OFFICIAL ABP TOPIC:

Stridor – Understand the Differential Diagnosis, Evaluation, and Management of Stridor

BACKGROUND

Stridor is an abnormal, high-pitched monophonic sound caused by turbulent airflow through a narrowed airway, usually indicating obstruction in the supraglottis, glottis, subglottis, or trachea. Stridor warrants prompt evaluation and, in some cases, emergency intervention.

DIFFERENTIAL DIAGNOSIS OF STRIDOR

Causes of Acute or Subacute Stridor

• Croup (Viral Laryngotracheitis): Barky cough, inspiratory stridor, low-grade fever. “Steeple sign” on X-ray.
• Bacterial Tracheitis: High fever, toxic appearance, purulent secretions.
• Epiglottitis: Abrupt onset, drooling, muffled voice, tripod position. “Thumbprint sign” on lateral neck X-ray.
• Retropharyngeal Abscess: Fever, neck stiffness, “hot potato” voice, bulging of the posterior pharynx.
• Peritonsillar Abscess: Severe sore throat, trismus, uvular deviation, unilateral tonsillar swelling.
• Foreign Body Aspiration: Sudden onset of choking, focal wheeze, or stridor.
• Anaphylaxis: Rapid onset of stridor, urticaria, swelling, hypotension after allergen exposure.
• Thermal/Chemical Epiglottitis: Hot liquid burns or caustic ingestion causing drooling, stridor.

Causes of Chronic Stridor

• Laryngomalacia: Most common congenital cause. Inspiratory stridor, worse with feeding or crying.
• Vocal Cord Paralysis: Unilateral (hoarseness, aspiration) or bilateral (respiratory distress).
• Subglottic Stenosis: Biphasic stridor, recurrent croup.
• Vascular Rings/Slings: Extrinsic tracheal compression, dysphagia, expiratory stridor.
• Hemangiomas, Papillomas, Webs, Cysts: Progressive stridor with respiratory distress.
• Tracheomalacia: Expiratory stridor, associated with other congenital abnormalities.

EVALUATION OF STRIDOR

INITIAL RAPID ASSESSMENT

Evaluate for cyanosis, mental status changes, retractions, tachypnea, and hypoxia. Sniffing position, drooling, and anxiety suggest impending obstruction. Initial evaluation should try to keep child calm and comfortable since anxiety and crying can worsen symptoms. If respiratory distress is present, prioritize emergency airway management initially over diagnostic testing.

HISTORY

• Onset and progression: Age at onset, sudden vs. gradual progression.
• Associated symptoms: URI, fever, cough, dysphagia, voice changes, hives.
• Triggers: Position changes, activity, feeding, crying.
• Medical history: Allergens, choking, congenital anomalies, prematurity, surgeries.

PHYSICAL EXAM

• ENT: Craniofacial abnormalities, size of tongue, tonsils, enlarged lymph nodes in infection or malignancy.
• Characterize stridor: Inspiratory (extrathoracic obstruction), expiratory (intrathoracic obstruction), or biphasic (fixed central airway obstruction).
  • Inspiratory: Suggests extrathoracic obstruction (supraglottic/glottic).
  • Expiratory: Suggests intrathoracic obstruction (trachea or bronchi).
  • Biphasic: Common with fixed central airway obstruction (subglottic stenosis).
• Work of breathing: During rest and after activity.
• Skin: Exam for hemangiomas or café au lait spots in neurofibromatosis.

DIAGNOSTIC TESTS

• Children with typical croup usually do NOT need any labs or radiographs.
• CBC with diff: For suspected bacterial infections.
• Neck radiographs: “Steeple sign” (croup), “Thumbprint sign” (epiglottitis), enlarged retropharyngeal space (retropharyngeal abscess).
• CXR: If intrathoracic cause suspected: masses, mediastinal lymphadenopathy, foreign body aspiration.
• Airway examination: Visualization with laryngoscopy or bronchoscopy is the gold standard for diagnosing foreign bodies or structural abnormalities (e.g., subglottic stenosis).
• CT: Can identify external tracheal compression (vascular rings/slings), subglottic stenosis, tracheomalacia, masses, or lymphadenopathy.
• MRA: Shows vascular anatomy if a vascular ring is suspected after CXR.

For a table that includes specific conditions, associated ages, key symptoms, and management of those specific conditions, please refer to the “CONDITION SPECIFIC MANAGEMENT” table at the end of this topic summary.

MANAGEMENT OF STRIDOR

Immediate stabilization of the airway if respiratory distress is present. Call for anesthesiologist and ENT to help with securing the airway.

Near-total/total obstruction: (Tripod or sniffing position, severe respiratory distress, cyanosis, unable to speak or cough):

• If foreign body suspected, perform back/chest thrusts (infants) or Heimlich maneuver (children ≥1 year old). Consider laryngoscopy with forceps to remove the foreign body if unsuccessful.
• If no foreign body suspected, start bag mask ventilation with oxygen and prepare for intubation in a controlled setting. If hypoxemia does not improve, try emergent intubation or other airway interventions (laryngeal mask airway, cricothyrotomy) until a definitive airway has been secured.

CONDITION SPECIFIC MANAGEMENT  

REFERENCES

https://www.uptodate.com/contents/assessment-of-stridor-in-children

https://www.uptodate.com/contents/emergency-evaluation-of-acute-upper-airway-obstruction-in-children

https://publications.aap.org/pediatricsinreview/article/42/11/635/181209/Acute-Infectious-Stridor