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Related to stridor: croup




Stridor is a term used to describe noisy breathing in general, and to refer specifically to a high-pitched crowing sound associated with croup, respiratory infection, and airway obstruction.


Stridor occurs when erratic air currents attempt to force their way through breathing passages narrowed by:
Stridor can usually be heard from a distance but is sometimes audible only during deep breathing. Someone who has stridor may crow and wheeze when:
  • inhaling
  • exhaling
  • inhaling and exhaling
Most common in young children, whose naturally small airways are easily obstructed, stridor can be a symptom of a life-threatening respiratory emergency.

Causes and symptoms

During childhood, stridor is usually caused by infection of the cartilage flap (epiglottis) that covers the opening of the windpipe to prevent choking during swallowing. It can also be caused by a toy or other tiny object the child has tried to swallow.
Laryngomalacia is a common cause of a rapid, low-pitched form of stridor that may be heard when a baby inhales. This harmless condition does not require medical attention. It usually disappears by the time the child is 18 months old.
The most common causes of stridor in adults are:
  • abscess or swelling of the upper airway
  • paralysis or malfunction of the vocal cords
  • tumor.
Other common causes of stridor include:
  • enlargement of the thyroid gland (goiter)
  • swelling of the voice box (largyngeal edema)
  • narrowing of the windpipe (tracheal stenosis)
When stridor is caused by a condition that slowly narrows the airway, crowing and wheezing may not develop until the obstruction has become severe.


When stridor is present in a newborn, pediatricians and neonatologists look for evidence of:
  • heart defects inherent at birth (congenital)
  • neurological disorders
  • General toxicity.
If examinations do not reveal the reasons for the baby's noisy breathing, the air passages are assumed to be the cause of the problem.
Listening to an older child or adult breathe usually enables pediatricians, family physicians, and pulmonary specialists to estimate where an airway obstruction is located. The extent of the obstruction can be calculated by assessing the patient's:
  • complexion
  • chest movements
  • breathing rate
  • level of consciousness
X rays and direct examination of the voice box (larynx) and breathing passages indicate the exact location of the obstruction or inflammation. Flow-volume loops and pulse oximetry are diagnostic tools used to measure how much air flows through the breathing passages, and how much oxygen those passages contain.
Pulmonary function tests may also be performed.


The cause of this condition determines the way it is treated.
Life-threatening emergencies may require:
  • the insertion of a breathing tube through the mouth and nose (tracheal intubation)
  • the insertion of a breathing tube directly into the windpipe (tracheostomy)



Berkow, Robert, editor. The Merck Manual of Medical Information: Home Edition. Whitehouse Station, NJ: Merck & Co., Inc., 1997.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


a shrill, harsh sound, especially the respiratory sound heard during inhalation with a laryngeal obstruction. adj., adj strid´ulous.
laryngeal stridor that due to laryngeal obstruction. A congenital form, marked by stridor and dyspnea, is due to an infolding of a congenitally flabby epiglottis and aryepiglottic folds during inspiration; it is usually outgrown by two years of age.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


A high-pitched, noisy respiration, like the blowing of the wind; a sign of respiratory obstruction, especially in the trachea or larynx.
[L. a harsh, creaking sound]
Farlex Partner Medical Dictionary © Farlex 2012


(strī′dər, -dôr′)
1. A harsh, shrill, grating, or creaking sound.
2. Medicine A harsh, high-pitched sound in inhalation or exhalation.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


ENT A harsh medium- to high-pitched crowing heard when breathing, especially on inspiration, due to an airway obstruction in the larynx or trachea; in children, stridor may occur in a background of congenital laryngeal stridor–laryngomalacia, which usually improves with age, or persists or recurs due to allergies, URIs, papillomas, foreign bodies, mediastinal masses, cysts of lung parenchyma
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


A high-pitched, noisy respiration, like the blowing of the wind; a sign of respiratory obstruction, especially in the trachea or larynx.
[L. a harsh, creaking sound]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


Noisy breathing caused by narrowing or partial obstruction of the LARYNX or TRACHEA.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


A high-pitched, noisy respiration; sign of respiratory obstruction.
[L. a harsh, creaking sound]
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
Stridor and lingual thyroglossal duct cyst in a newborn.
Stridor or a high-pitched breath sound is one of the most important symptoms indicating upper airway obstruction.
Failed extubation was significantly associated (p value < 0.05) with post extubation stridor, prolonged duration of MV, reintubation, prolonged duration of FiO2 > 60% and VAP.
At the psychiatric examination, the patient has a psychomotor agitation, with a demanding attitude, the cooperation is difficult due to her difficulties in breathing (the laryngeal stridor), she doesn't keep eye contact, responds with simple and short phrases when questioned, vocabulary limited to simple and concrete notions, reduced gestures.
So far, there is a general agreement in the literature that patients with signs and symptoms (including dyspnea, stridor, drooling, respiratory distress, and hypoxia) of severe airway obstruction require an immediate definitive airway, either as an endotracheal tube or a tracheotomy.[2],[3],[4] Patients with milder symptoms or without respiratory symptoms should be closely monitored and treated with antibiotics and steroids in an intensive care setting,[2],[3],[4] especially for patients with multiple comorbidities such as diabetes mellitus, because rapid complete airway obstruction is a possibility.
In this case, an allergic reaction to iodinated contrast was initially suspected when stridor and wheezing developed after completion of the procedure.
She had no postoperative stridor, no respiratory distress, or increased work of breathing.
Significantly, there was a history of neonatal stridor in two previous siblings, both male.
Stridor is an abnormal noisy sound heard during respiration and is produced by turbulence of airflow through the airway.
Bilateral paralysis of the recurrent laryngeal nerve manifests as dysphagia, slight changes in voice quality, dyspnea, aspiration and stridor, which increase during physical activity and sleep [7].
A 12-year-old male presented with a 2-week history of sore throat and sleep-disordered breathing and 48 hours of stridor. Imaging confirmed a retrotracheal soft tissue mass with airway compromise.
There was inspiratory stridor, nasal flaring, paradoxical abdominal breathing, and accessory respiratory muscle use.