Neonatal and Infant Mandibular Distraction as an Alternative to Tracheostomy in Severe Obstructive Sleep Apnea

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1 Neonatal and Infant Mandibular Distraction as an Alternative to Tracheostomy in Severe Obstructive Sleep Apnea Jeffrey Hammoudeh, M.D., D.D.S., Vijay K. Bindingnavele, M.D., Brian Davis, M.D., Sally L. Davidson Ward, M.D., Pedro A. Sanchez-Lara, M.D., Grant Kleiber, M.D., Sheila S. Nazarian Mobin, M.D., M.M.M., Cameron S. Francis, M.D., Mark M. Urata, M.D., D.D.S., F.A.C.S. Context: Surgical management for severe obstructive sleep apnea has been tracheostomy, which has significant morbidity. Objective: To determine the efficacy of internal mandibular distraction in treating severe obstructive sleep apnea in infants and neonates. Design: Retrospective review of medical records of 29 patients who underwent internal mandibular distraction for obstructive sleep apnea secondary to micrognathia. Setting: Nonprofit, academic, pediatric medical center. Patients: A total of 29 infants with obstructive sleep apnea were studied. Nine were included in the respiratory failure group requiring intubation prior to distraction surgery. The other 20 were included in the respiratory distress group and underwent preoperative polysomnography that assessed the severity of obstructive sleep apnea as measured by the apnea-hypopnea index. One patient expired following surgery; the remaining 28 underwent postoperative polysomnography determining their postoperative apnea-hypopnea index. Interventions: Bilateral mandibular distraction with internal microdistractors. Main Outcome Measure: Improvement in the apnea-hypopnea index or extubation. Results: The nine respiratory failure patients avoided tracheostomy and were successfully extubated postdistraction. Eight in this group had postoperative polysomnographies showing a mean apnea-hypopnea index of 3.13 (range, 0 to 13.9). All 20 patients in the respiratory distress group underwent polysomnography and showed improved apnea-hypopnea indices (p,.001). The mean pre-op apneahypopnea index was 39.7 (range, 4.5 to 177), and the mean post-op apnea-hypopnea index was 5.8 (range, 0 to 34). Average improvement in the apnea-hypopnea index was33.9.themeanfollow-upperiodwas18.7months(1.6to45.2months). Conclusions: Infants with micrognathia and obstructive sleep apnea may avoid tracheostomy and its inherent risks and complications by undergoing internal mandibular distraction, which is a viable alternative to tracheostomy. KEY WORDS: internal mandibular distraction, micrognathia, obstructive sleep apnea, Pierre Robin sequence, polysomnogram, tracheostomy Dr. Hammoudeh is Assistant Professor Plastic Surgery, Keck School of Medicine, University of Southern California (USC), and Director Jaw Deformities, Children s Hospital Los Angeles (CHLA), Los Angeles, California. Dr. Bindingnavele is Co-chair, Department of Surgery, Christus Spohn Hospital, Corpus Christi, Texas. Dr. David is Resident, Surgery, University of California Los Angeles, Los Angeles, California. Dr. Ward is Associate Professor Pediatrics, Keck School of Medicine, University of Southern California, and Division Head for Pediatric Pulmonology and Medical Director, Sleep Laboratory, Children s Hospital Los Angeles, Los Angeles, California. Dr. Sanchez-Lara, is Assistant Professor of Pediatrics, Keck School of Medicine, University of Southern California, and Director of Craniofacial Genetics at Children s Hospital Los Angeles, Los Angeles, California. Dr. Kleiber is recent graduate, Keck School of Medicine, University of Southern California, Los Angeles, California. Dr. Nazarian Mobin is Plastic Surgery Resident, University of Southern California, Los Angeles, California. Dr. Francis is Research Fellow, Division of Plastic and Maxillofacial Surgery, Children s Hospital Los Angeles, Los Angeles, California. Dr. Urata is Associate Professor and Chief of the Division of Plastic and Reconstructive Surgery, Keck School of Medicine, University of Southern California, and Division Head, Plastic and Maxillofacial Surgery, Children s Hospital Los Angeles, Los Angeles, California. Obstructive apnea is a significant cause of morbidity in children with congenital micrognathia. The correlation between micrognathia and neonatal airway obstruction was originally described by Pierre Robin in the 1920s. The Dr. Sanchez-Lara is supported by the Harold Amos Faculty Development Program through the Robert Wood Johnson Foundation and the CHLA-USC California Child Health Research Career Development Program (NIH K12-HD05954), Los Angeles, California. There are no other sources of funding or financial interests to disclose. This research was presented at the American Cleft Palate-Craniofacial Association (ACPA) 66th Annual Meeting in Scottsdale, Arizona, in April 2009 and received the ACPA Kawamoto Award. Submitted April 2010; Accepted October Address correspondence to: Dr. Jeffrey Hammoudeh, M.D., D.D.S., Assistant Professor of Plastic Surgery, Keck School of Medicine of University of Southern California, Children s Hospital Los Angeles, Plastic Surgery #96, Los Angeles, CA JHammoudeh@ chla.usc.edu. DOI: /

2 Hammoudeh et al., NEONATAL/INFANT MANDIBULAR DISTRACTION AND OBSTRUCTIVE SLEEP APNEA 33 constellation of findings that he described is now known as the Pierre Robin sequence and consists of glossoptosis, respiratory distress, micrognathia, and often a cleft palate (Robin, 1923). In cases of neonatal obstructive apnea where prone positioning and supplemental oxygen have not sufficed, tracheostomy has long been considered the standard approach to treatment (Bath and Bull, 1997). However, tracheostomy in neonates is associated with both perioperative and postoperative morbidity such as hemorrhage, pneumothorax, and tracheal stenosis. Additionally, these patients are at risk of further complications such as delayed language development, not to mention the significant psychosocial impact on family and the financial impact of the surgical burden of disease (Singer et al., 1989). Also, tracheostomy in the pediatric population has been associated with significant mortality, especially when dealing with the premature infant who has nearly double the complication rate (Rabuzzi and Reed, 1971; Sasaki et al., 1979; Prescott, 1992; Schlessel et al., 1993; Pereira et al., 2004). In order to avoid these complications, other forms of treatment for neonatal airway obstruction have been sought. These include insertion of a nasopharyngeal airway, subperiosteal floor-of-mouth release, glossopexy, and mandibular distraction osteogenesis (MDO). Recent studies have described the utility of MDO in neonates with obstructive apnea and its success in treating airway obstruction without the need for tracheostomy (Cohen et al., 1998; Denny et al., 2001; Izadi et al., 2003; Wittenborn et al., 2004; Steinberg and Fattahi, 2005). Mandibular distraction osteogenesis, first described by McCarthy and colleagues in 1992, is a novel approach to the micrognathic patient in that it avoids the morbidity of a sagittal split osteotomy and can be performed in infancy (McCarthy et al., 2002). The technique entails making an osteotomy on the mandible, stabilizing it in a rigid fixator, and gradually lengthening the mandible using the principle of distraction osteogenesis. The aforementioned studies of mandibular distraction have stimulated an evolution in the surgical approach to Pierre Robin sequence, with many surgeons now employing MDO as the primary treatment for the most severe cases of this disorder. Potential morbidity related to internal distraction includes damage to the inferior alveolar nerve, failure to improve the airway, unfavorable osteotomy, scarring, and infection. The purpose of this study is to analyze the effect of MDO on severe obstructive sleep apnea in micrognathic patients and evaluate its efficacy in achieving our goals of extubating patients in respiratory failure and weaning off supplemental oxygen those patients who were in respiratory distress. METHODS After approval was obtained from the Committee on Clinical Investigations, all patients with respiratory distress who were candidates for MDO at Children s Hospital Los Angeles were retrospectively studied. The patients were evaluated by Ear, Nose, and Throat (ENT), Pulmonary/ Critical Care, and Plastic/Maxillofacial Surgery services. The patient population was then stratified into respiratory distress and respiratory failure groups. Patients in the respiratory failure group were intubated preoperatively and remained so until a postoperative skeletal class III relationship was obtained. The respiratory distress group included patients who had an abnormal apnea-hypopnea index (AHI) on polysomnography (PSG) and failed initial conservative measures, including prone positioning, oxygen supplementation, and/or watchful waiting. If the initial conservative measures failed or the patient s condition worsened, further evaluation was performed to determine whether the patients were candidates for surgical treatment for severe obstructive apnea. The Pulmonary/ Critical Care team assessed the patients to determine whether their respiratory deficiency was due to intrinsic pulmonary disease such as pulmonary hypoplasia. Patients were then examined by ENT for secondary lesions leading to airway obstruction such as tracheal malacia or subglottic stenosis. Finally, all patients were examined by the Plastic/ Maxillofacial Surgery team to determine whether the patient had a class II skeletal relationship and to assess whether there was clinical evidence of retrognathia or micrognathia. A computerized axial tomography (CAT) scan with three-dimensional reconstruction was performed in all patients with a class II skeletal relationship. To document the severity of the sleep-related breathing disorder, PSG was performed. This took place either during a daytime nap or overnight in the Sleep Laboratory using standard techniques in a quiet darkened room. Infants were placed to sleep in their customary sleep position. No sedation was used. Surface electrodes were connected to the patient to monitor electrocardiogram, chin electromyogram, electroencephalogram, and electrooculogram. Respiratory effort was recorded with respiratory inductance plethysmography of the chest and abdomen. Oxygen saturation by pulse oximetry was recorded continuously. Exhaled carbon dioxide was measured continuously with a sampling catheter, and a thermistor was placed at the nose and mouth to evaluate combined airflow. The subjects were observed continuously by the PSG technician, and behavioral observations were recorded in real time in the polysomnographic record. Data were collected and stored by a computerized PSG data acquisition system (Somnostar Pro 7-3a; Somnostar/Cardinal Health, Dublin, OH), and oxygen saturation data were tabulated by the computer program after manual removal of artifacts. Using visual analysis, the sleep staging and respiratory events were scored by a board-certified sleep specialist according to 2007 American Academy of Sleep Medicine criteria (Iber, 2007). The obstructive AHI was calculated based on the number of obstructive apneas, mixed apneas, and hypopneas per hour of sleep.

3 34 Cleft Palate Craniofacial Journal, January 2012, Vol. 49 No. 1 Patients with respiratory distress who had a class II skeletal relationship, in whom a CAT scan confirmed micrognathia and a PSG confirmed obstructive sleep apnea, were then considered potential candidates for either tracheostomy or MDO as part of their treatment algorithm. Both tracheostomy and MDO were offered to the parents of these patients. A detailed explanation of the potential risks and benefits of each was provided to them. Subjects were not randomized, and this approach was part of their clinical care. The outcomes of the infants who underwent MDO are reported here. These patients were divided into two groups. Those who required intubation preoperatively were placed in the respiratory failure group. The rest were placed in the respiratory distress group. The severity of the obstructive sleep apnea of patients in the respiratory distress group was evaluated with preoperative PSG. Each patient s obstructive AHI, lowest O 2 saturation, baseline O 2 saturation, baseline CO 2, and highest CO 2 were all recorded (Table 1). These results were compared with a second PSG performed after MDO to assess the efficacy of the operation in treating obstructive sleep apnea. The results were considered statistically significant if the p value was less than.05 using a paired t test. The patients who were in the respiratory failure group also received postoperative PSG. When patients were taken to the operating room, a laryngoscopy/bronchoscopy was performed to evaluate for any other airway anomaly that might contribute to their respiratory condition. OPERATIVE TECHNIQUE All distraction surgeries were performed by individuals from a single surgical group trained by the same surgeon and using a unified approach. Internal Zurich microdistractors designed for use in neonates and infants (KLS Martin LP, Jacksonville, FL) were used for all patients. A modified Risdon incision was made approximately 1 cm inferior to the angle of the mandible. Dissection was carried out to expose a subperiosteal plane along the ramus and body of the mandible and up to the coronoid process. An inverted-l osteotomy was planned with the horizontal component parallel to the inferior border of the mandible and the vertical component 1 cm anterior to the posterior border of the mandible. A reciprocating saw was used to make a bicortical osteotomy along the entire horizontal component and the caudal portion of the vertical component. A unicortical osteotomy was made through the outer cortex at the superior portion of the vertical osteotomy. The distractors were positioned to be nearly perpendicular to the vertical component of the osteotomy to direct most of the distraction anteriorly. They were applied directly to the external surface of the mandible and fixed in place with self-tapping titanium screws on either side of the osteotomy. At this point an osteotome and a mallet were used to complete the osteotomy through both cortices, and the distractor was tested to ensure free motion at the osteotomy site. The distractor activation arm was then passed through a subcutaneous tunnel created posteriorly and brought out through an incision in the postauricular sulcus. The submandibular incision was closed in layers with absorbable sutures. The patients remained intubated in the pediatric intensive care unit until their respiratory status was determined to be stable enough to tolerate extubation. Distraction was started on the day following surgery at a rate of 1.5 mm per day (one turn every 8 hours) and continued until the distractors were fully extended. In the initial portions of our study, the maximum length of the distractors were 15 or 20 mm. A special order was made with the distractor manufacturers who made a 30-mm distractor available to us that was used in the latter portion of the study. Once active distraction was complete, the patients were returned to the operating room for removal of the activation arms. The skin surrounding the exit point of the activation arm was excised, and all granular tissue was removed from the wound. After the callus was allowed to consolidate for several weeks, a final outpatient procedure was performed to remove the distraction device and revise the submandibular scar. RESULTS A total of 31 patients were taken to the operating room for possible MDO between 2003 and 2007 at Children s Hospital Los Angeles. Two patients were found to have subglottic stenosis on bronchoscopy and did not receive MDO. The remaining 29 patients underwent MDO. Of these, 19 had Pierre Robin sequence, one had Pierre Robin versus Cornelia de Lange, one had cerebro-costo-mandibular syndrome, three had Goldenhar syndrome, one had Beckwith-Wiedemann syndrome, one had hemifacial microsomia, and three had congenital micrognathia not otherwise specified. There were nine patients in the respiratory failure group and 20 in the respiratory distress group. All patients had bilateral procedures except the patient with hemifacial microsomia. The mean length of mandibular distraction was 24.4 mm (range, 15 to 30 mm). Patients remained intubated postoperatively for an average of 11.4 days (range, 0 to 46 days), until they were stable enough to tolerate extubation. All patients but one were subsequently discharged home without supplemental oxygenation. The mean length of hospital stay following surgery was 42.3 days (range, 3 to 140 days). Following completion of the distraction phase, the activation arms were removed, and the callus was allowed to consolidate for a mean of 28.9 weeks (range, 4 to 159 weeks). The mean preoperative obstructive AHI of the 20 patients in the respiratory distress group was 39.7 (range, 4.5 to 177). Following mandibular distraction in these patients, the mean obstructive AHI was 5.8 (range, 0 to 34),

4 Hammoudeh et al., NEONATAL/INFANT MANDIBULAR DISTRACTION AND OBSTRUCTIVE SLEEP APNEA 35 TABLE 1 Results of Preoperative and Postoperative Sleep Studies Pre-op Post-op Corrected Age (mo) Sex Diagnosis % Sleep Time O2-sat,90 Lowest O2-sat Baseline CO2 Peak CO2 AHI % Sleep Time O2-sat,90 Lowest O2-sat Baseline CO2 Peak CO2 AHI Post-op Days Intubated Distracted, mm Laterality Respiratory Distress 0.9 M Pierre Robin * B 1.1 M Pierre Robin { B 1.1 M Micrognathia NOS B 1.2 M Pierre Robin * B 1.6 F Pierre Robin * { B 1.7 F Pierre Robin { { { { B 1.9 F Pierre Robin * * * * B 1.9 M Pierre Robin { B 2.0 M Pierre Robin B 2.3 F Micrognathia NOS B 2.6 F Pierre Robin B 2.8 F Beckwith-Wiedemann B 2.9 M Goldenhar { B 3.3 M Goldenhar 6.2 * * * B 4.7 M Pierre Robin B 5.8 F Pierre Robin B 9.2 M Micrognathia NOS B 17.3 M Pierre Robin 0 * * * B 18.5 M Goldenhar R 32.1 F Hemifacial microsomia * { { B Respiratory Failure 0.7 F Pierre Robin { { { { { B 0.8 M Pierre Robin { { { { { * B 1 M Pierre Robin { { { { { B 1 M CCMS { { { { { B 1.6 M Pierre Robin { { { { { 6 75 { { B 1.75 M Cornelia de Lange { { { { { B 1.8 M Pierre Robin { { { { { B 1.9 M Pierre Robin { { { { { 0 94 { { B 2.2 F Pierre Robin { { { { { * 84 { { B * Record not available. { CO2 measurement not collected due to lack of hypoventilation, inadequate monitoring, or intolerance to testing. { Pre-op sleep study not obtained because patient was intubated due to respiratory failure. 1 Post-op sleep study not obtained because patient expired. AHI 5 apnea-hypopnea index; B 5 bilateral; NOS 5 not otherwise specified; CCMS 5 cerebro-costo-mandibular syndrome.

5 36 Cleft Palate Craniofacial Journal, January 2012, Vol. 49 No. 1 which gave a mean AHI improvement of All patients AHIs improved following MDO. The difference was statistically significant with p,.001 by paired t test (see Table 1). All nine patients in the respiratory failure group were extubated following distraction surgery. One of the patients in the respiratory failure group with multisystem disease died of respiratory failure unrelated to the distraction and prior to the postoperative sleep study. The other eight patients in the respiratory failure group had postoperative PSGs with a mean AHI of 3.13 (range, 0 to 13.9). Three patients, one of whom had been in the preoperative respiratory failure group, had normal AHIs (,1.0) on postoperative PSGs. The mean age at surgery was 4.5 months (range, 0.5 to 32.1 months), and the mean follow-up period was 18.7 months (range, 1.6 to 45.2 months). Five patients experienced perioperative complications following distractor placement for an operative complication rate of 17.9%. These included mechanical failure of a distractor unilaterally in one patient, requiring surgical replacement. One patient developed a transient facial nerve palsy that resolved within 1 week. In another patient, the distraction device became partially exposed through the postauricular exit point of the activation arm. This patient also eventually required a tracheostomy due to severe interstitial lung disease and central apnea due to seizures. One patient had a local infection in the surgical site that resolved after a course of Keflex. There was one patient who expired after postdistraction extubation. This patient was afflicted with many other medical conditions prior to surgery, including coarctation of the aorta (which was surgically repaired 3 weeks before the distractors were placed), decreased left ventricular function, a thickened left ventricle, an atrial septal defect, pulmonary hypertension, bilateral dysplastic kidneys, renal failure, intermittent hypertension (which was self-resolving), intrauterine growth restriction, mixed acidosis on day 9 of life that required intubation, micrognathia, and cleft palate. The patient was diagnosed with Pierre Robin sequence versus Cornelia de Lange syndrome. Despite the many medical conditions affecting multiple organ systems, distractors were surgically placed at 1 month of age. The patient initially did well and was extubated 11 days following surgery and was saturating well on room air. However, 20 days postoperatively, the patient aspirated and experienced acute respiratory failure that required reintubation. Following this event the patient continued to deteriorate from what the physicians on his primary team believed was sepsis. Two days later the child was determined to be in a persistent vegetative state, and the decision was made to withdraw life support. DISCUSSION Severe congenital micrognathia is often complicated by obstructive apnea. This is well illustrated by patients who exhibit Pierre Robin sequence. Conservative measures including prone positioning, supplemental oxygen, and, if required, tongue-lip adhesion are usually adequate temporizing measures until there is sufficient native mandibular growth to permit unobstructed respiration. Although historically, the mortality of infants so managed has been low, it is unknown how partially treated obstructive apnea and hypoxemia affect outcomes such as growth and development. Patients who failed conservative measures usually underwent tracheostomy (Denny et al., 2004; Meyer et al., 2008). Mandibular distraction osteogenesis addresses the primary deformity of mandibular hypoplasia to ameliorate airway obstruction without the morbidity inherent with tracheostomy. Advancement of the mandible leads to an increase in the volume of the posterior airway space, effectively relieving obstruction (Rachmiel, 2005). The genial tubercle of the mandible has insertions of the genioglossus muscle and as well as insertions of the geniohyoid, mylohyoid, and anterior digastric muscles that connect it to the hyoid bone. This relationship causes the tongue to move anteriorly and elevates and advances the hyoid bone when the mandible is advanced. The physiologic rationale of distraction osteogenesis has been examined and described in detail elsewhere (Castano et al., 2001; Yates et al., 2002; Glowacki et al., 2004). These sources describe three phases of distraction osteogenesis: latency, distraction, and consolidation. The length of time for each phase is dependent on the individual patient and situation. In this study we allowed for a latency phase of 24 hours. Subsequently in the distraction phase the bone segments are actively distracted at the osteotomy site, which stimulates new bony growth in the newly created intervening space. The amount of distraction we performed was the maximal amount allowed by the distractor. Distraction was begun whether or not the patient was extubated postoperatively. During the initial period of this study the available distractors allowed for a maximal distraction of only 15 mm. Later, the maker of the distractor supplied us with longer distractors, including those that are 20, 25, and 30 mm long. The reason for the longer distractors was to further improve the postoperative AHI. Because the distraction rate was 2 mm per day, the length of the distraction phase was determined by the amount of distraction performed. The distractor arms were removed after this stage. During the final stage of consolidation, the bony segments are rigidly stabilized, which allows the intervening callus to mineralize into mature bone. We allowed for a consolidation phase of at least 12 weeks, after which the device was removed and the scar revised. Two major techniques currently exist for distraction: an externally based distractor affixed with K-wires or fixation pins, or placement of a buried internal distractor affixed directly to the mandible with screws. We exclusively use internally placed distractors because we have found that they avoid some complications of external devices, such as

6 Hammoudeh et al., NEONATAL/INFANT MANDIBULAR DISTRACTION AND OBSTRUCTIVE SLEEP APNEA 37 pin-track infections, pin dislodgement, hypertrophic pintrack scars, and disruption of tooth buds. External distractors are affixed to the bone segments by percutaneously placed pins or K-wires, which have a potential for injury to internal structures such as the inferior alveolar artery and nerve, the marginal mandibular nerve, and the developing tooth buds. Although there is a risk of injury to these structures with internal distractors as well, we feel that direct visualization allows for better avoidance of these vital structures. Additionally, the internal distractors are closely affixed to the mandible and thus have a greater fidelity of movement transmission from the distractor to the mandible itself. We used an inverted-l osteotomy when performing distractions. This form of osteotomy is preferred over other types such as the sagittal split-ramus osteotomy or intraoral vertical ramus osteotomy because it is more easily performed, provides a greater contact area for plating and rigid fixation, and helps prevent nerve and tooth bud damage (Muto et al., 2008) Previous studies have examined the utility of mandibular distraction to treat airway obstruction secondary to micrognathia. Excellent results have been reported using internal distractors to treat airway obstruction in micrognathic neonates (Izadi et al., 2003; Wittenborn et al., 2004). With 29 patients, our study is the largest to date using internal mandibular distraction to treat neonatal obstructive sleep apnea secondary to micrognathia. Our success in patients who were intubated preoperatively, the respiratory failure group, was excellent. All intubated patients were extubated postoperatively. In patients who had respiratory distress, the success rate can be measured by comparing the preoperative and postoperative PSGs. Only one of our 29 patients required a tracheostomy, which was required to manage the patient s medical conditions other than obstructive sleep apnea. Further study is required to develop selection criteria for the MDO procedure in infants who may have congenital anomalies of multiple organ systems. CONCLUSIONS Mandibular lengthening by distraction osteogenesis is an effective surgical alternative to tracheostomy in the neonate and infant with obstructive sleep apnea secondary to micrognathia. When compared with previous studies, our comprehensive team approach to internal mandibular distraction is associated with a lower morbidity and mortality versus tracheostomy. Additionally, there was significant improvement in the AHIs of all patients who underwent mandibular distraction in our series. Mandibular distraction osteogenesis is effective at avoiding tracheostomy in infants with upper airway obstruction due to micrognathia with all its attendant risks and potential complications. Further prospective studies that compare MDO with other forms of treatment are required before MDO can be considered the standard of care for treatment of obstructive apnea in children with micrognathia. This preliminary study, however, shows the need to develop more objective criteria in evaluating patients with multiple comorbidities in order to determine candidacy for distraction osteogenesis. Acknowledgments. The authors are grateful to all of the participating families who made this research possible. We would like to acknowledge Ashley Karatsonyi and Wendy Moh for their time and effort on data collection for this project. We would also like to thank the Neonatal Intensive Care Unit staff for their support of and care for these families. 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