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Chapter I

Introduction

1.1 Background

The word "stridor" is derived from the Latin word "stridulus," which means

creaking, whistling or grating. Stridor is a harsh, vibratory sound of variable

 pitch caused by partial obstruction of the respiratory passages that results in

turbulent airflow through the airway. Although stridor may be the result of a

relatively benign process, it may also be the first sign of a serious and even

life-threatening disorder. Stridor is a distressing symptom to its victims and

their parents, and presents a diagnostic challenge to physicians. As such,

stridor demands immediate attention and thorough evaluation to uncover the

 precise underlying cause.

Stridor is a sign of upper airway obstruction. It sounds high pitch resulting

from turbulent air flow in the upper airway. In children, laryngomalacia is the

most common cause of chronic stridor, while croup is the most common cause

of acute stridor. Generally, an inspiratory stridor suggests airway obstruction

above the glottis while an expiratory stridor is indicative of obstruction in the

lower trachea. A biphasic stridor suggests a glottic or subglottic lesion.

Laryngeal lesions often result in voice changes. A child with extrinsic airway

obstruction usually hyperextends the neck. The airway should be established

immediately in children with severe respiratory distress. Treatment of stridor 

should be directed at the underlying cause.

Stridor is indicative of a potential medical emergency  and should always

command attention. Wherever possible, attempts should be made to

immediately establish the cause of the stridor (e.g., foreign body, vocal cord 

edema, tracheal compression by tumor, functional laryngeal dyskinesia, etc.)

That examination requires visualization of the airway to control the airway.

1.2 Etiology and Clinical Manifestation

1.2.1 Causes of stridor in children

These may be acute or chronic and the presentation and causes are

considered below.

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Historical data Possib

le

etiolog

y

Age of onset  

Birth Vocal cord paralysis, congenital lesions such as choanal

atresia, laryngeal web and vascular ring

4 to 6 weeks Laryngomalacia

1 to 4 years Croup, epiglottitis, foreign body aspiration

Chronicity  Acute onset Foreign body aspiration, infections such as croup and

epiglottitis

Long duration Structural lesion such as laryngomalacia, laryngeal web or  

larynogotracheal stenosis

Precipitating factors  

Worsening with straining or 

crying

Laryngomalacia, subglottic hemangioma

Worsening in a supine

 position

Laryngomalacia, tracheomalacia, macroglossia, micrognathi

Worsening at night Viral or spasmodic croup

Worsening with feeding Tracheoesophageal fistula, tracheomalacia, neurologic

disorder, vascular compression

Antecedent upper respiratory

tract infection

Croup, bacterial tracheitis

Choking Foreign body aspiration, tracheoesophageal fistula

Associated symptoms  

Barking cough Croup

Brassy cough Tracheal lesion

Drooling Epiglottitis, foreign body in esophagus, retropharyngeal or  

 peritonsillar abscess

Weak cry Laryngeal anomaly or neuromuscular disorder  

Muffled cry Supraglottic lesion

Hoarseness Croup, vocal cord paralysisSnoring Adenoidal or tonsillar hypertrophy

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Dysphagia Supraglottic lesion

Past health  

Endotracheal intubation Vocal cord paralysis, laryngotracheal stenosis

Birth trauma, perinatal

asphyxia, cardiac problem

Vocal cord paralysis

Atopy Angioneurotic edema, spasmodic croup

Family history  

Down syndrome Down syndrome

Hypothyroidism Hypothyroidism

Psycosocial history  

Psychosocial stress Psychogenic stridor  

1.2.1.1 Acute stridor in children

Croup or laryngotracheobronchitis:

• The most common acute stridor in children.

• Usually age 6 months to 2 years.

• Barking, seal-like cough, low fever and worse at night.

Inhaled foreign body:

• Common especially in children aged 1 to 2 years.

• Preceded by choking or coughing.

Tracheitis:

• Uncommon cause.

• Usually occurs under age 3 years.

• Bacterial infection following a viral infection in

toddlers.

Abscesses:

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• May be retropharyngeal (under age 6 years).

• Or peritonsillar (usually in adolescents).

• Present with high fever and difficulty swallowing.

• Retropharyngeal abscesses present with pain on

swallowing and hyperextension of the neck.

• Peritonsillar abscess presents with trismus, difficulty

with swallowing and difficulty with speaking.

Anaphylaxis:

• Hoarseness and inspiratory stridor.

• Accompanied by other symptoms of an allergic

reaction.

• Usually within 30 minutes of exposure to an allergen.

Epiglottitis:

• Usually occurs between ages 2 and 7 years.

• A medical emergency with high fever, sore throat,

drooling and dysphagia accompanying the acute stridor.

1.2.1.2 Chronic stridor in children

Laryngomalacia:

• This is the most common cause of stridor.

• It occurs in neonates and early infancy.

• The stridor is often exacerbated by the prone position,

and crying and feeding.

Vocal cord dysfunction:

• This is the next most common cause of infant stridor.

• The stridor is biphasic and associated with a weak cry.

• Unilateral vocal cord palsy is most common and can be

secondary to birth trauma or intrathoracic surgery.

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• It usually resolves in the first 2 years of life.

Subglottic stenosis:

•

This may be congenital with narrowing of the subglottisand cricoid rings.

• It can be acquired after prolonged intubation.

• It causes inspiratory stridor but this can be biphasic and

misdiagnosed as asthma.

Laryngeal disorders:

•

Congenital laryngeal webs can cause biphasic stridor.

• Laryngeal dyskinesia, exercise-induced laryngomalacia

and other disorders produce stridor.

• Laryngeal tumours may cause stridor. These may be

laryngeal cysts, haemangiomas (rare), or papillomas (vertical

transmission of human papillomavirus).

Tracheomalacia:• This is caused either by external compression or, more

commonly, by a defective tracheal cartilage

• It is the most common cause of expiratory stridor.

Choanal atresia:

• Most common congenital anomaly of the nose in

infants.• Unilateral may be asymptomatic.

• Bilateral may present with apnoea or  cyanosis during

feeding.

• It can be diagnosed by an inability to pass a nasal

catheter.

Tracheal stenosis:• Congenital tracheal stenosis is usually caused by

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tracheal rings and presents with persistent stridor and a

 prolonged expiratory phase.

• Other congenital causes of tracheal stenosis include

external compression from aortic arch abnormalities.