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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

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.

MicroNAPS: A Novel Classification for Infants with Micrognathia, Robin Sequence, and Tongue-based Airway Obstruction

Background

Robin sequence (RS) describes a heterogeneous population with micrognathia, glossoptosis, and upper airway obstruction (UAO). Workup, treatment, outcomes assessment, and research inclusion are widely variable. Despite several classifications and algorithms, none is broadly endorsed. The objective of this investigation was to develop and trial a novel classification system designed to enhance clinical communication, treatment planning, prognostication, and research.

Methods

This is a retrospective cross-sectional study. A classification system was developed with five elements: micrognathia, nutrition, airway, palate, syndrome/comorbidities (MicroNAPS). Definitions and a framework for "stage" assignment (R0-R4) were constructed. Stage "tongue-based airway obstruction" (TBAO) was defined for infants with glossoptosis and UAO without micrognathia. MicroNAPS was applied to 100 infants with at least 1-year follow-up. Clinical course, treatment, airway, and feeding characteristics were assessed. Descriptive and analytic statistics were calculated and a P value less than 0.05 was considered significant.

Results

Of the 100 infants, 53 were male. Mean follow-up was 5.0 ± 3.6 years. R1 demonstrated feeding-predominant mild RS for which UAO was managed nonoperatively but gastrostomy tubes were prevalent. R2 was characterized by airway-predominant moderate RS, typically managed with mandibular distraction or tongue-lip adhesion, with few gastrostomy tubes and short lengths-of-stay. R3 denoted severe RS, with similar UAO treatment to R2, but with more surgical feeding tubes and longer admissions. R4 represented a complex phenotype with 33% tracheostomies, protracted hospitalizations, and delayed palatoplasty. R0 ("at risk") and TBAO groups displayed the most variability.

Conclusions

MicroNAPS is easy to use and associated with relevant disease characteristics. We propose its adoption in clinical and research settings.

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 role of upper airway endoscopy in craniofacial malformations

OBJECTIVE

To study the role of upper airway endoscopy (UAE) in craniofacial malformations in all different management approaches described in the literature.

METHODS

A narrative review was performed, based on a search in pubmed.

RESULTS

UAE use was reviewed over five domains: 1) Diagnosis of glossoptosis and endoscopic classification: drug-induced sleep endoscopy is recommended to graduate tongue base obstruction; there is still no consensus on the graduation system to be used. 2) Airway abnormalities: there is a high incidence of additional lesions in conjunction with glossoptosis. 3) Swallowing evaluation: a formal comparison with fluoroscopy (gold standard) has not yet been performed in this population. 4) Intubation: thin bronchoscopes allow intubation of small babies; moreover, intubation with rigid video-assisted laryngoscopes show a high success rate in this population. 5) Treatment outcome monitoring: there is no consensus on the ideal parameters to be checked.

CONCLUSION

Some approaches have already been well established in the management of patients with craniofacial malformations, e.g. the endocopic evaluation of glossoptosis and associated lesions and its role as an intubation assistance tool, while others need to be subject of further research, e.g. its role in swallowing investigation and as a postoperative success control predictor.

Pediatric drug-induced sleep endoscopy: An updated review of the literature

The field of drug-induced sleep endoscopy (DISE) has grown considerably over the last 10∼15 years, to now include its use in pediatric patients. In this review article, we outline our approach to the use of this technology in Children with Airway Obstruction, most specifically in the management of children with airway obstruction and known or suspected adenotonsillar enlargement.

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.

4D Computed Tomography for Dynamic Upper Airway Evaluation in Robin Sequence

Thorough assessment of dynamic upper airway obstruction (UAO) in Robin sequence (RS) is critical, but traditional evaluation modalities have significant limitations. Four-dimensional computed tomography (4D-CT) is promising in that it enables objective and quantitative evaluation throughout all phases of respiration. However, there exist few protocols or analysis tools to assist in obtaining and interpreting the vast amounts of obtained data. A protocol and set of data analysis tools were developed to enable quantification and visualization of dynamic 4D-CT data. This methodology was applied to a sample case at 2 time points. In the patient with RS, overall increases in normalized airway caliber were observed from 5 weeks to 1 year. There was, however, continued dynamic obstruction at all airway levels, though objective measures of UAO did improve at the nasopharynx and oropharynx. Use of 4D-CT and novel analyses provide additional quantitative information to evaluate UAO in patients with RS.

Longer upper airway lengths in Robin Sequence: A case-control study using computed tomography

BACKGROUND

Direct laryngoscopy and intubation are often difficult in children with Robin Sequence. Previous research characterizing anatomic airway differences has focused on parameters influencing airway patency; there is a paucity of data pertaining to intubation trajectories and depth. Such information could impact airway management approaches and decrease the incidence of endotracheal tube malpositioning.

AIM

The study goal was to examine whether longitudinal airway parameters pertaining to intubation are different in children with Robin Sequence compared with age-matched controls.

METHOD

This case-control study compared patients with RS <4 years of age who had computed tomography scans of the head and neck to age- and sex-matched controls. Measurements were made of the nasopharynx, oropharynx, hypopharynx, tongue, hyoid, and the front teeth to vocal cord, nares to vocal cord, and nasion-basion distances. Statistical analysis was performed using multiple ANCOVA models with the categorical predictor of Robin Sequence vs control and potential covariates including subject height/length, weight, and age.

RESULTS

Thirty-three patients with Robin Sequence and 33 control subjects were included. After controlling for subject height/length, mean front teeth to vocal cord distance was 1.2 cm longer (95% CI: 0.9 to 1.6 cm, P < .001) and mean nares to vocal cord distance was 0.8 cm longer (95% CI: 0.4 to 1.2 cm, P < .001) in patients with Robin Sequence than in controls. The tongue was positioned on average 0.5 cm higher (95% CI: 0.3 to 0.8, P < .001) and 0.9 cm more posterior (95% CI: 0.6 to 1.0 cm, P < .001) in cases than in controls. Moreover, in patients with Robin Sequence, the hyoid was positioned on average 0.5 cm more inferiorly (95% CI: 0.2 to 0.8 cm, P < .001) and 0.2 cm more posteriorly (95% CI: 0.1 to 0.4 cm, P < .01) than controls.

CONCLUSION

In patients with Robin Sequence under 4 years of age, the mean front teeth to vocal cord distance was found to be 1.2 cm longer while the mean nares to vocal cord distance was found to be 0.8 cm longer controlling for subject length. Clinicians should account for these differences when selecting and placing endotracheal tubes, particularly those with a preformed bend.

International Pediatric ORL Group (IPOG) Robin Sequence consensus recommendations

OBJECTIVE

To provide recommendations for the comprehensive management of airway obstruction in patients with Robin Sequence.

METHODS

Expert opinion by the members of the International Pediatric Otolaryngology Group (IPOG).

RESULTS

The consensus statement provides recommendations for medical specialists who manage infants with Robin Sequence including: evaluation and treatment considerations for commonly debated issues in post-natal airway obstruction, assessment of antenatal obstruction and perinatal airway management.

CONCLUSION

Consensus recommendations are aimed at improving management of airway obstruction in patients with Robin Sequence.