Does Mandibular Distraction Vector Influence Airway Volumes and Outcome?

Computerized Surgical Planning for Mandibular Distraction Osteogenesis

Mandibular distraction osteogenesis is a technically challenging procedure due to complex mandibular anatomy, especially in the treatment of Pierre-Robin Sequence due to variable bone thickness in the infant mandible and the presence of tooth buds. Computerized surgical planning (CSP) simplifies the procedure by preoperatively visualizing critical structures, producing cutting guides, and planning distractor placement. This paper describes the process of using CSP to plan mandibular distraction osteogenesis, including discussion of recent advances in the use of custom distractors.

How does changing the vector of transport disc distraction affect the outcomes of surgery in patients of temporomandibular joint ankylosis with obstructive sleep apnea?

PURPOSE

Temporomandibular joint ankylosis (TMJA) in children is associated with retrognathia, reduction in pharyngeal airway volume (PAV), and obstructive sleep apnea (OSA). Distraction-osteogenesis (DO) is the proven method in the management of OSA. There is paucity in literature about the effect of distraction vector on PAV. It can be expected that an oblique vector would improve PAV and relieve OSA. Thus, the study was designed to explore the feasibility, advantages, and disadvantages of this modified technique for managing TMJA and OSA simultaneously.

MATERIALS AND METHOD

The investigators designed a prospective study on patients of TMJA with retrognathia. Ethical approval was obtained (IECPG-547/14.11.2018). In all patients, simultaneous ankylosis release and mandibular distraction were performed. Primary outcome variables were improvement in 3-dimensional (3D) PAV and maximal interincisal opening (MIO). Secondary outcome variables were changed mandibular length, distraction relapse, and re-ankylosis. Paired t-test and multivariate ANOVA were used to assess all the parameters.

RESULT

The study included 13 joints in 8 patients of TMJA with retrognathia (2 unilateral and 6 bilateral ankylosis) with mean age of 14.25 ± 7.37 years. Mean distraction performed was 19 ± 4.0 mm. There was a statistically significant improvement of PAV by 225% (p = 0.002), a reduction in Epworth's scale (p = 0.017), an increase in MIO (p = 0.001), and an increase in mandibular length. Three patients had re-ankylosis at the 25-month follow-up.

CONCLUSION

The results of the present study conclude that modification of distraction vector improves 3D PAV and MIO in TMJA patients, with the added advantage of a reduction in overall treatment time and improved patient compliance.

Complications of Mandibular Distraction Osteogenesis in Infants with Isolated Robin Sequence

Mandibular Distraction Osteogenesis (MDO) is now the preferred procedure to alleviate airway obstruction in infants with severe Robin Sequence (RS). However, there have been very few studies investigating complications related to MDO surgery performed on patients affected by isolated RS. In this study, age at distraction, weight at distraction, preoperative intubation, repeat MDO and complications associated with MDO were included as variables. Minor, moderate and major problems were evaluated and recorded as surgical site infections (SSI), injuries to the facial nerve, self-extinction hypertrophic scars, temporomandibular joint ankylosis, device failures, early ossification and fibrous non-union. One hundred and fifty one patients with isolated RS were included. At distraction, the mean age was 72 days (12-540 days) and the mean weight was 4.05 kg (2.4-12.2 kg). Only one patient needed tracheostomy after MDO, and none required further distraction. Ultimately, the complication rate was 15.23%, and there was a total of 7.95% minor, 9.27% moderate and 0% major complications. Minor incidents included surgical site infection (SSI) managed with antibiotics taken orally (n = 8), neuropraxia in the VII cranial nerve (CN) (n = 1), and hypertrophic scarring (n = 3). Incidents reported as moderate were SSIs managed with intravenous antibiotics (n = 9), incision and drainage (n = 3) and self-extubation (n = 2). There was no case of TMJ ankylosis. There were no cases of early or premature ossification, fibrous non-union and device fracture. In conclusion, MDO is an effective and appropriate management technique for infants with isolated RS and severe airway obstruction. Infections at the surgery site accounted for the vast majority of the complications. Further investigations may be needed to determine the long-term consequences of MDO.

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.

Facial Nerve Dysfunction After Mandibular Distraction Osteogenesis in Patients with Robin Sequence: A Systematic Review and Meta-Analysis

OBJECTIVE

Robin Sequence (RS), characterized by micrognathia, glossoptosis, and upper airway obstruction, is an increasingly recognized diagnosis. An effective surgical intervention is mandibular distraction osteogenesis (MDO). This study analyzes published evidence regarding facial nerve dysfunction (FND) associated with MDO.

DESIGN AND SETTING

According to PRISMA guidelines, a systematic review was carried out with databases queried in June 2019 using MESH terms, or equivalent terms, as follows: "distraction osteogenesis" and "Robin Sequence". A review of original Spanish and English articles, were included. Outcome measures included the prevalence of FND; the affected branches; the rate of permanent vs. transient FND; the use of an internal vs. external device; the daily distraction rate; and finally, the overall distraction length. Subsequently, a meta-analysis was conducted to collate results regarding the prevalence of FND and the factors associated with it.

RESULTS

Of 239 unique studies identified, 19 studies with 729 patients met inclusion criteria; 52 patients developed FND after MDO. A random-effects meta-analysis yielded a pooled prevalence of FND of 6.40%, with moderately heterogeneous studies (I2 = 41%, τ2 = 0.006). Marginal mandibular nerve involvement was most commonly noted. Nine studies reported transient FND, six permanent, one both, and two unspecified. Internal distractors were used in 8 studies and external in 3 and both in 2. Distraction rate was 1.00 to 2.00 mm/day and total distraction length ranged from 13.00 to 22.3 mm. Sample size was the only parameter inversely associated with rate of FND (p = 0.04).

CONCLUSION

This analysis of FND associated with MDO for patients with RS demonstrates a lack of consistent documentation. MDO-associated FND does not appear to be uncommon, and permanent dysfunction can occur. This review underscores the importance of thorough documentation to elucidate the mechanism of FND.

Can Dynamic Magnetic Resonance Images Improve Prenatal Diagnosis of Robin Sequence

BACKGROUND

Robin sequence (RS) is a triad of micrognathia, glossoptosis, and airway obstruction. Prenatal diagnosis of RS improves delivery planning and postnatal care, but the process for prenatal diagnosis has not been refined. The purpose of this study was to determine if dynamic cine magnetic resonance imaging (MRI) can improve the reliability of prenatal diagnosis for RS compared to current static imaging techniques.

MATERIALS AND METHODS

This is a retrospective cross-sectional study including fetuses with prenatal MRIs obtained in a single center from January 2014 to November 2019. Fetuses were included if they: 1) had a prenatal MRI with cine dynamic sequences of adequate quality, 2) were live born, and 3) had postnatal craniofacial evaluation to confirm RS. Patients without postnatal confirmation of their prenatal findings were excluded. The primary predictor variable was imaging type (cine or static MRI). Outcome variables were tongue and airway measurements: 1) tongue height, 2) length and width, 3) tongue shape index, 4) observation of tongue touching the posterior pharyngeal wall, and 5) measurement of oropharyngeal space. All measurements were made independently on the cine images and on static MRI sequences for the same cohort of subjects by a pediatric radiologist. Data were analyzed using paired samples t tests and Fisher exact tests, and significance was set as P < .05.

RESULTS

A total of 11 patients with RS were included in the study. The smallest airway space consistently demonstrated complete collapse on the cine series compared to partial collapse on static images (0 mm vs 1.7 ± 1.4 mm, P = .002). No other imaging variable was statistically significantly different between techniques.

CONCLUSIONS

Cine imaging sequences on prenatal MRI were superior to static images in discerning complete collapse of the smallest airway space, an important marker of RS. This suggests a possible benefit to adding dynamic MRI evaluation for prenatal diagnosis of this condition.

Mandibular Distraction Osteogenesis in Robin Sequence Using Three-Dimensional Analysis and Planning

SUMMARY

The optimal management of patients with Robin sequence may include neonatal mandibular distraction osteogenesis, which has been used to achieve excellent functional and aesthetic outcomes in appropriate patients. This article and video vignette depict the treatment of micrognathia and airway obstruction secondary to Robin sequence, demonstrating the planning and surgical approach of the senior author (D.M.S.) using mandibular distraction osteogenesis.

Timing and Duration of Facial Nerve Dysfunction After Mandibular Distraction Osteogenesis for Robin Sequence

Objective

Collect data from craniofacial surgeons to analyze mandibular distraction osteogenesis (MDO) protocols, and facial nerve dysfunction (FND) to characterize this common, but poorly documented complication after MDO in infants with Robin Sequence (RS).

Design, Setting, and Participants

A 16-question anonymous survey designed through REDCap was digitally distributed to members of the American Cleft Palate-Craniofacial Association and International Society of Craniofacial Surgery (ISCFS).

Main Outcome Measure(s)

Demographic information, MDO perioperative variables, surgeon experience with FND after MDO for patients with RS, and the timing and duration of FND were analyzed.

Results

Eighty-four responses were collected, with 80 included for analysis. Almost two-thirds of respondent surgeons reported FND as a complication of MDO in patients with RS (51, 63.8%); 58.8% (n   =   47) transient FND and 5% (n   =   4) with permanent facial nerve palsy only. Both transient and permanent FND was documented by 13 (16.3%) respondents. Among respondents, FND was observed immediately following initial device placement/osteotomies in 45.1%, during distraction in 45.1%, during consolidation in 19.6%, and following device removal in 43.1%. Twenty-five of these respondent surgeons reported resolution of FND between 1 and 3 months (53.2%, n   =   25).

Conclusions

FND after MDO in patients with RS was noted by most respondents in this survey study. While most surgeons noted temporary FND, one-fifth reported long-term dysfunction. FND was documented most commonly following device placement/osteotomies or during active distraction. Further research should seek to establish risk factors associated with FND and identify surgical and perioperative prevention strategies

Feeding and swallowing outcomes following mandibular distraction osteogenesis: an analysis of 22 non-isolated paediatric cases

Patients with mandibular hypoplasia and upper airway obstruction are at an increased risk of feeding and swallowing difficulties. Little has been described regarding these outcomes following mandibular distraction. The aim of this study was to evaluate the effect of mandibular distraction on feeding and swallowing function. A retrospective study was performed on 22 patients with non-isolated mandibular hypoplasia and severe upper airway obstruction treated with mandibular distraction. Median age at first mandibular distraction was 3.1 years (interquartile range 2.3-6.0 years) and the median follow-up time was 3.5 years (interquartile range 2.0-9.4 years). Prior to mandibular distraction, feeding difficulties were present in 18 patients. Swallowing difficulties were present in 20 patients, all of whom had problems in the oral phase of swallowing, while 11 patients had additional problems in the pharyngeal phase. Following mandibular distraction, at the time of follow-up, feeding difficulties persisted in 13 patients. Swallowing difficulties in the oral phase remained present in all 20 patients, while pharyngeal phase problems persisted in seven patients. In conclusion, feeding and swallowing difficulties are highly prevalent in non-isolated patients and often persist following mandibular distraction. Moreover, these can be the reason that decannulation cannot be accomplished. Hence, awareness and close follow-up by a specialized speech therapist is of paramount importance.

Changes in Hyoid Bone Position before and after Distraction Osteogenesis in Infants with Robin Sequence

PURPOSE

To study the changes of hyoid position in infants with Robin sequence before and after mandibular distraction osteogenesis, and to explore the related factors.

MATERIAL AND METHODS

Twenty-six infants with Robin sequence underwent bilateral mandibular distraction osteogenesis from May 2016 to April 2020. Three-dimensional computed tomography data of patients before and after surgery were analyzed with Materialise Mimics 17.0. Changes in the three-dimensional position of the hyoid bone were studied.

RESULTS

The angle between the long axis of the tongue body and hard palate plane, and the angle between the long axis of the tongue body and mandibular plane were significantly decreased after surgery than before surgery. The hyoid bone-cranial base vertical distance, hyoid bone-mental point distance, and hyoid bone-epiglottis distance were significantly increased after surgery. The differences in the above-mentioned data were statistically significant (P < 0.05). Changes in the angle between the long axis of the tongue body and the hyoid bone-mental point line correlated with changes in the position of the hyoid bone relative to the cervical spine (P = 0.006). Postoperatively, the hyoid bone moved forward and the increase in the hyoid bone-mental point osseous distance interval (41.28%) was significantly greater than the increase in the hyoid bone-epiglottis distance (18.73%). Differences in the total mandibular length and the hyoid bone-cranial base vertical distance are related to the age at the operation (P < 0.05). The younger the age at the time of surgical intervention, the greater the difference before and after surgery for the same follow-up interval.

CONCLUSIONS

The three-dimensional direction of the hyoid bone changes after the distraction osteogenesis of the mandible, and the hyoid bone moves downward and forward. Because the mandibular length and airway changed, the relative positions of the long axis of the tongue body on the sagittal plane rotated clockwise.

Robin Sequence: Neonatal Mandibular Distraction

Pierre Robin sequence is defined by the clinical triad: mandibular hypoplasia, glossoptosis, and airway obstruction. Mandibular distraction osteogenesis (MDO) is a standard treatment of Robin sequence associated with severe airway obstruction and is the only intervention that directly corrects the underlying anatomic pathologic condition. Compared with tongue-lip adhesion, MDO has demonstrated more success in treating airway obstruction in infants with Pierre Robin sequence, including patients with syndromic diagnoses and concomitant anomalies. This article provides a current, comprehensive review of neonatal mandibular distraction and offers treatment guidelines based on a combined surgical experience of more than 400 patients.

Evaluation of Hyoid Position and Retroglossal Airway After Mandibular Alveolar Archwise Distraction Osteogenesis

The interaction between form and function in the craniofacial region is a well-accepted fact in orthodontics. The aim of the present study is to objectively evaluate if mandibular sagittal symphyseal distraction causes an increase in the retroglossal airway size and hyoid position in a retrospective clinical study. The pretreatment (T0) and 3 months post-distraction (T1) cone-beam computed tomography images of 12 patients (mean age 17.1 years) were retrieved. The retroglossal airway volume and hyoid-mandibular plane distance, hyoid-C3 distance, sella-nasion-B point angle angle, lower incisor to mandibular plane, and Mandibular plane angles were measured using 3D medical imaging software. The average amount of distraction at the superior border of the bony transport segment was 6.2 mm and 4.4 mm at the inferior border. The changes in retroglossal airway volume (2943.2 mm), incisor to mandibular plane (6.5°), and mandibular plane (2.1°) were significant. The changes in hyoid-mandibular plane distance and hyoid-C3 distances were not significant. However, a downward repositioning in Hyoid position was observed along with the mandibular clockwise rotation. This study showed that symphyseal dentoalveolar distraction osteogenesis, as a complementary to orthodontic therapy, can affect the form and size of the pharynx. Therefore, the airway size should be one of the diagnostic and decisive factors for an ideal treatment planning.

Novel Approach of Mandibular Distraction to Avoid Tracheostomy in KAT6B-related Gene Disorders

Previously, severe upper airway obstruction in patients with retrognathia and glossoptosis has been managed with tracheostomy. However, tracheostomy is associated with significant morbidity. In recent years, mandibular distraction has become an alternative management strategy in infants, but these applications have been limited to patient populations with retrognathia and glossoptosis. The authors present 2 unique cases of patients with KAT6B-related gene disorders, who present with a paradox of tongue-based airway obstruction in the absence of retrognathia. In both cases mandibular distraction osteogenesis with an obliquely oriented vector was successfully performed and both children avoided the need for tracheostomy.

Laryngoscopy Grade Improvement and Difficult Airway Resolution in Infants With Robin Sequence Undergoing Mandibular Distraction Osteogenesis: A Multi-Institutional Study

OBJECTIVE

Mandibular distraction osteogenesis (MDO) aims to relieve tongue-based airway obstruction in Robin Sequence (RS). We investigated direct laryngoscopy grade (DLG) improvement and difficult airway (DA) resolution following MDO.

DESIGN

Retrospective cohort analysis.

SETTING

Three tertiary care institutions.

PATIENTS

Sixty-four infants with RS who underwent a single MDO procedure in their first year of life were identified from January 2010 to January 2019.

MAIN OUTCOME MEASURES

The primary outcome was DLG pre- and post-MDO. Secondary outcomes included DA designation, pre- and post-MDO polysomnographic assessment for obstructive sleep apnea (OSA), length of stay, need for gastrostomy, and major/minor adverse events.

RESULTS

Median DLG improved from II pre-MDO to I at the time of distractor removal (n = 43, P < .001). No significant change was seen in patients with a third recorded time point (eg, palatoplasty; n = 78, P = .52). Twenty-six (47%) of 55 patients were designated as DA pre-MDO, and 10 (18%) of 55 patients retained the label post-MDO (P < .01). Five (50%) of these 10 patients appeared to be inappropriately retained. Median obstructive apnea-hypopnea index improved from 38.6 (range 31.2-62.8) pre-MDO to 2.9 (range 1-3.9) post-MDO (n = 12; P = .002).

CONCLUSION

Mandibular distraction osteogenesis allowed for DLG improvement that was stably maintained as well as functional improvement in OSA, with minimal morbidity. Difficult airway designation persisted in the electronic record of some infants despite clinical resolution.

Is Intensive Care Unit Admission Necessary After Removal of Mandibular Distraction Devices in Infants With Robin Sequence?

OBJECTIVE

Intensive care unit (ICU) care is routinely required after the operation to initiate mandibular distraction osteogenesis (MDO) in infants with Robin sequence (RS). Many patients are also managed in the ICU after subsequent device removal. It is uncertain if ICU care, which is expensive and limited, is necessary after this second operation. The objective of this study was to evaluate the incidence of respiratory events following device removal. We hypothesized that respiratory events would be infrequent and non-ICU inpatient monitoring would be adequate.

DESIGN

This is a retrospective study of patients with RS from 2013 to 2018.

PATIENTS

Patients were included if they had MDO and distractor removal during the first year of life. Patients were excluded if they had a tracheostomy or remained intubated after distractor removal.

MAIN OUTCOME MEASURE

Postoperative respiratory events.

RESULTS

Twenty-five (60% male) patients were included. Mean age and weight at distractor removal were 142 ± 79 days of life and 5.5 ± 1.1 kg. Mean apnea-hypopnea index after completion of distraction was 1.1 ± 1.5 events/hour. Two (8%) patients experienced postoperative respiratory events that required intervention. In 1 (4% of sample) of these, the event was deemed to have benefited from ICU-level care. Two variables were significantly associated with these events: congenital heart disease (P = .020) and concomitant procedure performed during the same operation (P = .020).

CONCLUSIONS

Intensive care unit-level care is rarely needed after distractor removal in infants with RS. Intensive care unit admission should be considered in patients with congenital cardiac disease and when having multiple operations during the same anesthetic.

Imaging characteristics of the mandible and upper airway in children with Robin sequence and relationship to the treatment strategy

Some patients with Robin sequence (RS) may respond to conservative therapy, while others require surgery; however, there are currently no objective anatomical criteria to gauge surgical indication. The purpose of this study was to explore the imaging characteristics of the mandible and upper respiratory tract in children with RS and examine how individual morphometric parameters influence the treatment strategy. Cone beam computed tomography (CBCT) images were obtained from 57 children with RS. Twenty parameters were measured as potential surgical indicators. The children were divided into two groups according to surgical requirement: a non-surgical group (26 children) and a surgical group (31 children who underwent mandibular osteodistraction). Differences in the imaging parameters were compared between the groups. The mandibular ramus was shorter bilaterally (left, P = 0.047; right, P = 0.027) and the mandibular body was longer bilaterally (left, P = 0.030; right, P = 0.025) in the surgical group when compared to the non-surgical group. In addition, the mandibular angle bilaterally (left, P = 0.023; right, P = 0.003) and the cross-sectional area at the epiglottis tip (P = 0.010) were smaller in the surgical group. Compared to RS patients receiving conservative treatment, children requiring surgery have specific anatomical features of the mandible and upper airway that can be used as surgical indications.

A Novel Geometric Morphometric Analytical Method for Classifying Mandibular Morphology in Infants With Isolated Pierre Robin Sequence

PURPOSE

There is a lack of uniformity in the diagnostic criteria and system for the morphologic classification of micrognathia in infants with isolated Pierre Robin sequence (IPRS). Therefore, the aim of this study was to create a morphologic classification system for IPRS-affected mandibles that may guide surgical management and osteotomy design.

PATIENTS AND METHODS

We designed and implemented a retrospective cross-sectional study. The study sample included infants with IPRS. The predictor variables included shape variables of the IPRS-affected mandibles. The outcome of interest was morphologic differences among the IPRS-affected mandibles in the infancy stage. The original coordinate data of the mandibular images were analyzed by a generalized Procrustes analysis and 2-block partial least squares analysis to identify the focal and nonfocal areas in the IPRS-affected mandibles. The original feature points were modified according to the results of 2-block partial least squares analysis. The modified feature points were further analyzed by principal component analysis, K-means cluster analysis, and canonical variate analysis to obtain a morphologic classification of the IPRS-affected mandibles.

RESULTS

One hundred fifty infants with IPRS were enrolled in this study. Principal component analysis showed that the variations among IPRS-affected mandibles were mostly in terms of the shapes of the mandibular ramus, mandibular body, and angle of the mandible. On the basis of the results of K-means cluster analysis and canonical variate analysis, the mandibles in group A3 showed characteristics such as a simply shorter mandibular body. Group B3 was adjusted to show characteristics such as a shorter mandibular body with a more obtuse mandibular angle, whereas group C3 showed characteristics such as a shorter mandibular body with a shorter mandibular ramus.

CONCLUSIONS

Our study confirmed the hypothesis that there are quantifiable morphologic differences among the IPRS-affected mandibles, and it provided a morphologic classification of the IPRS-affected mandibles that will help to promote the clinical diagnosis and treatment.

Airway Morphological Changes in Pierre Robin Sequence: A Retrospective Study

Objective:

To investigate airway morphology changes in patients with Pierre Robin sequence (PRS) pre–/post–mandibular distraction osteogenesis (MDO) and to compare morphologic changes to age-matched controls.

Design:

Retrospective case–control study.

Setting:

Urban, academic, tertiary medical center.

Patients, Participants:

Fifteen patients with PRS after MDO to relieve upper airway obstruction (UAO) (2008-2018); age-matched controls for post-MDO patients.

Interventions:

Mandibular distraction osteogenesis, curvilinear internal mandibular distractors.

Main Outcome Measures:

(1) Physiologic improvement after MDO (apnea–hypopnea index; minimum oxygen saturation); (2) airway size (volume, surface area, length, mean/minimum cross-sectional area), shape (lateral:anterior–posterior ratio, cross-sectional area ratios, uniformity, sphericity), and changes with MDO; and (3) post-MDO airway size, shape versus age-matched controls.

Results:

Airway size increased after MDO (volume, P = .01; surface area, P = .02; length, P = .01), as did cross-sectional area (mean, P = .02; minimum, P = .02; minimum retropalatal, P = .05, mid-retroglossal, P = .02). Post-MDO PRS airways were larger than controls (volume, P < .01; surface area, P < .01; length, P < .01, cross-sectional area, P = .03). Airway shape remained nonuniform and flat post-MDO; control airways were round. Two syndromic patients required repeat MDO and had subphysiologic post-MDO airway cross-sectional area. Post-MDO PRS patients with supraphysiologic cross-sectional area along the entire airway had no UAO recurrence.

Conclusions:

In this small, heterogenous patient sample, MDO increases airway size, may preferentially affect the retropalatal airway, and often results in supraphysiologic airway dimensions. These retropalatal changes may be important in relieving severe UAO in patients with PRS. Generalizability of our results is limited by small cohort size and patient heterogeneity.

Dynamical Changes of Mandible and Upper Airway After Mandibular Distraction Osteogenesis in Pierre Robin Sequence

OBJECTIVE

To present the dynamical evaluation of mandible and upper airway size among Chinese infant patients following mandibular distraction osteogenesis in a short-term follow-up and compare predistraction measurements with a normal age- and sex-matched control.

METHODS

All the patients have undergone the computed tomography (CT) scan before mandibular distraction osteogenesis (T0), at the end of the distraction phase (T1), and 3 months after the end of the distraction phase before the distractor removal (T2). A CT analyzing computer software MIMICS was utilized to analyze the anatomic variables of upper airway size and mandible size. All analysis was based on a significance level of 0.05.

RESULTS

Eight patients with Pierre Robin sequence differed mainly in the mandibular body length and the minimum anteroposterior dimension of the retroglossal airway from the control. After mandibular distraction osteogenesis, the mandibular body length and the ramus height both increased significantly, the ramus height also increased after 3 months of consolidation. Only small increase in the airway dimension of the retroglossal area at T2 was observed compared with T1.

CONCLUSION

Mandibular distraction osteogenesis is an effective modality in treating Pierre Robin sequence. Compared with normal control, the main difference may be the length of mandibular body and the area of the retroglossal airway. There may not be an increase in the diameter of airway and the length of mandibular body after 3 months of growth and development in Pierre Robin sequence. Individual surgical plan should be made to gain a better prognosis.

A clinical prediction rule to identify difficult intubation in children with Robin sequence requiring mandibular distraction osteogenesis based on craniofacial CT measures

BACKGROUND

Airway management is challenging in children with Robin sequence (RS) requiring mandibular distraction osteogenesis (MDO). We derived and validated a prediction rule to identify difficult intubation before MDO for children with RS based on craniofacial computed tomography (CT) images.

METHOD

This was a retrospective study of 69 children with RS requiring MDO from November 2016 to June 2018. Multiple CT imaging parameters and baseline characteristic (sex, age, gestational age, body mass index [BMI]) were compared between children with normal and difficult intubation according to Cormack-Lehane classification. A clinical prediction rule was established to identify difficult intubation using group differences in CT parameters (eleven distances, six angles, one section cross-sectional area, and three segment volumes) and clinicodemographic characteristics. Predictive accuracy was evaluated by receiver operating characteristic (ROC) curve analysis.

RESULTS

The overall incidence of difficult intubation was 56.52%, and there was no significant difference in sex ratio, age, weight, height, BMI, or gestational age between groups. The distance between the root of the tongue and posterior pharyngeal wall was significantly shorter, the bilateral mandibular angle shallower, and the cross-sectional area at the epiglottis tip smaller in the difficult intubation group. A clinical prediction rule based on airway cross-sectional area at the tip of the epiglottis was established. Area > 36.97 mm² predicted difficult intubation while area < 36.97 mm² predicted normal intubation with 100% sensitivity, 62.5% specificity, 78.6% positive predictive value, and 100% negative predictive value (area under the ROC curve = 0.8125).

CONCLUSION

Computed tomography measures can objectively evaluate upper airway morphology in patients with RS for prediction of difficult intubation. If validated in a larger series, the measures identified could be incorporated into airway assessment tools to guide treatment decisions. This was a retrospective study and was granted permission to access and use these medical records by the ethics committee of Guangzhou Women and Children's Medical Center.

TRIALS REGISTRATION

Registration No. ChiCTR1800018252, NaZhang, Sept 7 2018.

Retropalatal Cross-Sectional Area Is Predictive of Obstructive Sleep Apnea in Patients With Syndromic Craniosynostosis

OBJECTIVE

There is a high rate of obstructive sleep apnea (OSA) in patients with syndromic craniosynostosis (SCS). Little is known about the airway anatomy in this population. The purpose of this study is to characterize the 3 dimensional (3D) upper airway in patients with SCS with and without OSA.

DESIGN

This is a retrospective study of patients with SCS treated at Boston Children's Hospital from 2000 to 2015. Patients were divided into OSA and no-OSA groups based on polysomnography. Predictor variables included age, sex, body mass index (BMI), and 3D upper airway measurements. The primary outcome variable was the presence or absence of OSA. Secondary outcome variables were apnea-hypopnea index and oxygen saturation nadir. Descriptive and bivariate statistics were computed, and significance was set as P < .05.

RESULTS

There were 24 patients: 16 in the OSA group and 8 in the no-OSA group. The 2 groups did not differ significantly by age, BMI, or syndromic diagnosis. The presence of OSA was associated with a smaller minimum retropalatal cross-sectional area (minRPCSA; P < .001). In a logistic regression model controlling for age, sex, and upper airway length, minRPCSA was the primary predictor of OSA (P ≤ .002). Receiver operating characteristic analysis determined minRPCSA = 55.3 mm² to be the optimal diagnostic threshold for OSA, with sensitivity = 100% and specificity = 87.5% (P < .001).

CONCLUSION

A minRPCSA ≤55.3 mm² is predictive of the presence of OSA in patients with SCS.

Surgical Management and Outcomes of Pierre Robin Sequence: A Comparison of Mandibular Distraction Osteogenesis and Tongue-Lip Adhesion

There is a paucity of literature directly comparing tongue-lip adhesion versus mandibular distraction osteogenesis in surgical treatment of patients with Pierre Robin sequence. This study comprehensively reviews the literature for evaluating airway and feeding outcomes following mandibular distraction osteogenesis and tongue-lip adhesion. A search was performed using the MEDLINE and Embase databases for publications between 1960 and June of 2017. English-language, original studies subjects were included. Extracted data included prevention of tracheostomy (primary airway outcome) and ability to feed exclusively by mouth (primary feeding outcome). A total of 67 studies were included. Ninety-five percent of subjects (657 of 693) treated with mandibular distraction osteogenesis avoided tracheostomy, compared to 89% of subjects (289 of 323) treated with tongue-lip adhesion. Eighty-seven percent of subjects (323 of 370) treated with mandibular distraction osteogenesis achieved full oral feeds at latest follow-up. Seventy percent of subjects (110 of 157) treated with tongue-lip adhesion achieved full oral feeds at latest follow-up. The incidence of second intervention for recurrent obstruction ranged from 4 to 6 percent in mandibular distraction osteogenesis studies, compared to a range of 22 to 45 percent in tongue-lip adhesion studies. Variability of patient selection, surgical techniques, outcomes measurement methods, and follow-up length across studies precluded meta-analysis of the data. Both mandibular distraction osteogenesis and tongue-lip adhesion are effective alternatives to tracheostomy for patients who fail conservative management and improve feeding. Mandibular distraction osteogenesis may be superior to tongue-lip adhesion in long-term resolution of airway obstruction and avoidance of gastrostomy, but is associated with notable complications.

Micrognathia and Oropharyngeal Space in Patients With Robin Sequence: Prenatal MRI Measurements

PURPOSE

Micrognathia is the initiating feature of Robin sequence (RS) and leads to airway obstruction. Prenatal identification of micrognathia is currently qualitative and has not correlated with postnatal findings in previous studies. Oropharyngeal airway space has not been evaluated prenatally. The purposes of this study were to 1) quantitate mandibular characteristics and oropharyngeal size at prenatal magnetic resonance imaging (MRI) and 2) identify differences in fetuses with postnatal RS compared with those with micrognathia (without RS) and normal controls.

MATERIALS AND METHODS

This is a retrospective case-control study of fetuses with prenatal MRIs performed from 2002 through 2017 who were live born and evaluated postnatally for craniofacial findings. Postnatal findings were used to divide patients into 3 groups: 1) RS (micrognathia, glossoptosis, and airway obstruction), 2) micrognathia without RS ("micrognathia"), and 3) a gestational-age matched control group with normal craniofacial morphology ("control"). Inferior facial angle (IFA), jaw index, and oropharyngeal space (OPS) were calculated and compared among groups.

RESULTS

Of 116 patients in this study, 27 had RS (23%), 35 had micrognathia (30%), and 54 were control subjects (47%). IFA, jaw index, and OPS were statistically significantly smaller in the RS group compared with the comparison groups (P < .0001).

CONCLUSIONS

Prenatal MRI measurements of micrognathia and OPS are considerably different in patients with RS compared with other groups, including those with micrognathia alone. These measurements might serve as reliable prenatal predictors of RS.