#definition

Obstructive Sleep Apnea (OSA) is part of a spectrum of Sleep Disordered Breathing (SDB).

• It is characterized by repeated episodes of prolonged upper airway obstruction during sleep despite continued or increased respiratory effort.

• This results in either a complete cessation of airflow (apnea) or a partial cessation (hypopnea) at the nose and/or mouth, leading to disrupted sleep.

  • Hypopnea: Defined as a >30% reduction in airflow accompanied by a $\ge 3\mathrm{\%}$ O2​ desaturation and/or an arousal from sleep.

• The intermittent hypoxia and multiple arousals from these events can contribute to significant metabolic, cardiovascular, and neurocognitive-neurobehavioral morbidity.

• Primary Snoring: Refers to snoring that occurs without associated ventilatory abnormalities like apneas, hypopneas, hypoxemia, or hypercapnia on a polysomnogram (PSG).

  • While generally considered nonpathological, it may be associated with subtle breathing abnormalities and adverse neurodevelopmental outcomes similar to those in OSA.

Etiology

OSA is caused by an anatomically or functionally narrowed upper airway. This typically involves a combination of:

• Decreased upper airway patency (obstruction or reduced diameter).
• Increased upper airway collapsibility due to reduced pharyngeal muscle tone.
• Decreased central ventilatory drive to breathe against the obstruction.

Anatomic Factors Predisposing to OSA

High-Risk Groups and Conditions

• Adenotonsillar hypertrophy is the most frequent cause of upper airway obstruction.
• Obesity: A large percentage of children with OSA are overweight or obese.
  • Increased adipose tissue in the throat, neck, and chest wall increases airway resistance.
  • Obese children are at high risk for metabolic and cardiovascular complications of OSA.
  • They also have an increased risk of postoperative complications and residual OSA after adenotonsillectomy.
• Down Syndrome: Patients are at particularly high risk, with a prevalence as high as 70%. This is due to a combination of factors including their facial anatomy, hypotonia, macroglossia, central adiposity, and a higher incidence of hypothyroidism.
• Other conditions:
  • Allergies with chronic rhinitis.
  • Craniofacial abnormalities.
  • Neuromuscular diseases (e.g., hypotonic cerebral palsy, muscular dystrophies). - increased collapsablity
  • Hypothyroidism.
  • Arnold-Chiari malformation, meningomyelocele, thalamic dysregulation - decreased central respiratory drive

Epidemiology

• The prevalence of OSA as documented by overnight sleep studies is 1-4% in the pediatric population.
• Parent-reported habitual snoring occurs in approximately 8% of children.
• Prevalence is higher in certain demographics:
  • Age: Increased prevalence between 2 and 8 years.
  • Gender: More common in males, especially after puberty.
  • Ethnicity: Increased prevalence in African American and Asian children.
  • Other factors: History of prematurity and a family history of OSA.

Pathogenesis

• OSA upregulates inflammatory pathways (CRP and interleukins), which is linked to metabolic dysfunction like insulin resistance, dyslipidemia and alternation in the neurohormones like leptin
• Systemic inflammation and increased sympathetic nervous system activity contribute to increased cardiovascular risk by altering vascular endothelium. This can lead to elevated systemic blood pressure and ventricular dysfunction.
• Negative effects on cognitive function are believed to result from:
  • Repeated arousals leading to sleep fragmentation and sleepiness.
  • Intermittent hypoxia leading to inflammatory vascular changes in the brain.

Clinical Manifestations

Nocturnal Symptoms

• Loud, frequent, and disruptive snoring.
• Observed breathing pauses, choking, or gasping.
• Restless sleep and nocturnal diaphoresis (sweating).
• Unusual sleeping positions, such as hyperextending the neck.
• Secondary enuresis (bedwetting) may occur.
• Increased frequency of parasomnias like sleepwalking and sleep terrors.

Daytime Symptoms

• Mouth breathing and dry mouth.
• Chronic nasal congestion and hyponasal speech.
• Morning headaches.
• Difficulty swallowing and poor appetite.
• In some cases, failure to thrive.

Neurobehavioral Consequences

• Daytime sleepiness, difficulty waking in the morning, and napping.
• Mood changes such as irritability, emotional dysregulation, and low frustration tolerance.
• Behavioral issues including hyperactivity, impulsivity, aggression, and oppositional behavior.
• Symptoms show substantial overlap with the diagnostic criteria for ADHD, such as inattention and poor concentration.

Diagnosis

The gold standard for diagnosing OSA is an in-lab overnight polysomnogram (PSG).

Physical Examination

• Findings may suggest OSA but are not pathognomonic, and many children appear normal.
• Growth: Obesity is common, but failure to thrive can also occur.
• Nasal/Allergic: Signs of chronic nasal obstruction (mouth breathing, "allergic shiners").
• Oropharyngeal: Enlarged tonsils, narrowed posterior pharyngeal space.
• Craniofacial: "Adenoidal facies" (open mouth posture, long face), retrognathia, micrognathia, high-arched palate.
• Cardiovascular: Systemic hypertension may be present, especially in obese children. In severe cases, signs of pulmonary hypertension or cor pulmonale may be seen.

Polysomnography (PSG)

• An overnight sleep study that monitors brain activity, heart rate, breathing, oxygen saturation, and body movements during sleep.
• The key parameter is the
  Apnea-Hypopnea Index (AHI), which is the number of apnea and hypopnea events per hour of sleep.
• Diagnostic Criteria:
  • Children (≤ 12 years): Obstructive AHI > 1 event/hour or total AHI > 1.5 events/hour is generally considered abnormal.
  • Adolescents: An $AHI\ge 5$ is generally used, similar to adults.

AAP Clinical Practice Guidelines

The American Academy of Pediatrics provides guidelines for the diagnosis and management of childhood OSA.

Management

The decision to treat depends on the severity of symptoms, sleep study results, duration of the disease, and individual patient factors.

• Adenotonsillectomy: This is the first-line treatment for most children with OSA and adenotonsillar hypertrophy. It results in complete resolution in 70-90% of uncomplicated cases.

• For residual OSA, a drug-induced sleep endoscopy (DISE) can help identify other sites of obstruction for further surgical correction.

• Positive Airway Pressure (PAP):

  • CPAP or BiPAP is the most common non-surgical treatment.
  • It is recommended for residual disease after surgery or when surgery is not an option (e.g., due to obesity or hypotonia).
  • It works by delivering pressurized air through a mask to keep the airway open during sleep.

• Other Therapies:

  • Weight loss for overweight and obese children is crucial.
  • Medical Management: Intranasal corticosteroids and leukotriene inhibitors can be helpful for mild OSA by reducing airway inflammation. Aggressive treatment of allergies and gastroesophageal reflux is also important.
  • Oral Appliances: Mandibular advancing devices and palatal expanders may be considered in select cases, often requiring consultation with a pediatric dentist or orthodontist.
  • Myofunctional therapy: Exercises to re-pattern oral and facial muscles can be beneficial.
  • Novel Treatments: Hypoglossal nerve stimulation has shown promise in adult and select pediatric cases, especially in children with Down syndrome. High-flow nasal cannula therapy is another potential approach

Polysomnograph

#definition

Polysomnography (PSG) is an in-lab, technician-supervised, overnight sleep study that documents various physiologic variables during sleep. It is considered the

gold standard for diagnosing certain sleep disorders, most notably Obstructive Sleep Apnea (OSA), because clinical history and physical findings alone cannot accurately predict the condition. An overnight PSG is not routinely required for all childhood sleep problems but is indicated when there are symptoms of specific disorders like OSA, periodic limb movement disorder, or unexplained daytime sleepiness.

Indications for Use in Children

Obstructive Sleep Apnea (OSA)

• PSG is the primary tool for diagnosing OSA and differentiating it from primary snoring.
• The American Academy of Pediatrics recommends a PSG for any child who snores regularly and presents with other signs or symptoms of OSA, such as breathing pauses, restless sleep, or daytime neurobehavioral problems.
• It is also used for reevaluation after treatment, such as an adenotonsillectomy, especially in high-risk patients (e.g., those with obesity, Down syndrome, or craniofacial anomalies) or if symptoms persist.

Sleep-Related Movement Disorders

• Periodic Limb Movement Disorder (PLMD): The diagnosis requires an overnight PSG to document the characteristic, repetitive, and stereotyped limb jerks using electromyography (EMG) leads on the anterior tibialis muscles.
• Restless Sleep Disorder (RSD): The diagnosis includes objective documentation of frequent large body movements during sleep, which is recorded via videography during a PSG.

Central Disorders of Hypersomnolence

• Narcolepsy & Idiopathic Hypersomnia (IH): An overnight PSG is a crucial part of the evaluation for a child with profound, unexplained daytime sleepiness.
  • The primary purpose of the PSG is to rule out other causes of sleepiness, such as OSA or PLMD.
  • The PSG is immediately followed by a Multiple Sleep Latency Test (MSLT), which measures the tendency to fall asleep during the day.
  • Specific PSG findings, such as a REM sleep latency of 15 minutes or less, are part of the diagnostic criteria for narcolepsy.

Parameters Monitored

A comprehensive PSG records multiple physiological signals simultaneously to get a complete picture of sleep architecture and function.

Interpretation of Results

While there are no universally accepted normal PSG reference values for children, certain parameters are key to diagnosis.

• The most common metric used to evaluate sleep-disordered breathing is the
  Apnea-Hypopnea Index (AHI), which represents the total number of apneas and hypopneas per hour of sleep.

• Normal Values & Severity in Children (≤ 12 years):

  • Normal: An obstructive AHI of <1 event/hour or a total AHI of <1.5 events/hour is generally considered normal.
  • Mild OSA: AHI is between 1 and 5 events/hour.
  • Moderate OSA: AHI is between 5 and 10 events/hour.
  • Severe OSA: AHI is >10 events/hour.

• Adolescents: The adult cutoff of an $AHI\ge 5$ is typically used to diagnose OSA.

Alternatives to In-Lab PSG

In situations where a full, in-lab polysomnogram is not available, the American Academy of Pediatrics suggests that clinicians may consider alternative diagnostic tests. These include:

• Nocturnal video recording.
• Nocturnal oximetry
• Daytime nap polysomnography.
• Ambulatory (home) polysomnography.