showed a mean movement of 0.25 ± 0.17 mm for CoR, and 0.52 ± 0.51 mm for CoL. The Y-axis showed a mean movement of 0.29 ± 0.2 mm for CoR, and 0.51 ± 0.8 mm for CoL. The Z-axis was 0.33 ± 0.2 mm for CoR, and 0.5 ± 0.49 mm for CoL. No statistically significant difference was calculated comparing the movement of condylar surface between asymmetric and not asymmetric patients (p = 0.26 for CoR; p = 0.13 for CoL). No statistically significant difference was found in intercondylar distance between T1 and T2 (p = 0.39).

CONCLUSION

No statistically nor clinically significant condylar displacement are recorded in orthognathic surgery patients at 12 to 18 months of follow-up.

Dental outcomes after neonatal mandibular distraction

PURPOSE OF REVIEW

The aim of this study was to understand dental complications associated with neonatal mandibular distraction and subsequent dental outcomes.

RECENT FINDINGS

Dental injury is often associated with neonatal mandibular distraction osteogenesis. Newer technology offers safer techniques to minimize this risk. Long-term follow up and dental outcomes in permanent dentition are needed to better understand the actual risk associated with the procedure.

SUMMARY

Surgeons performing neonatal mandibular distraction osteogenesis need to understand the associated risks to deciduous and permanent dentition as well as techniques to mitigate this risk.

Early weight gain in infants with Robin sequence after mandibular distraction

This retrospective cohort study was performed to assess weight gain in infants with Robin sequence (RS) treated by mandibular distraction osteogenesis (MDO). The primary outcome variable was average daily weight gain for the following time periods: (1) birth to MDO (T1), (2) MDO to distractor removal (T2), (3) distractor removal to 6 months later (T3), and (4) 6 months to 12 months following distractor removal (T4). Published growth curves were used for comparison. Differences were assessed using the Wilcoxon matched-pairs signed rank test. Twenty-two infants were included in the study. During T1, the infants had 9.47 ± 12.61 g/day less weight gain than expected (P = 0.001). However, for T2, T3, and T4, the infants demonstrated 3.48 ± 6.17 g/day (P = 0.028), 2.19 ± 4.47 g/day (P = 0.030), and 1.83 ± 3.25 g/day (P = 0.028) more weight gain than expected. Feeding tube use resulted in improved weight gain during T1 (P < 0.001), but was associated with poorer weight gain in T3 (P = 0.003) and T4 (P = 0.001). In conclusion, infants with RS treated by MDO demonstrated poorer weight gain relative to their peers between birth and the MDO operation. However, from the MDO procedure to 12 months post-distractor removal, infants who had MDO showed faster weight gain than their age-matched peers.

Incidence and management of condylar resorption after orthognathic surgery: An overview

Objective

Condylar resorption (CR) is one of the major post-surgical complications of orthognathic surgery. This systematic review (SR) aimed to evaluate epidemiological data, risk factors, and therapeutical management of CR.

Methods

Six databases were screened by two investigators until September 2020 to obtain all SRs. After reading the titles and abstracts, eligible SRs were determined and data extraction was performed. Using the latest version of A Measurement Tool to Assess Systematic Reviews, the methodological quality of the included SRs was determined.

Results

Ten SRs with low or critically-low methodological quality were included in this review. Mandibular hypoplasia on the sagittal plane and hyperdivergent growth pattern on the vertical plane were the most common skeletal alterations in which CR could occur after orthognathic surgery. Post-operative condylar changes were analyzed both on two-dimensional and three-dimensional (3D) radiographic examinations. The incidence of CR was not related to the fixation method. Based on the severity of the pathological conditions, management of CR can include conservative or surgical therapy.

Conclusions

Despite the limited evidence in literature, CR is considered a consequence of orthognathic surgery. However, an accurate diagnosis of CR and a better orthognathic surgical planning must include 3D radiographic examinations to improve pre- and post-surgical comparison. Well-designed studies with long-term follow-up and 3D data are needed to clarify the findings of this analysis..

Positioning as a conservative treatment option in infants with micrognathia and/or cleft

Evaluation and management of airway obstruction in prone position were reviewed from studies in infants with micrognathia and/or cleft palate, using polysomnography (PSG) or similar measures, and comparing prone against other positions. Most studies identified were case series from specialist referral centres. Airway obstruction appears more severe on PSG than clinical assessment, but there is no consensus for PSG definitions of mild, moderate or severe airway obstruction. Infants show individual variability in responses to positioning; sleep quality tends to improve when prone, but 22-25% have better respiratory outcomes when supine. Most centres recommend home monitoring if advising that an infant be placed prone to manage their airway obstruction. In conclusion, in case series, success rates for managing infant airway obstruction by prone positioning vary from 12 to 76%. PSG studies comparing prone with other sleep positions can help differentiate which infants show improved airway obstruction and/or sleep quality when positioned prone.

Sex and age biological variation of the mandible in a Portuguese population- a forensic and medico-legal approaches with three-dimensional analysis

The medico-legal identification is based on a set of discriminatory characteristics between individuals in their biological, social, cultural, religious, legal and economic framework. The purpose of this study was to characterize the biological variation, regarding gender and age, in a Portuguese population. A three-dimensional (3D) analysis of 215 mandibles (7-20 years old) from the database of the Laboratory of Forensic Dentistry, Faculty of Medicine, University of Coimbra (CE-112/2019) was performed. A total of 13 cephalometric points defined 10 linear variables and 7 angular variables, on 3D reconstructions from ConeBeam Computed Tomography (CBCT) images. Intra and inter-observer errors were analyzed by Technical Measurement Error test. A descriptive statistics was performed. To verify the influence of gender and age on the variables and to determine its predictive value, ANOVA and Logistic Regression Analysis were performed. Gender and age influence most of the linear variables, however, the same is not true for angular variables. In the analysis of all variables, the model has a reasonable level of sensitivity (67.8%) according to gender. For the age prediction, with all variables, the model presented a reasonable level of sensitivity, classifying 79.4% of the individuals. The results supported, with a high level of statistical significance, an adequate recognition of individuals highlighting the identification and criminal imputability of Portuguese individuals.

Association of Upper Lip Morphology Characteristics with Sagittal and Vertical Skeletal Patterns: A Cross Sectional Study

Background: Upper lip morphology is essential in diagnosis and treatment of orthodontics and orthognathic surgery. This study is aimed to evaluate the association between upper lip characteristics (ULCs) and skeletal patterns (SPs). Methods: 2079 patients were involved and grouped by sagittal and vertical. Class I, II, and III were identified by ANB angle, while normodivergent, hyperdivergent, and hypodivergent were identified by Facial Height Index and Sum of Angles. ULCs were evaluated by superior sulcus depth, nasolabial angle, upper lip length, basic upper lip thickness, and upper lip thickness. Confounders including demography, malocclusion, upper incisors, and upper lips were adjusted by multivariate linear regression to identify the association between ULCs and SPs. Group differences were evaluated with analysis of variance and Chi-square test. Results: The mean value of ULCs and prevalence of SPs were explored in the Western China population. ULCs were significantly different in various sagittal, vertical, and combined SPs. Superior sulcus depth was negatively related to Class II, and positively related to Class III and the hypodivergent pattern after adjusted by confounders. Conclusions: ULCs significantly varied among different SPs, while only superior sulcus depth was independently associated with SPs, indicating superior sulcus depth is the only ULC that might be significantly corrected by intervention of skeletal growth.

Does Mandibular Gonial Angle Influence the Eruption Pattern of the Lower Third Molar? A Three-Dimensional Study

Lower third molars (M3M) are the most frequent impacted teeth. The aim of this study was to evaluate the correlation between M3M position and gonial angle. A retrospective cross-sectional study was conducted. The study population included patients with unilateral or bilateral M3M and underwent Cone Beam Computed Tomography. A morphometric analysis of the mandible was performed after three-dimensional reconstruction, recording gonial angle (GA), ramus high, ramus width, ramus divergency, and retromolar space. GA was the primary predictor variable. The primary outcome variable was the position of M3M analyzed in sagittal, axial, and coronal planes. Descriptive, bivariate, and multiple regression statistics were performed (p < 0.05). Study sample included 172 patients (mean age: 26.3 ± 4.6 years); 266 M3Ms were analyzed. The average GA was 122.6° ± 4.8°. A reduced GA value was significantly associated with a deeply impacted M3M in the ramus. With a progressive decrease of GA, M3M assumed a more horizontal position closer to the mandibular canal (p < 0.05). A lower GA showed a reduced retromolar space with more complex impacted M3M (p < 0.05). The results confirm a statistically significant correlation between GA and the position of M3M. Higher incidence of impacted M3M was related to a reduction of the GA value.

Epidemiology of Pierre-Robin sequence in Europe: A population-based EUROCAT study

BACKGROUND

Pierre Robin sequence (PRS) is a rare congenital anomaly. Respiratory disorders and feeding difficulties represent the main burden.

OBJECTIVE

The aim of this study was to investigate the epidemiology of PRS using a cohort of cases from EUROCAT, the European network of population-based registries of congenital anomalies.

METHODS

We analysed cases of PRS born in the period 1998-2017 collected by 29 population-based congenital anomaly registries in 17 different countries. We calculated prevalence estimates, prenatal detection rate, survival up to 1 week, and proportions of associated anomalies. The effect of maternal age was tested using a Poisson regression model.

RESULTS

Out of 11 669 155 surveyed births, a total of 1294 cases of PRS were identified. The estimate of the overall prevalence was 12.0 per 100 000 births (95% CI 9.9, 14.5). There was a total of 882 (68.2%) isolated cases, and the prevalence was 7.8 per 100 000 births (95% CI 6.7, 9.2). A total of 250 cases (19.3%) were associated with other structural congenital anomalies, 77 cases (6.0%) were associated with chromosomal anomalies and 77 (6.0%) with genetic syndromes. The prenatal detection rate in isolated cases was 12.0% (95% CI 9.8, 14.5) and increased to 16.0% (95% CI 12.7, 19.7) in the sub-period 2008-2017. The prevalence rate ratio of non-chromosomal cases with maternal age ≥35 was higher than in cases with maternal age <25 for total (PRR 1.26, 95% CI 1.05, 1.51) and isolated cases (PRR 1.33, 95% CI 1.00, 1.64). Survival of chromosomal cases (94.2%) and multiple anomaly cases (95.3%) were lower than survival of isolated cases (99.4%).

CONCLUSIONS

This epidemiological study using a large series of cases of PRS provides insights into the epidemiological profile of PRS in Europe. We observed an association with higher maternal age, but further investigations are needed to test potential risk factors for PRS.

Spatial Analysis of the Temporomandibular Joint and Condyle Following Mandibular Distraction in Robin Sequence

ABSTRACT

To comprehensively assess changes in temporomandibular joint and mandibular condyle morphology in Robin sequence (RS) patients undergoing mandibular distraction osteogenesis (MDO). A retrospective analysis of pediatric patients with RS and functional temporomandibular joints who underwent MDO by a single surgeon was performed. Preoperative and postoperative computed tomography (CT) scans were morphometrically analyzed three-dimensional in 3-matic and Mimics (Materialise). Comparative analysis was performed using Wilcoxon signed-rank tests. Fourteen RS patients were included (28 condyles, 56 CT scans), 78% male and 22% females. The mean age at surgery was 9.4 weeks (range 1.6-46.7 weeks). The average age at initial CT was 5.3 days (range 0-11 days). The mean time interval for CT scan before MDO and after hardware removal were 8.8 ± 6.4 days and 11.2 ± 25.8 days, respectively. Rotatory changes of the condyle revealed a significantly decreased horizontal angle following MDO (-7.55°, 95% confidence interval -11.13° to -3.41°; P < 0.001). Anteroposteriorly, the angle between condylar process and ramus (incline) increased significantly (14.14°, 95% confidence interval 10.71°-19.59°; P < 0.001). Intragroup analysis revealed no difference between left versus right condylar position measurements. The condyle itself increased in size and length and the intercondylion distance increased post-MDO. There were no complications and all patients achieved relief of airway obstruction without tracheostomy. Morphologic and positional changes of the mandibular condyle following MDO in RS patients parallel changes that occur during normal development in non-RS patients. As a result, MDO may facilitate normal condylar morphology and function in RS patients.

Effects of Mandibular Distraction Osteogenesis on Three-Dimensional Upper Airway Anatomy in Newborns Affected by Isolated Pierre Robin Sequence

Background

Effective airway management is critical to Pierre Robin Sequence treatment. The goal of this study is to assess the three-dimensional changes in airway size and shape in 117 newborns with isolated Pierre Robin sequence who underwent mandibular distraction osteogenesis.

Methods

During the study period (11/29/2016 to 11/26/2019), 117 newborns affected by isolated Pierre Robin sequence met the inclusion criteria for the present study. All 117 included patients underwent linear distraction. Demographic variables were recorded and analyzed. Cone-beam computed tomography were performed before and after mandibular distraction osteogenesis. A systemic quantitative three-dimensional analysis of size and shape of upper airway was performed.

Results

The mean age was 71 day (range 12 to 213). The mean weight was 3.9 kg (range 2.3-6.8). A total of 53 patients are female and 64 are male. When the distraction device was removed, the upper and lower jaws were symmetrically aligned. Pre- and post-distraction comparison clearly showed osteogenesis. For the size of the upper airway, airway volume, anteroposterior dimension of the retroglossal airway, lateral dimension of retroglossal airway, minimum retropalatal area, minimum retroglossal area, average cross-sectional area and minimum cross-sectional area increased significantly after mandibular distraction osteogenesis (P < 0.001). However, the airway length did not change significantly (P > 0.05). For the shape of the upper airway, the lateral/anteroposterior ratio in the retroglossal region and the ratio of the retropalatal airway diameter to the retroglossal airway diameter significantly decreased after mandibular distraction osteogenesis (P < 0.001). The airway uniformity significantly increased after mandibular distraction osteogenesis (P < 0.001).

Conclusion

Mandibular distraction osteogenesis for isolated Pierre Robin sequence improved size and shape of the upper airway, further confirming mandibular osteogenesis distraction as an effective surgical modality to address the airway obstruction in newborns affected by isolated Pierre Robin sequence. Cone-beam computed tomography scanning and analysis can serve as a safe and effective examination modality for upper airway applications of PRS newborns.

Accuracy and Reliability of 4D-CT and Flexible Laryngoscopy in Upper Airway Evaluation in Robin Sequence

OBJECTIVES

To evaluate the performance of 4-dimensional computed tomography (4D-CT) in assessing upper airway obstruction (UAO) in patients with Robin sequence (RS) and compare the accuracy and reliability of 4D-CT and flexible fiber-optic laryngoscopy (FFL).

STUDY DESIGN

Prospective survey of retrospective clinical data.

SETTING

Single, tertiary care pediatric hospital.

METHODS

At initial and 30-day time points, a multidisciplinary group of 11 clinicians who treat RS rated UAO severity in 32 sets of 4D-CT visualizations and FFL videos (dynamic modalities) and static CT images. Raters assessed UAO at the velopharynx and oropharynx (1 = none to 5 = complete) and noted confidence levels of each rating. Intraclass correlation and Krippendorff alpha were used to assess intra- and interrater reliability, respectively. Accuracy was assessed by comparing clinician ratings with quantitative percentage constriction (QPC) ratings, calculated based on 4D-CT airway cross-sectional area. Results were compared using Wilcoxon rank-sum and signed-rank tests.

RESULTS

There was similar intrarater agreement (moderate to substantial) with 4D-CT and FFL, and both demonstrated fair interrater agreement. Both modalities underestimated UAO severity, although 4D-CT ratings were significantly more accurate, as determined by QPC similarity, than FFL (-1.06 and -1.46 vs QPC ratings, P = .004). Overall confidence levels were similar for 4D-CT and FFL, but other specialists were significantly less confident in FFL ratings than were otolaryngologists (2.25 and 3.92, P < .0001).

CONCLUSION

Although 4D-CT may be more accurate in assessing the degree of UAO in patients with RS, 4D-CT and FFL assessments demonstrate similar reliability. Additionally, 4D-CT may be interpreted with greater confidence by nonotolaryngologists who care for these patients.

Three-dimensional reconstruction of systematic histological sections: application to observations on palatal shelf elevation

Normal mammalian secondary palate development undergoes a series of processes, including palatal shelf (PS) growth, elevation, adhesion and fusion, and palatal bone formation. It has been estimated that more than 90% of isolated cleft palate is caused by defects associated with the elevation process. However, because of the rapidly completed elevation process, the entire process of elevation will never be easy to clarify. In this article, we present a novel method for three-dimensional (3D) reconstruction of thick tissue blocks from two-dimensional (2D) histological sections. We established multiplanar sections of the palate and tongue in coronal and sagittal directions, and further performed 3D reconstruction to observe the morphological interaction and connection between the two components prior to and during elevation. The method completes an imaging system for simultaneous morphological analysis of thick tissue samples using both synthetic and real data. The new method will provide a comprehensive picture of reorientation morphology and gene expression pattern during the palatal elevation process.

Genetic Mutations Associated with Pierre Robin Syndrome/Sequence: A Systematic Review

Pierre Robin syndrome/sequence (PRS) is associated with a triad of symptoms that includes micrognathia, cleft palate, and glossoptosis that may lead to respiratory obstruction. The syndrome occurs in 2 forms: nonsyndromic PRS (nsPRS), and PRS associated with other syndromes (sPRS). Studies have shown varying genetic mutations associated with both nsPRS and sPRS. The present systematic review aims to provide a comprehensive collection of published literature reporting genetic mutations in PRS. Web of Science, PubMed, and Scopus were searched using the keywords: "Pierre Robin syndrome/sequence AND gene mutation." The search resulted in 208 articles, of which 93 were excluded as they were duplicates/irrelevant. The full-text assessment led to the further exclusion of 76 articles. From the remaining 39 articles included in the review, details of 324 cases were extracted. 56% of the cases were sPRS, and 22% of the cases were associated with other malformations and the remaining were nsPRS. Genetic mutations were noted in 30.9% of the 300 cases. Based on the review, SOX9 was found to be the most common gene associated with both nsPRS and sPRS. The gene mutation in sPRS was specific to the associated syndrome. Due to the lack of original studies, a quantitative analysis was not possible. Thus, future studies must focus on conducting large-scale cohort studies. Along with generating data on genetic mutation, future studies must also conduct pedigree analysis to assess potential familial inheritance, which in turn could provide valuable insights into the etiopathogenesis of PRS.

The Hypoplasic Mandible: What Makes it Different From the Healthy Child?

OBJECTIVE

This study aimed to analyze the morphology of the hypoplasic mandible and its evolution during the growth period to better understand how it differs from the pediatric healthy mandible.

METHOD

Three-dimensional mandibular models of hypoplasic and healthy children aged from 39 gestational weeks to 7 years old were analyzed with a morphometric method including data clustering. Morphological distinctions between pathological and healthy mandibles were highlighted. Bilateral and unilateral mandibular hypoplasia were distinguished.

RESULTS

The study sample was composed of 31 hypoplasic children and as many sex- and age-matched healthy children. Morphological distinctions between pathological and healthy mandibles were highlighted only from the first year of life. In bilateral hypoplasia, the overall mandibular dimensions were reduced while there was only a ramus asymmetry in unilateral mandibular hypoplasia (mean ± SD of the difference between the Grp03c and Grp03b subgroups: 6.80 ± 6.37 - P value = 1.64e^-3 for the height of the left ramus versus 0.18 ± 4.18 - P value = .82 for the height of the right ramus). Supervised classification trees were built to identify the pathology and discriminate unilateral from bilateral mandibular hypoplasia (prediction rates = 81% and 84%, respectively).

CONCLUSIONS

Based on a morphometric analysis, we demonstrated that mandibular hypoplasia significantly impacts the mandibular morphology only from the first year of life, with a distinction between bilateral and unilateral hypoplasia.

Surgery-first orthognathic approach vs conventional orthognathic approach: A systematic review of systematic reviews

Surgery-first approach (SFA) has been introduced as an alternative for conventional orthognathic approach (COA) in the treatment of patients with dentoskeletal deformities. This review aimed to evaluate skeletal stability, treatment time, surgical complications, and quality of life in SFA and COA. Six databases were accessed up to May 2020 to obtain all systematic reviews (SRs). After title and abstract reading, data extraction was performed from eligible SRs. The methodological quality was calculated for the included SRs using the last version of A Measurement Tool to Assess Systematic Review (AMSTAR-2). Ten SRs were included in this review. A good stability of the jaws was assessed both with SFA and COA by most of low- or critically low-quality SRs. Less treatment time was reported for SFA than COA with a moderate quality level. Slightly higher complications rate was recorded with SFA than COA by SRs with low or moderate quality. A better quality of life with SFA than COA was reported by moderate- or low-quality SRs. SFA may represent a reasonable alternative to COA. However, for the heterogeneity of the included SRs, well-designed studies with a long term follow-up are needed to clarify the findings of this analysis.

Genetics and signaling mechanisms of orofacial clefts

Craniofacial development involves several complex tissue movements including several fusion processes to form the frontonasal and maxillary structures, including the upper lip and palate. Each of these movements are controlled by many different factors that are tightly regulated by several integral morphogenetic signaling pathways. Subject to both genetic and environmental influences, interruption at nearly any stage can disrupt lip, nasal, or palate fusion and result in a cleft. Here, we discuss many of the genetic risk factors that may contribute to the presentation of orofacial clefts in patients, and several of the key signaling pathways and underlying cellular mechanisms that control lip and palate formation, as identified primarily through investigating equivalent processes in animal models, are examined.

The Comparison of Pierre Robin Sequence and Non-Syndromic Cleft Palate

INTRODUCTION

The aim of this study was to evaluate pre-operative nutritional status, associated syndromes and abnormalities, and post-operative outcomes of patients with Pierre Robin Sequence (PRS) versus those with non-syndromic isolated cleft palate (CIP).

METHODS

Between January 1995 and December 2013, patients with a cleft palate Veau I-II according to the Veau classification with and without PRS who underwent primary repair were retrospectively analyzed. The nutrition status, age at the time of palatoplasty, additional anomalies, gestational complications, and post-operative speech abnormalities and outcomes were evaluated.

RESULTS

A total of 59 patients with PRS (PRS group) and 132 patients without PRS (non-PRS group) were included in the study. Of all patients, 92 were males and 99 were females with a mean age of 14 ± 4.18 (range, 6 to 26) years. The rate of gestational complications, enteral nutrition, complete cleft, additional anomalies, and velopharyngeal insufficiency was significantly higher in the PRS group (P < 0.05). However, the incidence of fistulas and age at the time of palatoplasty did not significantly differ between the groups.

CONCLUSION

Based on our study results, enteral nutrition, respiratory problems, pregnancy complications, velopharyngeal insufficiency, and additional anomalies, but not post-operative palatal fistulas, are more frequently seen in patients with PRS. Although pre-operative care and treatment and rehabilitation in patients with PRS are more complicated than those with the CIP, our experience demonstrates that meticulous repair and follow-up can minimize complications, such as fistulas.

Visual diagnosis in utero: Prenatal diagnosis of Treacher-Collins syndrome using a 3D/4D ultrasonography

OBJECTIVE

We present a case with prenatal diagnosis of Treacher-Collins syndrome in which micrognathia and other facial and ear abnormalities were described using a three- and four-dimensional (3D/4D) ultrasonography in utero.

CASE REPORT

A 39-year-old Japanese pregnant woman was referred because of polyhydramnios at 29 weeks' gestation. Conventional ultrasonography showed a hypoplastic mandible on the sagittal section of fetal head. Continuous observation using a 3D ultrasonography additionally demonstrated bilateral downslanting palpebral fissures with symmetry and macrostomia as well as micrognathia. Both ears were microtia and no polydactyly or missing fingers were found.

CONCLUSION

The advantage of the rendering mode of 3D images covering entire face including ears and limbs was enhanced by a continuous observation, so called 4D ultrasonography, under a condition of polyhydramnios, providing visual diagnosis in utero.

Can Robin Sequence Be Predicted From Prenatal Ultrasonography?

PURPOSE

Prenatal diagnosis of Robin sequence (RS) could promote safe delivery and improve perinatal care. The purpose of this study was to evaluate the correlation between prenatal ultrasonography (US) and magnetic resonance imaging (MRI) studies for assessing micrognathia to determine if US alone can be used to reliably screen for RS.

MATERIALS AND METHODS

This was a retrospective case-control study of fetuses evaluated in the Advanced Fetal Care Center at Boston Children's Hospital from 2002 to 2017. To be included, 1) prenatal MRI and US must have been performed during the same visit, 2) the infant must have been live-born, and 3) the diagnosis must have been confirmed postnatally. Patients with images of inadequate quality for analysis were excluded. Patients were divided into 4 groups based on postnatal diagnosis: 1) RS (micrognathia, glossoptosis, and airway obstruction) (RS group), 2) micrognathia without RS (micrognathia group), 3) cleft lip and palate (CLP) without micrognathia (CLP group), and 4) gestational age-matched controls with normal craniofacial morphology (control group). The inferior facial angle (IFA) was measured using both imaging modalities and compared. Receiver operating characteristic curves were applied to identify a threshold for the diagnosis of RS from US. The sensitivity, specificity, positive predictive value, negative predictive value, and odds ratio were calculated.

RESULTS

A total of 94 patients were included (mean gestational age at imaging, 24.9 ± 5.2 weeks), with 25 in the RS group (26.6%), 29 in the micrognathia group (30.9%), 23 in the CLP group (24.5%), and 17 in the control group (18.1%). The IFA was significantly smaller in the RS group than in all other groups on both US and MRI (P < .001). A moderate correlation was found between IFA measurements on US and MRI (intraclass correlation coefficient, 0.729). An IFA threshold on US of 45.5° maximized sensitivity (84%) and specificity (81%) for the diagnosis of RS.

CONCLUSIONS

We suggest incorporating the IFA into routine prenatal US and referring patients for confirmatory MRI when the US IFA is lower than 45.5°.

The use of three-dimensional reconstructions of CT scans to evaluate anomalies of hyoid bone in Pierre Robin sequence: A retrospective study

AIM

The aim of the study was to investigate hyoid bone anomalies in patients with Pierre Robin sequence (PRS) compared to the control group, using computed tomography (CT) examination and three-dimensional reconstruction of the hyoid bone and mandible.

METHODS

A retrospective study was performed of patients between birth and 12 months old with isolated PRS (i-PRS) and syndromic PRS (ni-PRS), who had undergone CT examination, and whose results were compared to the control group of the same age. DICOM data was processed to highlight bone tissue. The mandible and hyoid bones were the main targets of the three-dimensional reconstruction. The study outcomes were the analysis of hyoid bone ossification, volume, and position (distance between hyoid and mandibular symphysis). Univariate and multivariate statistical analyses were performed with α=0.05 as level of significance.

RESULTS

The study sample included 29 i-PRS and 21 ni-PRS patients, while 43 infants in the control group. Hyoid ossification was present in 26/50 (52%) PRS patients (14 i-PRS; 12 ni-PRS) but in 31/43 controls (72%). Statistical analysis showed that absence of hyoid ossification was significantly associated with the diagnosis of PRS (P<0.05). Only ni-PRS patients showed a significant reduction of the distance between hyoid and mandible compared to the control group (P<0.001). Hyoid volume was significantly lower only in the ni-PRS group than in controls (P<0.001).

CONCLUSION

I-PRS and ni-PRS patients differ both etiologically and clinically. Ni-PRS patients confirmed their worst clinical condition than i-PRS with severe anomalies of hyoid development, helping for their ontogeny classification.

RDH10 function is necessary for spontaneous fetal mouth movement that facilitates palate shelf elevation

Cleft palate is a common birth defect, occurring in approximately 1 in 1000 live births worldwide. Known etiological mechanisms of cleft palate include defects within developing palate shelf tissues, defects in mandibular growth and defects in spontaneous fetal mouth movement. Until now, experimental studies directly documenting fetal mouth immobility as an underlying cause of cleft palate have been limited to models lacking neurotransmission. This study extends the range of anomalies directly demonstrated to have fetal mouth movement defects correlated with cleft palate. Here, we show that mouse embryos deficient in retinoic acid (RA) have mispatterned pharyngeal nerves and skeletal elements that block spontaneous fetal mouth movement in utero. Using X-ray microtomography, in utero ultrasound video, ex vivo culture and tissue staining, we demonstrate that proper retinoid signaling and pharyngeal patterning are crucial for the fetal mouth movement needed for palate formation. Embryos with deficient retinoid signaling were generated by stage-specific inactivation of retinol dehydrogenase 10 (Rdh10), a gene crucial for the production of RA during embryogenesis. The finding that cleft palate in retinoid deficiency results from a lack of fetal mouth movement might help elucidate cleft palate etiology and improve early diagnosis in human disorders involving defects of pharyngeal development.

Summary: Fetal mouth immobility and defects in pharyngeal patterning underlie cleft palate in retinoid-deficient Rdh10 mutant mouse embryos.

Sleep-disordered breathing in paediatric setting: existing and upcoming of the genetic disorders

Childhood obstructive sleep apnea syndrome (OSAS) is characterized by anatomical and functional upper airway abnormalities as pathophysiological determinants, and clinical symptoms are frequently clear. OSAS is widely described in rare genetic disorders, such as achondroplasia, Down syndrome, Prader-Willi syndrome, Pierre Robin sequence, and mucopolysaccharidosis. Craniofacial and upper airway involvement is frequently morbid conditions. In children with genetic diseases, the clinical symptoms of OSAS are often slight or absent, and related morbidities are usually more severe and can be observed at any age. The present review is aimed to updating the discoveries regarding OSAS on Achondroplasia, Down syndrome, Prader-Willi syndrome, Pierre Robin sequence, Sickle cell disease, or encountered in our clinical practice (Ehlers-Danlos syndrome, Ellis-van Creveld syndrome, Noonan syndrome). Two additional groups of genetic disorders will be focused (mucopolysaccharidoses and osteogenesis imperfecta). The flowing items are covered for each disease: (I) what is the pathophysiology of OSAS? (II) What is the incidence/prevalence of OSAS? (III) What result from the management and prognosis? (IV) What are the recommendations? Considering the worries of OSAS, such as inattention and behavioural problems, daytime sleepiness, failure to thrive, cardiological and metabolic complications, the benefit of a widespread screening and the treatment in children with genetic diseases is undoubtful. The goals of the further efforts can be the inclusion of various genetic diseases into guidelines for the screening of OSAS, updating the shreds of evidence based on the research progression.