Three-Dimensional Assessment of Craniofacial Features in Patients With Down Syndrome During the Mixed Dentition Period: A Case-Control Study.

OBJECTIVES: Down syndrome (DS) is a common congenital chromosomal disorder related to trisomy 21. Lateral cephalometric radiography studies have shown that patients with DS have characteristic craniofacial morphology; however, no 3-dimensional analysis studies have been performed to investigate the craniofacial features, including volumetric aspects, of patients with DS. The present study was performed to evaluate the craniofacial features, including volumetric aspects, of patients with DS and to compare these findings with control participants using cone beam computed tomography (CBCT). MATERIALS AND METHODS: The study sample consisted of 12 patients with DS and 12 control participants. All participants were examined by means of CBCT; the resulting images were used for evaluation of maxillary and mandibular volume, cranial base, and craniofacial measurements. Differences between patients with DS and control participants were statistically analyzed using Student t test. RESULTS: Compared to control participants, patients with DS exhibited statistically significant reductions in maxillary and mandibular volumes. Both sagittal and axial cranial base linear measurements were shorter in patients with DS than in control participants. In contrast, the cranial base angle was enhanced in patients with DS, compared with control participants. Moreover, condylion (Co)-gnathion, anterior nasal spine-menton, and Co-subspinale (point A) measurements were shorter in patients with DS than in control participants; the sella-nasion-mandibular plane angle was significantly reduced in patients with DS, compared with control participants. CONCLUSION: Our results suggest that patients with DS have distinct skeletal volume and craniofacial morphology features, relative to individuals without DS.

Repeat Pediatric Trisomy 21 Radiographic Exam: Does Atlantoaxial Instability Develop Over Time?

BACKGROUND: Atlantoaxial instability (AAI) is common in pediatric patients with Trisomy 21 and can lead to spinal cord injury during sports, trauma, or anesthetized neck manipulation. Children with Trisomy 21 therefore commonly undergo radiographic cervical spine screening, but recommendations on age and timing vary. The purpose of this study was to determine if instability develops over time. METHODS: We performed a retrospective review for all pediatric Trisomy 21 patients receiving at least 2 cervical spine radiographic series between 2008 and 2020 at our institution. Atlantodens interval (ADI) and space available for the cord at C1 (SAC) were measured; bony abnormalities such as os odontoidium, and age and time between radiographs were noted. AAI was determined by ADI ≥6 mm or SAC ≤14 mm based on our groups' prior study. Those who developed instability were compared with those who did not. RESULTS: A total of 437 cervical spine radiographic series from 192 patients were evaluated, with 160 included. Mean age at first radiograph was 7.4±4.4 years, average ADI was 3.1 mm (±1.2), and SAC was 18.1 mm (±2.6). The average time between first and last radiographs was 4.3 years (±1.8), with average final ADI 3.2 mm (±1.4) and SAC 18.9 mm (±2.9). Seven patients (4%) had instability: 4 were unstable on their initial studies and 3 (1.6%) on subsequent imaging. Os odontoideum was found in 5 (71%) unstable spines and 3 (2%) stable spines (P<0.0001); only 1 patient that became unstable on subsequent radiograph did not have an os. There was no specific age cut-off or surveillance time period after which one could be determined no longer at risk. CONCLUSIONS: Trisomy 21 patients have a 4.4% overall rate of AAI in our series with a 1.6% rate of progression to instability over ∼4 years. Given this nearly 1 in 23 risk of instability, we recommend initial surveillance radiograph for all children over 3 years with Trisomy 21; repeat asymptomatic surveillance should continue in those with os odontoideum given their high instability risk. LEVEL OF EVIDENCE: Level II-diagnostic study.

3D facial morphometry in Italian patients affected by Aicardi syndrome.

Aicardi syndrome (AIC) is a rare congenital neurodevelopmental disorder of unknown etiology, that affects almost exclusively females, originally characterized by corpus callosum agenesis, chorioretinal lacunae, and infantile spasms. The current diagnostic criteria also include qualitative facial features (prominent premaxilla, upturned nasal tip, decreased nasal bridge angle, sparse lateral eyebrows, and microphthalmia) that still need quantification. A three-dimensional (3D) photogrammetric assessment of 11 Italian females, age 7-32 years, who satisfied AIC criteria, was performed. Linear distances and angles were computed from soft-tissue facial landmarks coordinates. The z-score values were calculated using data of 850 healthy reference females matched for age and compared by Mann-Whitney test (p < .01). Patients showed a shorter philtrum and right side orbital height (mean z-scores: -1.7, -0.9), shorter superior, middle, and inferior facial depths (mean z-scores: -1.3, -2.2, -2.3), and a smaller length of mandibular ramus (mean z-score: -2.1); conversely, they showed larger nasal and lower facial widths, and lower facial convexity (mean z-scores: 1.7, 1.4, 2.4). The inclinations of the orbit versus the true horizontal were increased bilaterally (mean z-scores: 1.8, 1.1). Some common facial abnormalities were quantified in AIC patients using a noninvasive instrument. They may help clinicians in performing a definite AIC diagnosis in atypical or doubt cases.

Evaluation of 2011 AAP cervical spine screening guidelines for children with Down Syndrome.

PURPOSE: Atlantoaxial instability (AAI) has a higher incidence rate among individuals with Down syndrome (DS) than the non-DS population. In 2011, the American Academy of Pediatrics (AAP) updated its AAI screening guidelines for children with DS from radiographic screening to radiographs only if there are clinical symptoms suggestive of cervical spine pathology. An assessment of whether this alteration has been associated with an increase in AAI-associated spinal cord injury has not been undertaken. METHODS: We provide the first neurosurgical review of a large experience implementing the 2011 AAP guidelines. We reviewed the courses of patients with DS seen at the Sie Center for Down Syndrome at Children's Hospital Colorado who were evaluated for cervical spine disease and determined whether screening radiographic imaging could have led to earlier diagnosis or prevented development of neurological deficits. We also report an illustrative case of a 5-year-old female with Down syndrome who presented with instability after normal screening radiographs per the pre-2011 guidelines. RESULTS: The clinical experience of the Sie Center demonstrates that even when limiting imaging to patients who show signs or symptoms of spine pathology, the vast majority of x-rays are negative. Our exemplary patient presented to the emergency department for neck pain without a history of significant trauma. She was diagnosed and treated for atlantoaxial subluxation associated with os odontoideum. CONCLUSION: Routine radiographic screening may not be sufficiently predictive of DS individuals at risk to develop AAI. This experience supports the appositeness of the de-escalation of care asserted by the guidelines.

Prenasal Thickness, Prefrontal Space Ratio and Other Facial Profile Markers in First-Trimester Fetuses with Aneuploidies, Cleft Palate, and Micrognathia.

OBJECTIVE: To investigate the feasibility and reproducibility of the prenasal thickness (PNT)/nasal bone length (NBL) ratio, maxilla-nasion-mandible (MNM) angle, facial profile line, profile line distance, and prefrontal space ratio (PFSR) in the first trimester of pregnancy, develop normal ranges, and evaluate these markers in abnormal fetuses. METHODS: All measurements were performed on stored images by two operators. Feasibility, interoperator agreement, and prediction intervals were calculated for all measurements. RESULTS: Feasibility was the highest for the NBL (74.3-79.7%) and the MNM angle (75.7-79.05%). Correlation was good for the NBL, the PNT, and the MNM angle (intraclass correlation coefficient 0.706-0.835). Mean difference between operators was the lowest for the PNT and PFSR (0.03-0.08). Measurements in abnormal fetuses showed that the majority of trisomy 21 fetuses had either an absent nasal bone or a shorter NBL. The PNT and PNT/NBL ratio were above the 97.5th centile in one third of the cases. Fetuses with facial clefts or micrognathia showed on average a large MNM angle (multiple of the median 0.96-5.15). CONCLUSION: First-trimester facial markers are feasible. The PNT and PNT/NBL ratio were increased in one third of the trisomic fetuses, and the MNM angle in the majority of fetuses with micrognathia and facial clefts.

Comparative study of dental anomalies assessed with panoramic radiographs of Down syndrome and non-Down syndrome patients.

AIM: The aim of this study was to compare the prevalence of dental anomalies from panoramic radiographs of age-matched individuals with and without Down Syndrome (DS). STUDY DESIGN: This is a retrospective cross-sectional study. A group of 41 patients (19 female and 22 male) with Down Syndrome (DS), mean age 10.6 ± 1.4 and a control group of 42 non- DS patients (26 female and 16 male), mean age 11.1 ± 1.3 were studied. METHODS: This study examined the medical history and a panoramic radiograph of each patient. The dental anomalies studied were agenesis of permanent teeth (except third molars), size and shape maxillary lateral anomalies and maxillary canine eruption path anomalies. STATISTICS: The groups were compared using Mann-Whitney and Wilcoxon non-parametric tests (p<0.05). Rho Spearman correlation coefficient was applied for associations. Results Agenesis of one permanent tooth was found in 73.17% of DS subjects and two or more permanent teeth in more than 50% (p<0.001). Maxillary lateral incisor was the most frequently absent tooth followed by mandibular second premolar, mandibular lateral incisor, maxillary second premolar and mandibular central incisor. No significant differences were detected between maxilla and mandible on either side. No differences in gender were observed. Significant differences were found for size and shape anomalies of maxillary lateral incisors, as well as for canine eruption anomalies (p<0.05). No gender differences were observed for either variable. No association was found between these two variables in the DS group. CONCLUSIONS: More dental anomalies were present in the DS group than in the control group, which implied that DS patients need periodical dental and orthodontic supervision so as to prevent or control subsequent oral problems.

Fetal facial profile markers of Down syndrome in the second and third trimesters of pregnancy.

OBJECTIVES: To investigate the use of the maxilla-nasion-mandible (MNM) angle and fetal profile (FP) line to assess the degree of midfacial hypoplasia in Down-syndrome fetuses in the second and third trimesters of pregnancy. METHODS: The MNM angle and FP line were measured retrospectively in stored two-dimensional images or three-dimensional volumes of fetuses with Down syndrome. Data collected from January 2006 to July 2013 were retrieved from the digital databases of participating units. The MNM angle was expressed as a continuous variable (degrees) and the FP line as positive, negative or zero. Measurements were obtained from stored images in the midsagittal plane by two experienced examiners and compared with our previously reported normal ranges for euploid fetuses. A MNM angle below the 5(th) centile of the reference range and a positive or negative FP line were considered as abnormal. RESULTS: A total of 133 fetuses with Down syndrome were available for analysis, eight of which were subsequently excluded because of inadequate images. The MNM angle was not influenced by gestational age (P = 0.48) and was significantly smaller in Down-syndrome fetuses than in euploid fetuses (mean, 12.90° vs 13.53°, respectively; P = 0.015). The MNM angle was below the 5th centile for euploid fetuses in 16.8% of fetuses with Down syndrome (P < 0.01). In the cohort of Down-syndrome fetuses, a positive FP line was present in 41.6% of cases (with a false-positive rate (FPR) of 6.3%) and was positively correlated with Down syndrome and gestational age (P < 0.01). There was no case with a negative FP line. In cases of Down syndrome, a positive FP line was correlated with a small MNM angle (P < 0.01). CONCLUSIONS: A small MNM angle and a positive FP line can be regarded as novel markers for Down syndrome. The FP line is an easy marker to measure, has a low FPR, does not require knowledge of normal reference values and has the potential to differentiate between Down syndrome and trisomy 18, as, in the latter, the FP line is often negative.

Is 3D technique superior to 2D in Down syndrome screening? Evaluation of six second and third trimester fetal profile markers.

OBJECTIVE: The objective of this article is to investigate whether in the clinical setting of second trimester ultrasound (US) investigations, 3D multiplanar correction prior to the measurement of Down syndrome (DS) facial markers (nasal bone length, prenasal thickness, fetal profile line, maxilla-nasion-mandible angle, prenasal thickness to nasal bone length ratio, and prefrontal space ratio) is superior to subjective judgment of a correct midsagittal plane by 2D technique. METHODS: Measurements were performed on 2D images and 3D volumes (corrected to the midsagittal plane), acquired during the same scanning session. RESULTS: All six markers were measured in 105 datasets (75 of euploid fetuses and 30 of DS fetuses). The maxilla-nasion-mandible angle measured on 2D images was significantly larger than on 3D volumes (p < 0.01). In all other markers, there was no significant difference between measurements performed on 2D images or 3D volumes. No statistical difference was found for any marker between measurements performed on images acquired by either 2D or 3D US in their ability to discriminate between normal and DS fetuses. CONCLUSIONS: Nasal bone length, prenasal thickness, fetal profile line, prenasal thickness to nasal bone length ratio, and prefrontal space ratio can be confidently used as DS markers in second trimester US examinations performed by 2D US. © 2014 John Wiley & Sons, Ltd.

Morphometry of the hard palate in Down's syndrome through CBCT-image analysis.

OBJECTIVES: To define the morphometry of the hard palate in Down's syndrome (DS) on cone beam computed tomography (CBCT) images. SETTING AND SAMPLE POPULATION: Santiago de Compostela University (Spain). The study group included 40 white DS individuals aged 10 to 40 years (mean = 18.8 ± 7.3 years), 25 males and 15 females. The control group consisted of 40 individuals matched for age and sex were selected. MATERIAL & METHODS: Nine measurements were taken on the CBCT images. Axial plane: anteroposterior length (aAPL) and arch length (aARL); sagittal plane: anteroposterior length (sAPL), maximum height (sMH) and sagittal arch (sAR); coronal plane: interdental width (cIDW), height (cHE), skeletal width (cSW) and coronal arch (cAR). RESULTS: aAPL, aARL, sAPL, sMH, sAR, cMH and cAR were comparable in the two groups. cIDW and cSW were greater in controls than in DS. We found no statistically significant differences between males and females with DS. In the controls, sAPL and sAR were greater in males than females. In DS, age only had a statistically significantly increasing effect on aAPL and sAPL. In the controls, age significantly affected sAR and cHE. CONCLUSION: The hard palate is narrower in DS than in controls, but the anteroposterior measurements and the height of the vault are comparable in both groups.

Dimensions of central incisors, canines, and first molars in subjects with Down syndrome measured on cone-beam computed tomographs.

INTRODUCTION: The literature on tooth dimensions in subjects with Down syndrome (DS) is scarce. To our knowledge, no studies have yet been published in which the morphometry of the teeth in DS subjects has been determined using computed tomography. METHODS: The study group consisted of 40 subjects with DS, aged 10 to 40 years. An age- and sex-matched control group was selected. Cone-beam computed tomography images were retrieved from the archive of the Santiago de Compostela University in Spain. The maxillary central incisors, canines, and first molars were evaluated. The following variables were analyzed: overall tooth length, crown height, root length, mesiodistal diameter, vestibular-palatine diameter, crown-to-root ratio, and cervical circumference. RESULTS: The teeth of subjects with DS were smaller than those of the controls, although the crown-to-root ratio was maintained. No clear sexual dimorphism was detected, but the root lengths of the incisors were greater in male subjects. Crown height, mesiodistal diameter, and crown-to-root ratio showed progressive reductions with age. There appeared to be a degree of "fluctuating dental asymmetry" with respect to vestibular-palatine diameter and cervical circumference. CONCLUSIONS: Our findings confirm microdontia of the permanent teeth and progressive reductions in tooth sizes with age in persons with DS. These variations might be relevant to orthodontic treatment planning.

Prefrontal space ratio in second- and third-trimester screening for trisomy 21.

OBJECTIVE: To evaluate the prefrontal space ratio (PFSR) in second- and third-trimester euploid fetuses and fetuses with trisomy 21. METHODS: This was a retrospective study utilizing stored mid-sagittal two-dimensional images of second- and third-trimester fetal faces that were recorded during prenatal ultrasound examinations at the Department of Prenatal Medicine at the University of Tuebingen, Germany and at a private center for prenatal medicine in Nuremberg, Germany. For the normal range, 279 euploid pregnancies between 15 and 40 weeks' gestation were included. The results were compared with 91 cases with trisomy 21 between 15 and 40 weeks. For the ratio measurement, a line was drawn between the leading edge of the mandible and the maxilla (MM line) and extended in front of the forehead. The ratio of the distance between the leading edge of the skull and the leading edge of the skin (d1) to the distance between the skin and the point where the MM line was intercepted (d2) was calculated. The PFSR was determined by dividing d2 by d1. RESULTS: In the euploid and trisomy 21 groups, the median gestational age at the time of ultrasound examination was 21.1 (range, 15.0-40.0) and 21.4 (range, 15.0-40.3) weeks, respectively. Multiple regression analysis showed that PFSR was independent of maternal and gestational age. In the euploid group, the mean PFSR was 0.97 ± 0.29. In fetuses with trisomy 21, the mean PFSR was 0.2 ± 0.38 (P < 0.0001). The PFSR was below the 5(th) centile in 14 (5.0%) euploid fetuses and in 72 (79.1%) fetuses with trisomy 21. CONCLUSION: The PFSR is a simple and effective marker in second- and third-trimester screening for trisomy 21.

The fetal frontomaxillary facial angle in normal and trisomy 21 ultrasounds at 11-13(+6) weeks of gestation: findings among the ethnic Chinese compared with Caucasian.

OBJECTIVE: The aim of this research was to compare the fetal frontomaxillary facial (FMF) angle between normal and trisomy 21 fetuses at 11(+0) -13(+6) weeks gestation in a Chinese population. METHODS: A prospective observational study was performed that included 640 euploid and 45 trisomy 21 singleton pregnancies undergoing first trimester ultrasound screening between 11 and 13(+6) weeks of gestation. The FMF angle was measured in the midsagittal plane using the standard technique. RESULTS: The fetal mean FMF angle decreased with the increasing crown-rump length (CRL) from 88.6°at a CRL of 45 mm to 78.5° at a CRL of 84 mm (FMF angle = 100.212 - 0.258 × CRL, R(2) = 0.222, p < 0.001). The overall mean FMF angle in the euploid population was 82.9° ± 4.1° and in trisomy 21 cases, 92.3° ± 5.2°. CONCLUSIONS: Fetal FMF angle is affected by gestational age in a Chinese population, although it remains a significant predictor of fetal trisomy 21.

Craniofacial morphological differences between Down syndrome and maxillary deficiency children.

Maxillary deficiency is one of the facial features of Down syndrome (DS). Differences in craniofacial morphology between DS and nonsyndromic skeletal Class III malocclusion with maxillary deficiency remain unclear. This study compared the craniofacial differences of white male children from Central-Western Brazil with DS (n = 30, mean age: 8 years 3 months), skeletal Class III profile with maxillary deficiency (n = 30, mean age: 7 years 9 months), and skeletal Class I profile (n = 30, mean age: 8 years 2 months), using lateral cephalometric radiographs. The differences among the three groups were compared with analysis of variance and Tukey's tests. The DS group showed reduced anterior cranial base (S-N, P < 0.001] and facial dimensions (Co-Gn, N-Me, N-ANS, and ANS-Me, P < 0.001), except in posterior dimensions (S-Go, P < 0.005; Ar-Go, P > 0.005). Maxillary length (Co-A, P < 0.001) and facial convexity (NAP, P < 0.005) were reduced when compared with the control group, although maxillary position to cranial base (SNA, P < 0.005) was within the normal range. A flattened cranial base (BaSN, P < 0.001) also contributed to differentiating DS from nonsyndromic groups. The group with maxillary deficiency showed a more unfavourable maxillomandibular relationship (MMD, P < 0.001) and a mandibular protrusion (SNB, P < 0.001). Subjects with DS differed from Class III with maxillary deficiency with respect to the flatter cranial base and reduced maxillary length. Maxillary deficiency was not so expressive in the face of DS subjects because of the overall reduction in craniofacial dimensions.

Prefrontal space ratio: comparison between trisomy 21 and euploid fetuses in the second trimester.

OBJECTIVE: To evaluate a novel ultrasound measurement, the prefrontal space ratio (PFSR), in second-trimester trisomy 21 and euploid fetuses. METHODS: Stored three-dimensional volumes of fetal profiles from 26 trisomy 21 fetuses and 90 euploid fetuses at 15-25 weeks' gestation were examined. A line was drawn between the leading edge of the mandible and the maxilla (MM line) and extended in front of the forehead. The ratio of the distance between the leading edge of the skull and that of the skin (d(1)) to the distance between the skin and the point where the MM line was intercepted (d(2)) was calculated (d(2)/d(1)). The distributions of PFSR in trisomy 21 and euploid fetuses were compared, and the relationship with gestational age in each group was evaluated by Spearman's rank correlation coefficient (r(s) ). RESULTS: The PFSR in trisomy 21 fetuses (mean, 0.36; range, 0-0.81) was significantly lower than in euploid fetuses (mean, 1.48; range, 0.85-2.95; P < 0.001 (Mann-Whitney U-test)). There was no significant association between PFSR and gestational age in either trisomy 21 (r(s) = 0.25; 95% CI, - 0.15 to 0.58) or euploid (r(s) = 0.06; 95% CI, - 0.15 to 0.27) fetuses. CONCLUSION: The PFSR appears to be a highly sensitive and specific marker of trisomy 21 in the second trimester of pregnancy.

The relationship between atlas hypoplasia and os odontoideum in children with Down syndrome: a preliminary case report.

The purpose of this study was to evaluate the relationship of os odontoideum and the size of atlas among children with Down syndrome. Understanding the risk of developing myelopathy in asymptomatic cases is important in children with Down syndrome. Children with os odontoideum are considered to be at high risk of developing myelopathy because of instability; however, in cases that are complicated by atlas hypoplasia, the risk remains the same, regardless of instability. This retrospective case-control study assessed atlas hypoplasia in children with Down syndrome with or without os odontoideum. We retrospectively assessed the records of 59 patients (36 males and 23 females) with Down syndrome who underwent spinal X-ray evaluations at our hospital. The average age at examination was 5.0 years (range, 4-7). We evaluated the following radiologically: the presence of os odontoideum; atlas-dens interval; space available for the spinal cord at the atlas level (C1SAC); instability index; sagittal atlas diameter (SAD) as an index of atlas hypoplasia and C5 level SAC (C5SAC), adjusted for child growth. Os odontoideum was present in seven cases (12%). Between the groups with and without os odontoideum, there was no significant difference in age (mean, 5.2 vs. 5.0 years) or male/female ratio (57 vs. 62% males). The SAD/C5SAC (mean, 1.6 vs. 1.9) was significantly smaller in the group with os odontoideum than in those without os odontoideum. The instability index was not significantly different between the two groups. Children with Down syndrome and os odontoideum have small SAD. Evaluations for atlas hypoplasia are necessary.

Learning curve in measurement of fetal frontomaxillary facial angle at 11-13 weeks of gestation.

OBJECTIVE: To determine the number of ultrasound examinations required to train sonographers to accurately measure the fetal frontomaxillary facial (FMF) angle at 11-13 weeks of gestation. METHODS: Eight sonographers accredited for nuchal translucency thickness (NT) measurement (and with different levels of experience) were trained to measure the fetal FMF angle using specially acquired three-dimensional (3D) volumes. Training was provided in cycles, and each cycle consisted of a training period on 20 randomly selected cases followed by an examination using 10 randomly selected cases. During training, the sonographer was informed of the true FMF angle value after each FMF angle measurement on a case-by-case basis. During examination, the difference between the measured and the true values of the FMF angle (i.e. the delta angle) was calculated. A measurement was considered accurate if the delta angle was less than 5 degrees . The sonographer was considered to be competent and the training finished if all 10 examination cases satisfied this criterion. Otherwise, the sonographer would undergo further cycles of training-examination, until he/she became competent. RESULTS: The number of training cases required for a sonographer to become competent was 40 for two sonographers, 60 for one, 80 for one, 100 for two, 120 for one and 140 for one, with a median of 90. The median number of failed cases reduced from 2.5 (out of 10) at the first cycle to 0 by the 7(th) cycle. As training cycles increased, the mean angle deviation and measurement time required both reduced significantly. The average delta angle of the passing examination cycle was 2.06 +/- 1.40 degrees . The number of training cases required to become competent in FMF angle measurement was 40 for the two most experienced trainees and 80, 120 and 140 for the three least experienced ones. CONCLUSIONS: We have demonstrated that competence in FMF angle measurement was achieved after a median number of 90 cases, with a range of up to 140. The number required was substantially lower, at 40 cases, among those with extensive experience of NT measurement.

Detailed evaluation of the upper airway in the Dp(16)1Yey mouse model of Down syndrome.

A high prevalence of obstructive sleep apnea (OSA) has been reported in Down syndrome (DS) owing to the coexistence of multiple predisposing factors related to its genetic abnormality, posing a challenge for the management of OSA. We hypothesized that DS mice recapitulate craniofacial abnormalities and upper airway obstruction of human DS and can serve as an experimental platform for OSA research. This study, thus, aimed to quantitatively characterize the upper airway as well as craniofacial abnormalities in Dp(16)1Yey (Dp16) mice. Dp16 mice demonstrated craniofacial hypoplasia, especially in the ventral part of the skull and the mandible, and rostrally positioned hyoid. These changes were accompanied with a shorter length and smaller cross-sectional area of the upper airway, resulting in a significantly reduced upper airway volume in Dp16 mice. Our non-invasive approach, a combination of computational fluid dynamics and high-resolution micro-CT imaging, revealed a higher negative pressure inside the airway of Dp16 mice compared to wild-type littermates, showing the potential risk of upper airway collapse. Our study indicated that Dp16 mice can be a useful model to examine the pathophysiology of increased upper airway collapsibility of DS and to evaluate the efficacy of therapeutic interventions for breathing and sleep anomalies.

Surface Electromyography as a Method for Diagnosing Muscle Function in Patients with Congenital Maxillofacial Abnormalities.

Electromyography (EMG) is the most objective and reliable method available for imaging muscle function and efficiency, which is done by identifying their electrical potentials. In global surface electromyography (sEMG), surface electrodes are located on the surface of the skin, and it detects superimposed motor unit action potentials from many muscle fibers. sEMG is widely used in orthodontics and maxillofacial orthopaedics to diagnose and treat temporomandibular disorders (TMD) in patients, assess stomatognathic system dysfunctions in patients with malocclusions, and monitor orthodontic therapies. Information regarding muscle sEMG activity in subjects with congenital maxillofacial abnormalities is limited. For this reason, the aim of this review is to discuss the usefulness of surface electromyography as a method for diagnosing muscle function in patients with congenital malformations of the maxillofacial region. Original papers on this subject, published in English between 1995 until 2020, are located in the MEDLINE/PubMed database.

Does the combination of fronto-maxillary facial angle and nasal bone evaluation improve the detection of Down syndrome in the second trimester?

OBJECTIVE: To determine if the combination of fronto-maxillary facial (FMF) angle and nasal bone (NB) evaluation improves the detection of Down syndrome (DS) in the second trimester. STUDY DESIGN: We compared the FMF angle measurements in euploid and DS fetuses seen between 2005 and 2008. The FMF angles were measured from stored two-dimensional (2-D) images by investigators blinded to the DS status of the fetus. All NB measurements were obtained prospectively. Receiver operator characteristic curve plot was used to determine the optimal definition for abnormal FMF angle. The detection and false positive rates and likelihood ratios positive and negative for the DS markers and their combinations were compared. RESULTS: Of 22 fetuses with DS seen between 16 and 22 weeks over the study period, NB and FMF angle evaluation was available for 21. These were compared with a control group of 201 fetuses seen at similar gestational age ranges without DS. NB alone identified 10/21 (47.6%) of Down syndrome while FMF angle identified 2/21 (9.5%). The combination of FMF angle and NB identified only one additional case of Down syndrome. CONCLUSIONS: While FMF angle and NB are independent markers for DS, their combination resulted in a minimal but nonsignificant improvement in DS detection.

Study on the applicability of frontomaxillary facial angle in the first-trimester trisomy 21 fetuses in Chinese population.

OBJECTIVE: To evaluate the measurement of frontomaxillary facial (FMF) angle at 11 weeks to 13 weeks, 6 days in a Chinese population and its applicability in the screening for fetal trisomy 21. METHOD: In a retrospective study, the stored images for the measurement of fetal nuchal translucency (NT) thickness in a Chinese population from August 2003 to March 2007 were reviewed for the comparison of the FMF angle between 22 trisomy 21 fetuses (study group) with 220 randomly selected normal fetuses with satisfactory images (control group). RESULTS: No association between FMF angle and NT, nasal bone length, or fetal heart rate was shown (P > 0.05). But the FMF angle was significantly greater in the trisomy 21 fetuses (89.7 vs 82.8, P < 0.001). The intraobserver and interobserver agreement were assessed in 9.5% (n = 21) normal cases. Mean (SD) differences of two observers were -0.83 (2.69) degrees (P > 0.05). For each observer, mean (SD) differences between the two paired measurements were -0.98 (3.11) degrees and 0.93 (1.80) degrees , respectively (P > 0.05). CONCLUSION: Our results indicated that measurement of the FMF angle in the first trimester can be incorporated into the screening of trisomy 21 in the Chinese population, and its application is not affected by intraobserver and interobserver variability.