Stridor
Stridor is a high-pitched sound that is
usually heard best when a child breathes in (inspiration). It is usually caused
by an obstruction or narrowing in your child's upper airway, which includes the
following structures:
- Larynx - also known as the voice box, the larynx is a cylindrical grouping
of cartilage, muscles, and soft tissue which contains the vocal cords. The
vocal cords are the upper opening into the windpipe (trachea), the passageway
to the lungs.
- Trachea (windpipe) - a tube that reaches from the voice box to the bronchi
in the lungs.
The sound of stridor depends on location of the obstruction in the upper
respiratory tract. Sometimes, the stridor is heard when the child breathes in
(inspiration) and can also be heard when the child breathes out
(expiration).
Causes of stridor
There are many
different causes of stridor. Most of the causes are problems with the anatomical
structure of the child's airway. The upper airway in children is shorter and
narrower than that of an adult, and, therefore, more likely to lead to problems
with obstruction. The following are some of the more common causes of stridor in
children:
Congenital causes (problems present at birth)
- Laryngomalacia - the most common cause of stridor in infants and children
due to floppiness of the upper structures of the larynx. The diagnosis is made
by flexible laryngoscopy in the doctor's office.
- Tracheomalacia - part of the trachea may be too soft. The child will
usually outgrow this condition by the time he/she is 18 months old.
- Subglottic stenosis - the larynx (voice box) may become too narrow below
the vocal cords. Children with subglottic stenosis are usually not diagnosed
at birth, but, more often, a few months after, particularly if the child's
airway becomes swollen by a cold. Cough and recurrent croup are common
symptoms. The child usually outgrows this problem without intervention. Some
children may need a surgical procedure if the obstruction is severe. The
diagnosis is made by bronchoscopy.
- Subglottic hemangioma - a type of mass that consists mostly of blood
vessels. Subglottic hemangioma grows in the child's first few months of life.
The child will usually shows signs around the age of 3 to 6 months. Some
children may outgrow this problem, as the hemangioma will begin to get smaller
after the first year of life.
- Vascular rings - the trachea, or windpipe, may be
completely enclosed by a blood vessel around the outside.