3D-CT measurements of facial symmetry in severe CFM patients: A comparative study between mandibular ascending ramus distraction osteogenesis and bone grafting

This study aims to compare the effects of mandibular distraction osteogenesis (MDO) and bone grafting on the facial symmetry of children with Pruzansky-Kaban type IIB and III craniofacial microsomia (CFM). Medical records and three-dimensional computed tomography (3D-CT) data of CFM patients who had primarily undergone MDO and bone grafting were collected. A retrospective analysis of pre-and post-operative 3D imaging data was conducted to compare the improvement rate in facial symmetry between the two groups based on occlusal cant, affected/unaffected ramus height ratio and chin point deviation. The data were tested for normality using the Shapiro-Wilk test. When the data followed a normal distribution, a paired sample t-test was employed for the comparison between preoperative and postoperative data. When the data did not follow a normal distribution, the Wilcoxon signed-rank test for paired samples was used for preoperative and postoperative comparison. The study included 18 children with type IIB and III CFM, 11 in the MDO group and 7 in the bone grafting group. In the MDO group, postoperative Gn-FH and Gn-Cor distances increased significantly, whereas the postoperative Gn-Mid distance decreased significantly. Occlusal cant decreased significantly and ramus height affected/unaffected ratio increased significantly after MDO. In the bone graft group, there was no statistically significant difference in the postoperative ratios of chin deviation, occlusal cant, and ramus height affected/unaffected compared to the preoperative values. Compared to bone grafting, MDO can significantly enhance ramus height ratio, level occlusal plane, and centralize the chin point among patients with CFM. Furthermore, MDO achieves superior enhancements in facial symmetry.

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.

The Impact of Mandibular Distraction Osteogenesis on Cephalometric Measurements in Infants with Pierre Robin Sequence

BACKGROUND

The obstruction of the upper airway (UAO) in infants diagnosed with Robin Sequence (RS) is caused by micrognathia, and in severe cases, it can result in obstructive sleep apnea (OSA). Mandibular distraction osteogenesis (MDO) is a secure and efficient remedy for significant UAO. However, there is insufficient data on the related cephalometric changes. Therefore, this study meticulously analyzes the mandibular cephalometric changes in infants with RS who have undergone MDO using internal devices. The aim is to gain a more comprehensive understanding of the short- and long-term impacts of distraction on the mandible.

METHODS

The study examined 73 consecutive cases of mandibular distraction osteogenesis (MDO) performed by a single surgeon. Preoperative and postoperative lateral cephalograms, as well as CT scans of the mandible, were utilized to assess population averages for both time points. A two-sample T-Test with equal variance was used for this analysis.

RESULTS

After the MDO procedure, 19 out of 21 cephalometric parameters exhibited significant morphological changes. On average, there were notable improvements of 20.3 mm (60.7%) in length, 9.8 mm (49.7%) in height, 12.6 mm (36.1%) in width, and 211% in airway parameters. However, most parameters showed only mild regression at the time of device removal and 6 to 12 months post-MDO. Nonetheless, the cephalometric parameters remained significantly improved compared to the preoperative measurements.

CONCLUSIONS

The use of cephalometric measurement is a potent approach that provides a clear and measurable understanding of how MDO influences both immediate and long-term growth of the mandible. This quantitative assessment of the effects of mandibular distraction allows for the refinement of surgical techniques and the optimization of outcomes. Therefore, incorporating cephalometric measurements in the evaluation of patients undergoing MDO can lead to better surgical planning and more favorable results.

Condylar resorption post mandibular distraction osteogenesis in craniofacial microsomia: A retrospective study

The aim of this study was to investigate the characteristics of condylar resorption in craniofacial microsomia (CFM) patients following mandibular distraction osteogenesis (MDO). Patients with unilateral type-IIa and type-IIb CFM, who had completed MDO and mandibular distractor extraction (MDE), were recruited. The height and volume of the condyle were measured on three-dimension models created by the analysis of computed tomography (CT) data. Normality analysis was performed using the Shapiro-Wilk test. Data for the affected and unaffected sides were compared using the paired t-test or Wilcoxon signed-rank test. Data for both type-IIa and type-IIb CFM were compared using the independent-samples t-test or Mann-Whitney U test. The Pearson or Spearman correlation was used to determine the correlations of condylar resorption rate with related measurements. In total, 48 type-IIa and 48 type-IIb CFM patients were included. The condylar resorption rate in type-IIa CFM (0.35 ± 0.32) was significantly associated with the height of the condyle (r = 0.776, p < 0.001) and distraction distance (r = 0.447, p = 0.001), while the condylar resorption rate in type-IIb CFM (0.49 ± 0.46) was significantly associated with the height of the condyle (r = 0.924, p < 0.001). However, there was no significant difference in condylar resorption rate between type-IIa and type-IIb CFM (p = 0.075). In addition to occlusal changes, no other negative symptoms of the TMJ were observed with condylar resorption. Condylar resorption was evident in CFM patients following mandibular distraction osteogenesis, and the condylar resorption rate showed a relationship with distraction distance and condylar height.

An infant with congenital micrognathia and upper airway obstruction was diagnosed as Hutchinson-Gilford progeria syndrome caused by a novel LMNA mutation: Case report and literature review

Hutchinson-Gilford progeria syndrome (HGPS) is an extremely rare disease characterized by appearance of premature aging, including the skin, bones, heart, and blood vessels caused by LMNA mutation. In this study, the patient presented with congenital micrognathia and progressively aggravated upper airway obstruction as the initial symptom, which required bilateral mandibular distraction osteogenesis (MDO) surgery intervention. This was not commonly described in the literature, and the primary clinical diagnosis of Pierre Robin sequence (PRS) was made. However, other clinical features included sclerotic skin, dry skin, growth failure, lipoatrophy, joint stiffness, prominent scalp veins, small ear lobes, hair loss, and craniofacial disproportion gradually emerged, the diagnosis of HGPS was preferred when the patient was 5 months old. The genetic testing result with a novel and de novo LMNA mutation (c.1968 + 3_1968+6delGAGT) further confirmed the diagnosis and expanded the clinical and mutational spectrum of HGPS. During the 12-month follow-up period after surgery, the patient no longer suffered dyspnea. Complications of other organs and systems have not happened at the moment. In addition, the pathogenesis, the role of LMNA gene mutation, the progress in clinical treatment, and breakthrough studies about genetic treatment in animals of HGPS are described in the literature review.

Respiratory outcome of mandibular distraction osteogenesis on obstructive sleep apnea in craniofacial microsomia: A retrospective study

This study aimed to evaluate the effect of mandibular distraction osteogenesis (MDO) on respiratory function in CFM patients with obstructive sleep apnea (OSA) according to polysomnography (PSG). This study retrospectively analyzed patients with CFM who underwent PSG before surgery and after completion of mandible distraction. Patients who met the inclusion criteria were selected. The Pediatric Sleep Questionnaire (PSQ) was used to assess patients' signs and symptoms related to OSA. The obstructive apnea-hypopnea index (OAHI) and lowest oxygen saturation (LSaO₂) were imported into SPSS version 26.0. The Wilcoxon signed-rank test was used to assess the differences in PSG before and after MDO. Other data were described using descriptive statistics. A P-value less than 0.05 was considered statistically significant. A total of 25 unilateral CFM patients were included in this study. Most patients (72%) had mild OSA; moderate and severe OSA were 12% and 16%, respectively. Snoring (52%) was the most common symptom among these patients. After completion of mandibular distraction, snoring and other OSA-related symptoms were significantly improved. Twelve patients had normalized PSG and the severity of OSA improved significantly in 3 patients. The total effective rate of MDO for OSA was 60%. The statistical results showed that OAHI (P = 0.045) decreased and LSaO₂ (P = 0.009) increased significantly compared to preoperative values. MDO can improve OSA-related symptoms in CFM patients. In addition, respiratory function was improved in most patients after MDO, based on PSG. CFM patients, especially those with OSA, can benefit from MDO.

The management of upper airway obstruction in Pierre Robin Sequence

Pierre Robin Sequence (PRS) is defined by a constellation of characteristics including micrognathia, glossoptosis and airway obstruction. PRS can occur in isolation or can be associated with syndromes and another anomalies. Airway obstruction and feeding difficulties are the major presenting issues, and the severity of the condition ranges from mild, with minimal to no symptoms, to severe, with overt obstruction resulting in apnoeas, severe respiratory distress and cyanosis. The presence of airway obstruction can result in obstructive sleep apnoea and abnormalities in gas exchange, as well as exacerbation of already present feeding difficulties and failure to thrive, secondary to mismatch of caloric intake to energy usage associated with increased effort of breathing. Management of airway obstruction for infants with PRS varies between centres. This paper explores the surgical and non-surgical management options available, their effectiveness and pitfalls in children with PRS. Despite the pros and cons of each management option, it is evident that resource availability and multidisciplinary clinical support are key factors to successful management.

A new treatment strategy for hemifacial microsomia: Auricular reconstruction with an expanded two-flap method and simultaneous mandibular distraction osteogenesis

BACKGROUND

Owing to the complex clinical manifestations of hemifacial microsomia (HFM), multidisciplinary cooperation is required to achieve better therapeutic effects in terms of function and aesthetics. This study aimed to explore the efficacy of the expanded two-flap auricular reconstruction combined with mandibular distraction osteogenesis in the treatment of HFM.

METHODS

This surgical strategy was performed in three stages. In the first stage, the retroauricular skin was expanded with a tissue expander and a mandibular distraction device was installed. In the second stage, the traditional expanded two-flap method for auricular reconstruction was adapted, and the framework was fabricated with costal cartilage and wrapped with the expanded skin flap, retroauricular fascia flap, and full-thickness skin graft. In the final stage, the tragus and lobule were rebuilt, the concha cavity deepened, and the mandibular distraction device removed.

RESULTS

From January 2014 to November 2018, 166 HFM patients underwent auricular reconstruction with the expanded two-flap method and simultaneous mandibular extension in our hospital. The median follow-up period was 9.3 months. Of the 166 patients, 154 patients and their families were satisfied with the results, and only 16 patients experienced complications.

CONCLUSIONS

This three-stage technique of simultaneous auricular reconstruction and mandibular distraction osteogenesis is safe and effective in achieving facial symmetry, improving occlusal contact, shortening treatment course, and relieving patient's suffering, especially for HFM patients.

Mandibular distraction to correct severe non-isolated mandibular hypoplasia: The role of drug-induced sleep endoscopy (DISE) in decision making

OBJECTIVES

In patients with mandibular hypoplasia, mandibular distraction osteogenesis (MDO) aims to relieve tongue-based airway obstruction. Drug-induced sleep endoscopy (DISE) provides a dynamic assessment of the upper airway and visualizes anatomical site and cause of airway obstruction. The aim of this study was to evaluate the effect of MDO on tongue-based airway obstruction found by DISE within a non-isolated patient population with severe upper airway obstruction (UAO). Furthermore, we aimed to assess the additional value of DISE in clinical decision making by correlating DISE findings to functional airway outcomes after MDO.

METHODS

Findings on DISE in children who underwent MDO were retrospectively gathered and evaluated. According to DISE findings, severity of tongue-based obstruction was scored using a 4-step classification similar to the one that is used by Bravo et al.. Intubation conditions were scored according to the Cormack Lehane score (CLS). Pre-and postoperative DISE findings were compared and correlated with functional airway outcomes following MDO.

RESULTS

In 19 out of 28 MDO procedures, both a pre-and postoperative DISE was available. Tongue-based obstruction scores improved in 13 procedures, which correlated to a functional improvement in seven. Postoperative tongue-based obstruction differed significantly between patients with successful MDO and patients treated unsuccessfully (2.00 ((Interquartile range (IQR) 1.00-2.00) vs. 3.00 (IQR 2.00-4.00), p = 0.028), whereas this difference was not significant for the CLS (1.00 (IQR 1.00-1.50) vs. 2.00 (IQR 1.00-4.00), p = 0.066). If no improvement of tongue-based obstruction was seen, MDO is very unlikely to be successful on the functional airway.

CONCLUSIONS

DISE provides information on the site and nature of airway obstruction and can visualize the effect of MDO on the severity of tongue-based airway obstruction. Therefore, it can be of additional value in understanding the differences in functional airway outcomes after MDO and aids in deciding appropriate and targeted treatment. Hence, standardized use of DISE, in addition to the clinical assessment of mandibular position and a polysomnography, during MDO management is highly recommended.

Latency phase in mandibular distraction osteogenesis: a systematic review in animal models

The aim of the present study was to perform a systematic review of the need for the latency period in distraction osteogenesis to obtain adequate bone formation. Searches were performed in the Web of Science, Pubmed/MEDLINE, Scopus, and Cochrane electronic databases. Nine articles were selected for qualitative analysis. Quality assessment was performed using the 10-item SYRCLE tool. Clinical stability was evaluated in two articles, histology was analysed in seven, histomorphometry was analysed in three, and mechanical testing was used in two. The results favoured the five-day latency group in two studies and the seven-day latency group in one. No differences were found between latency and no-latency groups in six studies. A latency period greater than seven days did not provide any additional benefit. Important risks of bias were found in all articles. Some of the results were influenced by uncontrolled intervening factors, such as consolidation time. The need for a latency period for distraction osteogenesis in animal models is not yet clear. Caution must be exercised when extrapolating the results of animal protocols to applications with humans in the clinical setting.

Treacher Collins Mandibular Distraction

Treacher Collins syndrome (TCS) is a genetic disorder that presents with a variety of craniofacial deformities. One classic feature of TCS is a steep, counterclockwise rotation of the occlusal plane, and microretrognathia with bony deficiencies in both the body and ramus of the mandible. This morphology commonly necessitates reconstruction by the craniofacial surgeon. This article discusses strategies and considerations for surgically correcting the mandibular deformity associated with TCS using mandibular distraction osteogenesis and other related techniques. The proper implementation of these techniques can yield excellent results that greatly improve quality of life in this challenging patient population.

Incidence of mandibular distraction osteogenesis in Stickler Syndrome: Variation due to COL2A1 and COL11A1

OBJECTIVE

To determine whether the two most common genetic mutations seen in Stickler Syndrome (SS) (COL2A1 and COL11A1) affect the incidence of mandibular distraction osteogenesis (MDO) and what impact Robin sequence (RS) has on diagnosis. SS is an autosomal dominant connective tissue disorder characterized by almost complete penetrance. COL2A1 and COL11A1 are the two most common mutations seen in SS patients. SS often presents at birth with RS, which is characterized by the triad of micrognathia, glossoptosis, and tongue-based airway obstruction. MDO is one surgical intervention that has been shown to be successful in relieving tongue base obstruction and is the surgical intervention of choice for this condition.

METHODS

A retrospective chart review was performed on all patients with a diagnosis of SS at a tertiary pediatric hospital between January 1, 2003 and December 31, 2018. The included patient charts were reviewed for demographic information, SS mutation, and history of MDO. Forty-six patients had a clinical diagnosis of SS. Of those, 31 met inclusion criteria which involved having a molecular diagnosis of SS and sufficient follow up information to determine if MDO was indicated or performed. Twenty-two of the 31 included patients had a diagnosis of RS (70.96%). Thirteen of the 31 patients (41.94%) included in this study required MDO as a neonate.

RESULTS

Fifty-percent of patients with type I (COL2A1) required MDO as a neonate compared to only 31% of patients with type II (COL11A1), though the difference between the two groups was not statistically significant.

CONCLUSION

The findings of this study suggest that patients with type I mutation may have a higher incidence of MDO than patients with a type II mutation, though further research with larger sample sizes is needed. This information is helpful in counseling those with SS or family history of SS about what they can expect related to RS and need for MDO based on genetic findings.

LEVEL OF EVIDENCE

3.

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.

Modern Mandibular Distraction Applications in Hemifacial Microsomia

Phenotypic severity dictates the timing and type of surgical intervention required. Mandibular distraction in children without respiratory and feeding difficulties remains controversial with regard to long-term mandibular growth outcomes and reducing surgical burden. Early mandibular distraction does not obviate secondary orthognathic surgery at skeletal maturity; it provides improved functional, aesthetic, and psychosocial outcomes, at least in the short term. Costochondral rib grafting for Pruzansky type IIB and III mandibles can produce reliable results, especially when combined with subsequent mandibular distraction. Secondary 2-jaw orthognathic surgery plus genioplasty at skeletal maturity benefits from improved bone volume from prior mandibular distraction.

Development of a novel mandibular distraction osteogenesis simulator using Computer Aided Design and 3D printing

INTRODUCTION

Micrognathia, a component of Robin Sequence, can cause glossoptosis, failure of palatal fusion, and critical obstruction of the airway. Mandibular distraction osteogenesis (MDO) is at times offered to anteriorly translate the mandible and tongue, relieving airway obstruction. MDO is an intricate reconstructive procedure that may be ideal for teaching using a high-fidelity educational simulator, allowing early hands-on experience in a zero-risk environment.

OBJECTIVES

To design a novel, low-cost, high-fidelity neonatal MDO simulator that can be used for trainee education and refinement of surgical technique.

METHODS

A novel MDO simulator was developed using additive manufacturing techniques. Three experts in MDO surgery completed a 20-item survey, rating the simulator's physical attributes, the realism of experience, the simulator's value, its relevance to practice and the surgeon's ability to perform tasks on a 4-point Likert scale.

RESULTS

Computer Aided Design (CAD) and 3D printing allowed for the production of a realistic surgical simulator that emulates important aspects of MDO surgery. This preliminary evaluation indicated adequate means across the five domains relevant to the simulator's fidelity and usability (M = 3.33 to 3.75) out of a maximum of 4 points. Lowest rated items were consistent with expert comments allowing future refinement on subsequent iterations. Consumable material costs per model were $9.39 USD.

CONCLUSIONS

The MDO model demonstrated adequate fidelity and holds promise as a skill-development tool for surgeons in training. Further studies are planned to determine its utility as a training and assessment tool.

Total facial nerve injury during mandibular distraction osteogenesis

INTRODUCTION

Over the last 10-15 years, usage of internal mandibular distraction systems has increased in the pediatric population, particularly for craniofacial syndromes. Mandibular distraction osteogenesis (MDO) has been shown to be effective in avoiding tracheostomy or achieving early decannulation in patients with micro-retrognathic mandibles in hemifacial microsomia or Pierre Robin sequence. As the frequency of the application of MDO has increased, so has the awareness and management of subsequent complications from the procedure. In this study, we discuss a complication involving paresis and eventual recovery of cranial nerve (CN) VII after the application of an MDO internal device at our institution in two cases. We also review the literature and propose multiple anatomic considerations that can impact more than just the marginal branch of CN VII.

METHOD

This study is a retrospective case study from our institution and a review of the literature. Pubmed was queried for terms singularly and in combination including "mandibular distraction osteogenesis", "facial nerve", "cranial nerve", "complications", "micrognathia", "retrognathia". After reviewing the results, studies discussing complications of MDO that involved CN VII were reviewed and included.

RESULTS

In the literature review and our retrospective review, CN VII injuries from MDO vary in their length and timing of onset. Management of this complication depended on the timing of onset and ranged from conservative management to removal of the distraction device. Majority (7/9) of the cases resolved to an eventual House-Brackmann of 0/6 with conservative measures.

CONCLUSION

Total facial nerve injury in association with MDO, has been scarcely reported, though the facial nerve is at great risk given its intimate location near the mandible particularly in neonates. It is encouraging that though it could be a devastating complication, out of all the cases reported, the large majority resolve with a combination of time and steroids.

Early hemi-mandibular lengthening by distraction osteogenesis contributes to compensatory maxillary growth

Mandibular distraction osteogenesis at an early age is the standard hemifacial microsomia treatment. Nevertheless, the recurrence rate remains high and the definition of early age is controversial. We explored the optimal timing for mandibular distraction, when the surrounding skeleton, such as maxilla, can grow compensatory, to reduce recurrence. Hemifacial microsomia patients were prospectively divided into Groups A (1-3 years old) and B (4-6 years old), according to maxillary and mandibular growth curves. Computed tomography scans were obtained before distractor implantation and after removal surgery. Maxillary volume increase percentage was the main outcome indicator; other indicators (maxillary symmetry and complications) were secondary outcomes. Fifty-eight patients were enrolled and all but one patient in Group A (failed distraction) completed the study. Two patients had facial nerve injury and another two had mouth-opening limitation, which was relieved after coracoid resection. The difference in percentage increase in maxillary volume between the affected and unaffected sides was 5.06 ± 2.73% and 3.18 ± 1.99% in Groups A and B, respectively, suggesting better compensatory growth in younger patients (P = 0.004). Maxillary symmetry was apparently elevated after mandibular distraction. Mandibular distraction osteogenesis was confirmed to be feasible and safe at age <4 years.

Micrognathia with temporomandibular joint ankylosis and obstructive sleep apnea treated with mandibular distraction osteogenesis using skeletal anchorage: a case report

Background

We describe the case of a 16-year-old female patient with micrognathia, temporomandibular joint (TMJ) ankylosis, and obstructive sleep apnea, who was treated with mandibular distraction osteogenesis (DO) combined with sliding genioplasty, using skeletal anchorage.

Case presentation

We first performed interpositional arthroplasty, in which an interposition of fascia temporalis and surrounding fat tissue was inserted into the defect after bilateral condylectomy, increasing the maximum mouth opening from 5.0 to 32.0 mm. Subsequently, orthodontic treatment and advancement of the mandible were carried out by mandibular DO, using miniscrews and miniplates. Finally, sliding genioplasty was performed to bring the tip of the mandible forward. The total amount of mandibular advancement at the menton was 16.0 mm. An improved facial appearance and good occlusion were eventually achieved, and the apnea-hypopnea index decreased from 37.1 to 8.7. There was no obvious bone resorption or pain in the temporomandibular region, limited mouth opening (maximum mouth opening: 33.0 mm), myofascial pain or headache, downward rotation of the mandible, or lateral shift of mandibular position evident at 5 years and 6 months after mandibular DO.

Conclusion

Mandibular DO using skeletal anchorage with intermaxillary elastics is useful for preventing extrusion of the upper and lower anterior teeth, thereby preventing rotation of the mandible. In addition, mandibular DO combined with sliding genioplasty is effective at improving both dentofacial deformities and impaired respiratory function.

3D computed tomographic evaluation of the upper airway space of patients undergoing mandibular distraction osteogenesis for micrognathia

Mandibular distraction osteogenesis (MDO) is currently an accepted method of treatment for patients requiring reconstruction of hypoplastic mandibles. To date one of the unsolved problems is how to assess the quantitative increase of mandible length needed to achieve a significant change in the volume of the posterior airway space (PAS) in children with mandibular micrognathia following distraction osteogenesis. The purpose of this study is to present quantitative volumetric evaluation of PAS in young patients having distraction osteogenesis for micrognathia using 3D-CT data sets and compare it with pre-operative situation. In this observational retrospective study, we report our experience in five consecutive patients who underwent MDO in an attempt to relieve severe upper airway obstruction. Each patient was evaluated before treatment (T0) and at the end of distraction procedure (T1) with computer tomography (CT) in axial, coronal, and sagittal planes and three-dimensional CT of the facial bones and upper airway. Using parameters to extract only data within anatomic constraints, a digital set of the edited upper airway volume was obtained. The volume determination was used for volumetric qualification of upper airway. The computed tomographic digital data were used to evaluate the upper airway volumes both pre-distraction and post-distraction. The mean length of distraction was 23 mm. Quantitative assessment of upper airway volume before and after distraction demonstrated increased volumes ranging from 84% to 3,087% with a mean of 536%. In conclusion, our study seems to show that DO can significantly increase the volume of the PAS in patients with upper airway obstruction following micrognathia, by an average of 5 times. Furthermore, the worse is the starting volume, the greater the increase in PAS to equal distraction.

The role of curvilinear distraction system in pediatric obstructive sleep apnea: A case report

OBJECTIVE

The authors present a case of obstructive sleep apnea associated with severe mandibular micrognathia treated by mandibular bone distraction with curvilinear system planned under computer assistance.

CLINICAL PRESENTATION

A 15-year-old child with limited compliance to continuous positive airway therapy was referred to the authors' department. Observation revealed severe mandibular micrognathia as the major cause for obstructive sleep apnea syndrome. The first polysomnography study revealed 14 obstructive apneas, 16 obstructive hypopneas, and 4.6/h apnea-hypopnea index.

CONCLUSION

Mandibular distraction osteogenesis can be a successful technique in alleviating upper airway obstruction secondary to micrognathia, while also improving the patient's appearance. Surgical planning under computer assistance is a useful tool to predict bone movements, and curvilinear distraction could be considered valuable in mandibular distraction.

Sleep architecture in Pierre-Robin sequence: The effect of mandibular distraction osteogenesis

INTRODUCTION

Pierre-Robin Sequence (PRS), a triad of micro/retrognathia, glossoptosis, and upper airway obstruction, usually in conjunction with a cleft palate is frequently associated with significant morbidity. Mandibular distraction osteogenesis (MDO) is an effective treatment modality to address retroglossal upper airway obstruction by increasing the anterior-posterior diameter of the infant airway. Although MDO has been shown to improve the apnea-hypopnea index (AHI) in children with PRS, the consequences of MDO on other aspects of infant sleep, including hypercapnea, hypoxia, the REM to Non-REM ratio, as well as its effect on central and mixed apneas has not been investigated with an adequate sample size.

OBJECTIVE

To characterize the effect of MDO on key components of sleep architecture in infants with PRS.

METHODS

Charts from 32 infants with PRS that were addressed with MDO at our tertiary-care children's hospital were retrospectively reviewed. Of these, 26 infants (57.7% male; mean age = 4.1 weeks, SD = 5.0) had pre- and post-operative polysomnograms (PSG). Paired samples t-tests were used to compare pre- and post- MDO sleep architecture mean score differences.

RESULTS

Among the 26 infants, 73.1% demonstrated severe pre-MDO sleep apnea (AHI > 10). Several aspects of sleep architecture were found to improve post-operatively. Significant improvements were found in AHI (30.3 vs. 8.7; t = 4.1, p < 0.001), obstructive apneas (79.3 vs. 5.8; t = 4.0, p < 0.001), hypopneas (48.1 vs. 22.1; t = 2.2, p = 0.040), time spent below 90% SpO2 (3.9% vs. 0.7%; t = 3.3, p = 0.003), and lowest SpO2 nadir (75.4% vs. 82.9%; 3.4, p = 0.002). In addition, a marginally significant improvement was found for mixed apnea (6.3 vs. 1.6; t = 1.99, p = 0.058).

CONCLUSION

MDO improves several sleep architecture parameters in this sample of infants with PRS. Statistically significant improvement was seen in obstructive apneas, hypopneas, AHI, obstructive AHI, and several indicators of hypoxia during sleep.

Characteristics of sleep apnea in infants with Pierre-Robin sequence: Is there improvement with advancing age?

OBJECTIVES

To investigate changes in obstructive sleep apnea (OSA) and central sleep apnea (CSA) in infants with Pierre-Robin sequence (PRS) with advancing age and after mandibular distraction osteogenesis (MDO).

METHODS

Charts from 141 infants with PRS that presented to our tertiary-care children's hospital between 2005 and 2015 were retrospectively reviewed. Forty-five patients received a polysomnogram (PSG) prior to surgical intervention. Linear regression was utilized to compare age at pre-operative PSG with apnea-hypopnea index (AHI), obstructive apnea-hypopnea index (OAHI), and central apnea index (CAI). We then analyzed a subset of 9 patients who underwent MDO with pre- and post-operative PSGs. Wilcoxon signed-rank test was utilized to examine differences in pre- and post-operative OSA and CSA scores.

RESULTS

Forty-five patients received pre-operative PSGs. Of these, 80.0% demonstrated severe sleep apnea (AHI≥10), 68.9% demonstrated severe obstructive sleep apnea (OAHI≥10), and 55.6% demonstrated central sleep apnea (CAI≥1). There was no significant pattern of decrease in AHI, OAHI, and CAI with increased age up to 1 year. Among the 9 patients who underwent MDO with pre- and post-operative PSGs, significant reductions in AHI, OAHI, CAI, and percentage of total sleep time with arterial oxygen saturation (SaO2) <90% and significant increases in SaO2 nadir were identified after MDO.

CONCLUSIONS

Contrary to previously examined literature in non-PRS patients, we did not find a decreased severity of central or obstructive sleep apnea with advancing age. Infants with PRS who underwent MDO demonstrated significant decreases in both obstructive and central apnea indices.

Precise positioning of an intraoral distractor using augmented reality in patients with hemifacial microsomia

BACKGROUND

Through three-dimensional real time imaging, augmented reality (AR) can provide an overlay of the anatomical structure, or visual cues for specific landmarks. In this study, an AR Toolkit was used for distraction osteogenesis with hemifacial microsomia to define the mandibular osteotomy line and assist with intraoral distractor placement.

METHODS

20 patients with hemifacial microsomia were studied and were randomly assigned to experimental and control groups. Pre-operative computed tomography was used in both groups, whereas AR was used in the experimental group. Afterwards, pre- and post-operative computed tomographic scans of both groups were superimposed, and several measurements were made and analysed.

RESULTS

Both the conventional method and AR technique achieved proper positioning of the osteotomy planes, although the AR was more accurate. The difference in average vertical distance from the coronoid and condyle process to the pre- and post-operative cutting planes was significant (p < 0.01) between the two groups, whereas no significant difference (p > 0.05) was observed in the average angle between the two planes. The difference in deviations between the intersection points of the overlaid mandible across two cutting planes was also significant (p < 0.01).

CONCLUSION

This study reports on an efficient approach for guiding intraoperative distraction osteogenesis. Augmented reality tools such as the AR Toolkit may be helpful for precise positioning of intraoral distractors in patients with hemifacial microsomia in craniofacial surgery.

Neonatal mandibular distraction osteogenesis: converting virtual surgical planning into an operative reality

Mandibular distraction osteogenesis (DO) has become an accepted method to manage severe cases of micrognathia-induced airway obstruction in neonates. Current imaging used to plan these procedures aids in surgical planning, but offers only a rough guide for the operating room. To our knowledge the following report offers the first description of virtual surgery used to guide DO in the mandible of a neonate. The plan provided a valuable link between the simulated procedure and the actual operative steps. Such technology can serve an important role in DO and offers objective guidance in device selection, vector planning and operative guide positioning.

Tracheostomy versus mandibular distraction osteogenesis in infants with Robin sequence: a comparative cost analysis

Many treatments have been described for infants with Robin sequence and severe respiratory distress, but there have not been many comparative studies of outcome and cost-effectiveness. The aim of this study was to compare the cost and complications of two common interventions - mandibular distraction osteogenesis and tracheostomy. Nine patients with isolated Robin sequence (mandibular distraction osteogenesis, n=5, and tracheostomy, n=4) were included in the analyses. Predetermined costs and complications were obtained retrospectively from medical records and by questionnaires to the parents over a 12-month period. Overall direct costs (admission to hospital, diagnostics, surgery, and homecare) were 3 times higher for tracheostomy (€105.523 compared with €33.482, p=0.02). Overall indirect costs (absence from work) were almost 5 times higher (€2.543 compared with €543, p=0.02). There was a threefold increase in overall total cost/patient (both direct and indirect) for tracheostomy (€108.057 compared with 34.016, p=0.02) and 4 times more complications were encountered. This study shows that mandibular distraction osteogenesis in infants diagnosed with Robin sequence costs significantly less and results in fewer complications than tracheostomy, and this contributes to our current knowledge about the ideal approach for infants with Robin sequence and might provide a basis for institutional protocols in the future.

Impact of mandibular distraction osteogenesis on the oropharyngeal airway in adult patients with obstructive sleep apnea secondary to retroglossal airway obstruction

AIM

To evaluate the impact of mandibular advancement by distraction osteogenesis on the oropharyngeal airway in adult patients with retroglossal airway obstruction using two different techniques of mandibular distraction.

MATERIALS AND METHODS

13 adult patients with mandibular hypoplasia secondary to TMJ ankylosis with OSAS and radiographic, CT and polysomnographic evidence of OSAS were included in the study. MDO was performed (corpus distraction in 8 cases and morphometric distraction in 5 patients). Post-operatively the patients were followed up by radiographs, CT and polysomnography after 1 month and 6 months.

RESULTS

There was an increase in the linear dimension of mandible by 11.07 mm, the volume by 19.3% and a decrease in AHI from 44.8 to 13.2.

CONCLUSION

Mandibular distraction (corpus and orthomorphic-equivocal results) is an effective method of relieving the retroglossal airway obstruction in adult patients with OSAS.

Management of obstructive sleep apnea in pediatric craniofacial anomalies

INTRODUCTION

Obstructive sleep apnea (OSA) is often associated with congenital craniofacial malformations such as Pierre-Robin Syndrome, Hemifacial Microsomia, Treacher Collins Syndrome resulting in decreased pharyngeal airway, which, in severe cases, leads to tracheostomy dependence. Some pediatric patients had tracheostomies done and others with severe respiratory distress were considered tracheostomy candidates.

MATERIALS AND METHODS

Twelve patients with severe respiratory distress without tracheostomy and ten patients with tracheostomy were treated by mandibular distraction osteogenesis using either external or internal devices. The expansion of mandibular framework was analyzed using bony cephalometric landmarks and computed tomography (CT).

RESULTS

The results demonstrated average mandibular elongation of 29 mm on each side using the external devices and 22 mm using the internal devices, and an increase in mandibular volume and pharyngeal airway. The group of patients with tracheostomies were decannulated and in the patients with respiratory distress there was improved airway with improvement of signs and symptoms of OSA with elimination of oxygen requirement.

CONCLUSIONS

Mandibular distraction is a useful method in younger children with OSA expanding the mandible and concomitantly advancing the base of tongue and hyoid bone increasing the pharyngeal airway. The external devices permit greater distraction length, the removal is simple but the devices are uncomfortable for the patients. On the other hand, the internal devices are more comfortable for patients but permit shorter distraction length and require a second operation for removal.