Stridor is the noisy, harsh, vibratory, or high-pitched breathing sound that occurs when air flows through a narrowed or partially obstructed airway. It is not a disease; rather, it is a symptom or sign of an airway disorder.
Croup is the common cause of acute stridor, and laryngomalacia is the common cause of chronic stridor in children. Irrespective of whether other signs and symptoms are present, immediate medical care is recommended if your child develops stridor.
Read this post to know about the types, causes, symptoms, complications, diagnosis, and treatment for stridor in children.
Types Of Stridor
Stridor can be of the following types depending on the timing and sound of your child’s breathing (1).
- Inspiratory stridor: This occurs when the child breathes in (inhalation) and often occurs when the tissue above the vocal cords is affected.
- Expiratory stridor: This happens during exhalation (breathing out) and usually indicates a problem in the respiratory tract below the trachea (windpipe).
- Biphasic stridor: This is heard during exhalation and inhalation and is often due to the narrowing of the subglottis, the cartilage below the vocal cords.
Risk Factors And Causes Of Stridor In Children
Stridor can be caused by any process that narrows or obstructs the airways. Young children can have congenital stridor due to congenital disorders (problems present at birth), whereas older children may develop stridor due to infections, trauma, or foreign body aspiration. The following are some causes of stridor in children (2).
- Foreign body aspiration, including food or other objects, can cause acute stridor in children. Cough and shortness of breath are associated with stridor caused by foreign bodies stuck in the larynx or trachea (windpipe). This may often lead to bacterial infection and move down to bronchi in some children.
The following conditions affecting the nose and pharynx can cause stridor in children.
- Choanal atresia is a rare congenital abnormality of the nose where the tissue blocks the airway. Unilateral choanal atresia may not cause symptoms until obstruction of the other side occurs due to an
- A lingual thyroid or thyroglossal cyst can cause airway obstruction and stridor in children.
- Macroglossia, a condition in which the tongue is larger than normal, may obstruct the airway. This may often be seen in children with Down syndrome, glycogen storage disease, Beckwith-Wiedemann syndrome, and congenital hypothyroidism.
- Micrognathia refers to a condition in which the lower jaw is undersized. It can obstruct airways due to displacement of the tongue. In this condition, the stridor may worsen in the supine position.
- Retropharyngeal or peritonsillar abscess may cause edema of the upper airway and result in stridor. This condition is often associated with drooling, dysphagia, and fever, and the child may have a stiff neck and find trouble opening their mouth.
- Hypertrophic tonsils or adenoids can also obstruct the upper airway. The stridor may often be noticed during sleep in this condition.
Laryngeal abnormalities that can cause stridors in children include the following.
- Laryngomalacia occurs due to delayed maturation or defects of the structures supporting the larynx. A displacement of the underdeveloped supporting structures causes partial airway obstruction, resulting in inspiratory stridor. This is the most common cause of chronic stridor in younger children and may worsen while crying, when in a supine position, or when a respiratory infection occurs.
- Laryngotracheobronchitis (viral croup) is the common cause of acute inspiratory stridor in children. Parainfluenza virus (most common), influenza virus type A or B, rhinoviruses, and respiratory syncytial virus (RSV) are common causes of viral croup in children. Stridor may be preceded by several days of respiratory tract infection followed by cough and fever. This can worsen at night and while crying.
- Laryngocele or cyst and laryngeal web may cause airway obstruction and lead to stridor in young children.
- Spasmodic croup or acute spasmodic laryngitis can mimic viral croup, and it is triggered by allergy, GERD, or psychological factors.
- Epiglottitis, usually caused by Haemophilus influenzae type B, can cause stridor and is often associated with fever, shortness of breath, and drooling in children.
- Vocal cord paralysis occurs due to recurrent disruption to the laryngeal nerves. It can cause biphasic stridor in children.
- Laryngeal stenosis is a congenital or acquired narrowing of the larynx that can partially obstruct the airways. Trauma, gastroesophageal reflux, and external compression are common causes of acquired stenosis.
- Laryngeal papilloma, caused by the papillomavirus at birth, is the most common laryngeal tumor. This may cause stridor and hoarseness of voice in children.
- Angioneurotic edema can result in the acute swelling of the upper airway and lead to shortness of breath and stridor.
- Laryngospasm associated with hypocalcemic tetany can cause stridor. This can be associated with tremors, carpopedal spasms (hand and feet spasms), and twitching.
The following conditions that affect the trachea may cause stridor in children.
- Tracheomalacia is the abnormal collapse of the trachea due to the collapse of structures supporting the trachea. Flaccid tracheal structures can narrow the airway during expiration and lead to stridor. Also, respiratory tract infections can worsen the stridor in children.
- Bacterial tracheitis, also called membranous croup or bacterial croup is the bacterial infection of the trachea caused by Staphylococcus aureus, H. influenzae type b, or Moraxella catarrhalis. High fever and respiratory distress can also be present with stridors in bacterial croup.
- External compression of the trachea can cause stridor. For example, vascular anomalies such as double aortic arch and anomalous left carotid artery can cause tracheal compression. Further, cysts, lymphadenopathy, and tumors can also compress the trachea in young children.
Structural airway defects present at birth, injury to the neck or jaw, and being on breathing machines (mechanical ventilators) for a long time may increase the risk of stridors in children (3).
Symptoms Of Stridor In Children
Noisy breathing is the characteristic symptom of stridor. The sound and type of stridor may vary depending on the cause and where the airway is obstructed. Children with congenital stridor may face eating or drinking difficulties, leading to poor weight gain (4).
Stridor due to upper respiratory tract infections can be associated with fever and other respiratory symptoms. The following signs are often associated with stridor due to severe airway obstruction(3) (5).
- Bluish skin (cyanosis)
- Gasping for air
- Widened nostrils while breathing
- Chest retractions
- Behavioral changes
Call a pediatrician immediately if your child has any symptoms of stridor.
Complications Of Stridor In Children
The upper airways of children are narrower and shorter than that of adults; and thus, children are more prone to airway blockage than adults. If left untreated, severe airway obstruction can be life-threatening or even cause death in children (6).
Children with congenital stridor can have airway compromise and respiratory failure over time. This may also cause failure to thrive (FTT) in young children due to the increased work for breathing (7).
Diagnosis Of Stridor In Children
Pediatricians may do physical examinations and obtain the health history of children with stridor. Examination with a stethoscope helps identify the type of stridor. In some cases, diagnosis can be made clinically without any specific tests. Doctors may refer the child to an ENT (ear, nose, and throat specialist) specialist if required. The following tests are often ordered to identify the cause (5).
- X-rays of the chest and neck
- MRI or CT scans of the chest and neck
- Spirometry to measure the amount of air inhaled and exhaled and how quickly air is exhaled
- Laryngoscopy to check the back of the throat and larynx
- Bronchoscopy to check the throat, larynx, trachea, and bronchi (tubes in lungs)
- Pulse oximetry using a sensor on the finger or toe to measure the amount of oxygen in the blood
- Sputum culture to look for infections
Foreign bodies are often removed during bronchoscopy. Pediatricians may choose diagnostic tests based on the clinical features.
Treatment For Stridor In Children
Treatment options may vary depending on the cause, symptoms, severity, child’s age, and health status. Severe stridor may require hospitalization and emergency surgeries. The treatment options may include (7).
- Oral medications or injections to decrease airway swelling or infections causing stridor. Some children may receive antibiotic therapy or steroid therapy, depending on the conditions.
- Bronchoscopy is often used to remove the foreign body from the airways.
Some children with severe stridor may require tracheostomy to maintain air circulation. This procedure helps bypass the upper airway defects. The following conditions that cause stridor may require surgical care.
- Laryngeal and tracheal stenosis
- Severe laryngomalacia
- Tracheal and laryngeal tumors and lesions such as laryngeal hemangiomas and papillomas
- Forign body aspiration
Close monitoring and follow-ups are recommended for children with stridor due to congenital anomalies to look for disease progression.
Stridor in children always requires prompt medical care since it is an indication that the airway is obstructed. Parents are advised to comfort the child while waiting for medical care and during diagnosis since crying, agitation, and stress may worsen airway obstruction.