Congenital laryngomalacia
0
From the Department of Anaesthesia, Children's Hospital of Eastern Ontario
, 401 Smyth Rd,
Ottawa
,
Ontario K1H 8LI. Accepted for publication 11th December
, 1993
There is at present, very little information on congenital laryngomalacia in the anaesthetic literature. The purpose o f this article is to review this topic, which in 90% o f patients represents a benign self-limiting condition, disappearing by the age o f two to five years. However, i f untreated, the remaining 10% o f cases can prove fatal. This severe f o r m presents as persistent sternal recession, feeding difficulties, and failure to thrive, progressing to apnoeic attacks, cor pulmonale and eventually death. The developmental and functional anatomy o f the larynx will be included, with a discussion o f the pathophysiology and history o f the disorder. Its diagnosis and a rdsumd o f the various treatment strategies, will be presented. The anaesthetic management is controversial as is the surgical technology. Our technique, f o r diagnosis or definitive repair, is based upon suspension laryngoscopy using topical local analgesia and spontaneous yen. tilation. Halothane is then administered by insufflation into the pharynx, using a #8 nasopharyngeal catheter, and suction is applied to the mouth. During the surgical repair, an endotracheal tube (ETT), may be insertea~ at the discretion o f the anaesthetist and surgeon. Finally, the role o f the carbon dioxide C02 laser and its hazards will be introduced.
-
Jusqu~ present, la litt~ratum ane~th~sique donne trbs peu
d~nformation sur la laryngomalacie congdnitale. Le propos d e vet
article est de revoir ce sujet, qui dans 900/0 des cos est b~nin
et dispara~t vers l'~ge de 2 fi 5 ans. Cependant, les 10% des
cos restant peuvent devenir I~thanx sfls ne sore pas trait~s.
Cette f o r m e grave se manifeste par un enfoncement sternal
persistant, des difficult~s d'alimentation et un retard de croissance.
Elle s'aggrave de crises apn$iques, de coeur pulmonaire et
~ventuellement il y a d~cbs. L'anatomie fonctionnelle ainsi que le
Anatomy of the larynx
The larynx extends from the superior tip of the epiglottis,
which is narrower in infants and children than in adults,
to the inferior border of the ericoid cartilage. The cficoid
is the only complete cartilaginous ring in the respiratory
Baxter: C O N G E N I T A L L A R Y N G O M A L A C I A
FIGURE 1 Embryologyof the larynx. Fourstagesin the
developmentof the larynx,whichizformedfrombranchialarches
III-VI. The laryngotrachealgrooveappearsin thefloorof the pharynx
in the 4 mmembryoat fourweeksof gestation,and continuesto
developoverthe nextsixmonths,untillhe fetusis 28 wk(seven
months).(Reproduced,withpernussion,fromCorlissCE, 19762)
tract and forms the foundation of the larynx. The cricoid
is also the narrowest part of the infant larynx. The rima
glottidis is higher in the newborn being opposite the C3~
interspace, descending to the adult level of the C4_5
interspace at 12 years. In addition, the glottis is angled
antero-inferiorly, rather than horizontally as in adults.4
The framework consists of cartilages and membranes,
which are partly ossified. There are nine cartilages, three
single and three paired. The single cartilages are the
epiglottic, thyroid, and erieoid cartilages. The paired
eartilages are the arytenoids, cornicdates and cuneiforms.
The thyroid cartilage forms the shield of the larynx. The
inferior horns of the thyroid, and the arytenoids articulate
with the erieoid (Figure 2).
The superior opening of the larynx is bound anteriorly
by the epiglottis, laterally by the aryepiglottic folds, and
posteriorly by the arytennids. In this way, the sphincter
of the aditus is formed.
The sphincter operates by contraction of the
aryepiglottic muscles, drawing the arytenoids anteriorly to the
FIGURE2 Posteriorviewof the laryngealcartilages.
back of the epiglottis. The epiglottis is also capable of
rolling posteriorly by the action of the paired
thyroepiglottis muscles.
Pathophysiology of C L M
Anatomically, in addition to the presence of redundant
supraglottie mucosa, six mechanisms of CLM have been
reported. The fast three are the most commonly seen
(Figure 3, Table I).
Neuromuscular a n d / o r cartilaginous defects or
immaturity are thought to contribute to this disorder. However,
no specific association has been confu-med with CLM
in the recent literature. 5,7
As the aetiology of these mechanisms is undetermined,
the term laryngomalacia is inaccurate (Greek: malakia
= sot~ening).
Severe congenital laryngomalacia - clinical features
Stridor (Table 111)
In one study, i stridor presenting secondary to congenital
laryngeal malformation was reported to be due to CLM
in 59.8% of eases. Its onset is usually in the neonatal
period.14 The stridor is high pitched in nature and
inFIGURE 3 The three most common anatomical abnormalitiesof
congenital laryngemalacia. All three variations may coexistduring the
relativelynegativepressurecreated during inspi (...truncated)