eMedicine Specialties > Pediatrics: Surgery > Otolaryngology

Stridor

Author: Brian E Benson, MD, Staff Physician, Division of Otolaryngology, New Jersey Medical School
Coauthor(s): Soly Baredes, MD, Associate Professor of Clinical Surgery, Chief, Section of Otolaryngology-Head and Neck Surgery, Director, Division of Head and Neck Surgery, University of Medicine and Dentistry of New Jersey, New Jersey Medical School; Robert A Schwartz, MD, MPH, Professor and Head of Dermatology, Professor of Medicine, Professor of Pediatrics, Professor of Pathology, Professor of Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School; Mudra Kumar, MD, MBBS, MRCP, Associate Professor, Department of Pediatrics, University of South Florida College of Medicine
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Updated: Aug 29, 2006

Introduction

Background

Stridor is a harsh, high-pitched, musical sound produced by turbulent airflow through a partially obstructed airway.

Stridor is a symptom, not a diagnosis or disease, and the underlying cause must be determined. Stridor may be inspiratory, expiratory, or biphasic depending on its timing in the respiratory cycle. Inspiratory stridor suggests an extrathoracic lesion (eg, laryngeal, nasal, pharyngeal). Expiratory stridor implies an intrathoracic lesion (eg, tracheal, bronchial). Biphasic stridor suggests a subglottic or glottic anomaly.

Pathophysiology

Gases produce pressure equally in all directions; however, when a gas moves in a linear direction, it produces pressure in the forward vector and decreases the lateral pressure. When air passes through a narrowed flexible airway in a child, the lateral pressure that holds the airway open can drop precipitously (the Venturi principle) and cause the tube to close. This process obstructs airflow and produces stridor.

Stridor may result from lesions involving the CNS, the cardiovascular system, the GI system, and the respiratory tract.

Clinical

History

The most common presenting symptom is that the child has loud, raspy, noisy breathing. The caretaker may interpret this symptom as wheezing or even as a bad cold. Depending on the underlying etiology, the presentation may be acute or chronic and may be accompanied by other symptoms. If symptoms are not observed in the office, especially when they are present only at night, having parents make a tape recording, preferably even videotaping, can provide useful information.

A thorough history may provide helpful clues to the underlying etiology of stridor.

• Place particular emphasis on the age of onset, duration, severity, and progression of the stridor; precipitating events (eg, crying, feeding); positioning (eg, prone, supine, sitting); quality and nature of crying; presence of aphonia; and other associated symptoms (eg, paroxysms of cough, aspiration, difficulty feeding, drooling, sleep disordered breathing).
• Perinatal history is especially important and should include direct questioning regarding maternal condylomata, endotracheal intubation use and duration, and presence of congenital anomalies.
• Obtain a detailed developmental history.
• In addition, elicit history of color change, cyanosis, respiratory effort, and apnea to determine the severity of stridor.
• A feeding and growth history should be evaluated because significant airway obstruction can lead to caloric waste, resulting in lack of or slow weight gain and growth. Additionally, regurgitation and spitting up could be a sign of gastroesophageal reflux (GER) that can cause irritation of the mucosa of the larynx and trachea that could lead to edema and stridor.

Physical

On initial presentation, especially in patients with acute onset of symptoms, immediately assess the child for severity of stridor and respiratory compromise. Give special attention to the heart and respiratory rates, cyanosis, use of accessory muscles of respiration, nasal flaring, level of consciousness, and responsiveness.

• If distress is moderate to severe, further physical examination should be deferred until the patient reaches a facility equipped for emergent management of the pediatric airway.
• Physical examination of a patient with suspected acute epiglottitis is contraindicated.
• The patient may prefer certain positions that alleviate the stridor.
• Note the presence of infection in the oral cavity; crepitations or masses in the soft tissues of the face, neck, or chest; and deviation of the trachea.
• Use care when examining (especially palpating) the oral cavity or pharynx because sudden dislodgement of a foreign body or rupture of an abscess can cause further airway compromise.
• Drooling from the mouth suggests poor handling of secretions.
• Observe the character of the cough, cry, and voice.
• The presence of fever and toxicity generally implies serious bacterial infections.
• Careful auscultation of the nose, oropharynx, neck, and chest helps to discern the location of the stridor.
• In infants, give special attention to craniofacial morphology, patency of the nares, and cutaneous hemangiomas. Growth parameters are very helpful, especially in evaluation of chronic stridor.

Causes

• Acute stridor
  • Laryngotracheobronchitis, commonly known as croup, is the most common cause of acute stridor in children, especially children aged 6 months to 2 years. The patient has a barking cough that is worst at night and may have low-grade fever.
  • Aspiration of foreign body is common in children aged 1-2 years. Usually, foreign bodies are food such as nuts, hot dogs, popcorn, and hard candy that is inhaled. A history of coughing and choking that precedes development of respiratory symptoms may be present.
  • Bacterial tracheitis is relatively uncommon and mainly affects children younger than 3 years. It is a secondary infection (most commonly due to Staphylococcus aureus) following a viral process (commonly croup or influenza).
  • Retropharyngeal abscess is a complication of bacterial pharyngitis observed in children younger than 6 years. The patient presents with abrupt onset of high fevers, difficulty swallowing, refusal to feed, sore throat, hyperextension of the neck, and respiratory distress.
  • Peritonsillar abscess is an infection in the potential space between the superior constrictor muscles and the tonsil. It is common in adolescents and preadolescents. The patient develops severe throat pain, trismus, and trouble swallowing or speaking.
  • Spasmodic croup, also termed acute spasmodic laryngitis, occurs most commonly in children aged 1-3 years. Presentation may be identical to croup.
  • Allergic reaction (ie, anaphylaxis) occurs within 30 minutes of an adverse exposure. Hoarseness and inspiratory stridor may be accompanied by symptoms (eg, dysphagia, nasal congestion, itching eyes, sneezing, wheezing) that indicate the involvement of other organs.
  • Epiglottitis is a medical emergency occurring most commonly in children aged 2-7 years. Clinically, the patient experiences an abrupt onset of high-grade fever, sore throat, dysphagia, and drooling.
• Chronic stridor
  • Laryngomalacia is the most common cause of inspiratory stridor in the neonatal period and early infancy and accounts for up to 75% of all cases of stridor. Stridor may be exacerbated by crying or feeding. Placing the patient in a prone position with the head up improves the stridor; supine position worsens the stridor. Laryngomalacia is usually benign and self-limiting and improves as the child reaches age 1 year. If significant obstruction or lack of weight gain is present, surgical correction or supraglottoplasty may be considered if tight mucosal bands are present holding the epiglottis close to the true vocal cords or redundant mucosa is observed overlying the arytenoids.
  • Patients with subglottic stenosis can present with inspiratory or biphasic stridor. Symptoms can be evident at any time during the first few years of life. If symptoms are not present in the neonatal period, this condition may be misdiagnosed as asthma. Congenital subglottic stenosis occurs when an incomplete canalization of the subglottis and cricoid rings causes a narrowing of the subglottic lumen. Acquired stenosis is most commonly caused by prolonged intubation (see articles on glottic and subglottic stenosis).
  • Vocal cord dysfunction is probably the second most common cause of stridor in infants. Unilateral vocal cord paralysis can be congenital or secondary to trauma at birth or time of cardiac or intrathoracic surgery. It has been reported secondary to ligation of patent ductus arteriosus (PDA), the left vocal cord being the more commonly affected. Patients with unilateral paralysis present with a weak cry and biphasic stridor that is louder when awake and improves when lying with the affected side down. Bilateral vocal cord paralysis is a more serious entity. Patients usually present with aphonia and a high-pitched biphasic stridor that may progress to severe respiratory distress. It is usually associated with CNS abnormalities, such as Arnold-Chiari malformation or increased intracranial pressure. Vocal fold paralysis in infants usually resolves within 24 months.
  • Laryngeal dyskinesia, exercise-induced laryngomalacia, and paradoxical vocal fold motion are other neuromuscular disorders that may be considered.
  • Laryngeal webs are caused by an incomplete recanalization of the laryngeal lumen during embryogenesis. Most (75%) are in the glottic area. Infants with laryngeal webs have a weak cry and biphasic stridor.
  • Laryngeal cysts are a less frequent cause of stridor. They are usually found in the supraglottic region in the epiglottic folds. Patients may present with stridor, hoarse voice, or aphonia, or cysts may cause obstruction of airway lumen if they are very large.
  • Laryngeal hemangiomas (glottic or subglottic) are very rare, and half of them are accompanied by cutaneous hemangiomas in the head and neck. Patients usually present with inspiratory or biphasic stridor that may worsen as the hemangioma enlarges. Hemangiomas usually regress by age 12-18 months, and surgical or medical intervention is based on severity of symptoms. Treatment options consist of oral steroids, intralesion steroids, laser therapy with carbon dioxide or potassium-titanyl-phosphate (KTP) lasers, or resection.
  • Laryngeal papillomas occur secondary to vertical transmission of the human papilloma virus in maternal condylomata or infected vaginal cells to the pharynx or larynx of the infant during the birth process.
  • Tracheomalacia is the most common cause of expiratory stridor. It is caused by a defect on the cartilage resulting in the loss of rigidity necessary to maintain the tracheal lumen patent or by an extrinsic compression of the trachea.
  • Tracheal stenosis can be congenital or secondary to extrinsic compression. Congenital stenosis is usually related to complete tracheal rings, is characterized by a persistent stridor, and requires surgery based on severity of symptoms. The most common extrinsic causes of stenosis include vascular rings, slings, and a double aortic arch that encircles the trachea and esophagus. Pulmonary artery slings are also associated with complete tracheal rings. External compression can also result in tracheomalacia. Patients usually present during the first year of life with noisy breathing, intercostal retractions, and a prolonged expiratory phase.
  • Choanal atresia is the most common congenital anomaly of the nose that is noted in infants. Patients with unilateral choanal atresia may be asymptomatic. Patients with the bilateral condition may present with episodes of apnea or cyanosis that are aggravated with feeding. Diagnosis can be made at bedside by attempting to pass a plastic catheter through the nose. The characteristic sound is usually more of stertor than stridor.

• Search for CME/CE on This Topic »

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• Croup (Radiology)
• Laryngomalacia (Pediatrics: General Medicine)
• Bacterial Tracheitis (Pediatrics: General Medicine)

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