Robin Sequence Patients Research Articles

Pre-Operative Characteristics Helping to Avoid Gastrostomy Tube After Mandibular Distraction in Neonates With Pierre-Robin Sequence: A Institutional Case-Series and Review of the Literature.

to investigate the ability of mandibular distraction osteogenesis (MDO) to avoid gastrostomy tube (G-tube). PubMed, EBSCOhost, Cochrane, and Embase. We retrospectively reviewed the number of MDO cases performed at our institution for patients with Robin Sequence (RS) over the past 10 years. In our institutional review, patients were excluded if they had a G-tube already placed at the time of surgery. We also performed a systematic review of the literature. Articles were excluded if they did not detail feeding outcomes after MDO, or if MDO was performed on patients that did not have RS. In our systematic review, 12 articles were included that comprised a total of 209 neonates with RS that underwent MDO. A total of 174 (83.3%) patients avoided a G-tube once MDO was performed. A total of 14 patients met the inclusion criteria at our institution. Of the 14 RS patients, 9 (64%) avoided having a G-tube placed and all (14/14) avoided tracheostomy. The average birth weight of patients avoiding a G-tube was 3.11 kg compared to 2.25 kg (P = .045) in the group requiring a G-tube. In the group avoiding a G-tube, the average weight at time of operation was 3.46 kg compared to 2.83 kg (P = .037) in the group requiring a G-tube. MDO may be considered as a surgical option to prevent G-tube placement for neonates with non-syndromic RS who have difficulty with PO feeding but whose airway obstruction is not severe enough to require respiratory support. Based on our institutional experience, a minimum weight of 3.00 kg correlated with higher success rates of PO intake and avoiding a G-tube.

Impact of upper airway obstruction management in Robin Sequence on need for myringotomy tubes

ObjectiveInvestigate an association between upper airway obstruction (UAO) management in Robin Sequence (RS) and need for bilateral myringotomy and tubes (BMT). MethodsRetrospective chart review of RS patients treated at a tertiary free-standing pediatric hospital from 1995 to 2020 was performed. Patients were grouped based on airway management: conservative, tracheostomy, tongue-lip adhesion (TLA), and mandibular distraction osteogenesis (MDO). Demographic data, cleft palate (CP) association, numbers of BMT and ear infections, and audiogram data including tympanograms were collected. One-way ANOVA and Chi-square/Fisher's exact tests were used to compare continuous and categorical data, respectively. Multivariable regression analysis was used to compare BMT rates between treatment groups. ResultsOne hundred forty-eight patients were included, 70.3 % of which had CP. Most patients (67.6 %) had at least one BMT; 29.1 % required two or more BMT. The rate of BMT was higher in patients with CP compared to those with intact palates (p = 0.003; 95 % CI 1.30–3.57) and those treated with tracheostomy (p = 0.043; 95 % CI 1.01, 2.27). Surgically managed patients were more likely to have hearing loss (67.5 % vs. 35.3 %, p = 0.017) and ear infections (42.1 % vs. 20.0 %, p = 0.014) pre-compared to post-procedure for airway management. ConclusionMost RS patients require at least 1 set of BMT. Those with CP and/or treated with tracheostomy had a higher likelihood of needing BMT. Rate of hearing loss and ear infection was higher in surgically managed RS patients. Patients with RS and overt CP require a statistically higher number of BMTs compared to those with either submucous cleft palate or intact palate.

The Outcome of Mandibular Distraction Osteogenesis in Infants with Severe Pierre Robin Sequence in Vietnam.

The purpose of this study was to provide the experience of a single center with mandibular distraction osteogenesis (MDO) in Pierre Robin Sequence (PRS) patients. A longitudinal research analysis was conducted to identify PRS patients who underwent MDO at Vietnam National Children's Hospital between 2019 and 2021. The following criteria were used to determine inclusion: 1) those pediatric patients with PRS who were not well handled with conservative therapy, 2) those who received MDO with internal mandibular distractors, and 3) no previous treatment elsewhere. Demographic data, postoperative complications, and surgical results were all evaluated. The inclusion criteria were met by 73 patients. There were no difficulties associated with our distraction strategy. The majority of individuals with tracheostomies were successfully decannulated, and the remainder were able to avoid tracheostomies. Using MDO in PRS is an effective technique to avoid future airway issues. The success rate was lower and the complication rate higher for patients who had a tracheotomy before distraction and for those who underwent distraction at an age older than 2 months. The presence of laryngomalacia, gastric reflux disease, cardiac abnormalities, and GI anomalies did not increase the likelihood of MDO failure in PRS patients.

Pharyngeal Airway Changes Following Mandibular Distraction Osteogenesis as Evaluated with Laryngoscopy.

Mandibular distraction osteogenesis (MDO) may improve airway grade in patients with Robin Sequence (RS), but little is known about the response of the oropharyngeal airway to the distraction process in cases of tongue base obstruction (TBAO). This study used drug-induced sleep endoscopy (DISE) to evaluate the impact of MDO on the oropharynx. RS patients with severe obstructive sleep apnea (OSA) were prospectively enrolled, and underwent DISE prior to MDO, and at the time of distractor removal. Laryngoscopy views, glossoptosis degree, polysomnography (PSG) results, oxygen saturations and airway measurements were compared pre- and post-MDO. Twenty patients met inclusion criteria. At the time of distractor placement, a grade II laryngoscopic view was most frequently observed (63%), and one patient (5%) had a grade I view. Median obstructive apnea hypopnea index (OAHI) improved after MDO (49.1 [30.2-74.0] to 9.1, [3.9-18.0], p ≤ .001). Median oxygen saturation nadir also improved (preoperative 69% [60-76] to 85% [82-91], p ≤ .001). At distractor removal, mean laryngoscopic view improved (p ≤ .002) with no views that were grade 3 or higher. Median intraoperative oropharyngeal width improved, (3.1 mm [2.8-4.4] to 6.0 mm [4.4-6.8], p ≤ .021), as did median cephalometric anteroposterior oropharyngeal width (3.5 mm [2.7-4.1] to 6.3 mm [5.6-8.2], p ≤ .002). Following MDO, RS patients with TBAO have an approximate doubling of oropharyngeal width and an improvement in laryngoscopic grade. These findings likely contribute to improved oxygenation, OAHI and ease of intubation.

Incidence, Characteristics, and Outcomes of Robin Sequence: A Population-Based Analysis in the United States.

While the literature is replete of clinical studies reporting on the Robin sequence (RS), population-based analyses are scarce with significant variability within the literature in terms of reported incidence, demographic parameters, and outcomes. The authors have conducted a 20-year population-based analysis to guide clinical practice. A birth cohort was created from the available datasets in the Healthcare Cost and Utilization Project-Kids' Inpatient Database (HCUP-KID; 2000-2019). Robin sequence patients were identified and further stratified by syndromic status. Incidence, demographic parameters, and outcomes including mortality and tracheostomy rates were computed. A subset analysis comparing the isolated and syndromic cohorts was conducted. Data was analyzed through a χ 2 or t test. The incidence of RS was 5.15:10,000 (95% CI: 4.99-5.31) from a birth cohort of 7.5 million. Overall, 63.3% of the cohort was isolated RS and 36.7% had syndromic RS. Robin sequence patients had a significantly higher rate of cardiac (25.9%) and neurological (8.6%) anomalies compared with the general birth cohort and were most commonly managed in urban teaching hospitals ( P <0.0001). The pooled mortality and tracheostomy rates were 6.6% and 3.6%, respectively. Syndromic status was associated with a longer length of hospital stay (27.8 versus 13.6d), tracheostomy rate (6.2% versus 2.1%), and mortality (14.1% versus 2.2%) compared with isolated RS ( P <0.0001). The true incidence of RS is likely higher than previously reported estimates. Isolated RS patients have a low associated mortality and tracheostomy rate and are typically managed in urban teaching hospitals. Syndromic status confers a higher mortality rate, tracheostomy rate, and length of stay compared with nonsyndromic counterparts.

Trends in Natural Decannulation in Patients with Robin Sequence: A Twenty-five Year Retrospective Review.

Robin sequence (RS) consists of micrognathia and glossoptosis that result in upper airway obstruction (UAO). In RS patients who undergo tracheostomy, long-term goals include natural decannulation (ND) without further surgical airway intervention. The objective of this study was to identify long-term trends in the rate and length of time to ND. Retrospective chart review on 144 patients with RS treated from 1995 to 2020 at a pediatric tertiary care center. Patients were grouped by year of tracheostomy. Demographic data, UAO management, postoperative care, complications, and time to decannulation were recorded. Thirty-six patients met the inclusion criteria. Tracheostomy was performed at a median age of 45.5 days. 19 (53%) patients experienced ND at a median time of 66.1 months. ND rate was higher in non-syndromic patients (93% non-syndromic vs 27% syndromic; P < .0001) and during the first study period (1995-2006: 78%, 2007-2020: 28%; P = .003). Cox proportional-hazard regression demonstrated that white race [aHR 0.15 (0.03-0.8); P = .023] and higher birthweight [aHR 0.9 (0.8-0.98); P = .018] were associated with a higher likelihood of ND while a syndromic diagnosis had a negative association with ND [aHR 12.5 (3.3-50.0); P < .001]. Our study documented that ND in patients with RS who underwent tracheostomy was significantly associated with ethnicity, birthweight, and syndromic status. The negative impact on successful ND was most observed in patients with syndromic associations. Additionally, ND rates are lower in the 2007 to 2020 subgroup. We suspect this is because alternative management techniques such as tongue lip adhesion and mandibular distraction osteogenesis became primary surgical treatment in severe RS upper airway obstruction at our institution starting in 2007.

The Montreal Children's Hospital Experience Managing Robin Sequence: An Analysis of Outcomes and Algorithm for Surgical Technique Selection.

The development of mandibular distraction osteogenesis (MDO) and tongue-lip adhesion (TLA) has led to significant improvements in respiratory outcomes for the Robin sequence (RS) population. Despite such advances, there continues to be debate regarding management strategies. The authors present their experience managing the RS population with insights on technique selection. A retrospective review of RS patients treated at the senior author's institution from 2003 to 2021 was conducted. Baseline patient demographics and clinical parameters including feeding and respiratory status were recorded. Outcomes included the need for tracheostomy or tracheostomy, decannulation rates, and feeding status. Patients were evaluated through overnight oximetry and drug-induced sleep endoscopy (DISE). Outcomes were stratified according to management technique (MDO, TLA, versus conservative) and compared through statistical analysis. Fifty-nine RS patients were included. Twenty-eight were managed conservatively, 19 underwent MDO, 10 underwent TLA, one underwent both TLA and MDO, and one underwent tracheostomy primarily. Overall, 1.7% of the cohort required a tracheostomy and 86% achieved oral feeding after the procedure. The MDO cohort had lower Apgar scores and mean birth weight compared with the conservative and TLA cohorts ( P < 0.05). There were no statistical differences in respiratory and feeding outcomes across all three cohorts. A therapeutic algorithm was developed with insight into the use of DISE and risk stratification with overnight oximetry to guide procedural selection. Using this approach, safe and satisfactory respiratory outcomes were achieved with a low tracheostomy rate. Risk stratification is possible without polysomnography, and DISE is a promising tool (that requires further validation) for procedural selection in this population. Therapeutic, IV.

D23. Quarter Century Review of Velopharyngeal Insufficiency Rates between Palatoplasty Techniques among Patients with Robin Sequence

PURPOSE: Children with Robin sequence (RS) have wide U-shaped cleft palates. Following primary palatoplasty, RS patients have high rates of velopharyngeal insufficiency (VPI), often requiring speech-correcting surgery. This study compares VPI rates between palatoplasty techniques among the RS population. METHODS: A retrospective review of patients with isolated RS without concomitant syndromes from 1997-2022 was completed. Clinical and operative data were collected. Surgical techniques were performed by multiple senior surgeons and were categorized as Furlow double-opposing Z-plasty or straight-line palatoplasty. The primary outcome is surgical VPI rates. RESULTS: Upon review, 91 patients were identified to have isolated RS, of which 79 had a concomitant cleft palate. Overall surgical VPI rate was 11.4%. Follow-up time was 6.3±4.8 years (Furlow) and 4.2±4.0 years (straight-line; p=0.0593). Excluding patients with less than two years of follow-up, 35.7% (15/42) of Furlow patients had clinically diagnosed VPI compared to 11.8% (2/17) of the straight-line cohort (p=0.066). No patients in the straight-line cohort required speech-correcting surgery. The Furlow cohort had higher surgical VPI rates (21.4% vs. 0.0%; p=0.038) compared to straight-line. Upon Kaplan-Meier analysis, the 5-year surgical VPI rate was 11.6% and 0.0% for the Furlow and straight-line cohorts, respectively (p= 0.066). CONCLUSION: Our findings suggest the Furlow technique resulted in higher surgical VPI rates than straight-line repair among our RS patients. Though the Furlow technique offers palatal lengthening, this technique may compromise velum function in this wide cleft RS population.

Structural elements promote architectural stripe formation and facilitate ultra-long-range gene regulation at a human disease locus

Enhancer clusters overlapping disease-associated mutations in Pierre Robin sequence (PRS) patients regulate SOX9 expression at genomic distances over 1.25 Mb. We applied optical reconstruction of chromatin architecture (ORCA) imaging to trace 3D locus topology during PRS-enhancer activation. We observed pronounced changes in locus topology between cell types. Subsequent analysis of single-chromatin fiber traces revealed that these ensemble-average differences arise through changes in the frequency of commonly sampled topologies. We further identified two CTCF-bound elements, internal to the SOX9 topologically associating domain, which promote stripe formation, are positioned near the domain's 3D geometric center, and bridge enhancer-promoter contacts in a series of chromatin loops. Ablation of these elements results in diminished SOX9 expression and altered domain-wide contacts. Polymer models with uniform loading across the domain and frequent cohesin collisions recapitulate this multi-loop, centrally clustered geometry. Together, we provide mechanistic insights into architectural stripe formation and gene regulation over ultra-long genomic ranges.

Long-term speech outcome in patients with Robin sequence after cleft palate repair and tongue-lip adhesion: A 21-year retrospective analysis

The purpose of this study was to assess the effect of tongue−lip adhesion (TLA) on the long-term speech and articulation outcomes of patients with Robin sequence (RS) after cleft palate repair. Outcomes were compared to those in patients with RS who required positioning alone and to patients with isolated cleft palate (ICP).All consecutive patients with RS (with or without TLA) versus isolated cleft palate (ICP) who underwent cleft palate repair were retrospectively reviewed. Speech and articulation included all assessments between the age of 3–6 years. Secondary speech operations, velopharyngeal insufficiency (VPI), hypernasality, and articulation errors by cleft-type characteristics (CTC), including 4 categories (passive), non-oral, anterior-oral, and posterior-oral. A total of 41 RS patients and 61 ICP patients underwent repair with sufficient follow-up. Of them, 23 patients underwent a TLA at median age of 12 days. Rates of hypernasality (p = 0.004), secondary speech operations (p = 0.004), and posterior oral CTC (p = 0.042) were higher in RS compared to ICP. Isolated RS had speech outcomes similar to those of ICP; however, syndromic RS patients needed more secondary speech operations compared to isolated RS (p = 0.043). TLA-RS patients did not demonstrate differences in speech outcomes or any CTCs (all p > 0.05) compared to non−TLA-RS patients, except for the anterior oral CTC (74% TLA-RS vs 28% non−TLA-RS, p = 0.005).Within the limitations of the study, it seem that TLA does not affect long-term velopharyngeal function in patients with RS. However, TLA-RS patients demonstrated higher rates of anterior-oral CTC, which might be related to a different positioning of the tongue after TLA. Every effort should be taken to treat patients with RS conservatively instead of with TLA because of this demonstrated a negative effect on one type of articulation error. However, if conservative therapy fails, a TLA is still a valuable adjunct in the treatment of RS, and cleft speech pathologists who treat such patients should be more aware of this phenomenon in order to improve long-term articulation outcomes.

Mandibular morphology and distraction osteogenesis vectors in patients with Robin sequence

The aims of this cohort study were to compare the mandibular morphology between patients with Robin sequence (RS) and controls, and to examine the effects of mandibular distraction osteogenesis (MDO) using different vectors. Measurements of the mandibles of 80 patients with RS and 46 controls aged< 90 days were made using computed tomography. The data were compared among isolated RS patients (n = 58), syndromic RS patients (n = 22), and controls. Patients with RS exhibited significantly shorter ramus and body lengths and larger symphyseal angles than controls (all P < 0.001). Patients with isolated RS had shorter body lengths (P < 0.001), while syndromic patients had shorter ramus and body lengths (both P < 0.001) than controls. Seventy RS patients underwent MDO. Pre-MDO (n = 37) and post-MDO (n = 29) mandibular measurements were compared between patients undergoing MDO with a vertical vector and those undergoing MDO with a horizontal vector. Polysomnography data from part of the cohort highlighted the effectiveness of both vectors. MDO with a horizontal vector conferred 11% and 36% increases in ramus and body length, respectively, while these increases were 34% and 27.5%, respectively, with a vertical vector. MDO with a vertical vector was effective in lengthening ramus and body components and should be considered in the presence of ramus hypoplasia.

Analysis of Upper Airway Flow Dynamics in Robin Sequence Infants Using 4-D Computed Tomography and Computational Fluid Dynamics.

Robin Sequence (RS) is a potentially fatal craniofacial condition characterized by undersized jaw, posteriorly displaced tongue, and resultant upper airway obstruction (UAO). Accurate assessment of UAO severity is crucial for management and diagnosis of RS, yet current evaluation modalities have significant limitations and no quantitative measures of airway resistance exist. In this study, we combine 4-dimensional computed tomography and computational fluid dynamics (CFD) to assess, for the first time, UAO severity using fluid dynamic metrics in RS patients. Dramatic intrapopulation differences are found, with the ratio between most and least severe patients in breathing resistance, energy loss, and peak velocity equal to 40:1, 20:1, and 6:1, respectively. Analysis of local airflow dynamics characterized patients as presenting with primary obstructions either at the location of the tongue base, or at the larynx, with tongue base obstructions resulting in a more energetic stenotic jet and greater breathing resistance. Finally, CFD-derived flow metrics are found to correlate with the level of clinical respiratory support. Our results highlight the large intrapopulation variability, both in quantitative metrics of UAO severity (resistance, energy loss, velocity) and in the location and intensity of stenotic jets for RS patients. These results suggest that computed airflow metrics may significantly improve our understanding of UAO and its management in RS.

The Impact of Neonatal Mandibular Distraction on Long-Term Mandibular Growth and Morphology

Introduction: Mandibular distraction osteogenesis (MDO) is the gold standard treatment for upper airway obstruction associated with Robin Sequence (RS). The long-term effects of MDO on mandibular morphology approaching or at skeletal maturity remain unknown. The objective of this study was to morphologically characterize the mandibles of MDO and conservatively managed (CM) RS patients at or approaching skeletal maturity. Methods: Mandibular morphometric analysis was performed on MDO and CM patient mandibles via 3D-rendered computed tomographic (CT) images. Age- and sex-matched unaffected controls were used for comparison. Mean ± standard deviation was reported, Mann Whitney U Test was utilized, and a P-value of .05 or less was considered statistically significant. Results: RS patients (57.1% female, mean age 16.9 ± 2.6) treated with either CM (n = 5) or MDO (n = 7) were included. Age at latest CT was 17.3 ± 2.3 years for the CM group and 16.5 ± 2.9 for the MDO group. When compared to controls, CM patient mandibular body length was shorter, volumetrically smaller, and the anterior symphyseal angle was more obtuse ( P = .008, P = .06, and .008, respectively). When compared to controls, the MDO patient ramus height and body length were shorter ( P = .01 and &lt;.001, respectively), the gonial angle and anterior symphyseal angle were more obtuse ( P = .02 and &lt;.001, respectively), and mandibular volume was less ( P = .05). Conclusion: Neonatal MDO was associated with morphologic changes unique to the RS mandible at or approaching skeletal maturity. This study provides further insight into the long-term effects of MDO on mandibular morphology.

Polysomnography-guided mandibular distraction osteogenesis in Pierre Robin sequence patients.

Craniofacial malformations with micrognathia cause high grades of obstructive sleep apnea (OSA) measured by polysomnography (PSG). Mandibular distraction osteogenesis is a novel procedure for upper airway obstruction relief. Our primary objective was to describe the utilization of PSGs to improve obstruction in patients undergoing mandibular distraction. This is a retrospective study. Patients with micrognathia and severe upper airway obstruction, presenting with severe OSA diagnosed by PSG, were included from a single tertiary care center between 2015 and 2019. PSGs were done (1) prior to surgery, (2) once the cosmetic goal was achieved (Post-Op 1), and (3) if residual moderate-to-severe OSA was seen, every 2 nights until mild or no OSA was achieved (Post-Op 2). Thirteen patients were included. The median age at surgery was 1.1 months (10 days-3 months). All 13 patients had baseline severe OSA, with a median obstructive apnea-hypopnea index of 33 events/h and a median O2 nadir of 73%. Post-Op 1 PSG was done at a median of 6 days after surgery. Median first postoperative obstructive apnea-hypopnea index in all 13 patients was 6.8 events/h, with a median O2 nadir of 87%. A median additional distraction of 3 mm was needed beyond the traditionally recommended advancement. Long-term follow-up studies at or after 1 year were done in 5 patients, all showing persistent nonsevere OSA. This is the first case series utilizing PSGs as a guide for mandibular distraction osteogenesis in patients with micrognathia showing the need for jaw overcorrection to achieve resolution of OSA. Kochhar R, Modi V, de Silva N, etal. Polysomnography-guided mandibular distraction osteogenesis in Pierre Robin sequence patients. J Clin Sleep Med. 2022;18(7):1749-1755.

Efficacy and Complications of Mandibular Distraction Osteogenesis for Airway Obstruction in the Robin Sequence Population: A Comprehensive Literature Review.

Mandibular distraction osteogenesis (MDO) is becoming the procedure of choice for patients with Robin Sequence (RS) as it offers superior long-term respiratory outcomes in avoidance of tracheostomy. Lacking, is an analysis of the short- and long-term complications. To that end, we have conducted a comprehensive review focusing on complications of MDO. A systematic review of primary clinical studies reporting outcomes and complications of MDO in RS patients. Outcomes included tracheostomy avoidance and decannulation rate. Complications included dental trauma, nerve injury, surgical site infection and hardware failure. Complications were stratified according to distractor type (internal versus external) and age (>2 months versus <2months). A total of 49 studies yielded 1209 patients with a mean follow-up of 43.78 months. The tracheostomy avoidance rate was 94% (n = 817/870) and the mortality rate was 0.99% (n = 12/1209). The complication rate was 28.9% (n = 349/1209) with surgical site infections (10.5%) being most common. Dental and nerve injuries occurred in 7.9% and 3.2% of patients, respectively. Hardware replacement occurred in 1.2% of patients. internal distractors had higher rates of dental injury whereas external distractors had higher technical failure rates. There were no differences in complication rates ( P= 0.200), mortality ( P = 0.94) or tracheostomy avoidance ( P = 0.058) between patients >2months or <2months of age. Mandibular distraction osteogenesis is highly reliable and effective with a low mortality and high tracheostomy avoidance rate. There are important complications including nerve and dental injuries which require long-term follow-up. Neonatal patients do not appear to be at higher risk of complications reinforcing the safety of MDO in this population.

Can the Nasion-Mandibula Ratio Predict Obstructive Sleep Apnea in Patients With Retrognathia?

Introduction: Robin Sequence (RS) is characterized by retrognathia, glossoptosis, and upper airway obstruction (UAO). Nonetheless, the exact role of retrognathia in RS remains unclear. The aim of this study was to evaluate if measuring retrognathia could be of use next to the polysomnography (PSG) in the diagnosis of RS by differentiating RS patients and controls. Furthermore, this study endeavored to evaluate mandibular growth over time. Methods: A retrospective study was performed on RS patients without life-threatening UAO and controls. Mandibular length was assessed by using the Nasion-Mandibula Ratio (NMRatio) at the following three time points: 0 to 3 months, 1 year, and 4 years of age. Results: A total of 107 patients were included of whom 38 were diagnosed with RS. Thirty-two patients presented with clinical retrognathia but without obstructive sleep apnea (OSA), whilst 37 patients had an isolated cleft palate (CP). At 0 to 3 months, 1 year, and 4 years of age, significant higher NMRatios were found in RS patients compared to isolated CP patients, whilst no significant differences were found compared to retrognathia-only patients. Within RS patients, no significant differences were found between isolated versus non-isolated and invasively versus non-invasively treated patients. In all three patient groups, a significant decrease of the NMRatio was seen at the age of 4 years compared to 0 to 3 months and 1 year of age. Conclusions: Although the NMRatio differs between RS and isolated CP patients, a seemingly small mandible (in a-p direction) does not reflect functional outcomes in RS patients and a PSG should always be performed to confirm the diagnosis. Despite that mandibular length significantly increased after the first year of life, mandibular size of RS patients does not seem to reach values of normal infants. Accordingly, mandibular catch up growth, that is suggested to be typically present in RS patients, was not found by our study.

Evaluating Sensory Nerve Outcomes After Horizontal Osteotomy for Mandibular Distraction in Infant Robin Sequence Patients.

There has yet to be a consensus on the appropriate technique for mandibular distraction in the infant Pierre Robin population nor is their sufficient data on sensory nerve outcomes. The purpose of this study is to validate the safety of the horizontal osteotomy by: (1) determining mandibular foramen location in infant Pierre Robin patients relative to the dentoalveolar plane and (2) evaluate long-term function of the inferior alveolar nerve in previously distracted Pierre Robin patients. Preoperative 3D Computed tomography (CT) scans of Pierre Robin patients < 1 year old were reviewed. A line at the level of the mandibular dentoalveolar plane was drawn across the lingual surface of the ramus and the distance to the mandibular foramen was then measured. Semmes-Weinstein monofilaments of the lower lip and chin bilaterally was performed on mandibular distraction patients in clinic. Inclusion criteria was patients >6 years of age having undergone bilateral mandibular distraction at <1 year of age. Fifteen patients' CT studies were examined. The mandibular foramen was consistently below the level of the dentoalveolar plane at an average distance of 4.7 mm. Eight patients were included in the prospective arm. Average age was 12.2. All patients had normal sensation at 2.83 through all areas. The mandibular foramen reliably exists below the dentoalveolar plane. In addition, all patients reviewed postoperatively with >10 years of follow up demonstrated normative sensation. The horizontal corticotomy performed just above the mandibular dentoalveolar plane spares the inferior alveolar nerve in young Pierre Robin patients undergoing distraction.

1173 Airway and Breathing Problems in Pierre Robin Sequence: A Systematic Review Protocol

Abstract Aim The primary aim is to systematically review the specific airway and/or breathing problems which have been reported in Pierre Robin Sequence (PRS). Secondary aims are to understand the prevalence and severity of these airway and breathing problems, and options for screening, assessment, and monitoring. Method A search strategy will be designed to search the following databases: MEDLINE, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials(CENTRAL) including a grey literature search, to identify publications on airway and/or breathing problems in Pierre Robin Sequence patients. Airway or breathing problems to be included are defined upper airway conditions (e.g., sleep apnoea) or clinically or objectively defined airway/breathing problems (e.g., increased respiratory rate, polysomnography). Screening will exclude non-English articles, abstracts, letters, editorials, expert opinions and breathing problems not anatomically related to craniofacial underdevelopment. Results This systematic review has been successfully registered on the PROSPERO International Prospective Register of Systematic Reviews (CRD42020210572) Conclusions PRS is a rare craniofacial condition which presents at birth, consisting of micrognathia, glossoptosis and airway problems, and is usually, but not always, associated with a cleft palate. There is no consensus on the type of airway problems that affect patients with PRS. The findings of this systematic review will help to develop a consensus on the airway and breathing problems in PRS and options for assessment and monitoring of the airway and breathing problem. This data may also contribute to development of a standardized guideline for management of airway and breathing problems in PRS.

Maxillomandibular Development after Mandibular Distraction Osteogenesis in Isolated Pierre Robin Sequence Patients

Mandibular distraction osteogenesis (MDO) is a favored surgical technique for addressing the airway difficulties that result in patients with Pierre Robin sequence. Devices are placed to distract the micrognathic mandible forward and generate bone at bilateral mandibular osteotomies.1 Though it is generally accepted that these patients will continue to develop with disproportionate maxillomandibular growth after distraction2, the timeline for relapse back to a skeletal class II relationship, as well as differences between male and female development post-distraction, is not well-described.The purpose of this study is to characterize a timeline of maxillomandibular growth for patients with isolated Pierre Robin sequence (iPRS) after MDO during infancy based on Steiner's analysis and clinical impressions, as well as to identify differences in post-distraction growth between males and females. The researchers hypothesized that these patients would demonstrate disproportionate growth after distraction and that females would relapse at a faster rate than males. By improved understanding of this timeline, clinicians may better educate parents with expectations for their child's craniofacial development after distraction.Department records were retrospectively reviewed to identify patients with iPRS who underwent MDO during infancy from 2004 through 2016. Patients with post-distraction imaging from which cephalometric data could be traced (i.e., lateral cephalograms or cone beam computerized tomography [CBCT] scans) were included. These were traced by 2 independent reviewers for SNA, SNB, and ANB angles, according to Steiner's analysis to determine skeletal classification. Patients with pre- and post-distraction lateral profile photos were assessed by 1 reviewer for skeletal classification based on clinical appearance. Patient age at distraction, sex, time from initial distraction to imaging study, and prior maxillomandibular surgeries were abstracted. Descriptive statistics and significance testing were performed; 38 patients with iPRS who underwent MDO were identified. Of these, 15 (39.5%) had at least 1 postoperative lateral cephalogram. Average time from surgery to initial lateral cephalogram (TAS) was 67.81 months for all patients (range 25.53 to 129.93 months). The majority of patients (n = 12) had an ANB > 2° at the time of lateral cephalogram. One patient (TAS 25.53 months) had an ANB of 1.3°, whereas 2 patients (both with prior cleft palate repair) had an ANB < 0° (TAS 32.67 and 97.17 months). Nine (60%) of all patients with lateral cephalogram data fell within 1 standard deviation of average TAS (39.52 to 96.1 months), with corresponding average SNA, SNB, and ANB angles of 80.97, 73.99, and 7.03, respectively; 33% of these patients (n = 3) had prior palatal surgery. Of the 38 patients, 37 had pre- and post-distraction lateral photographs; 13 of 15 (86.7%) females, and 12 of 22 (54.5%) males relapsed to a skeletal class II relationship by the last follow-up appointment (P = .04). The mean postoperative follow-up months for females (69.3 months) and males (79.9 months) was similar (P = .50). Based on post-distraction cephalometric tracing, 80% of patients reverted back to a skeletal class II relationship by an average of 68 months. Based on post-distraction clinical appearance, 68% of patients reverted to a class II relationship by an average of 76 months. Furthermore, a more significant percentage of females relapsed to a skeletal class II relationship compared to males at similar follow-up points. These findings may help clinicians and parents better understand and prepare for the maxillomandibular developmental timeline of these patients post-distraction.

Maxillomandibular Development after Mandibular Distraction Osteogenesis in Isolated Pierre Robin Sequence Patients

Mandibular distraction osteogenesis (MDO) is a favored surgical technique for addressing the airway difficulties that result in patients with Pierre Robin sequence. Devices are placed to distract the micrognathic mandible forward and generate bone at bilateral mandibular osteotomies.1 Though it is generally accepted that these patients will continue to develop with disproportionate maxillomandibular growth after distraction2, the timeline for relapse back to a skeletal class II relationship, as well as differences between male and female development post-distraction, is not well-described.The purpose of this study is to characterize a timeline of maxillomandibular growth for patients with isolated Pierre Robin sequence (iPRS) after MDO during infancy based on Steiner's analysis and clinical impressions, as well as to identify differences in post-distraction growth between males and females. The researchers hypothesized that these patients would demonstrate disproportionate growth after distraction and that females would relapse at a faster rate than males. By improved understanding of this timeline, clinicians may better educate parents with expectations for their child's craniofacial development after distraction.Department records were retrospectively reviewed to identify patients with iPRS who underwent MDO during infancy from 2004 through 2016. Patients with post-distraction imaging from which cephalometric data could be traced (i.e., lateral cephalograms or cone beam computerized tomography [CBCT] scans) were included. These were traced by 2 independent reviewers for SNA, SNB, and ANB angles, according to Steiner's analysis to determine skeletal classification. Patients with pre- and post-distraction lateral profile photos were assessed by 1 reviewer for skeletal classification based on clinical appearance. Patient age at distraction, sex, time from initial distraction to imaging study, and prior maxillomandibular surgeries were abstracted. Descriptive statistics and significance testing were performed; 38 patients with iPRS who underwent MDO were identified. Of these, 15 (39.5%) had at least 1 postoperative lateral cephalogram. Average time from surgery to initial lateral cephalogram (TAS) was 67.81 months for all patients (range 25.53 to 129.93 months). The majority of patients (n = 12) had an ANB > 2° at the time of lateral cephalogram. One patient (TAS 25.53 months) had an ANB of 1.3°, whereas 2 patients (both with prior cleft palate repair) had an ANB < 0° (TAS 32.67 and 97.17 months). Nine (60%) of all patients with lateral cephalogram data fell within 1 standard deviation of average TAS (39.52 to 96.1 months), with corresponding average SNA, SNB, and ANB angles of 80.97, 73.99, and 7.03, respectively; 33% of these patients (n = 3) had prior palatal surgery. Of the 38 patients, 37 had pre- and post-distraction lateral photographs; 13 of 15 (86.7%) females, and 12 of 22 (54.5%) males relapsed to a skeletal class II relationship by the last follow-up appointment (P = .04). The mean postoperative follow-up months for females (69.3 months) and males (79.9 months) was similar (P = .50). Based on post-distraction cephalometric tracing, 80% of patients reverted back to a skeletal class II relationship by an average of 68 months. Based on post-distraction clinical appearance, 68% of patients reverted to a class II relationship by an average of 76 months. Furthermore, a more significant percentage of females relapsed to a skeletal class II relationship compared to males at similar follow-up points. These findings may help clinicians and parents better understand and prepare for the maxillomandibular developmental timeline of these patients post-distraction.