Obstructive sleep apnea in children with syndromic craniosynostosis: long-term respiratory outcome of midface advancement

Abstract

Almost 50% of patients with Apert, Crouzon or Pfeiffer syndrome develop obstructive sleep apnea (OSA), mainly due to midface hypoplasia. Midface advancement is often the treatment of choice, but the few papers on long-term outcome report mixed results. This paper aimed to assess the long-term respiratory outcome of midface advancement in syndromic craniosynostosis with OSA and to determine factors contributing to its efficacy. A retrospective study was performed on 11 patients with moderate or severe OSA, requiring oxygen, continuous positive airway pressure (CPAP), or tracheostomy. Clinical symptoms, results of polysomnography, endoscopy and digital volume measurement of the upper airways on CT scan before and after midface advancement were reviewed. Midface advancement had a good respiratory outcome in the short term in 6 patients and was ineffective in 5. In all patients without respiratory effect or with relapse, endoscopy showed obstruction of the rhino- or hypopharynx. The volume measurements supported the clinical and endoscopic outcome. Despite midface advancement, long-term dependence on, or indication for, CPAP or tracheostomy was maintained in 5 of 11 patients. Pharyngeal collapse appeared to play a role in OSA. Endoscopy before midface advancement is recommended to identify airway obstruction that may interfere with respiratory improvement after midface advancement.

Craniosynostosis is a congenital disorder affecting in 1 in 2500 births; it is characterized by the premature fusion of calvarial sutures. This fusion restricts normal growth of the skull, brain, and face, and necessitates surgical correction. In about 40% of cases it is part of a syndrome such as the Apert, Crouzon, Pfeiffer, Muenke or Saethre-Chotzen syndrome .

Almost 50% of children with Apert, Crouzon or Pfeiffer syndrome develop obstructive sleep apnea (OSA), mainly during the first 6 years of life . These patients are at risk for OSA due to midface hypoplasia, but other factors such as adenotonsillar hypertrophy, and mandibular hypoplasia may be involved as well . According to its severity and cause, OSA can be treated pharmacologically, surgically (e.g. with adenotonsillectomy, midface advancement or tracheostomy), or non-surgically (e.g. with nocturnal oxygen or continuous positive airway pressure (CPAP)) . If OSA is not treated sufficiently, disturbed sleep patterns may result in major physical and functional impairment, for instance failure to thrive, recurrent infections, disturbed cognitive functions, delayed development, cor pulmonale or sudden death . As midface hypoplasia is the main cause of OSA in syndromic craniosynostosis, midface advancement appears to be the treatment of choice .

In the long-term, mixed respiratory results were reported following midface advancement in patients with syndromic craniosynostosis . It is unclear how long and to which level the improvement in breathing lasts, and which factors are predictors of respiratory outcome. To assess the respiratory outcome of midface advancement for moderate to severe OSA and to determine predictive factors, the authors carried out a retrospective study in patients suffering from Apert, Crouzon or Pfeiffer syndrome.

Material and methods

Study group

Over 100 patients with Apert, Crouzon and Pfeiffer syndrome have been treated at the Dutch Craniofacial Center since 1983. For this study, the authors were only interested in the 14 patients with moderate or severe OSA, requiring treatment with nocturnal oxygen, CPAP, nasopharyngeal tube (NPT), or tracheostomy, who presented between 1987 and 2006. Their records were analyzed for clinical symptoms of OSA, results of polysomnography (PSG) and endoscopy of the upper airways, and the different treatment modalities for OSA. CT scans were used to measure the airway volume before and after midface advancement. For this case series, sufficient data and follow-up were available in 11 patients.

Obstructive sleep apnea

The clinical symptoms of OSA scored were snoring, difficulty in breathing, apnea during sleep, perspiration, and daytime sleepiness. PSG was carried out ambulatory or during admission to hospital and the following criteria for analysis were used. Apnea was defined as absence of airflow for more than 2 breaths and hypopnea as reduction by ≥50% in nasal flow signal amplitude for more than 2 breaths. The analysis was expressed in an apnea-hypopnea index (AHI), the number of obstructive apneas in combination with hypopneas followed by desaturation per hour, and an oxygenation-desaturation index (ODI), the number of desaturations (≥4% decrease with respect to the baseline) per hour. A score <1 is considered to be normal, 1–5 is defined as mild OSA, 6–25 as moderate OSA, and >25 as severe OSA .

Respiratory outcome of midface advancement

The timing, type and outcome of the following interventions were evaluated: oxygen, NPT, CPAP, adenotomy and tonsillectomy, tracheostomy and midface advancement. The different interventions in each patient were added to evaluate the total number of procedures carried out to improve the breathing.

The efficacy of treating OSA was determined on the basis of clinical symptoms and PSG before and after midface advancement. Midface advancement was considered to be effective on respiration, in the short term, if oxygen, CPAP, NPT or tracheostomy were discontinued within 1 year after midface advancement. Relapse of OSA was defined as the need for respiratory support again. Long-term effectiveness was defined as independence of respiratory support at least 2 years after midface advancement.

Endoscopy of the upper airway

Endoscopies were carried out under general anesthesia in a supine position. In 2 patients an additional endoscopy was carried out at the outpatient clinic in a sitting position. The endoscopies were carried out to identify the possible level of obstruction including anatomical malformations in the rhino- and hypopharynx.

Volume measurements of the upper airway

A software program (MevisLab) was used to import and analyze the CT scans by means of a custom-designed tool. Preoperative and postoperative scans were analyzed on transversal slices. The maxillary, ethmoidal, frontal and sphenoidal sinuses, concha bullosa and the oral cavity were manually excluded. The respiratory active air-holding cavities were segmented using semi-automatic region growing. The volumes of 2 separate anatomically defined areas were measured in mm 3 , taking the scale into consideration: nasal cavity and rhinopharynx (defined to range from the most caudal point of the frontal sinus to the cranial point where the soft palate transformed into the uvula); and oro- and hypopharynx (ranged from the most cranial point where the soft palate transformed into the uvula, to the most caudal point of the hyoid bone). The total volume was calculated by adding the volumes of the 2 areas. All patients were scanned according to a protocol, using the same CT scan, and the thickness of the transversal slices was similar.

Statistical analysis

The results were analyzed using SPSS 14.0 for Windows 2000. All numbers are expressed as median and range.

Results

Eleven patients with Apert ( n = 3), Crouzon ( n = 6) or Pfeiffer ( n = 2) syndrome who had moderate or severe OSA, requiring treatment with nocturnal oxygen, CPAP, NPT, or tracheostomy, were included. Four of the 11 patients were boys (36%), aged 14.9 years (range 4.1–23.1 years). All patients had midface hypoplasia. Six of the 11 patients underwent PSG before the start of treatment for OSA; this showed moderate OSA in 3 patients and severe OSA in 3 (median ODI 25, range 10–66). In the other patients, no PSG was performed due to the severity of the respiratory distress at presentation, which necessitated instant airway management, namely intubation or insertion of a tracheostomy. Airway treatment after diagnosis of OSA involved tracheostomy in 4 patients, oxygen in 3, CPAP or NPT in 3, and monobloc with NPT in 1. All patients underwent a midface advancement with distraction followed by a control PSG; in 3 a monobloc was performed; and in 8 a le Fort III.

In 10 of the 11 patients, an endoscopy of the upper airway was performed to identify the level of obstruction; this was done preoperatively in 5, postoperatively in 1, and both in 4. In 4 patients, a CT scan carried out before and after midface advancement was available. After advancing the midface for at least 20 mm the occlusion was corrected from class III in class II with overcorrection in all patients ( Fig. 1 ). Clinically, a sufficient advancement of the midface was achieved in all patients. Final adjustment of the level of occlusion is performed in patients aged 18 or older. So far, an additional Le Fort I has been performed in 2 patients, no patient underwent mandibular correction. The follow-up time after midface advancement was 3.5 years (range 2.4–11.4 years, mean 5.7 years).

Fig. 1
Sufficient correction was achieved in all patients; after advancing the midface for 20 mm the occlusion changed from class III to class II including the overcorrection.

Respiratory outcome of midface advancement

The follow-up of the 11 OSA patients at different ages is shown in Fig. 2 . The respiratory outcome of each treatment option was considered. Adenotomy and tonsillectomy had a temporary beneficial effect on respiration in 1 of 5 patients, and no effect in 4.

Fig. 2
Follow-up of OSA in 11 patients at different ages.

In 6 of the 7 patients, oxygen and CPAP or NPT were effective in bridging time to the midface advancement. In the other patient, tracheostomy was required despite monobloc and NPT. Midface advancements were carried out in 3 different modes: monobloc with and without distraction, and le Fort III with distraction.

The patients with moderate or severe OSA underwent a median number of 5 (2–8) invasive or non-invasive treatment procedures to improve their breathing. Midface advancement in the short term had a good or improved respiratory outcome in 6 patients (patients 1, 2, 8, 10, 11 and patient 9, respectively), and was unsatisfactory in 5 (patients 3, 4, 5, 6 and 7) ( Table 1 ). In 2 patients (patients 1 and 11) OSA relapsed. In the long term, 4 of the 11 patients (patients 3, 4, 6 and 7) were still dependent on CPAP (2.5, 8.1 and 8.2 years after advancement) or tracheostomy (10.6 years) in spite of a surgically successful midface advancement and 1 (patient 11) had severe OSA without treatment (following a parental decision).

Table 1
Respiratory outcome of midface advancement in the short term.
Treatment Number of treatments Effect Insufficient effect
Monobloc without distraction 3 1 2
Monobloc with distraction 3 2 1
Le Fort III with distraction 8 4 4
Total view (N patients) 14 (11) 7 (6) 7 (5)

Endoscopy and volume measurements of the upper airway

Anatomical malformations of the rhino- and hypopharynx were a common feature in nearly all patients, causing a functional obstruction at this level. Only one patient did not have this feature and had a good respiratory outcome after midface advancement. All patients had a narrow nasal cavity.

The volumes of the upper airway on CT scan before and after midface advancement were calculated in patients 1, 4, 6 and 8 ( Table 2 ). In Fig. 3 the changes in these volumes are shown. In patient 1 the CT scan 4 months post-surgery showed an increase in airway volume (1.4 times), mostly in the region nasal cavity and rhinopharynx (1.6 times). One year after midface advancement the CT scan illustrated the narrow hypopharynx seen with endoscopy, with a volume decrease in the region oro- and hypopharynx (0.7 times). The CT scans of patient 4, made 7 months before and 1 year after midface advancement, showed no increase in the total volume of the upper airway. The volume of the oro- and hypopharynx increased 1.2 times. Patient 6 showed no change in total volume of the upper airway 4 months after midface advancement in comparison with 1 year before, which matches the clinical presentation. After midface advancement the nasal cavity and rhinopharynx volume increased, but the oro- and hypopharynx region was 0.7 of the volume before. In patient 8, with a good clinical result, the volume of the upper airway increased by a factor of 1.6, 13 months after midface advancement in comparison with 3 months before. The volume of the nasal cavity and rhinopharynx increased 1.6 times and the volume of the oro- and hypopharynx was 1.7 times larger.

Feb 8, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Obstructive sleep apnea in children with syndromic craniosynostosis: long-term respiratory outcome of midface advancement
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