Congenital Stridor 

Updated: Mar 05, 2018
Author: Timothy D Murphy, MD; Chief Editor: Denise Serebrisky, MD 


Practice Essentials

Stridor is a clinical sign characterized by monophonic, audible breath sounds (noisy breathing) that usually originates from the extrathoracic airways. The presence of stridor indicates a partial obstruction of the upper airways, glottis, or trachea. The pitch of the stridor is determined by the degree of airway obstruction and the velocity of the airflow; the loudness and tone of the sound also varies by the specific cause. Congenital stridor presents at birth or within the first few weeks (4-6) of life.[1]

See the video of breath sound assessment, below.

Breath sound assessment. Video courtesy of Therese Canares, MD, and Jonathan Valente, MD, Rhode Island Hospital, Brown University.


Stridor results from partial obstruction of an airway with turbulent flow characteristics. Such respiratory tract areas are the upper airway, glottis, and trachea. The obstruction can be fixed or variable. Variable extrathoracic obstructions are primarily associated with inspiratory stridor. This is because, during inspiration, extrathoracic intraluminal airway pressure is negative relative to atmospheric pressure, leading to collapse of supraglottic structures. During expiration, intrathoracic pressure is positive and tends to collapse the airway. Thus, stridor caused by intrathoracic obstructions tends to be more prominent upon expiration. Stridor heard during both phases of respiration is usually due to either a fixed airway obstruction or to 2 areas of obstruction (ie, intrathoracic and extrathoracic).



Congenital stridor is rarely life-threatening. Immediately life-threatening obstruction from congenital lesions such as severe micrognathia are apparent at birth, and are treated with emergent tracheotomy. Bilateral vocal cord paralysis and subglottic hemangioma may present as causes of congenital stridor that are life-threatening. Significant airway obstruction can lead to respiratory distress and failure to thrive, secondary to the increased work of breathing.


Congenital stridor is present either at birth or shortly afterward.




The most common presentation for congenital stridor is chronic noisy breathing since birth. Most patients come to attention by the first 4-6 weeks of life. The stridor may emerge only after a few weeks, as the baby gains strength and airflow velocity increases during that time.

The history can be helpful in determining the cause of stridor. Characteristics of stridor that should be elicited include the following:

  • Association with position

  • Association with feeding

  • Persistent versus intermittent

  • Abnormal phonation

  • Foreign body exposure

  • Presence of other congenital abnormalities


Physical examination should focus on examination of the respiratory tract, the quality and characteristics of the stridor, and other physical findings that may be associated with stridor.

  • Characteristics of the patient's stridor

    • Effect of position

    • Effect of feeding[2]

    • Inspiratory versus expiratory

    • Pitch and loudness

  • Respiratory examination

    • Lower respiratory tract sounds (eg, wheezes, crackles)[3]

    • Retractions

    • Quality of voice or crying

  • Other physical findings

    • Skin lesions (eg, hemangiomas)

    • Neurologic status

    • Klein et al conducted a study to find early clues to the diagnosis of DOK7 congenital myasthenic syndrome. The study concluded that stridor and feeding difficulties at birth or progressive weakness despite normal milestones in infancy point to the diagnosis and should lead to neurophysiological and genetic investigation. Fatigability can be absent or easily missed in the first years of life.[4]


Differential diagnosis of stridor can be divided into supralaryngeal, laryngeal, tracheal, and nonanatomic categories.

  • Supralaryngeal causes of stridor: Supralaryngeal causes include choanal atresia, vallecular cysts, thyroglossal cysts, and tongue dermoid or teratoma.

  • Laryngeal causes of stridor

    • Laryngomalacia is the most common cause of congenital stridor.[5] Patients typically have high-pitched inspiratory stridor that increases with crying and when supine. It rarely interferes with feeding. Symptoms are usually present at birth or within the first 4-6 weeks of life. Laryngomalacia usually resolves of its own accord within 18-24 months.

    • Vocal cord paralysis may cause a patient to have a weak cry. Patients may also be worse with feeding. Ruling out underlying conditions that may result in vocal cord paralysis, in particular neurologic conditions such as Arnold-Chiari malformation, is important.[6] Bilateral paralysis is more commonly associated with neurologic problems and is a life-threatening emergency.

    • Subglottic stenosis can be congenital or acquired. Stridor of subglottic stenosis is typically biphasic. Acquired forms usually arise from endotracheal (ET) intubation.

    • Other laryngeal abnormalities leading to stridor include webs, cysts, hemangiomas, papillomata, and laryngotracheoesophageal clefts.[7]

  • Tracheal causes of stridor

    • Extrinsic compression of the trachea by vascular abnormalities is a common cause of stridor. Anomalies that may lead to stridor include double aortic arch, innominate artery compression, aberrant right subclavian vein, and pulmonary artery sling.[8]

    • Bronchogenic cysts can also cause extrinsic compression of the trachea.

    • Tracheomalacia may be observed in association with laryngomalacia or as an isolated lesion.

    • Tracheal stenosis can be a complication of long-term ET intubation or a congenital lesion.

    • Complete tracheal rings are a subset of tracheal stenosis with severe biphasic airway sounds.

  • Nonanatomic causes of stridor

    • Cardio-vocal syndrome occurs when cardiac abnormalities lead to compression of the recurrent laryngeal nerve.

    • Foreign body may be present.

    • Gastroesophageal reflux (GER) has been associated with stridor, although no controlled studies have been performed to demonstrate that GER is actually responsible for the stridor.





Imaging Studies

See the list below:

  • Chest radiography may be helpful in diagnosing a vascular ring if a right-sided aortic arch is observed in patients with congenital stridor.

  • Standard neck radiography is rarely helpful unless a large mass is responsible for the obstruction. High-kilovoltage radiography can highlight the tracheal structures better and may provide more information. These radiographs use a higher radiation dose.

  • CT scanning of the neck and chest may be helpful, especially if the radiology facility can perform airway reconstruction imaging. However, the need for cooperation in generating such images limits the use of CT imaging in infants and young children with congenital stridor.

  • Barium esophagraphy can be helpful in diagnosing vascular rings if an indentation in the esophagus is present. The pattern of indentation may also be helpful in indicating what type of vascular anomaly may be present. However, the lesion of anomalous innominate artery does not yield abnormal findings on esophagraphy.

  • Laryngeal ultrasound (LUS) can demonstrate arytenoid adduction during inspiration to provisionally diagnose laryngomalacia.[9]

Other Tests

See the list below:

  • A multichannel sleep study that measures airflow, chest wall excursion, oxygen saturation, and heart rate can provide useful information about the severity of obstruction.

  • An ABG study can reveal the presence of carbon dioxide retention or chronic hypoxemia.

  • In cases of suspected gastroesophageal reflux (GER), 24-hour mid esophageal pH monitoring may be helpful in establishing the diagnosis.


See the list below:

  • Fiberoptic laryngoscopy and bronchoscopy, valuable diagnostic tools for the evaluation of congenital stridor, offer several important advantages over radiographic imaging, including the following:

    • Lesions can be directly visualized. Evidence of inflammation or bleeding can be observed. Characteristics of the lesion, such as vascularity, can be determined.

    • Biopsies and bronchoalveolar lavage samples can be taken if necessary.

    • The examination is conducted while the patient is actively breathing, allowing assessment of dynamic events.

  • Fiberoptic direct laryngoscopy can be performed in the office. However, in the pediatric population this procedure can be performed most safely while the patient is sedated. Bronchoscopy in a child requires intravenous conscious sedation or general anesthesia.



Medical Care

Medical care is primarily supportive because many causes of congenital stridor resolve spontaneously over time. For those that do not, such as vascular rings, surgical treatment is usually definitive. However, in some patients, tracheomalacia persists for some time after such a repair. In severe cases of congenital stridor, nonsurgical therapy may have a role prior to definitive surgical correction.[5]

  • Supplemental oxygen can be used to treat hypoxemia.

  • Noninvasive positive pressure mechanical ventilation can maintain a patent airway in cases of airway collapse, such as tracheomalacia.

  • If an airway cannot be maintained by noninvasive positive pressure mechanical ventilation, intubation with mechanical ventilation may be indicated.

Surgical Care

Surgical management depends on the specific lesion that causes stridor.

  • In general, indications for surgical correction include the following:

    • Inability to maintain a patent airway

    • Feeding difficulties or failure to thrive[2]

    • Inability to maintain adequate oxygenation

  • Some of the surgical procedures used to treat congenital stridor include the following:

    • Epiglottoplasty for laryngomalacia[10]

    • Tracheostomy for severe subglottic stenosis or tracheomalacia

    • Division of a vascular ring

    • Tracheoplasty for complete tracheal rings




See the list below:

  • The primary complication from congenital stridor is airway compromise and respiratory failure.

  • Other complications include failure to thrive secondary to increased work of breathing.


See the list below:

  • The prognosis for congenital stridor depends on the specific cause. In general, it is very good.

  • For conditions such as laryngomalacia, the condition is self-limited and resolves on its own.

  • For other conditions, such as subglottic stenosis, surgical correction is curative.