Diseases Of The Nose Throat And Ear

CHAPTER 40
PAEDIATRIC LARYNGOLOGY

ANATOMY

In order to understand how laryngological problems in children differ from
those in adults it is necessary to appreciate the anatomical differences. During
fetal life the larynx descends from the level of the basi-occiput at the sixth
week to He opposite the 2nd, 3rd and 4th cervical vertebrae at birth. At the
age of 6 years it is opposite the 5th cervical vertebra, and at puberty the
larynx lies opposite C6, a position which it occupies throughout adult life.
The lumen of the larynx and trachea in the child is small, especially in
proportion to the rest of the body. The anteroposterior length of the glottis at
birth is 7-9 mm and its lateral width in full abduction is 6 mm. Thus the area
of the glottis in the newborn is some 24 mm2. From this it is apparent that
1 mm of oedema in the neonate will reduce the area of the glottic space by
50 per cent to 12 mm2. The diameter of the immediate subglottis at birth is
5-7 mm and that of the trachea is 6-8 mm. The area of this region is thus
about 9?r and this is reduced by 1 mm of oedema to 4?r, or to 44 per cent of
normal. By the same token 1 mm of oedema in a 3-mm bronchus reduces its
area to 11 per cent of normal. The trachea is 4 cm long at birth, 5-5 cm about
the age of 7 years and 9-15 cm in length in the adult.

The laryngeal cartilages in childhood are softer and more pliable than in the
adult. The infantile epiglottis is infolded, and as the child grows the epiglottis
opens out to become omega-shaped, and finally develops into the adult form
after the age of 2 years. The mucosa of the child's larynx, especially in the
subglottis, is very lax so that oedema forms more easily in this region than in
the adult. The infant's larynx also has a rich sensory nerve supply and so the
responses tend to be exaggerated.

Some of the more common laryngeal conditions seen mainly in children will
be described.

LARYNGOMAIACIA

This is the name now used for what used to be called 'congenital laryngeal
stridor'. It is the most common condition causing an inspiratory stridor at or
shortly after birth. It may persist throughout infancy. There is abnormal
flaccidity of the laryngeal cartilages allowing the laryngeal structures to
vibrate like a small elongated reed. On inspiration the air flow draws the
laryngeal tissues into the lumen (Plate VIII, 2) thus causing an inspiratory
stridor whkh is worse during exertion such as crying. The usual course of the
condition is that the stridor is noticed shortly after birth, increases during the
first few months of life and thereafter remains static. Most cases usually

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