Stridor (noisy breathing) is abnormal breathing produced by turbulent airflow through a partially obstructed airway located outside of the chest (extrathoracic) at the level of the supraglottis, glottis, subglottis, or extrathoracic trachea. Stridor is not in and of itself a diagnosis or a disease, but rather a symptom of a narrowed airway.
There are three forms of stridor depending on which phase of the respiratory cycle it occurs. Stridor during inspiration is the most common, but may occur during expiration or during both phases (biphasic stridor).
Stridor has a tonal quality that can be extremely variable (ie, harsh, coarse, grating sound with a crowing quality); however, when combined with the respiratory phase and associated symptoms, the sound may provide additional information for a diagnosis. The three forms of stridor each suggest different causes.
Three Forms of Stridor
- Inspiratory only stridor is usually secondary to a dynamic extrathoracic source and often suggests a laryngeal obstruction
- Expiratory stridor implies tracheobronchial obstruction
- Biphasic stridor suggests a subglottic or glottic anomaly and implies a fixed airflow obstruction
A careful history and physical exam is needed to assess timing of the symptoms and workup of the patient. Diagnosing stridor’s etiology requires a thorough assessment:
- Acute or Chronic Stridor
- Congenital (present from birth) Stridor
- Acquired Stridor
- Severity of the Symptoms
- Does it require aggressive evaluation or observation?
- Croup (laryngotracheobronchitis) occurs in children aged 6 months to 2 years and exhibits a barking cough that is worse at night. Croup is the most common cause of acute stridor in this age group.
- Acute spasmodic laryngitis or spasmodic croup presents identically to croup.
- Foreign body aspiration, usually food (nuts, hot dog), occurs in children aged 1-2 years. Often a history of choking or coughing precedes symptoms of stridor.
- Peritonsillar abscess is more common in older children and teenagers. Symptoms include severe throat pain, difficulty opening mouth secondary to pain (trismus), fever, and trouble with swallowing or speaking.
- Anaphylaxis is a severe allergic reaction to that results in rapid (within 30 min) development of symptoms of throat swelling, wheezing, nasal congestion, watery eyes and itching. This can be a medical emergency and requires immediate treatment.
- Laryngomalacia accounts for 75% of all stridor and is the most common inspiratory stridor present at birth. Surgical correction or supraglottoplasty is considered in infants who have significant obstruction or lack of weight gain.
- Subglottic stenosis can present with inspiratory or biphasic stridor. It can be congenital or acquired after a prolonged intubation
- Vocal cord dysfunction is probably the second most common cause of stridor in infants
- Bilateral vocal cord paralysis may progress to severe respiratory distress and exhibit a biphasic stridor or no sound at all (aphonia)
Determining the etiology of stridor in a child, one should consider other associated symptoms like difficulty in feeding, drooling, sleep-disordered breathing, and paroxysms of cough. Particular emphasis should be placed on the following:
- Timing of onset, age, duration, severity, and progression of stridor: Present since birth, consider laryngomalacia and congenital stenosis.
- Positioning: Laryngomalacia improves with the prone position and hypotonia of the hypopharynx symptoms worsen with sleep.
- Precipitating events: Relationship to crying or feeding suggests gastroesophageal reflux (GERD) and aspiration. Previous history of choking or coughing suggests an airway foreign body. History of trauma.
- Quality and nature of crying
- Presence of aphonia
How aggressive should I be in the evaluation of the child with stridor?
- If the child is noisy, but comfortable and are growing well it may be reasonable to wait or go slowly with the workup. Children may out grow stridor due to laryngomalacia.
- If children with stridor show signs of distress, poor growth, have history of apnea, or cyanosis, they require aggressive evaluation and stabilization.
Stridor Differential Diagnosis (Video)
- Nasopharyngeal malformations occur in dysmorphic or syndromic children
- Hypopharyngeal hypotonia stridor is worse in sleep
- Laryngomalcia stridor is better in sleep or the prone position and is biphasic
- Vocal cord paralysis stridor has a weak cry or hoarse voice
- Subglottic stenosis stridor is usually biphasic and could be associated with a previous history of intubation
- Subglottic hemangioma is the most common vascular tumor, a benign lesion usually found in infants
- Vascular malformation may demonstrate an abnormal barium swallow
- Airway or esophageal foreign body may cause stridor
- Gastroesophageal reflux (GERD) can have symptoms of laryngospasm which causes stridor
- Hypocalcemia may precipitate tetany of the vocal cords resulting in stridor
- Vocal cord dysfunction will result in stridor being worse with exercise
For more information about stridor in children submit an online appointment request or contact the office of Dr. Peter N. Schochet and Dr. Hauw Lie.
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