- Email: [email protected]
Mandibular Advancement by Distraction Osteogenesis for Tracheostomy-Dependent Children With Severe Micrognathia
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Web site (www.massgeneral.org/ newomfs/) (Fig 2). The MGH program accepts 3 residents each year who are graduates of dental schools throughout the country. The present group of residents includes graduates of the University of Pennsylvania, University of California San Francisco, University of California Los Angeles, University of Connecticut, McGill University, Temple University, Tufts University, Ohio State University, and Harvard, among
others. Acceptance as a resident in OMFS automatically provides advanced standing admission to the Harvard Medical School after the first year of internship. Perhaps the greatest strength of any OMFS department is its faculty. The MGH program has 20 full-time faculty at MGH and affiliated institutions: Brigham and Women’s, Children’s Hospital, Beth Israel Deaconess Medical Center, and Harvard School of Dental Medicine. There also are
26 part-time faculty. This dedicated group has had a significant impact on our students and trainees for generations. The MGH program in OMFS has a strong commitment to diversity, which is reflected in its significant number of women and minorities who are its trainees and staff. It also continues to demonstrate its commitment to continuing requirement and expansion of the art and science of OMFS through basic and clinical research.
Mandibular Advancement by Distraction Osteogenesis for Tracheostomy-Dependent Children With Severe Micrognathia Derek M. Steinbacher, DMD, MD,* Leonard B. Kaban, DMD, MD,† and Maria J. Troulis, DDS, MSc‡ Purpose: The purpose of this study was to evaluate mandibular lengthening by distraction osteogenesis
(DO) to achieve decannulation of micrognathic children with “permanent” tracheostomies. Patients and Methods: Using a retrospective chart review, patients were included who had 1) airway compromise/tracheostomy, 2) micrognathia, 3) polysomnography-documented obstructive apnea, and 4) mandibular advancement using DO. Excluded were 1) adults, 2) neonates without tracheostomy, and 3) patients with central apnea. Patient age, past medical history, age at tracheostomy, and distraction protocol were documented. Oxygen saturation, posterior airway space (in millimeters), and sella-nasion-B point (SNB) angle were recorded. The distraction protocol consisted of a latency of 48 hours and a rate of 1 mm/day. Results: There were 5 children, aged 2 to 14 years, who received a tracheostomy between ages 2 and 36 months for airway obstruction. All patients underwent bilateral mandibular distraction using semiburied, unidirectional devices. The average latency was 58 hours, the rate was 1 mm/day, the duration of fixation was 40 to 60 days, and the magnitude of advancement was 23 mm. Healing was evaluated by clinical, radiologic, and ultrasound examinations. No complications were experienced. Mean follow-up was 3.2 years. Postdistraction sleep studies demonstrated no obstructive apneic events and a mean oxygen saturation of 98% (preoperative, 76%, P ⬍ .005). Cephalometric values improved: posterior airway space 4 to 14 mm; SNB 66° to 72° (P ⬍ .005 for both variables). Four of the 5 patients have been successfully decannulated to date. Conclusions: The results of this preliminary study indicate that mandibular advancement by DO is a potentially viable treatment option for tracheostomy-dependent children with upper airway obstruction secondary to micrognathia. © 2005 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 63:1072-1079, 2005
Airway obstruction may result from abnormalities in respiratory physiology, airway anatomy, or both. Apnea is defined as cessation of breathing for a period of 10 seconds or more and may be mediated by neurologic dysfunction (central apnea) or may be secondary to airway obstruction (obstructive apnea). Patients with congenital craniofacial anomalies have varying degrees of airway obstruction. This respiratory compromise is usually secondary to micrognathia and resultant malposition of the tongue base. Children with acquired craniofacial anomalies (eg, posttrauma, post–tumor resection, or post–radiation therapy) may also have obstructive apnea. Severe airway obstruction is associated with significant morbidity and mortality in infants and children. They may exhibit frequent episodes of oxygen desaturation, hypoxemia, hypercarbia, acidosis, persistent inspiratory stridor, severe sternal retraction, and poor feeding (secondary to airway compromise). Infants and children with long-term airway obstruction exhibit failure to thrive, daytime somnolence, hemodynamic changes (including cor pulmonale and pulmonary hypertension), developmental disabilities, insufficient weight gain/malnutrition, increased pulmonary morbidity, and death.1 Some neonates exhibit mild obstructive apnea. This is often managed by instructing the parents in prone positioning and in feeding techniques and to be alert to breathing difficulties. These infants will often improve as the craniofacial skeleton, including the mandible, grows during the first 3 to 6 months of life. In cases where obstruction is refractory to the above techniques, more aggressive treatment is necessary. Glossopexy, tongue-lip adhesion, hyomandibulopexy, and subperiosteal release of floor of mouth musculature have been reported as temporary treatment modalities for upper airway obstruction in infants and children. However, their efficacy is not well documented.2– 6 Endotracheal intubation may be used to address an emergency episode of airway obstruction. Tracheostomy is indicated for significant chronic episodes of airway obstruction.7 It provides a port for movement of air that bypasses the supralaryngeal anatomic obstruction to flow, thereby mitigating the morbidity of peripheral airway obstruction. This timeReceived from Massachusetts General Hospital, Boston, MA. *Resident in Oral and Maxillofacial Surgery. †Walter C. Guralnick Professor and Chairman, Department of Oral and Maxillofacial Surgery. ‡Associate Professor and Director, Minimally Invasive Oral and Maxillofacial Surgery. Presented in part at the 85th Annual Meeting of the American Association of Oral and Maxillofacial Surgeons, Orlando, FL, September 2003. This work was also the basis for an honors thesis presented to the Harvard Medical School Committee on Awards and Honors, April 2004 (D.S.).
honored procedure is effective for long-term airway management in patients with craniofacial anomalies. However, tracheostomy is associated with its own inherent morbidity.8,9 Longstanding tracheostomy produces increased risk for tracheomalacia, chronic bronchitis, laryngeal stenosis, and sudden death (risk of mucus plug or tube dislodgment).10 –12 In addition, family life may be interrupted and speech acquisition and development delayed. Other adverse consequences of permanent tracheostomy include intellectual and physical impairments, compromised social interactions, and the requirement for complex nursing care and parental education.13–17 Historically, tracheostomy was the only safe longterm treatment option for infants and children with micrognathia because of the magnitude of mandibular advancement required to correct the problem and the need for bone grafts (donor site morbidity). Furthermore, it was sometimes technically difficult or impossible to advance the mandible the required amount to improve the airway and the relapse rate was prohibitively high. It was recognized however, that lengthening of the osseous tongue-supporting architecture would be beneficial.18 –21 Early results of mandibular lengthening by distraction osteogenesis (DO) indicate that operative morbidity and stability of advancement are significantly better than standard techniques in children. This is especially true for advancements of large magnitude. DO has also been shown to be effective in lengthening the mandible with consequent airway improvement allowing removal of the tracheostomy.7,22–30 Relief of respiratory obstruction is thought to be secondary to advancement of the tongue-base as the tongue muscles move forward with the mandible. The appropriate management strategies for infants and children with airway obstruction secondary to micrognathia are currently being investigated. There is controversy surrounding both surgical and nonsurgical interventions and the timing of treatment. We hypothesize that mandibular lengthening by DO will effectively improve upper airway anatomy and allow for tracheostomy decannulation in tracheostomy-dependent children (older than 18 months). The purpose of this study was 1) to evaluate mandibular lengthening using DO to achieve decannulation Supported by a research grant from the Hanson Foundation (Boston, MA), an NIH grant (NIDCR, M.J.T., Principal Investigator), and the Department of Oral and Maxillofacial Surgery Education and Research Fund. Address correspondence and reprint requests to Dr Troulis: Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02112; e-mail: [email protected] © 2005 American Association of Oral and Maxillofacial Surgeons
0278-2391/05/0-06305$30.00/0 doi:10.1016/j.joms.2005.04.013
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Table 1. DEMOGRAPHIC DATA OF 5 CONSECUTIVE CHILDREN
Patient
Syndrome
Other Procedures
1 2 3 4 5
Pierre Robin syndrome No. No. CHARGE No.
Glossopexy T&A, U3P T&A Choanal atresia repair T&A
Age (trach)
Age (DO)
Age Decan
2 mo 2 yr 3 yr 4 mo Infancy
3 yr 2 yr 3 yr 8 yr 14 yr
3 yr 3 yr 4 yr 8 yr Pending
Abbreviations: T&A, tonsillectomy and adenoidectomy; U3P, uvulopharyngopalatoplasty. Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
of children with permanent, in-dwelling tracheostomies and 2) to suggest a management strategy for children presenting with severe airway obstruction secondary to micrognathia.
Patients and Methods This was a retrospective study performed in concordance with the regulations and approval of the Institutional Review Board of the Human Research Committee at Massachusetts General Hospital. Outpatient and hospital charts of consecutive children treated at the Massachusetts General Hospital, Department of Oral and Maxillofacial Surgery from January 1998 to June 2002 were reviewed. Included in the study were patients who met the following criteria: 1) history of significant upper airway compromise and tracheostomy dependence, 2) micrognathia and tongue-base obstruction, 3) polysomnography-documented obstructive apnea, and 4) treatment by mandibular advancement using DO. Patients excluded from this study were 1) adults (age ⬎18 years), 2) neonates (age ⬎ year), 3) children without tracheostomy, and 4) patients with significant central apnea. From the charts, patient age, past medical and family histories, and age at tracheostomy were documented. In the setting of an overnight sleep study, the percent oxygen saturation with an occluded port was recorded both before and after treatment. Preoperative and postoperative lateral cephalograms were used to measure and compare posterior airway space (PAS) in millimeters and sella-nasion-B point (SNB)
angle. Finally, data pertaining to the distraction device and distraction protocol were collected. Statistical analysis was performed comparing preoperative and postoperative oxygen saturation and cephalometric values, including SNB and PAS. Using a computerized SAS program, a paired t test was used, with statistical significance set at P ⬍ .05.
Results DEMOGRAPHICS
Five children (3 girls and 2 boys, aged 2 to 14 years, mean age 6 year) were evaluated (Tables 1, 2). Three patients were nonsyndromic, one carried the diagnosis of CHARGE association, and one had Robin sequence. All children had upper airway obstruction and severe retrognathia with a posteriorly displaced tongue-base. All 5 patients received a tracheostomy at 2 to 36 months of age (mean age, 15.4 months) for airway obstruction and oxygen desaturation. Glossopexy was used without airway benefit for one patient, in infancy, prior to tracheostomy. No child demonstrated improvement with posttracheostomy ancillary procedures, including tonsillectomy and adenoidectomy (n ⫽ 3), uvulopharyngopalatoplasty (n ⫽ 1), and right choanal atresia repair (n ⫽ 1). PLANNING
The vector of distraction was determined by measurements on the plain radiographs and computed tomography (CT) scans. The planned distraction vec-
Table 2. DISTRACTION PROTOCOL
Patient
Latency (hr)
1 2 3 4 5
48 48 48 72 72
Rate and duration (d) 1 1 1 1 1
mm/d mm/d mm/d mm/d mm/d
⫻ ⫻ ⫻ ⫻ ⫻
30 25 29 30 19
Magnitude (mm)
Consolidation (d)
Time Devices in (d)
30 31 L, 20 R 28 26 L, 23 R 12 L, 11 R
60 60 60 60 40
67 61 125 74 104
Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
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STEINBACHER, KABAN, AND TROULIS
osteotomy with four 2.0-mm-diameter screws (Fig 3). They were activated to ensure proper function and then reversed. The wounds were irrigated and closed in a standard fashion. The patients were observed overnight and discharged the following day. DISTRACTION PROTOCOL AND HEALING
FIGURE 1. A 4-year-old nonsyndromic boy who required tracheostomy at age 3 for worsening respiratory distress, stridor, and O2 desaturation into the 70s (patient 3, Tables 1, 2). Note the retruded chin position and obtuse chin-throat angle. Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
tor was anterior and slightly inferior, with a 110° angle from the mandibular occlusion plane in all 5 cases (Figs 1, 2). A navigation device was constructed, using the dental models, a lateral cephalogram, and CT scan. This consisted of an acrylic occlusal splint with a metal “outrigger” indicating the orientation of the osteotomy. The distraction device was then placed perpendicular to the osteotomy to achieve the correct vector of movement (Fig 3). SURGICAL PROCEDURE
Semiburied unidirectional distraction devices (Synthes Maxillofacial, Paoli, PA) were used in all 5 patients. General anesthesia was induced and maintained via the child’s existing tracheostomy. Standard intraoral incisions were used to access the mandibular body. Corticotomies were performed with the aid of previously fabricated navigation devices (Fig 3). Semiburied distraction devices without (n ⫽ 2) and with (n ⫽ 3) detachable footplates were fixed across the
Distraction was initiated following 48 to 72 hours of latency (mean of 58 hours). A rate of 1 mm/day was instituted for a mean of 27 days (range, 19 to 30 days) resulting in mean mandibular lengthening of 23 mm (range, 11 to 31 mm). Because of slight asymmetry in some patients, the distraction gap averaged 22 mm on the right and 25 mm on the left (ranges of 11 to 30 mm and 12 to 31 mm, respectively). Active distraction was followed by a fixation phase of 60 days in 4 of the 5 patients. The fifth patient was held in neutral fixation for 40 days. Healing was evaluated by clinical, radiologic, and ultrasonographic examination. Clinical evaluations were performed at weekly intervals during active distraction and every 2 weeks during the fixation period. When possible lateral cephalograms and panoramic radiographs were obtained (preoperatively, immediately postoperatively, at end-DO (Fig 4) and prior to distractor removal). All patient’s had a preoperative CT scans. Prior to distractor removal, ultrasonographic examination was performed to evaluate healing during the mean 58 days of fixation (range, 43 to 84 days). All 10 sides exhibited marked osseous growth between the distracted segments. The detachable activation arms were removed at a mean of 86 days after placement (range, 61 to 125 days). There were no postoperative complications related to device placement, activation, or removal. One child presented with an infected residual footplate 2 years postdistraction, also associated with a decayed tooth. Mean follow-up was 3.2 years (range, 1.5 months to 5 years).
FIGURE 2. Three-dimensional computed tomography scan illustrates the planned distraction vector for the patient shown in Figure 1. The preoperative lateral cephalogram revealed a posterior airway space of 3 mm and an SNB of 63. Note also the planned vector of correction (scribed). Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
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DISTRACTION OSTEOGENESIS FOR CHILDREN WITH MICROGNATHIA FIGURE 3. The intraoperative sequence included the use of a prefabricated primitive navigation device to aid with osteotomy placement. The semiburied distractors were placed bilaterally, with the long axes being oriented perpendicular to the plane of the osteotomy. Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
POLYSOMNOGRAPHY
Polysomnography was used to demonstrate obstructive apnea. Each child was admitted for overnight observation to the Pediatric Intensive Care Unit at Massachusetts General Hospital. Standard cardiorespiratory and oxygen saturation monitoring was instituted. Once a somnolent state was achieved, the tracheostomy port was occluded and the patient continued gas exchange by way of natural airway. Both the percent oxygen saturation and respiratory rate were carefully recorded. Periods of persistent desaturation and/or apnea resulted in termination of the formal polysomnogram and the tracheostomy port was opened. The ability of each patient to tolerate tracheostomy occlusion could be grossly appreciated and the oxygen saturation allowed the degree of obstruction to be quantified. Preoperatively, the group did not tolerate intentional occlusion of the port, verifying tracheostomy dependence. Prior to intervention by distraction, each child exhibited apneic episodes and oxygen desaturation to a mean nadir of 76% (range, 68% to 82%). Following treatment, there were no obstructive apneic events in any patients and a mean oxygen saturation of 98% (range, 95% to 100%) was recorded for all 5 patients (Table 1). Subjective bronchoscopic examination demonstrated hypopharyngeal constriction, visualized as epiglottic retrodisplacement by the tongue, and true vocal cord mobility with a patent subglottic space in all patients prior to mandibular lengthening. Postoperatively, “widely patent airways” were noted in all 5 patients. CEPHALOMETRIC ANALYSIS
Average predistraction PAS measured on lateral cephalograms went from 4 mm (range, 3 to 8 mm) to 14 mm (range, 10 to 18 mm) following treatment. The mean preoperative SNB was 66 (range, 55 to 74), and it increased to 72 (range, 60 to 80) prior to decannulation (Fig 5). STATISTICAL ANALYSIS
The postoperative changes in oxygen saturation, PAS and SNB, were all statistically significant (P ⬍
.005) (using paired t test; Table 1). Comparing the lowest oxygen saturation from overnight sleep studies before and after intervention demonstrated a value of P ⫽ .003. The postoperative increase in PAS was significant at a value of P ⬍ .001. Pretreatment versus posttreatment SNB showed a value of P ⫽ .001. Following mandibular advancement by DO, all 5 patients have been deemed candidates for tracheostomy decannulation. To date, 4 of the 5 patients have been successfully decannulated (Fig 5). The fifth patient is awaiting tracheostomy removal pending resolution of other nonairway medical problems.
Discussion Advancing the mandible to correct retrognathia and relieve associated airway distress was first proposed early in the 20th century using skeletal traction.31,32 Although the concept was correct, these techniques were abandoned because of temporomandibular joint ankylosis and unpredictable results. As treatment modalities have evolved, the focus has shifted to mandibular lengthening surgery for patients with tongue-base obstruction. This allows for simultaneous advancement of the tongue-base, which enlarges the hypopharyngeal space and improves airway obstruction. In 1972, Cosman and Crikelair33 reported 3 cases of micrognathia-induced respiratory difficulty that responded to mandibular advancement. Surgically positioning the mandible forward is an effective and commonly used technique to manage adults with obstructive sleep apnea.18,19 Therefore, applying mandibular expansion to children with upper airway obstruction was a natural extension of the success seen in adults. However, traditional procedures (eg, including bilateral sagittal split or inverted L-osteotomies) are not well suited for children. Standard osteotomies with advancement lack stability in the young child because of unreliable long-term fixation and resorption or unpredictable growth of the bone graft.34 In the appropriately selected pediatric age group, lengthening by mandibular DO is currently the favored surgical technique to overcome upper airway
STEINBACHER, KABAN, AND TROULIS
FIGURE 4. Same patient at end-distraction prior to tracheostomy removal. Appropriate healing was observed prior to percutaneous device arm removal. Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
compromise secondary to micrognathia. Distraction can effectively attain the large magnitude of advancement required in these children, with minimal relapse and no donor site morbidity. Additional advantages of DO include shorter operative time, fewer complications, decreased length of hospital stay, no requirement for blood transfusion or maxillomandibular fixation, less distortion and loading of the temporomandibular joint, and a lower incidence of neurosensory deficits. Although DO is an attractive option for the pediatric population with airway obstruction secondary to micrognathia, the ideal timing and treatment are subject to controversy. Children less than 2 years of age are not optimal candidates for treatment by distraction. Technical issues include diminished mandibular bone quality and amount and difficulty in identifying developing tooth follicles. Family adherence to the treatment protocol can also prove to be a difficult challenge in this age group. Neonatal distraction requires prolonged intubation and sedation, with continued hospital observation. Finally, the fact that natural mandibular growth may obviate the need for operative intervention and that surgical intervention itself can adversely affect mandibular growth should be carefully considered. In many previous reports, infants undergoing mandibular distraction for micrognathia initially present with sublethal airway obstruction.20,26,27,29,35 That is, the obstruction is not serious enough to require immediate tracheostomy. Instead, mandibular lengthening by DO is carried out, and the resultant improvement in airway dimension has caused several authors to claim that a tracheostomy is avoided.20,26,27,29,35 This implies that a tracheostomy will be eventually required unless mandibular lengthening by DO is performed. This may not be the case. Significant endog-
1077 enous mandibular growth, as neuromuscular control is increased, can allow the child to reach normal chin projection and alleviate anatomical airway constriction, without surgical intervention. Therefore, nonoperative treatment is favored for as long as possible to allow for mandibular growth to obviate the need for surgical management. A number of studies allude to the airway benefit of mandibular DO, but no group has reported on the airway effects in a serial or prospective manner.20,22,26 –29,34 –36 These cases have indicated that enhanced upper airway dynamics, secondary to mandibular lengthening, obviated the need for a tracheostomy port, and the child could be decannulated. However, only a paucity of reports exist focusing solely on the tracheostomy-dependent child22,28 (as opposed to nontracheostomized infants with obstructive symptoms to purportedly prevent tracheostomy). In the cohort reported here, the efficacy of mandibular DO to achieve decannulation for 5 tracheostomy-dependent children with a history of obstructive apnea was investigated. All children were referred to the Massachusetts General Hospital after the neonatal period. Each child underwent placement of a life-saving tracheostomy in the early phases of life, prior to referral. This is advantageous for several reasons. Studying children who are objectively tracheostomy dependent removes the nebulous notion that a future tracheostomy would be prevented. Preoperative tracheostomy dependence also allows for a binary measure of treatment success—the polysomnographically documented ability to be decannulated or not. It is also of note that all children who underwent treatment by DO were older than 2 years in this study. This means that the technical considerations of completing mandibular DO in young infants were circum-
FIGURE 5. The patient at end treatment after both tracheostomy and distraction device removal. The lateral cephalogram at the end of treatment shows the posterior airway space of 18 (versus a pretreatment 3) and an SNB of 72 (preoperative value of 63). Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
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Table 3. PRE– AND POST–MANDIBULAR LENGTHENING VARIABLES
Mean Lowest
O2
Lowest
PAS
Lowest
SNB
Pre-DO Post-DO Pre-DO Post-DO Pre-DO Post-DO
76 98 4 14 66 72
Range 68 96 3 10 55 60
to to to to to to
82 99 8 18 74 80
P Value P ⫽ .003 P ⬍ .001 P ⫽ .001
Abbreviations: O2, oxygen saturation; PAS, posterior airway space (mm); SNB, sella-nasion-B point angle; DO, distraction osteogenesis. The change with treatment is shown to be statistically significant (paired t test SAS program). Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
vented and the window for endogenous mandibular growth to allow for spontaneous improvement of airflow obstruction had likely passed. The most critical gauge of success is the polysomnogram. Following distraction, each of the 5 patients underwent a sleep study with the tracheostomy port blocked to assess for adequacy of the improved natural airway. Results were compared with the preoperative baseline values (Table 3). A successful polysomnogram entails the absence of apneic episodes and the presence of oxygen saturation levels in the mid- to upper 90s. The lack of desaturations and apneic episodes are the most critical factors for success. Each child in our cohort tolerated the sleep study without ill effect and was deemed a candidate for decannulation. The ability to achieve decannulation is the clinically relevant measure of success in these patients. However, for completeness, quantitative analysis was performed on all objective variables (SaO2, SNB, PAS), comparing pretreatment versus posttreatment values. Statistical significance (P ⬍ .005) was calculated using Student’s t test (SAS software, SAS Institute, Cary, NC), and all variable comparisons were significant (Table 3). It is clear that mandibular DO is a successful technique to treat micrognathic children with tracheostomy dependence; however, the approach to treatment logistics has not been adequately defined. The management strategy we propose for children with airway obstruction (secondary to micrognathia) under the age of 2, who are refractory to conservative measures, would involve receiving a tracheostomy of short duration, then, once physiologically stable, undergoing mandibular lengthening (if still necessary) by DO at an age greater than 2 when factors are more conducive to the procedure. Mandibular DO is then used to improve airway architecture and eliminate the need for artificial airway assistance. In this preliminary study, we concluded that mandibular lengthening by DO is a viable treatment option for children with upper airway obstruction
secondary to micrognathia. Tracheostomy-dependent patients treated by mandibular DO demonstrate resolution of tongue-base airway impingement and a predictable advancement of large magnitude, while preventing donor site morbidity. Delaying distraction until after the immediate neonatal period ensures improved mandibular osseous architecture and avoids prolonged intubation and sedation during treatment. As a result, young children with preexistent tracheostomies are afforded the option of waiting until later childhood for the DO procedure and tracheostomy removal, while being early enough to avoid long-term tracheostomy morbidity.
References 1. Menashe VD, Farrehi C, Miller M: Hypoventilation and cor pulmonale due to chronic upper airway obstruction. J Pediatr 67:198, 1965 2. Argamaso RV: Glossopexy for upper airway obstruction in Robin sequence. Cleft Palate Craniofac J 29:232, 1992 3. Hadley RC, Johnson JB: Utilization of the Kirschner wire in Pierre Robin syndrome. Plast Reconstr Surg 31:587, 1963 4. Myer CM, Reed JM, Cotton RT, et al: Airway management in Pierre Robin sequence. Otolaryngol Head Neck Surg 118:630, 1998 5. Douglas B: The treatment of retrognathia associated with obstruction by a plastic procedure. Plast Reconstr Surg 3:300, 1946 6. Bergoin M, Giraud JP, Chaix C: L’hyomandibulopexie dans le traitment des formes graves du syndrome de Pierre Robin. Ann Chir Infant 12:85, 1971 7. Cohen SR: Early decannulation with bilateral mandibular distraction for tracheostomy-dependent patients (Discussion). Plast Reconstr Surg 103:58, 1999 8. Motta J, Guilleminault C, Schroeder JS, et al: Tracheostomy and hemodynamic changes in sleep-induced apnea. Ann Intern Med 89:454, 1978 9. Guilleminault C, Simmons FB, Motta J, et al: Obstructive sleep apnea syndrome and tracheostomy: Long-term follow-up experience. Arch Intern Med 141:985, 1981 10. Conway WA, Victor LD, Magilligan DJ, et al: Adverse effects of tracheostomy for sleep apnea. JAMA 246:347, 1981 11. Sasaki, CT, Masatoshi H, Koss N: Tracheostomy related subglottic stenosis: Bacteriologic pathogensis. Laryngoscope 89:857, 1979 12. Zeitouni A, Manoukian J: Tracheostomy in the first year of life. J Otolaryngol 22:431, 1993 13. Tomaski SM, Zalzal GH, Saal HM: Airway obstruction in Pierre Robin sequence. Laryngoscope 105:111, 1995
STEINBACHER, KABAN, AND TROULIS 14. Singer LT, Kercsmar C, Legris G, et al: Developmental sequelae of long-term infant tracheostomy. Dev Med Child Neurol 31: 224, 1989 15. Arola MK: Tracheostomy and its complications: A retrospective study of 794 tracheostomized patients. Ann Chir Gynaecol 70:96, 1981 16. Wetmore RF, Handler SD, Potsic WP: Pediatric tracheostomy: Experience during the past decade. Ann Otol Rhinol Laryngol 91:628, 1982 17. Puhakka HJ, Kero P, Valli P, et al: Tracheostomy in pediatric patients. Acta Paediatr 81:231, 1992 18. Riley RW, Powell NB, Guilleminault C, et al: Maxillary, mandibular, and hyoid advancement: An alternative to tracheostomy in obstructive sleep apnea syndrome. Otolaryngol Head Neck Surg 94:584, 1986 19. Dierks E, Geller M, Roffwarg H, et al: Obstructive sleep apnea syndrome: Correction by mandibular advancement. South Med J 83:39, 1990 20. Sidman J, Sampson D, Templeton B: Distraction osteogenesis of the mandible for airway obstruction in children. Laryngoscope 111:1137, 2001 21. Caouette-Laberge L, Bayert B, Larocque Y: The Pierre-Robin sequence: Review of 125 cases and evolution of treatment modalities. Plast Reconstr Surg 93:934, 1994 22. Williams JK, Maull D, Grayson BH, et al: Early decannulation with bilateral mandibular distraction for tracheostomy-dependent patients. Plast Reconstr Surg 103:48, 1999 23. Karp NS, Thorne CH, McCarthy JG, et al: Bone lengthening in the craniofacial skeleton. Ann Plast Surg 24:231, 1990 24. McCarthy JG: The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Plast Surg 21:625, 1994 25. McCarthy JG, Schreiber J, Karp N, et al: Lengthening the human mandible by gradual distraction. Plast Reconstr Surg 89:1, 1992
1079 26. Denny AD, Talisman R, Hanson PR, et al: Mandibular distraction osteogenesis in very young patients to correct airway obstruction. Plast Reconstr Surg 108:302, 2001 27. Morovic CG, Monasterio L: Distraction osteogenesis for obstructive apneas in patients with congenital craniofacial malformations. Plast Reconstr Surg 105:2324, 2000 28. Moore MH, Guzman-Stein G, Prodman TW, et al: Mandibular lengthening by distraction for airway obstruction in Treacher Collins syndrome. J Craniofac Surg 5:22, 1994 29. Cohen SR, Ross DA, Burstein FD, et al: Skeletal expansion combined with soft-tissue reduction on the treatment of obstructive sleep apnea in children: Physiologic results. Otolaryngol Head Neck Surg 119:476, 1998 30. Molina F, Ortiz-Monasterio F: Mandibular elongation and remodeling by distraction: A farewell to major osteotomies. Plast Reconstr Surg 96:825, 1995 31. Callister AC: Hypoplasia of the mandible (micrognathia) with cleft palate: Treatment in early infancy by skeletal traction. Am J Dis Child 53:1057, 1937 32. Longmire WP, Sanford MC: Stimulation of mandibular growth in congenital micrognathia by traction. Am J Dis Child 78:750, 1949 33. Cosman B, Crikelair GF: Mandibular hypoplasia and the late development of glossopharyngeal airway obstruction. Plast Reconstr Surg 50:573, 1972 34. Rachmiel A, Levy M, Laufer D: Lengthening of the mandible by distraction osteogenesis: Report of cases. J Oral Maxillofac Surg 53:838, 1995 35. Izadi K, Yellon R, Mandell DL, et al: Correction of upper airway obstruction in the newborn with internal mandibular distraction osteogenesis. J Craniofac Surg 14:493, 2003 36. Chigurupati R, Massie J, Dargaville P, et al: Internal mandibular distraction to relieve airway obstruction in infants and young children with micrognathia. Pediatr Pulmonol 37: 230, 2004
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Web site (www.massgeneral.org/ newomfs/) (Fig 2). The MGH program accepts 3 residents each year who are graduates of dental schools throughout the country. The present group of residents includes graduates of the University of Pennsylvania, University of California San Francisco, University of California Los Angeles, University of Connecticut, McGill University, Temple University, Tufts University, Ohio State University, and Harvard, among
others. Acceptance as a resident in OMFS automatically provides advanced standing admission to the Harvard Medical School after the first year of internship. Perhaps the greatest strength of any OMFS department is its faculty. The MGH program has 20 full-time faculty at MGH and affiliated institutions: Brigham and Women’s, Children’s Hospital, Beth Israel Deaconess Medical Center, and Harvard School of Dental Medicine. There also are
26 part-time faculty. This dedicated group has had a significant impact on our students and trainees for generations. The MGH program in OMFS has a strong commitment to diversity, which is reflected in its significant number of women and minorities who are its trainees and staff. It also continues to demonstrate its commitment to continuing requirement and expansion of the art and science of OMFS through basic and clinical research.
Mandibular Advancement by Distraction Osteogenesis for Tracheostomy-Dependent Children With Severe Micrognathia Derek M. Steinbacher, DMD, MD,* Leonard B. Kaban, DMD, MD,† and Maria J. Troulis, DDS, MSc‡ Purpose: The purpose of this study was to evaluate mandibular lengthening by distraction osteogenesis
(DO) to achieve decannulation of micrognathic children with “permanent” tracheostomies. Patients and Methods: Using a retrospective chart review, patients were included who had 1) airway compromise/tracheostomy, 2) micrognathia, 3) polysomnography-documented obstructive apnea, and 4) mandibular advancement using DO. Excluded were 1) adults, 2) neonates without tracheostomy, and 3) patients with central apnea. Patient age, past medical history, age at tracheostomy, and distraction protocol were documented. Oxygen saturation, posterior airway space (in millimeters), and sella-nasion-B point (SNB) angle were recorded. The distraction protocol consisted of a latency of 48 hours and a rate of 1 mm/day. Results: There were 5 children, aged 2 to 14 years, who received a tracheostomy between ages 2 and 36 months for airway obstruction. All patients underwent bilateral mandibular distraction using semiburied, unidirectional devices. The average latency was 58 hours, the rate was 1 mm/day, the duration of fixation was 40 to 60 days, and the magnitude of advancement was 23 mm. Healing was evaluated by clinical, radiologic, and ultrasound examinations. No complications were experienced. Mean follow-up was 3.2 years. Postdistraction sleep studies demonstrated no obstructive apneic events and a mean oxygen saturation of 98% (preoperative, 76%, P ⬍ .005). Cephalometric values improved: posterior airway space 4 to 14 mm; SNB 66° to 72° (P ⬍ .005 for both variables). Four of the 5 patients have been successfully decannulated to date. Conclusions: The results of this preliminary study indicate that mandibular advancement by DO is a potentially viable treatment option for tracheostomy-dependent children with upper airway obstruction secondary to micrognathia. © 2005 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 63:1072-1079, 2005
Airway obstruction may result from abnormalities in respiratory physiology, airway anatomy, or both. Apnea is defined as cessation of breathing for a period of 10 seconds or more and may be mediated by neurologic dysfunction (central apnea) or may be secondary to airway obstruction (obstructive apnea). Patients with congenital craniofacial anomalies have varying degrees of airway obstruction. This respiratory compromise is usually secondary to micrognathia and resultant malposition of the tongue base. Children with acquired craniofacial anomalies (eg, posttrauma, post–tumor resection, or post–radiation therapy) may also have obstructive apnea. Severe airway obstruction is associated with significant morbidity and mortality in infants and children. They may exhibit frequent episodes of oxygen desaturation, hypoxemia, hypercarbia, acidosis, persistent inspiratory stridor, severe sternal retraction, and poor feeding (secondary to airway compromise). Infants and children with long-term airway obstruction exhibit failure to thrive, daytime somnolence, hemodynamic changes (including cor pulmonale and pulmonary hypertension), developmental disabilities, insufficient weight gain/malnutrition, increased pulmonary morbidity, and death.1 Some neonates exhibit mild obstructive apnea. This is often managed by instructing the parents in prone positioning and in feeding techniques and to be alert to breathing difficulties. These infants will often improve as the craniofacial skeleton, including the mandible, grows during the first 3 to 6 months of life. In cases where obstruction is refractory to the above techniques, more aggressive treatment is necessary. Glossopexy, tongue-lip adhesion, hyomandibulopexy, and subperiosteal release of floor of mouth musculature have been reported as temporary treatment modalities for upper airway obstruction in infants and children. However, their efficacy is not well documented.2– 6 Endotracheal intubation may be used to address an emergency episode of airway obstruction. Tracheostomy is indicated for significant chronic episodes of airway obstruction.7 It provides a port for movement of air that bypasses the supralaryngeal anatomic obstruction to flow, thereby mitigating the morbidity of peripheral airway obstruction. This timeReceived from Massachusetts General Hospital, Boston, MA. *Resident in Oral and Maxillofacial Surgery. †Walter C. Guralnick Professor and Chairman, Department of Oral and Maxillofacial Surgery. ‡Associate Professor and Director, Minimally Invasive Oral and Maxillofacial Surgery. Presented in part at the 85th Annual Meeting of the American Association of Oral and Maxillofacial Surgeons, Orlando, FL, September 2003. This work was also the basis for an honors thesis presented to the Harvard Medical School Committee on Awards and Honors, April 2004 (D.S.).
honored procedure is effective for long-term airway management in patients with craniofacial anomalies. However, tracheostomy is associated with its own inherent morbidity.8,9 Longstanding tracheostomy produces increased risk for tracheomalacia, chronic bronchitis, laryngeal stenosis, and sudden death (risk of mucus plug or tube dislodgment).10 –12 In addition, family life may be interrupted and speech acquisition and development delayed. Other adverse consequences of permanent tracheostomy include intellectual and physical impairments, compromised social interactions, and the requirement for complex nursing care and parental education.13–17 Historically, tracheostomy was the only safe longterm treatment option for infants and children with micrognathia because of the magnitude of mandibular advancement required to correct the problem and the need for bone grafts (donor site morbidity). Furthermore, it was sometimes technically difficult or impossible to advance the mandible the required amount to improve the airway and the relapse rate was prohibitively high. It was recognized however, that lengthening of the osseous tongue-supporting architecture would be beneficial.18 –21 Early results of mandibular lengthening by distraction osteogenesis (DO) indicate that operative morbidity and stability of advancement are significantly better than standard techniques in children. This is especially true for advancements of large magnitude. DO has also been shown to be effective in lengthening the mandible with consequent airway improvement allowing removal of the tracheostomy.7,22–30 Relief of respiratory obstruction is thought to be secondary to advancement of the tongue-base as the tongue muscles move forward with the mandible. The appropriate management strategies for infants and children with airway obstruction secondary to micrognathia are currently being investigated. There is controversy surrounding both surgical and nonsurgical interventions and the timing of treatment. We hypothesize that mandibular lengthening by DO will effectively improve upper airway anatomy and allow for tracheostomy decannulation in tracheostomy-dependent children (older than 18 months). The purpose of this study was 1) to evaluate mandibular lengthening using DO to achieve decannulation Supported by a research grant from the Hanson Foundation (Boston, MA), an NIH grant (NIDCR, M.J.T., Principal Investigator), and the Department of Oral and Maxillofacial Surgery Education and Research Fund. Address correspondence and reprint requests to Dr Troulis: Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02112; e-mail: [email protected] © 2005 American Association of Oral and Maxillofacial Surgeons
0278-2391/05/0-06305$30.00/0 doi:10.1016/j.joms.2005.04.013
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DISTRACTION OSTEOGENESIS FOR CHILDREN WITH MICROGNATHIA
Table 1. DEMOGRAPHIC DATA OF 5 CONSECUTIVE CHILDREN
Patient
Syndrome
Other Procedures
1 2 3 4 5
Pierre Robin syndrome No. No. CHARGE No.
Glossopexy T&A, U3P T&A Choanal atresia repair T&A
Age (trach)
Age (DO)
Age Decan
2 mo 2 yr 3 yr 4 mo Infancy
3 yr 2 yr 3 yr 8 yr 14 yr
3 yr 3 yr 4 yr 8 yr Pending
Abbreviations: T&A, tonsillectomy and adenoidectomy; U3P, uvulopharyngopalatoplasty. Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
of children with permanent, in-dwelling tracheostomies and 2) to suggest a management strategy for children presenting with severe airway obstruction secondary to micrognathia.
Patients and Methods This was a retrospective study performed in concordance with the regulations and approval of the Institutional Review Board of the Human Research Committee at Massachusetts General Hospital. Outpatient and hospital charts of consecutive children treated at the Massachusetts General Hospital, Department of Oral and Maxillofacial Surgery from January 1998 to June 2002 were reviewed. Included in the study were patients who met the following criteria: 1) history of significant upper airway compromise and tracheostomy dependence, 2) micrognathia and tongue-base obstruction, 3) polysomnography-documented obstructive apnea, and 4) treatment by mandibular advancement using DO. Patients excluded from this study were 1) adults (age ⬎18 years), 2) neonates (age ⬎ year), 3) children without tracheostomy, and 4) patients with significant central apnea. From the charts, patient age, past medical and family histories, and age at tracheostomy were documented. In the setting of an overnight sleep study, the percent oxygen saturation with an occluded port was recorded both before and after treatment. Preoperative and postoperative lateral cephalograms were used to measure and compare posterior airway space (PAS) in millimeters and sella-nasion-B point (SNB)
angle. Finally, data pertaining to the distraction device and distraction protocol were collected. Statistical analysis was performed comparing preoperative and postoperative oxygen saturation and cephalometric values, including SNB and PAS. Using a computerized SAS program, a paired t test was used, with statistical significance set at P ⬍ .05.
Results DEMOGRAPHICS
Five children (3 girls and 2 boys, aged 2 to 14 years, mean age 6 year) were evaluated (Tables 1, 2). Three patients were nonsyndromic, one carried the diagnosis of CHARGE association, and one had Robin sequence. All children had upper airway obstruction and severe retrognathia with a posteriorly displaced tongue-base. All 5 patients received a tracheostomy at 2 to 36 months of age (mean age, 15.4 months) for airway obstruction and oxygen desaturation. Glossopexy was used without airway benefit for one patient, in infancy, prior to tracheostomy. No child demonstrated improvement with posttracheostomy ancillary procedures, including tonsillectomy and adenoidectomy (n ⫽ 3), uvulopharyngopalatoplasty (n ⫽ 1), and right choanal atresia repair (n ⫽ 1). PLANNING
The vector of distraction was determined by measurements on the plain radiographs and computed tomography (CT) scans. The planned distraction vec-
Table 2. DISTRACTION PROTOCOL
Patient
Latency (hr)
1 2 3 4 5
48 48 48 72 72
Rate and duration (d) 1 1 1 1 1
mm/d mm/d mm/d mm/d mm/d
⫻ ⫻ ⫻ ⫻ ⫻
30 25 29 30 19
Magnitude (mm)
Consolidation (d)
Time Devices in (d)
30 31 L, 20 R 28 26 L, 23 R 12 L, 11 R
60 60 60 60 40
67 61 125 74 104
Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
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STEINBACHER, KABAN, AND TROULIS
osteotomy with four 2.0-mm-diameter screws (Fig 3). They were activated to ensure proper function and then reversed. The wounds were irrigated and closed in a standard fashion. The patients were observed overnight and discharged the following day. DISTRACTION PROTOCOL AND HEALING
FIGURE 1. A 4-year-old nonsyndromic boy who required tracheostomy at age 3 for worsening respiratory distress, stridor, and O2 desaturation into the 70s (patient 3, Tables 1, 2). Note the retruded chin position and obtuse chin-throat angle. Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
tor was anterior and slightly inferior, with a 110° angle from the mandibular occlusion plane in all 5 cases (Figs 1, 2). A navigation device was constructed, using the dental models, a lateral cephalogram, and CT scan. This consisted of an acrylic occlusal splint with a metal “outrigger” indicating the orientation of the osteotomy. The distraction device was then placed perpendicular to the osteotomy to achieve the correct vector of movement (Fig 3). SURGICAL PROCEDURE
Semiburied unidirectional distraction devices (Synthes Maxillofacial, Paoli, PA) were used in all 5 patients. General anesthesia was induced and maintained via the child’s existing tracheostomy. Standard intraoral incisions were used to access the mandibular body. Corticotomies were performed with the aid of previously fabricated navigation devices (Fig 3). Semiburied distraction devices without (n ⫽ 2) and with (n ⫽ 3) detachable footplates were fixed across the
Distraction was initiated following 48 to 72 hours of latency (mean of 58 hours). A rate of 1 mm/day was instituted for a mean of 27 days (range, 19 to 30 days) resulting in mean mandibular lengthening of 23 mm (range, 11 to 31 mm). Because of slight asymmetry in some patients, the distraction gap averaged 22 mm on the right and 25 mm on the left (ranges of 11 to 30 mm and 12 to 31 mm, respectively). Active distraction was followed by a fixation phase of 60 days in 4 of the 5 patients. The fifth patient was held in neutral fixation for 40 days. Healing was evaluated by clinical, radiologic, and ultrasonographic examination. Clinical evaluations were performed at weekly intervals during active distraction and every 2 weeks during the fixation period. When possible lateral cephalograms and panoramic radiographs were obtained (preoperatively, immediately postoperatively, at end-DO (Fig 4) and prior to distractor removal). All patient’s had a preoperative CT scans. Prior to distractor removal, ultrasonographic examination was performed to evaluate healing during the mean 58 days of fixation (range, 43 to 84 days). All 10 sides exhibited marked osseous growth between the distracted segments. The detachable activation arms were removed at a mean of 86 days after placement (range, 61 to 125 days). There were no postoperative complications related to device placement, activation, or removal. One child presented with an infected residual footplate 2 years postdistraction, also associated with a decayed tooth. Mean follow-up was 3.2 years (range, 1.5 months to 5 years).
FIGURE 2. Three-dimensional computed tomography scan illustrates the planned distraction vector for the patient shown in Figure 1. The preoperative lateral cephalogram revealed a posterior airway space of 3 mm and an SNB of 63. Note also the planned vector of correction (scribed). Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
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DISTRACTION OSTEOGENESIS FOR CHILDREN WITH MICROGNATHIA FIGURE 3. The intraoperative sequence included the use of a prefabricated primitive navigation device to aid with osteotomy placement. The semiburied distractors were placed bilaterally, with the long axes being oriented perpendicular to the plane of the osteotomy. Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
POLYSOMNOGRAPHY
Polysomnography was used to demonstrate obstructive apnea. Each child was admitted for overnight observation to the Pediatric Intensive Care Unit at Massachusetts General Hospital. Standard cardiorespiratory and oxygen saturation monitoring was instituted. Once a somnolent state was achieved, the tracheostomy port was occluded and the patient continued gas exchange by way of natural airway. Both the percent oxygen saturation and respiratory rate were carefully recorded. Periods of persistent desaturation and/or apnea resulted in termination of the formal polysomnogram and the tracheostomy port was opened. The ability of each patient to tolerate tracheostomy occlusion could be grossly appreciated and the oxygen saturation allowed the degree of obstruction to be quantified. Preoperatively, the group did not tolerate intentional occlusion of the port, verifying tracheostomy dependence. Prior to intervention by distraction, each child exhibited apneic episodes and oxygen desaturation to a mean nadir of 76% (range, 68% to 82%). Following treatment, there were no obstructive apneic events in any patients and a mean oxygen saturation of 98% (range, 95% to 100%) was recorded for all 5 patients (Table 1). Subjective bronchoscopic examination demonstrated hypopharyngeal constriction, visualized as epiglottic retrodisplacement by the tongue, and true vocal cord mobility with a patent subglottic space in all patients prior to mandibular lengthening. Postoperatively, “widely patent airways” were noted in all 5 patients. CEPHALOMETRIC ANALYSIS
Average predistraction PAS measured on lateral cephalograms went from 4 mm (range, 3 to 8 mm) to 14 mm (range, 10 to 18 mm) following treatment. The mean preoperative SNB was 66 (range, 55 to 74), and it increased to 72 (range, 60 to 80) prior to decannulation (Fig 5). STATISTICAL ANALYSIS
The postoperative changes in oxygen saturation, PAS and SNB, were all statistically significant (P ⬍
.005) (using paired t test; Table 1). Comparing the lowest oxygen saturation from overnight sleep studies before and after intervention demonstrated a value of P ⫽ .003. The postoperative increase in PAS was significant at a value of P ⬍ .001. Pretreatment versus posttreatment SNB showed a value of P ⫽ .001. Following mandibular advancement by DO, all 5 patients have been deemed candidates for tracheostomy decannulation. To date, 4 of the 5 patients have been successfully decannulated (Fig 5). The fifth patient is awaiting tracheostomy removal pending resolution of other nonairway medical problems.
Discussion Advancing the mandible to correct retrognathia and relieve associated airway distress was first proposed early in the 20th century using skeletal traction.31,32 Although the concept was correct, these techniques were abandoned because of temporomandibular joint ankylosis and unpredictable results. As treatment modalities have evolved, the focus has shifted to mandibular lengthening surgery for patients with tongue-base obstruction. This allows for simultaneous advancement of the tongue-base, which enlarges the hypopharyngeal space and improves airway obstruction. In 1972, Cosman and Crikelair33 reported 3 cases of micrognathia-induced respiratory difficulty that responded to mandibular advancement. Surgically positioning the mandible forward is an effective and commonly used technique to manage adults with obstructive sleep apnea.18,19 Therefore, applying mandibular expansion to children with upper airway obstruction was a natural extension of the success seen in adults. However, traditional procedures (eg, including bilateral sagittal split or inverted L-osteotomies) are not well suited for children. Standard osteotomies with advancement lack stability in the young child because of unreliable long-term fixation and resorption or unpredictable growth of the bone graft.34 In the appropriately selected pediatric age group, lengthening by mandibular DO is currently the favored surgical technique to overcome upper airway
STEINBACHER, KABAN, AND TROULIS
FIGURE 4. Same patient at end-distraction prior to tracheostomy removal. Appropriate healing was observed prior to percutaneous device arm removal. Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
compromise secondary to micrognathia. Distraction can effectively attain the large magnitude of advancement required in these children, with minimal relapse and no donor site morbidity. Additional advantages of DO include shorter operative time, fewer complications, decreased length of hospital stay, no requirement for blood transfusion or maxillomandibular fixation, less distortion and loading of the temporomandibular joint, and a lower incidence of neurosensory deficits. Although DO is an attractive option for the pediatric population with airway obstruction secondary to micrognathia, the ideal timing and treatment are subject to controversy. Children less than 2 years of age are not optimal candidates for treatment by distraction. Technical issues include diminished mandibular bone quality and amount and difficulty in identifying developing tooth follicles. Family adherence to the treatment protocol can also prove to be a difficult challenge in this age group. Neonatal distraction requires prolonged intubation and sedation, with continued hospital observation. Finally, the fact that natural mandibular growth may obviate the need for operative intervention and that surgical intervention itself can adversely affect mandibular growth should be carefully considered. In many previous reports, infants undergoing mandibular distraction for micrognathia initially present with sublethal airway obstruction.20,26,27,29,35 That is, the obstruction is not serious enough to require immediate tracheostomy. Instead, mandibular lengthening by DO is carried out, and the resultant improvement in airway dimension has caused several authors to claim that a tracheostomy is avoided.20,26,27,29,35 This implies that a tracheostomy will be eventually required unless mandibular lengthening by DO is performed. This may not be the case. Significant endog-
1077 enous mandibular growth, as neuromuscular control is increased, can allow the child to reach normal chin projection and alleviate anatomical airway constriction, without surgical intervention. Therefore, nonoperative treatment is favored for as long as possible to allow for mandibular growth to obviate the need for surgical management. A number of studies allude to the airway benefit of mandibular DO, but no group has reported on the airway effects in a serial or prospective manner.20,22,26 –29,34 –36 These cases have indicated that enhanced upper airway dynamics, secondary to mandibular lengthening, obviated the need for a tracheostomy port, and the child could be decannulated. However, only a paucity of reports exist focusing solely on the tracheostomy-dependent child22,28 (as opposed to nontracheostomized infants with obstructive symptoms to purportedly prevent tracheostomy). In the cohort reported here, the efficacy of mandibular DO to achieve decannulation for 5 tracheostomy-dependent children with a history of obstructive apnea was investigated. All children were referred to the Massachusetts General Hospital after the neonatal period. Each child underwent placement of a life-saving tracheostomy in the early phases of life, prior to referral. This is advantageous for several reasons. Studying children who are objectively tracheostomy dependent removes the nebulous notion that a future tracheostomy would be prevented. Preoperative tracheostomy dependence also allows for a binary measure of treatment success—the polysomnographically documented ability to be decannulated or not. It is also of note that all children who underwent treatment by DO were older than 2 years in this study. This means that the technical considerations of completing mandibular DO in young infants were circum-
FIGURE 5. The patient at end treatment after both tracheostomy and distraction device removal. The lateral cephalogram at the end of treatment shows the posterior airway space of 18 (versus a pretreatment 3) and an SNB of 72 (preoperative value of 63). Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
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DISTRACTION OSTEOGENESIS FOR CHILDREN WITH MICROGNATHIA
Table 3. PRE– AND POST–MANDIBULAR LENGTHENING VARIABLES
Mean Lowest
O2
Lowest
PAS
Lowest
SNB
Pre-DO Post-DO Pre-DO Post-DO Pre-DO Post-DO
76 98 4 14 66 72
Range 68 96 3 10 55 60
to to to to to to
82 99 8 18 74 80
P Value P ⫽ .003 P ⬍ .001 P ⫽ .001
Abbreviations: O2, oxygen saturation; PAS, posterior airway space (mm); SNB, sella-nasion-B point angle; DO, distraction osteogenesis. The change with treatment is shown to be statistically significant (paired t test SAS program). Steinbacher, Kaban, and Troulis. Distraction Osteogenesis for Children with Micrognathia. J Oral Maxillofac Surg 2005.
vented and the window for endogenous mandibular growth to allow for spontaneous improvement of airflow obstruction had likely passed. The most critical gauge of success is the polysomnogram. Following distraction, each of the 5 patients underwent a sleep study with the tracheostomy port blocked to assess for adequacy of the improved natural airway. Results were compared with the preoperative baseline values (Table 3). A successful polysomnogram entails the absence of apneic episodes and the presence of oxygen saturation levels in the mid- to upper 90s. The lack of desaturations and apneic episodes are the most critical factors for success. Each child in our cohort tolerated the sleep study without ill effect and was deemed a candidate for decannulation. The ability to achieve decannulation is the clinically relevant measure of success in these patients. However, for completeness, quantitative analysis was performed on all objective variables (SaO2, SNB, PAS), comparing pretreatment versus posttreatment values. Statistical significance (P ⬍ .005) was calculated using Student’s t test (SAS software, SAS Institute, Cary, NC), and all variable comparisons were significant (Table 3). It is clear that mandibular DO is a successful technique to treat micrognathic children with tracheostomy dependence; however, the approach to treatment logistics has not been adequately defined. The management strategy we propose for children with airway obstruction (secondary to micrognathia) under the age of 2, who are refractory to conservative measures, would involve receiving a tracheostomy of short duration, then, once physiologically stable, undergoing mandibular lengthening (if still necessary) by DO at an age greater than 2 when factors are more conducive to the procedure. Mandibular DO is then used to improve airway architecture and eliminate the need for artificial airway assistance. In this preliminary study, we concluded that mandibular lengthening by DO is a viable treatment option for children with upper airway obstruction
secondary to micrognathia. Tracheostomy-dependent patients treated by mandibular DO demonstrate resolution of tongue-base airway impingement and a predictable advancement of large magnitude, while preventing donor site morbidity. Delaying distraction until after the immediate neonatal period ensures improved mandibular osseous architecture and avoids prolonged intubation and sedation during treatment. As a result, young children with preexistent tracheostomies are afforded the option of waiting until later childhood for the DO procedure and tracheostomy removal, while being early enough to avoid long-term tracheostomy morbidity.
References 1. Menashe VD, Farrehi C, Miller M: Hypoventilation and cor pulmonale due to chronic upper airway obstruction. J Pediatr 67:198, 1965 2. Argamaso RV: Glossopexy for upper airway obstruction in Robin sequence. Cleft Palate Craniofac J 29:232, 1992 3. Hadley RC, Johnson JB: Utilization of the Kirschner wire in Pierre Robin syndrome. Plast Reconstr Surg 31:587, 1963 4. Myer CM, Reed JM, Cotton RT, et al: Airway management in Pierre Robin sequence. Otolaryngol Head Neck Surg 118:630, 1998 5. Douglas B: The treatment of retrognathia associated with obstruction by a plastic procedure. Plast Reconstr Surg 3:300, 1946 6. Bergoin M, Giraud JP, Chaix C: L’hyomandibulopexie dans le traitment des formes graves du syndrome de Pierre Robin. Ann Chir Infant 12:85, 1971 7. Cohen SR: Early decannulation with bilateral mandibular distraction for tracheostomy-dependent patients (Discussion). Plast Reconstr Surg 103:58, 1999 8. Motta J, Guilleminault C, Schroeder JS, et al: Tracheostomy and hemodynamic changes in sleep-induced apnea. Ann Intern Med 89:454, 1978 9. Guilleminault C, Simmons FB, Motta J, et al: Obstructive sleep apnea syndrome and tracheostomy: Long-term follow-up experience. Arch Intern Med 141:985, 1981 10. Conway WA, Victor LD, Magilligan DJ, et al: Adverse effects of tracheostomy for sleep apnea. JAMA 246:347, 1981 11. Sasaki, CT, Masatoshi H, Koss N: Tracheostomy related subglottic stenosis: Bacteriologic pathogensis. Laryngoscope 89:857, 1979 12. Zeitouni A, Manoukian J: Tracheostomy in the first year of life. J Otolaryngol 22:431, 1993 13. Tomaski SM, Zalzal GH, Saal HM: Airway obstruction in Pierre Robin sequence. Laryngoscope 105:111, 1995
STEINBACHER, KABAN, AND TROULIS 14. Singer LT, Kercsmar C, Legris G, et al: Developmental sequelae of long-term infant tracheostomy. Dev Med Child Neurol 31: 224, 1989 15. Arola MK: Tracheostomy and its complications: A retrospective study of 794 tracheostomized patients. Ann Chir Gynaecol 70:96, 1981 16. Wetmore RF, Handler SD, Potsic WP: Pediatric tracheostomy: Experience during the past decade. Ann Otol Rhinol Laryngol 91:628, 1982 17. Puhakka HJ, Kero P, Valli P, et al: Tracheostomy in pediatric patients. Acta Paediatr 81:231, 1992 18. Riley RW, Powell NB, Guilleminault C, et al: Maxillary, mandibular, and hyoid advancement: An alternative to tracheostomy in obstructive sleep apnea syndrome. Otolaryngol Head Neck Surg 94:584, 1986 19. Dierks E, Geller M, Roffwarg H, et al: Obstructive sleep apnea syndrome: Correction by mandibular advancement. South Med J 83:39, 1990 20. Sidman J, Sampson D, Templeton B: Distraction osteogenesis of the mandible for airway obstruction in children. Laryngoscope 111:1137, 2001 21. Caouette-Laberge L, Bayert B, Larocque Y: The Pierre-Robin sequence: Review of 125 cases and evolution of treatment modalities. Plast Reconstr Surg 93:934, 1994 22. Williams JK, Maull D, Grayson BH, et al: Early decannulation with bilateral mandibular distraction for tracheostomy-dependent patients. Plast Reconstr Surg 103:48, 1999 23. Karp NS, Thorne CH, McCarthy JG, et al: Bone lengthening in the craniofacial skeleton. Ann Plast Surg 24:231, 1990 24. McCarthy JG: The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Plast Surg 21:625, 1994 25. McCarthy JG, Schreiber J, Karp N, et al: Lengthening the human mandible by gradual distraction. Plast Reconstr Surg 89:1, 1992
1079 26. Denny AD, Talisman R, Hanson PR, et al: Mandibular distraction osteogenesis in very young patients to correct airway obstruction. Plast Reconstr Surg 108:302, 2001 27. Morovic CG, Monasterio L: Distraction osteogenesis for obstructive apneas in patients with congenital craniofacial malformations. Plast Reconstr Surg 105:2324, 2000 28. Moore MH, Guzman-Stein G, Prodman TW, et al: Mandibular lengthening by distraction for airway obstruction in Treacher Collins syndrome. J Craniofac Surg 5:22, 1994 29. Cohen SR, Ross DA, Burstein FD, et al: Skeletal expansion combined with soft-tissue reduction on the treatment of obstructive sleep apnea in children: Physiologic results. Otolaryngol Head Neck Surg 119:476, 1998 30. Molina F, Ortiz-Monasterio F: Mandibular elongation and remodeling by distraction: A farewell to major osteotomies. Plast Reconstr Surg 96:825, 1995 31. Callister AC: Hypoplasia of the mandible (micrognathia) with cleft palate: Treatment in early infancy by skeletal traction. Am J Dis Child 53:1057, 1937 32. Longmire WP, Sanford MC: Stimulation of mandibular growth in congenital micrognathia by traction. Am J Dis Child 78:750, 1949 33. Cosman B, Crikelair GF: Mandibular hypoplasia and the late development of glossopharyngeal airway obstruction. Plast Reconstr Surg 50:573, 1972 34. Rachmiel A, Levy M, Laufer D: Lengthening of the mandible by distraction osteogenesis: Report of cases. J Oral Maxillofac Surg 53:838, 1995 35. Izadi K, Yellon R, Mandell DL, et al: Correction of upper airway obstruction in the newborn with internal mandibular distraction osteogenesis. J Craniofac Surg 14:493, 2003 36. Chigurupati R, Massie J, Dargaville P, et al: Internal mandibular distraction to relieve airway obstruction in infants and young children with micrognathia. Pediatr Pulmonol 37: 230, 2004