1
Introduction
Sleep-related breathing disorders (SRBDs) span varying degrees of airway obstruction during sleep and contribute to significant epidemiologic burden, especially in developed countries. The first report of SRBD appeared in 1976, when Guilleminault described eight children with sleep apnea syndrome , confirmed by polygraphic monitoring. These children exhibited loud snoring, excessive daytime sleepiness, decrease in school performance, morning headaches, and nocturnal enuresis—all of which were attributed to sleep fragmentation due to upper airway obstruction.
Population estimates of the prevalence of SRBD show an increasing trend over the last 2 decades, with some reports suggesting that, on average, 1 in 10 children has some degree of SRBD. This alarming increase is associated with the increase in overweight and obesity in children. With most patients remaining undiagnosed, SRBD may be one of the most common chronic illnesses of childhood. This has important ramifications for pediatric health as well as health care economics in the United States and elsewhere. If left untreated, the natural history of SRBD intersects with cardiopulmonary, cognitive, growth, and development domains, thereby driving health care utilization in a wide variety of areas. Consequently, early identification and treatment of SRBD effectively translate to better population health.
2
Epidemiology and Risk Factors
Epidemiologic studies in children with SRBD show a similar prevalence of pediatric and adult cases. Large population-based studies have identified risk factors in childhood SRBD. These large studies based on geographic or national cohorts in the United States, Italy, and Iceland have each placed the prevalence between 1% and 5%. However, a larger proportion may remain undiagnosed. A summary of 41 studies that investigated the prevalence of parent-reported snoring is shown in Fig. 68.1 . A meta-analysis of these studies found an overall prevalence of 7.45% (95% confidence interval, 5.8–9.6).
Studies assessing demographics of SRBD have identified African American children at an elevated lifetime risk of developing the condition. The same investigators found that Hispanic parents may tend to report snoring more often than Caucasian parents, with no difference in further diagnostic workup. No definite evidence of gender-based predisposition has been identified, although some investigators report an increased prevalence in prepubertal boys, thought to be due to hormonal physiologic changes.
Small cohort studies show the same prevalence of SRBD in 2- to 14-year-old children and an increased prevalence in older boys (over the age of 15). The finding of increased blood hemoglobin levels in older children who snore supports the hypothesis that habitual snorers are in a chronic hypoxic state that trigger physiologic compensatory mechanisms.
The association between obesity and SRBD has been studied extensively in children. The largest study to date, with over 25,000 participants, based on a self-administered questionnaire, showed a clear quantitative relationship between body mass index (BMI) and snoring. Other studies have not only identified a dose–response relationship related to the BMI z-score, but also described imaging characteristics that highlight the increased anatomic risk related to parapharyngeal fat deposition in obese children with SRBD. Fig. 68.2 emphasizes the role of parapharyngeal fat in upper airway obstruction. The odds of SRBD are significantly greater in children with three affected members with obesity when compared with subjects without affected family members.
Prematurity is regarded as an independent risk factor for development of pediatric SRBD, potentially due to incomplete development of upper airway physiologic mechanisms. In a population-based cohort of 850 children with significant number of premature births, Rosen et al. estimated that the odds ratio of SRBD among former premature children is three to five times that of the normal full-term population.
Studies of the prevalence of pediatric SRBD in households with secondhand smoke exposure are sparse. Of note, increased snoring in infants was reported as a consequence of passive smoke exposure, although polysomnographic (PSG) testing revealed normal sleep indices. More research is needed to quantify the risk of pediatric SRBD in children exposed to secondhand smoke.
3
Pathophysiology
SRBD has been linked to fragmented sleep and abnormal breathing patterns leading to airway obstruction. SRBD is categorized into three principal types: primary snoring (PS), upper airway resistance syndrome (UARS), and obstructive sleep apnea (OSA). The fundamental differences between the three types may be related to both frequency and intensity of obstruction.
Studies of OSA measured by incremental inspiratory air pressures have described the upper airway behaving as a Starling resistor with a collapsible segment in the oropharynx. In this model, airway collapse occurs when the critical closing pressure within any given location begins to exceed the pressure within the distal, but not the proximal, airway. Collapse is complete when critical closing pressure exceeds both upstream and downstream pressures. In addition, airway obstruction during sleep is a functional process that results from systematic failure of neuromotor control mechanisms that are centrally activated in response to natural hypercapnia. Marcus et al. proposed that in children with SRBD there is compromise of the dynamic processes that guard against hypoventilation from increased airway collapsibility during sleep.
The principal pathophysiologic processes related to SRBD are (1) anatomic obstruction, (2) neuromotor tone abnormalities, and (3) inflammation. Various airway disorders of infancy and childhood could be classified under these categories, as shown in Table 68.1 . The contribution of obesity to any or all of these categories cannot be overstated and has prompted increased attention and awareness of the condition in recent years.
| Neonates and Infants |
|
| Toddlers and Older Children |
|
| Iatrogenic |
|
As shown in Table 68.1 , most children with SRBD have hypertrophy of lymphoid tissue within the palatine tonsils and the adenoids. Growth of adenotonsillar lymphoid tissue occurs in parallel with increase in skeletal dimensions until about 12 years of age, after which there is gradual cessation and regression of lymphoid tissue. The unopposed facial skeletal growth improves the upper airway during transition to adulthood. Recognition of adenotonsillar hypertrophy (ATH) as the principal cause for the reduction of oropharyngeal airway dimensions has resulted in tonsillectomy and adenoidectomy (T&A) becoming the first-line treatment for SRBD in children. By surgically removing the obstructive pathology, T&A results in resolution or significant reduction of SRBD symptoms in most children.
Airway obstruction other than ATH can occur at any nasal, oropharyngeal, or airway sites. Neonates and infants tend to present early due to their early dependence on the nasopharyngeal airway. Most causes of airway obstruction in this age group are related to congenital anomalies that affect the upper airway. They may be classified into (1) nasal or nasopharyngeal anomalies such as choanal atresia, piriform aperture stenosis, and nasal masses (e.g. dermoid, glioma, and encephalocele); (2) oral and oropharyngeal obstruction such as macroglossia (Beckwith–Wiedemann syndrome) and vascular malformations affecting the tongue; and (3) craniofacial anomalies that result in altered relationships between the maxilla and the mandible (Pierre–Robin sequence) as well as hypoplasia (e.g. Treacher–Collins syndrome).
Loss of pharyngeal dilator function that normally maintains the oropharyngeal airway during sleep may contribute to the risk of SRBD in children with neuromuscular conditions such as Down syndrome. The role of inflammation in the pathogenesis of SRBD has been investigated, specifically by markers such as C-reactive protein, and these studies have highlighted the robust correlation with severity of OSA and therapeutic response to intranasal corticosteroids and leukotriene antagonists.
4
Presentation of Pediatric SRBD
The symptoms of pediatric SRBD are related to physiologic consequences of nocturnal airflow obstruction. In its mildest form, a child may have snoring alone. However, the spectrum of symptoms is wide, and attempts at standardizing and validating questionnaires to correlate symptoms with SRBD severity have had mixed results. Chervin et al. used a 22-item modified pediatric sleep questionnaire (PSQ) that strongly correlated with SRBD; the most correlation was seen in items relating to snoring, sleepiness, and behavior. In another study, parents were asked about the child’s snoring, difficulty breathing, observed apnea, cyanosis, struggling to breathe, shaking the child to “make him or her breathe,” watching the child sleep, afraid of apnea, the frequency and loudness of snoring, and daytime symptoms such as excessive daytime sleepiness. The authors concluded that symptoms such as those listed were unable to distinguish between primary snoring and OSA. Questionnaires such as the PSQ are valid and reliable screening and clinical research instruments but cannot diagnose or quantify OSA.
The gold standard for diagnosis of SRBD in children is a pediatric PSG. Several clinical features of a snoring child should prompt suspicion and consideration of treatment in addition to the results of PSG. Fragmented sleep in a child can result in nocturnal symptoms such as snoring, enuresis, wakefulness, and observed apneic events as well as daytime symptoms that result from lack of sleep. The spectrum of daytime symptoms is intrinsically different in children with SRBD as opposed to adults. Whereas adults present with fatigability and sleepiness, pediatric SRBD manifests in the form of irritability, attention deficit, and hyperexcitability. In addition, cognitive dysfunction may result in poor school performance.
Untreated SRBD leads to a variety of sequelae as a result of intermittent hypoxemia during sleep. Cardiopulmonary compensation occurs via increase in pulmonary pressure and cor pulmonale. Chronic hypoxia has downstream effects on cerebral metabolism with adverse effects on cognitive function, executive ability, and brain development. Failure to thrive and growth retardation may be more pronounced in young children. Children with undiagnosed SRBD are likely to account for significant utilization of health care and ancillary services. There is compelling evidence that SRBD in children is associated with behavioral and neurocognitive problems and leads to reduced quality of life.
5
Diagnosis
Physical examination is critical in establishing the site of obstruction and will ultimately determine the most appropriate surgical intervention. The examination should include assessment of the patient’s weight and body habitus, a complete examination of the head and neck with attention to potential sites of obstruction, and auscultation of the patient’s heart and lungs. Children with SRBD may demonstrate significant ATH, which is the most common surgical site for management of SRBD. Friedman tongue position (FTP), described elsewhere on clinical staging, should be assessed. Children with FTP III or IV have significant retrolingual obstruction in addition to possible tonsillar and adenoid obstruction. Findings of nasal dyspnea or mouth breathing, hyponasal speech, mandibular hypoplasia, drooling, and neuromuscular deficits all suggest some degree of upper airway obstruction. In many cases, such as infants in whom the jaw is extremely micrognathic or toddlers in whom the tonsils are hypertrophied, office examination alone may suffice. Ancillary studies such as nasopharyngeal radiography and direct fiber-optic assessment of the nasal vault, adenoid pad, and distal pharynx and larynx may be useful in selected cases. In severely obstructed children, chest radiography and electrocardiography should be considered as well. In cases of nasal obstruction in infants and young children, computed tomography (CT) scanning may be desirable to define the bony anatomy and to assess the relationship of nasal masses to the sinonasal tract and the central nervous system.
SRBD occurs primarily during rapid eye movement sleep when children are less likely to be observed by their parents. In many cases of PS and UARS, parents may misinterpret the symptoms as snoring in the absence of obstruction. In addition, airway dynamics during sleep cannot be determined by static examination in the office, and fiber-optic assessment of the airway is often deceptive due to the distorted wide-angle view. Similarly, radiographic assessment of the adenoid tissue and tongue base may be difficult to interpret. In such cases, PSG is the gold standard for objective correlation of ventilatory abnormalities with SRBD. However, the severity of obstruction for which intervention is recommended remains controversial, with most authors advocating aggressive management of children whose Apnea/Hypopnea Index (obstructive apneas + hypopneas per hour) is greater than 1. Furthermore, the expense and scheduling difficulties associated with PSG make this a cumbersome method of assessment if performed in every child with snoring. In PS, the clinical presentation is associated with neither objective hypoxia from PSG nor clinical symptoms that arise from chronic hypoxia, and as such does not mandate treatment. Nevertheless, the underlying pathology of upper airway obstruction should be monitored for progression and requires reevaluation. UARS represents a condition that does not meet the criteria for OSA by PSG—the hallmark of UARS is the presence of frequent arousals and electroencephalographic changes consistent with increased sympathetic drive. It is important to distinguish PS from UARS, as the latter mandates treatment.
At our institution, methods such as drug-induced sleep endoscopy (DISE) and/or cine magnetic resonance imaging (cine MRI) are used for localization of obstruction, specifically for assessment of persistent OSA after initial treatment with T&A and continuous positive airway pressure (CPAP). Both procedures are performed under general anesthesia using propofol. The depth and duration of anesthesia are modulated to resemble natural sleep as much as possible. DISE uses flexible transnasal laryngoscopy to survey the upper airway from the nasopharynx and oropharynx to the hypopharynx under anesthesia. Cine MRI is a useful imaging modality that utilizes cerebrospinal fluid gating technology to remove motion artifacts and can provide dynamic images of the upper airway ( Fig. 68.3 ).
6
Management of Pediatric SRBD
6.1
Medical Therapy
Treatment of SRBD in children is tailored to the etiology of the airway obstruction. Pharmacotherapy may also be considered in less severe cases of OSA (e.g. mild to moderate OSA) or when surgical intervention does not address the pathology. Intranasal steroids are effective in reducing upper airway inflammation. Both intranasal corticosteroids and systemic antiinflammatory medications such as leukotriene inhibitors have been found to be useful and confirmed by a Cochrane review of the literature.
In chronic upper airway obstruction, positive airway pressure (PAP) has demonstrated high efficacy in treating SRBD in children; however, the dropout rate is high, and the rate and duration of nightly use are relatively low even among compliant children. Other alternatives, such as mechanical correction by prostheses, orthodontia, or weight loss, may be worth consideration as well, although these interventions are rarely tolerated in children and are often ineffective. As a result, even in cases of SRBD due to obesity and neuromuscular impairment, surgical management is generally considered a first-line therapy, and other modalities are considered postoperatively to address residual obstruction.
6.2
Surgical Management
6.2.1
Preoperative Planning
Preoperative planning is an essential component of the surgical management of patients with SRBD. Children with this condition are prone to airway obstruction during induction of anesthesia, and the surgeon and anesthesiologist should discuss emergency intervention for the airway should the patient become acutely obstructed. In most cases, dynamic airway collapse may be overcome by bag/mask ventilation used with an oral airway. In patients with severe micrognathia, macroglossia, or lingual tonsil hypertrophy, visualization of the larynx may be compromised. In such cases, the operating team should preoperatively assemble instruments necessary for intubation: flexible fiber-optic bronchoscope, video laryngoscope (GildeScope), or fiber-optic intubation wand, and patients should be intubated under conditions of maximal topical and minimal systemic anesthesia, preferably in the sitting position.
Postoperative respiratory distress is common after surgery for SRBD due to effects of anesthesia, bleeding, edema, and residual airway compromise. Patients at greatest risk include those with severe OSA, diminished neuromuscular tone (i.e. cerebral palsy), morbid obesity, skeletal and craniofacial abnormalities such as hypoplasia of the midface and/or mandible or nasopharyngeal vault, and very young children, under 2 years of age. As a result, high-risk individuals who are undergoing even routine procedures such as T&A should be admitted with continuous cardiac and oxygen saturation monitoring. Intraoperative use of steroids and postoperative placement of nasopharyngeal airways and tongue sutures for anterior traction may reduce the risk of airway compromise after surgery. Titrated protocols specifically tailored for use in children at risk of respiratory depression due to opioids should be considered. Obese children and those with reduced neuromuscular tone may benefit from airway support with CPAP. In the most extreme cases, overnight endotracheal intubation may be needed.
6.2.2
Nasal and Nasopharyngeal Obstruction
SRBD due to nasal and nasopharyngeal masses are best addressed by removal of the obstructive pathology. Depending on the pathology, the procedure may be as simple as a transoral, retropalatal approach for adenoidectomy or marsupialization of nasolacrimal duct cysts, or as complex as an anterior craniofacial approach for encephalocele. In most cases, microdebriders fitted with blades of appropriate size can be used to resect such lesions. Some nasal and nasopharyngeal neoplasms may require aggressive resection, as well as preoperative embolization (juvenile nasopharyngeal angiofibroma) or postoperative radiation therapy or chemotherapy (malignancies).
Choanal stenosis or atresia and stenosis of the piriform aperture are uncommon causes of obstructive apnea in neonates. Although unilateral disease is often well tolerated until school age years, bilateral cases usually require early intervention due to the dependence of neonates on nasal breathing. Affected infants present with cyclic cyanosis relieved by crying, and the diagnosis is further established by inability to pass a 6-French suction catheter through the nasopharynx. Respiratory distress can typically be relieved using an oropharyngeal airway; the diagnosis is then confirmed and characterized by CT scanning. Such infants should not otherwise leave an intensive care setting until a secure airway is established by tracheostomy or repair of the bony defect. Timing of surgery is controversial; early repair with avoidance of tracheostomy is always desirable, but children several weeks to several months old will better tolerate bleeding and accommodate sinonasal instruments used for repair.
Although choanal atresia may be approached by either the transpalatal or the transnasal route, improvements in endoscopic and powered instrumentation have made the transnasal approach the first choice for most otolaryngologists. Our preferred approach is as follows and is typically performed using intraoperative image guidance:
- 1.
Anatomy of the nasal cavity is confirmed endoscopically using a small rigid nasal endoscope. The mucosa overlying the atresia plate is injected with 1% lidocaine with 1 : 100,000 epinephrine, and the nose is briefly packed with pledgets of oxymetazoline.
- 2.
The patient’s head is placed in extension, and a Crowe–Davis mouth gag suspended on a stack of towels is used to facilitate exposure of the nasopharynx.
- 3.
A 120-degree rod lens telescope is placed in the oral cavity with the palate retracted to directly visualize the atresia plate(s) via the nasopharynx.
- 4.
A 6-French Van Buren urethral sound is passed into the nasal cavity on one side. Contact between the sound and the atresia plate is confirmed either endoscopically by visualizing the sound through the thin plate or by observing mucosal movement if the plate is thicker.
- 5.
The atretic plate is perforated with the sound ( Fig. 68.4A ), and the perforation is dilated as much as possible using progressively larger sounds. This procedure is replicated on the contralateral side.
