TITLE: Congenital
Laryngeal Anomalies
SOURCE: Grand Rounds Presentation, UTMB, Dept. of Otolaryngology
DATE:
RESIDENT PHYSICIAN: Russell D. Briggs, M.D.
FACULTY PHYSICIAN: Ronald W. Deskin, M.D.
SERIES EDITORS: Francis B. Quinn, Jr., MD and Matthew W. Ryan, MD
"This
material was prepared by resident physicians in partial fulfillment of
educational requirements established for the Postgraduate Training Program of
the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended
for clinical use in its present form. It was prepared for the purpose of
stimulating group discussion in a conference setting. No warranties,
either express or implied, are made with respect to its accuracy, completeness,
or timeliness. The material does not necessarily reflect the current or past
opinions of members of the UTMB faculty and should not be used for purposes of
diagnosis or treatment without consulting appropriate literature sources and
informed professional opinion."
Introduction
Congenital abnormalities of the larynx present the
otolaryngologist with a wide range of problems ranging from mild to
severe. Such anomalies may present at
the moment of birth with symptoms requiring immediate attention or may be more
insidious in presentation. Thus, it is
essential that all otolaryngologists treating children be aware of and have a
firm understanding of these conditions which arise from aberrations in
embryologic development.
Normal Anatomy
The larynx is a complex,
evolutionary structure that permits the trachea to be joined to the pharynx as
a common aerodigestive pathway. The
larynx is essential in several important functions: 1) ventilation of the
lungs, 2) protection of the lungs during swallowing, 3) clearance of secretions
by cough, and 4) production of sound.
The survival of the infant is predicated on the structural and
neurologic integrity of the larynx and, if altered, prompt diagnostic and
surgical intervention may be necessary.
The complex structures of the human
airway vary in anatomy and physiology from birth to adulthood. The infant larynx and trachea are
significantly smaller than that of an adult.
At birth, the infant larynx is approximately one third the size of an
adult. The glottis of the neonate
measures approximately 7 mm in the sagittal plane and 4 mm in the coronal
plane. The vocal cords of the newborn
infant are 6-8 mm long and the vocal processes of the arytenoids extend one
half of that length. In fact, the vocal
process of the arytenoid takes up half the length of the vocal cord in the
infant larynx, while it only takes up about ¼ of the length of the vocal cord
in the adult. The posterior glottis’ transverse length is approximately
4 mm. The subglottis has a diameter of
between 4.5 and 5.5 mm. These dimensions
leave little margin for obstruction in the infant, unlike the adult. The narrowest portion of the airway in the
older child and adult is the glottic aperture, while the narrowest part of the
airway in the infant is the subglottis.
A diameter of 4.0 mm is considered the lower limit of normal in a
full term infant and 3.5 mm in a premature infant. Indeed, an infant with one millimeter of
glottic edema will experience a 35% obstruction of the airway. In the subglottis, one millimeter of
circumferential edema leads to over 60%
narrowing.
The infant larynx is positioned
higher in the neck than the adult larynx.
The superior border of the larynx of the infant is located at about the
level of the first cervical vertebrae with the cricoid positioned at about the
fourth cervical vertebrae. In
comparison, the adult cricoid rests about the level of the sixth cervical
vertebrae. The structures of the infant
larynx are more pliable and less fibrous making the infant airway more
susceptible to narrowing from edema and less easily palpable.
The epiglottis is proportionally
narrower than that of an adult and assumes either a tubular form or the shape
of the Greek letter omega.
Embryology
Richter recorded the identification
of specific congenital laryngeal anomalies as early as 1792. In 1885, His described the appearance of the
respiratory primordium from an outpouching of the cephalic portion of the
developing pharynx by the third week of gestation. Indeed, the respiratory system is an
outgrowth of the primitive pharynx. The
development of the lower respiratory system begins at 26 days after conception
as the laryngotracheal groove (also known as the respiratory primordium) at the
ventral aspect of the foregut.
The laryngotracheal diverticulum becomes separated
from the foregut by the tracheoesophageal folds, which fuse to become the
tracheoesophageal septum. This septum
divides the foregut into a ventral laryngotracheal tube and a dorsal esophagus. Failure of the tracheoesophageal folds to
fuse during the fourth and fifth weeks can lead to a tracheoesophageal
fistula.
The larynx develops from the fourth and fifth
branchial arches. The laryngotracheal opening lies between these two
arches. This primitive laryngeal aditus
is altered to become a T-shaped opening by the growth of three tissue
masses. One is the hypobranchial
eminence. This mesodermal structure
eventually becomes the epiglottis. The
second and third growths are two arytenoid masses. As these masses grow between the fifth and
seventh weeks, the laryngeal lumen is obliterated. Recanalization occurs by the tenth week. Failure to recanalize may result in atresia,
stenosis or web formation in the larynx.
The arytenoid masses are separated by an interarytenoid notch, which
eventually becomes obliterated. If
obliteration does not occur, a posterior laryngeal cleft can result leading to
severe aspiration in the newborn.
Clinical Manifestations and Diagnosis
The clinical manifestations associated with
congenital anomalies of the larynx include: 1) respiratory obstruction, 2)
stridor, 3) a weakened or abnormal cry, 4) dyspnea, 5) tachypnea, 6)
aspiration, or 7) episodes of cyanosis, or 8) sudden death. The clinical presentation of each lesion varies
from the site being in the supraglottis, glottis, or subglottis. Although some congenital laryngeal lesions
will present later in life, the majority present with symptomatology in the
neonatal period or during infancy.
Laryngeal lesions typically present with stridor, hoarseness, aphonia, and
possibly feeding disorders. The stridor
is usually inspiratory or possibly biphasic in nature, and should be
differentiated from stertor, which primarily is caused by airway obstruction in
the nasal or pharyngeal regions. The
varied presentations of particular lesions will be discussed by region.
A child with a suspected congenital
laryngeal lesion should undergo a complete history and physical exam. In the infant or child, a thorough history
should be obtained which includes: history of prematurity and associated
medical problems and intubation records.
A premature infant who has been intubated for variable periods of time
may develop acquired lesions such as subglottis stenosis, subglottic cysts, or
intubation granulomas. Important
characteristics of the intubation include the date of first intubation,
duration, size of the endotracheal tube, number of intubations, and if any
intubations were traumatic. The birth
record should be reviewed to assess for any birth trauma. A history of noisy breathing and difficulty
feeding should lead to suspicion of airway problems. Growth curves should be reviewed and followed
to determine if the child has failure to thrive. Particularly the relationship of airway
symptoms to feeding is important to elicit in the history. Suspected foreign body aspirations should be
elicited and the details of changes in the baby’s cry should be discussed.
A complete head and neck exam should be performed on
all patients, if possible. It begins
with observing the patient for any apparent airway symptoms, which may include
irritability and restlessness in an infant or dyspnea, tachypnea, cyanosis, and
stridor in the infant. Voice quality in
a child and crying quality in an infant should be evaluated for weakness,
hoarseness, breathiness, or complete absence.
Flexible fiberoptic nasopharyngolaryngoscopy may be performed at the
bedside or in clinic on infants and some cooperative children if the patient is
stable. Vocal cord immobility, reflux
changes, immediate subglottic abnormalities, supraglottic sensation, and other
glottic and supraglottic abnormalities may be detected.
Radiographic evaluation includes AP and lateral views of the neck and chest. Such films are particularly useful to help rule out any stenotic lesions of the airway. A narrowed subglottic air column suggests a diagnosis of subglottic stenosis. If inspiratory and expiratory films are difficult to obtain, airway fluoroscopy can be beneficial to view the dynamic properties of the trachea. A barium swallow can be used in cases of swallowing difficulty to delineate conditions such as posterior laryngeal clefts, tracheoesophageal fistulae, or vascular rings which may compress the trachea. The use of computerized tomography or MRI has not been proven to be beneficial in assessing the majority of congenital laryngeal etiologies, but may be useful in select cases.
If the diagnosis remains uncertain, the gold standard for diagnosis of any congenital laryngeal abnormality remains direct laryngoscopy and tracheobronchoscopy under general anesthesia. This should be performed in the operating room with an experienced anesthesiologist. It is imperative to have all of your equipment arranged and checked prior to the patient coming into the operating room. Be sure to have a wide range of bronchoscope sizes in case the airway is much smaller than you anticipated! The potential need for tracheotomy should be discussed with the patient's family prior to endoscopy. A rigid bronchoscope or a rod lens telescope may be used to assess the airway. The important things to document during endoscopy are as follows: (1) the outer diameter of the largest bronchoscope or endotracheal tube that can be passed through a stenotic segment, if present, (2) the location/subsites (glottis, subglottis, trachea) and length of the stenosis, if present, (3) other separate sites of stenosis, (4) other airway anomalies in infants (clefts, webs, cricoarytenoid joint fixation, neoplasms, etc.), and (5) reflux changes.
Supraglottic Anomalies
Laryngomalacia
Laryngomalacia is the most common
congenital laryngeal anomaly. This
entity accounts for approximately 60 percent of laryngeal problems in the
newborn. Boys are affected twice as
often as girls. It is usually a
self-limiting condition, but when severe may produce life-threatening
obstructive apnea, cor pulmonale, and failure to thrive. Fatal outcomes have been described. Severe cases may require intubation or tracheotomy
to secure the airway. In a series of 56
infants wit congenital airway anomalies requiring tracheotomy, 21 cases had an
underlying laryngomalacia.
This condition arises from a
continued immaturity of the larynx, as if the fetal stage of laryngeal
development has persisted. The
abnormality appears to be flaccidity or incoordination of the supralaryngeal
cartilages, especially the arytenoids that is expressed when the infant is
stressed by excitation with an increased respiratory rate. Stridor is typically noted in the first few
weeks of life and is characterized by fluttering, high-pitched inspiratory
sounds. The supraglottic structures are
pulled into the lumen around a vertical axis with inspiration. The epiglottis is commonly omega shaped and the
aryepiglottic folds are short. Eating
difficulties and respiratory distress are rare.
Sternal retractions are seen frequently with labored respiratory effort.
The diagnosis can only be made by
clinical observation of the larynx during respiration. Inspection of the remainder of the
respiratory tract is sometimes necessary to rule out associated secondary
lesions such as innominate artery compression of the trachea or subglottic
stenosis. Radiologic assessment can
sometimes be a helpful adjunct if it captures the characteristic medial and
inferior displacement of the arytenoid cartilage or epiglottis.
Therapy consists of confirming the
diagnosis by flexible laryngoscopy and reassuring the parents that the
prognosis for the child is favorable.
Position changes of the infant may help alleviate the stridor as it typically
worsens in the supine position.
Continued vigilance by the pediatrician to be certain that the child
continues to grow, feed, and breath well is important.
In the past, tracheotomy was the
surgical procedure of choice for severe cases.
Variot was the first to describe incising the aryepiglottic folds in
severe cases of laryngomalacia. However,
the first effective surgical procedure was reported in 1922, when Iglauer
performed a partial epiglotticetomy.
Lane was the first to publish supraglottic trimming for the treatment of
laryngomalacia in 1984. A year later,
Seid described using the laser to divide the AE folds. Several series since have popularized this
supraglottoplasty technique with some investigators advocating the use of
associated epiglottiopexy in selected cases.
Supraglottoplasty has proven
successful for the correction of supraglottic obstruction and is now the
surgical procedure of choice. Direct
laryngoscopy and bronchoscopy should be done prior to the supraglottoplasty to
ensure that no other concomitant pathology is present. The precise mechanism of obstruction should
be confirmed with flexible laryngoscopy and surgical maneuvers should be
directed at those sites using sharp dissection or the CO2 laser. It is important to be conservative to prevent
supraglottis stenosis. Unilateral
supraglottoplasty should be considered and the second side operated on only if
symptoms continue. Polonovski describes
a suction test where an aspiration cannula is introduced in the supraglottic
inlet producing negative pressure, thereby reproducing the areas of
collapse. The test is repeated after
surgical excision to confirm improvement.
Results of supraglottoplasty have
been impressive. Roger published the
largest series comprising 115 cases.
Complete regression of symptoms occurred in 53% of cases. Stridor or effort dyspnea prevailed in
36%. Seven children improved after a
second procedure and 2 required eventual tracheotomy. Smaller studies have documented success rates
from 77-100%. Failures may be the result
of concomitant airway anomalies including pharyngomalacia. Tracheotomy may be necessary in these in
these cases, however some may respond to BiPAP, obviating the need for
tracheotomy.
Complications are rare and include
supraglottic stenosis and swallowing problems such as aspiration. Hemorrhage, granuloma formation, posterior
glottic stenosis, and cricoarytenoid joint fixation has been described.
The relationship of laryngomalacia
and GERD has been described but a direct causal relationship has not been
proven. Belmont found an 80%
radiological prevalence of GERD in infants with LM. Phelan suggested that GERD might be a result
of the high intraesophageal pressures generated. However, GERD may exacerbate
LM and some authors recommend treating this condition before eventual
surgery. Interestingly, however,
Polonovski did not find improved respiratory symptoms with antireflux therapy.
Supraglottic Webs
Congenital webs are diaphragmatic
growths of differing thickness that partially occlude the supraglottic
lumen. Supraglottic webs represent less
than 2 percent of congenital laryngeal webs with symptoms depending on the size
and position of the web. Symptoms can
include voice changes and dyspnea. Ten
percent of children have other associated anomalies.
Treatment consists of surgical lysis
using either the laser or sharp instrumentation, followed by dilatation. Tracheotomy should be considered if the web
is large and supraglottic swelling is anticipated postoperatively.
Bifid Epiglottis
Congenital bifid epiglottis is a
rare congenital laryngeal anomaly that may present with similar symptoms as
laryngomalacia with inspiratory stridor and airway obstruction. The patient’s history also frequently includes
episodes of cyanosis associated with feeding and occasional airway
obstruction. The midline split in the
epiglottis often renders the epiglottis incompetent in protecting the airway
during feeding and is often drawn into the airway during inspiration. Bifid epiglottis is associated with other
congenital syndromes including Pallister-Hall syndrome and polydactaly (40% of
cases). Patients should undergo an
endocrine evaluation because of the possible associations with hypothyroidism
and hypothalamic abnormalities. Surgical
management of the airway with tracheotomy may be necessary in severe cases.
Saccular Cysts
Congenital saccular cysts are
unusual laryngeal anomalies that are similar in their embryologic development
to laryngoceles. These lesions arise
from the vestigial laryngeal structure known as the saccule. Whereas the laryngocele is filled with air
and is connected to the airway, a saccular cyst is fluid filled. These cysts typically do not connect to the
internal laryngeal lumen.
Desanto has classified laryngeal
cysts as superior cysts (extend medially and posteriorly in the region of the
ventricle) or posterior cysts (extend into the region of the false cord and AE
fold). In cases of severe airway
obstruction at birth, immediate intervention is warranted with either
tracheotomy or intubation. Surgical
management of saccular cysts can be performed endoscopically using CO2 laser
and with sharp microlaryngeal instruments to marsupialize the cyst. Open surgical resection with an external
laryngofissure has also been described.
A high rate of recurrence is reported in several reports using
endoscopic techniques and many authors stress the importance of removing the
entire cyst lining.
Laryngocele
The laryngocele is a sac like
structure with an internal lumen that is dilated and filled with air. It represents a dilation of the ventricular
sinus of Morgagni beyond the confines of the laryngeal cartilage. They are classified as internal if they
remain within the laryngeal cartilage or external if they extend through the
thyrohyoid membrane. Combined lesions
may also occur. Fortunately, these are
rare in infants and can cause intermittent hoarseness and dyspnea that
increases with crying. Diagnosis may be
difficult as these can contract and may not be visualized under anesthesia. A CT may be valuable in these instances. Endoscopic and open procedures have been
advocated depending on the size and location of the laryngocele.
Lymphatic and Vascular Malformations
Hemangiomas are a type of hamartoma
that results in an anomalous development of blood vessels in a particular
region. Hemangiomas of the supraglottic
structures are rare. They can present
with dyspnea, stridor, or feeding difficulties.
As with hemangiomas of the subglottis, up to 30% are present at birth
and most grow over the first 6-18 months.
Most children, however, present in the first six months of life. Evaluation consists of careful endoscopic
examination with possible CO2 laser excision, observation, tracheotomy, or open
excision. As with other sites, gradual
regression is expected during the first five years of life.
Lymphatic malformations of the
supraglottis are cystic malformations that result from abnormal development of
lymphatic vessels. Lymphangiomas of the
valleculla may compress the epiglottis and cause airway distress. Symptoms may include bleeding, changes in
speech, dyspnea, and dysphagia. These
lesions do not regress with age and treatment typically consists of careful
endoscopic confirmation followed by reduction of the lesion with the CO2 laser
or YAG laser. Complete excision of these
lesions is often compromised by surrounding vital structures that should not be
sacrificed.
Anomalous Cuneiform Cartilages
This embryonic abnormality is the
result of a malformation of the lateral masses, which are derived from a
portion of the sixth branchial arch.
Symptoms mimic laryngomalacia with stridor, airway distress, and dyspnea
on exertion. Associated anomalies
including ankyloglossia and macroglossia may occur. Treatment should be tailored to
symptoms. Should severe airway
obstruction be present, tracheotomy and possible supraglottic laryngectomy may
be necessary.
Glottic Anomalies
Vocal Cord Paralysis
Vocal fold paralysis has long been
recognized as a significant cause of stridor and hoarseness in infants and
children. It is the second most common
cause of stridor in the newborn behind laryngomalacia. The frequency of vocal cord paralysis varies. Narcy quotes it as representing 23% of
congenital laryngeal pathology, whereas Holinger and Fearon quote lower figures
of 10% and 6.5% respectively. Some
authors report unilateral paralysis to be more common and others report
bilateral paralysis to be more frequent.
Laryngeal paralysis may be present at birth or may manifest itself in the
first month or two of life. The
neurologic impairment reflects an injury to the vagus nerve. The lesion can occur anywhere from the brain
through the neck into the chest and into the larynx. Many paralyses are idiopathic (cause unknown)
in up to 47% of cases, however the most common causative factors include
entities such as Arnold Chiari malformations, hydrocephalus, neonatal
hypotonia, and multiple peripheral paralysis (myasthenia gravis). Other causes include birth trauma and cardiac
anomalies. Associated laryngeal lesions
such as clefts and stenosis are also commonly often found.
Any or all of the normal laryngeal
functions (voice, respiration, deglutition) may be
abnormal in the pediatric patient with laryngeal paralysis. The most common symptom is stridor. Ineffective cough, aspiration, recurrent
pneumonia, and feeding difficulties are also commonly reported. Consistent stridor, cyanosis, and apnea are
frequent. Voice and cry, however, may be
normal particularly in cases of bilateral vocal cord paralysis. Hoarseness and dysphonia are common in cases
of unilateral vocal fold paralysis.
The initial concern in any child
with suspected laryngeal paralysis is airway stability. Extensive diagnostic evaluations are deferred
until the airway is stabilized and secured.
This is best achieved under the controlled setting of an operating room
with appropriate airway instrumentation available. In those instances in which respiratory
distress is not a primary concern, a thorough and unhurried evaluation is
warranted. A careful history and
physical exam is necessary. A complete
past medical history including a difficult delivery, prior surgical procedures,
or other congenital anomalies can provide important clues to this
diagnosis.
Various methods have been used to
document laryngeal paralysis. Neck
films, fluoroscopy, and ultrasound have all been evaluated and are
unsatisfactory in diagnosing this condition for a number of varied reasons. Chest films however are useful in diagnosing
associated cardiac or pulmonary anomalies, both of which are common in cases of
unilateral paralysis. Flexible
laryngoscopy in the awake patient, however, is the gold standard for the
diagnosis of this condition. Once the
diagnosis is made, a search for the underlying cause is warranted. The entire course of the vagus nerves should
be imaged. This should include CT or MR
imaging. A barium swallow can provide
evidence of subtle neurologic abnormalities, abnormal sensation to the larynx,
and can document associated mediastinal anomalies such as vascular rings. While flexible laryngoscopy is invaluable in
this diagnosis, rigid laryngoscopy and bronchoscopy is important for the
identification of associated anomalies or when the cause remains unknown after
a noninvasive workup has been complete.
Paralysis must be differentiated from cricoarytenoid joint fixation or
posterior glottic stenosis, both which can lead to a similar presentation.
Management strategies depend on the
child’s underlying condition. Children with
bilateral vocal fold paralysis frequently require surgical intervention. The airway is often markedly compromised and
in over 50% of cases a tracheotomy is required.
In cases of mild airway symptomatology with bilateral vocal fold
paralysis, expectant close follow up is possible. In cases of Arnold Chiari malformation and
bilateral vocal fold paralysis, many authors recommend that prior to an
invasive airway procedure (tracheotomy), a VP shunt or posterior fossa
decompression be performed. Some authors
contend that in these cases, nasotracheal intubation for four weeks should be
considered, as the potential for vocal cord return is good. Others recommend immediate tracheotomy to
secure the airway prior to further procedures and testing. Once a tracheotomy is performed, serial
endoscopy is performed to detect a return of function. Most authors recommend waiting at least one
year prior to any irreversible lateralization procedures. EMG may provide prognostic information during
this time frame. Spontaneous resolution
of vocal cord paralysis is thought it occur in 48-64% of cases, with rapid
improvement in many patients after correction of their hydrocephalus and
ACM. Multiple
lateralization procedures have been proposed for those patients who do not
resolve. Surgical widening of the
glottis must balance voice and airway patency issues. Older techniques such as the Woodman
procedure have been abandoned. CO2 laser
cordotomy and open arytenoidectomy, artenoidpexy, arytenoid separation with
cartilage grafting or laser arytenoidectomy and cordectomy have been proposed
as more efficacious alternatives.
Decannulation rates of over 60% can be expected. Reanimation of the larynx is another form of
vocal cord rehabilitation for patients with bilateral vocal cord
paralysis. Phrenic to recurrent
laryngeal nerve anastomosis, phrenic to PCA muscle, and omohyoid nerve muscle
pedicles have all been utilized. Success
rates in the pediatric population are reported to be 50%. Electrical stimulators are also being
explored.
The management of unilateral vocal
cord paralysis in children is usually less urgent than that of bilateral
paralysis. Children adjust well to
persistent unilateral vocal cord paralysis with few sequelae. A weakened cry may result but an adequate
airway is the typically maintained.
Lateral augmentation procedures and thyroplasty techniques are not
recommended in children, as speech therapy is the mainstay in this population. Thyroplasty may play a role in older children
that fail conservative measures with significant dysphonia.
Laryngeal Webs
Laryngeal webs form when there is a
failure of recanalization of the larynx during embryonic development, and if it
persists at birth, may cause respiratory distress. Seventy-five percent of webs occur at the
level of the glottis as a membrane of differing thickness that partially
occludes the lumen. The web is generally
located anteriorly with a concave posterior glottic opening. Most webs are thick and fibrous with a
subglottic extension.
The presentation of laryngeal webs
varies with the severity and type of the web.
Type I laryngeal webs involve 35% or less of the glottis. The true vocal cords are visible through the
web and there is little or no subglottic extension. Symptoms include a mildly abnormal cry with
some hoarseness. Respiratory distress is
usually not a feature. Type II webs are
anterior webs involving 35-50% of the glottis.
Subglottis involvement stems more from thick anterior webbing than from
cricoid abnormalities. Airway symptoms
are uncommon except during infection or after intubation trauma. The voice is typically weak. Type III webs involve 50-75% of the glottis. The web is thick anteriorly and the true
vocal cords may not be visualized. There may be associated cricoid
anomalies. Airway symptoms are often
severe and marked vocal dysfunction may occur.
Type IV webs occlude 75-90% or more of the glottis. It is uniformly thick and the true vocal cord
is not identifiable. The patient is
aphonic and immediate airway management is required at birth.
The diagnosis of this condition is
usually clear on flexible laryngoscopy, however airway films may aid in the
diagnosis if subglottic or cricoid pathology is also present. Treatment of this anomaly is dependent of the
type of web and symptomatology. Thin
membranous type I webs which produce only minimal symptoms can be observed
until age 3-4 years and then divided with either the CO2 laser or cold knife. Mitomycin-C may also be applied. Some authors employ local flaps to prevent
recurrence. Type II webs can be managed
by incising the web along one vocal cord and then proceeding with staged
dilations or by incising the web on the opposite cord two weeks later. Keel placement through an open or endoscopic
approach may be necessary and a tracheotomy is generally advised if a keel is
placed. Treatment of type III and IV
webs is usually delayed until the child is 3-4 years old. Most infants will have a tracheotomy in place
for airway control until definitive surgery is undertaken. The standard treatment for these conditions
entails a tracheotomy, laryngotomy, and keel insertion. An alternative treatment is an early single
stage laryngotracheal reconstruction with submucosal resection of the abnormal
cricoid, mucosal flap elevation, and rotation to the anteromedial aspect of the
TVC's. A tracheotomy may be avoided with
this approach.
Posterior glottic webbing is rare
but usually consists of a thin membranous sheet between the posterior
TVC's. Minor webs may respond to simple
division and dilation, however interarytenoid webs with significant posterior
glottic stenosis may require a laryngofissure, a posteriorly placed costal
cartilage graft, and stenting.
Laryngeal Atresia
Laryngeal atresia is a rare
congenital anomaly that is incompatible with life unless emergency measures are
undertaken at birth. This condition
represents the most severe end of a spectrum of diseases arising from failed
recanalization of the larynx during embryogenesis. These infants only survive if there is an
associated tracheoesophageal fistula or if a tracheotomy is performed
immediately after birth. If a
tracheoesophageal fistula is present, intubation of the esophagus may allow
ventilation while airway access is being obtained. Repair of the atresia requires a formal
laryngotracheal reconstruction at a later stage. This disorder is usually accompanied by a
host of another anomalies including tracheoesophageal fistulae, esophageal
atresia, urinary tract anomalies, and limb defects.
Congenital High Upper Airway Obstruction (CHAOS)
Congenital high airway obstruction
(CHAOS) was defined by Hedrick in 1994 as upper airway obstruction that is
diagnosed in utero by ultrasound, with concomitant findings of large echogenic
lungs, flattened diaphragms, dilated airways distal to
the obstruction, and fetal ascites or hydrops.
There have been several reports of survival in infants with CHAOS who
undergo the EXIT procedure (ex utero intrapartum treatment). The EXIT procedure was originally designed to
treat children with large cervical masses that where diagnosed in utero and
caused airway obstruction. CHAOS may not
be diagnosed if a TEF is present as the fetal lung fluid is able to pass from
the pulmonary system.
The EXIT procedure requires a multidisciplinary
team approach. A cesarean section is
performed with partial deliverance of the fetus while maintaining fetoplacental
circulation. Bronchoscopy and
tracheotomy can be performed expeditiously with successful outcomes reported.
Subglottic Anomalies
Subglottic Hemangiomas
Subglottic hemangiomas are
congenital vascular lesions that present with symptoms ranging from minimal
airway obstruction to severe, life threatening respiratory distress.
Hemangiomas are present at birth only 30% of the time, with the majority of
cases presenting within the first few months of life. The natural history of these lesions is
similar for hemangiomas found elsewhere in the body. Typically, there is a rapid growth period
that is initiated within the first few weeks or months of life and continues
for 12-18 months. There is a phase where
the lesion is stable and then a subsequent period of involution. Most hemangiomas involute completely by five
years of age though some may not involute completely. Subglottic hemangiomas have a 2:1 female
predominance.
Typically infants with subglottic
hemangiomas are asymptomatic for the first few months of life and become
symptomatic by the age of 3 months.
Almost all are symptomatic by the age of 6 months. Stridor may initially be inspiratory but
quickly becomes biphasic. The cry may be
altered and the infant may have a barking cough, hoarseness, croupy symptoms,
and occasional hemoptysis. Cutaneous
hemangiomas occur in approximately 50% of children with subglottic hemangiomas. Thus, a child's skin must be thoroughly
examined in all cases of infant stridor.
The diagnosis of subglottic
hemangioma, in most cases, can be made on clinical history, physical
examination, and endoscopic appearance.
Rigid endoscopy should be performed to make the definitive diagnosis,
however biopsy is not always necessary.
The lesion is typically a compressible symmetric bluish or reddish
submucosal mass most often found in the posterior lateral subglottis. Asymmetric subglottic narrowing seen on neck
films is almost pathognomic of a subglottic hemangioma as this finding is
rarely seen in croup, subglottic cysts, subglottic stenosis, or RRP. MRI or CT with contrast can better delineate
the lesion and assess for neck or mediastinal extension.
Numerous management options exist
for subglottic hemangiomas. The decision
of what therapeutic measure to take is directed at maintaining an airway while
minimizing the potential long-term sequelae of the treatment itself. The treatment modalities that have been
described include laser ablation using the CO2 or KTP laser, tracheotomy,
external beam radiation, radioactive gold grain implantation, cryotherapy,
sclerosing agents, corticosteroid therapy (systemic or intralesional), and open
surgical excision. The most common
intervention is CO2 laser ablation. When
used conservatively, this is an appropriate treatment modality. There is, however, a risk of subsequent
subglottic stenosis cause by overaggressive, circumferential lasering of large
lesions. A recent report documented a
20% rate of subglottic stenosis after this treatment modality. Laser therapy is often coupled with
intravenous and injectable corticosteroid therapy. Large lesions may respond solely to high dose
intravenous corticosteroid therapy (1-2 mg/kg/day). Long-term side effects from this therapy may
occur (growth retardation, cushingnoid appearance, and sepsis). Children with large subglottic hemangiomas
causing severe airway obstruction, necessitating tracheotomy, may benefit from
an open procedure. This may be performed
in a single stage procedure requiring postoperative intubation for 7-10
days. A delayed procedure with delayed
tracheotomy decannulation after subglottic healing may also be performed. Many authors feel the standard of care is
tracheotomy with observation for involution.
This method is the method by which all others should be compared.
Posterior Laryngeal Cleft
The laryngeal cleft arises at
approximately 35 days of gestation from failure of rostral development of the
tracheoesophageal septum. Failure of the
interarytenoid tissue or cricoid cartilage to fuse in the posterior midline
will result in a laryngeal cleft.
The incidence is less than 0.1% and
the majority of cases are sporadic.
There is a strong association with other anomalies such as
tracheoesophageal fistulae. It is
important to remember that 6% of patients with a TEF will have a concomitant
laryngeal cleft producing continued aspirations symptoms. Laryngeal clefts are also seen in Pallister-Hall
syndrome and G-syndrome. Respiratory
distress is usually precipitated by feeding and is often associated with
cyanosis. Voice abnormalities are often
present and GERD is a major contributor to overall pulmonary compromise. Infants with these clefts often have
recurrent aspiration, leading to pneumonia and death. The severity of the symptoms depends on the
extent of the laryngeal cleft.
Patients suspected of having a
laryngeal cleft require radiographic evaluation. Chest radiographs frequently show aspiration
pneumonitis that is severe. A barium
swallow is the most important diagnostic tool for showing spillover of contrast
material into the trachea. Endoscopy is required
to make the definitive diagnosis of a laryngeal cleft. Great care must be taken to document the
relationship of the cleft to the level of the vocal cords.
Numerous classification systems
exist for laryngeal clefts. Benjamin and
Inglis describe type I clefts as a supraglottic, interarytenoid clefts. Type II clefts are a partial cricoid
cleft. Type III clefts are a complete
cricoid cleft with or without extension into the esophagus and type IV cleft
are full laryngotrachealesophageal clefts.
Surgical repair must be taken in all
cases of symptomatic clefts. Type I clefts
can sometimes be managed nonsurgically with speech and feeding therapy aimed
towards decreasing aspiration. GERD must
be controlled. When conservative
measures fail to prevent aspiration, endoscopic or open repair of the cleft may
be possible. Type II and III clefts can
be approached via an anterior laryngofissure or a lateral pharyngotomy. A
tracheotomy and two-layer closure are then performed. Type IV clefts require a lateral pharyngotomy
and right thoracotomy or a midline anterior approach with a median sternotomy
with the patient on cardiac bypass.
The overall mortality rate of
laryngeal clefts is 43%. Type IV clefts
have a reported mortality rate of 93%, however the mortality rate is decreasing
with advances in surgical technique.
Subglottic Stenosis
Subglottic stenosis (SGS) may be classified as
either acquired or congenital. Although
congenital subglottic stenosis is uncommon, accounting for 5% of all cases, it
is the third most common congenital airway problem (after laryngomalacia and
vocal cord paralysis). Congenital SGS is
thought to be secondary to failure of the laryngeal lumen to recanalize
properly during embryogenesis. SGS is
considered congenital if there is no history of endotracheal intubation or
other forms of laryngeal trauma.
Congenital SGS is divided
histopathologically into membranous and cartilaginous types. Membranous SGS is usually circumferential and
consists of fibrous soft-tissue thickening caused by increased fibrous
connective tissue or hyperplastic submucous glands. It may involve the vocal folds as well. The cartilaginous type usually results from a
thickened or deformed cricoid cartilage that forms an anterior subglottic shelf
that extends posteriorly allowing only a small posterior opening. Other malformations can occur such as an
elliptical cricoid leaving a slit-like opening or a trapped first tracheal
ring. Membranous SGS is usually less severe than the cartilaginous type.
Congenital
SGS is often associated with other congenital malformations. A thorough search for associated anomalies is
necessary.
Subglottic stenosis is defined as a
subglottic lumen 4.0 mm in diameter or less at the level of the cricoid in a
full term infant. The normal newborn
subglottic diameter is 4.5 – 5.5 mm and in premature neonates around 3.5
mm. A subglottic diameter of less than
3.5 mm in a premature infant is stenotic.
The severity of congenital subglottic stenosis
depends on the degree of subglottic narrowing.
The symptoms can range from mild with a picture of recurrent croup to
severe with respiratory distress at delivery.
Children with subglottic stenosis usually present with stridor and/or
respiratory distress. Symptoms include
irritability, restlessness, dyspnea, tachypnea and cyanosis. The stridor is typically biphasic
(inspiratory and expiratory components) due to turbulent airflow through the
partially obstructed airway. Frequently,
children with mild congenital SGS have no symptoms until they develop an upper respiratory
tract infection or under physical exertion.
Any child under age one with recurrent croup should undergo endoscopy to
rule out congenital SGS.
The evaluation of SGS includes a complete history and physical examination. The standard for diagnosis is rigid endoscopy under general anesthesia however airway films can demonstrate subglottic narrowing, particularly at multiple levels. These should be taken prior to undergoing evaluation in the operating room.
Historically, classification of subglottic stenosis has been a
problem. Measurements were done either
subjectively or by using various instruments including rigid bronchoscopes,
laryngeal forceps and angioplasty catheters.
Today, there is still no universally accepted
staging system for subglottic stenosis.
The most commonly used system was developed by Cotton in 1984 then
revised in 1989. The percentage of
obstruction and anatomic location of the lesion were determined endoscopically
and assigned a grade I-IV based on perceived percentage of obstruction. Although this system was successful at
relating the severity of the obstruction with the prognosis for decannulation,
it remained imprecise and dependent on skilled judgment. For these reasons, Myer, Conner and Cotton
proposed a grading system based on endotracheal tube sizes.
The Myer-Cotton staging system is useful for
mature, firm, circumferential stenosis confined to the subglottis. It describes the stenosis based on the
percent relative reduction in cross-sectional area of the subglottis which is
determined by differing sized endotracheal tubes. Four grades of stenosis are described with
this system: grade I lesions have less
than 50% obstruction, grade II lesions have 51% to 70% obstruction, grade III
lesions have 71% to 99% obstruction, and grade IV lesions have no detectable
lumen or complete stenosis.
The McCaffrey system classifies
laryngotracheal stenosis based on the subsites involved and the length of the
stenosis. Four stages are
described: stage I lesions are confined to
the subglottis or trachea and are less than 1cm long, stage II lesions are
isolated to the subglottis and are greater then 1 cm long, stage III are
subglottic/tracheal lesions not involving the glottis, and stage IV lesions
involve the glottis.
Treatment of congenital SGS is tailored
to the symptoms and grade of the stenosis.
Symptoms are typically less severe in congenital SGS than in the
acquired form. Congenital SGS also
improves as the child grows, and less than half of children with this disorder
will require a tracheotomy. For those
children who do require surgical intervention, several options are available.
Mild stenosis (Cotton-Myer grades I
and II) can
usually be treated conservatively with observation. In cases that do require surgery, endoscopic
techniques such as CO2 laser resection of a membranous web can be
performed. Dilation has nothing to offer
in the management of cartilaginous subglottic stenosis. Factors associated with failure of these
endoscopic techniques include: previous attempts at endoscopic repair,
circumferential scarring, loss of cartilaginous support, exposure of cartilage
during laser excision leading to chondritis, severe bacterial infection,
posterior inlet scarring with arytenoid fixation, combined laryngeal or
tracheal stenosis or vertical scar length >1cm. Endoscopic dilation has had disappointing
results and should be abandoned for congenital SGS.
Grade III or IV stenosis may require some form of
open surgical procedure, as these typically are the result of a cartilaginous
stenosis. Several techniques have been
described.
The anterior cricoid split (ACS)
procedure was originally described for a neonate who has had multiple failed
extubations instead of performing a tracheotomy (Cotton and Seid, 1980). This procedure is also used for older infants
and those who are have already been tracheotomized. Indications were later expanded to patients
with congenital subglottic stenosis.
Strict criteria for ACS have been established by Cotton and include:
extubation failure on two occasions or more due to laryngeal pathology, weight
>1500g, no assisted ventilation for 10 days prior to evaluation, O2
requirements <30%, no CHF for one month prior to evaluation, no acute
respiratory tract infection, no antihypertensive medications ten days prior to
evaluation. The procedure is performed
after direct laryngoscopic and bronchoscopic confirmation of the
diagnosis. All other airway pathology
must be ruled-out.
A vertical midline incision is made
through the cricoid cartilage and first two tracheal rings as well as the lower
thyroid cartilage. This allows the
cartilages to spring open and allow edematous mucosa to drain, increasing
airway size. Prolene stay sutures are
placed on either side of the cricoid cartilage and the skin is re-approximated
after placement of a drain. The child is
then left intubated, sedated and paralyzed in the ICU for 7-14 days. Cotton has guidelines for endotracheal tube
sizes for stenting and for duration of stenting based on the infant’s weight.
Laryngotracheal
expansion surgery involves scar division with distraction of the edges by
interposition of graft material (augmentation) to widen the airway lumen. It is important to avoid removing scar, which
results in a large surface area of denuded mucosa and leads to restenosis. Cotton recommends augmenting the airway with
grafts when the distraction of the laryngotracheal framework must be greater
than approximately 3mm. There are several techniques depending on the location
and severity of the stenosis. Laryngotracheoplasty can be performed with a
tracheostomy and formal stenting or by using the endotracheal tube as a stent,
the latter known as a single-stage LTP (SS-LTP). There are a several stents that can be used
for LTS including: endotracheal tubes,
Silastic sheet rolls, Montgomery T-tubes, and laryngeal stents. Laryngeal stents include: teflon stents [Aboulker stent (short or
long), ETS Poirot, Paris], and silastic stents (Montgomery stents: Boston Medical Products, Boston. The primary consideration when deciding on
the type of reconstruction and stent material is to provide a safe airway and
adequate support for the graft. Success
of LTR among, other things, is determined by the surgical procedure, including
possible need for stenting; choice of type and length of stent; and duration of
stenting. Choosing the appropriate
method for stenting requires considering consistency of stenosis, altered
anatomy, size, location and stability of grafts when used for surgical repair
and host tissue healing factors (Zalzal, 1988)
Autogenous
costal cartilage is the material of choice for grafting. Many other materials have been used for
grafting including auricular, hyoid and thyroid cartilage and bone. Cartilage has much less resorption over time
compared to bone. Although bone provides
good structural support, grafts in the airway do no bear a lot of stress or
weight.
Anterior laryngofissure with anterior lumen augmentation is a technique that is good for anterior subglottic stenosis or anterior tracheal wall collapse. The lesion should not involve the glottis. Other procedures should be considered if there the cricoid cartilage is deformed or weak. Anterior grafts are made considerably larger and thicker than grafts placed posteriorly. The perichondrium is oriented to the luminal side to allow for epithelialization. The perichondrium is also a good barrier against infection. A large external flange is created to prevent the graft from prolapsing into the airway.
Laryngofissure
with division of posterior cricoid lamina is indicated for patients with
posterior subglottic stenosis, posterior glottic stenosis that extends to the
glottis, complete or circumferential stenosis, or if there is significant
cricoid deformity. Division of the
anterior and posterior cricoid must be carried out for this procedure. If possible, one should avoid a complete
laryngofissure to avoid damaging the anterior commissure, however this is often
needed for posterior glottic involvement for access. The posterior cricoid cartilage is incised in
a manner that is vertically oriented to the cartilage to allow maximal purchase
for the graft. The incision is extended
superiorly to the interarytenoid area and inferiorly 5 to 10 mm into the
membranous trachea. The graft is elliptical in shape. It should not be too thick as it can cause
swallowing difficulties and can lead to aspiration. The width of the graft is determined by the
desired distraction of the cut edges of the incised posterior cricoid
cartilage. 0.05 to 1.00 mm of
distraction can be obtained for each year of age, up to 1 cm. It is sutured in place with absorbable suture
on a small cutting needle. The knots
should be buried so that they remain extraluminal to prevent development of
granulation tissue. Long-term stenting
is usually necessary (3-6 months).
Laryngofissure and division of posterior cricoid
lamina with anterior and posterior grafts
should be used for patients who have SGS similar to those above but with a
significant amount of stenosis posteriorly such that grafting is necessary to
maintain the adequate separation.
Once the grafts have been sutured into place in any of
the above procedures, the decision must be made on whether it should be single
or double-staged. Cotton and Walner
(1999) recommend a double-staged procedure for patients with severe stenosis,
history of reactive airway, or poor pulmonary function. This should also be
considered at institutions with inadequate intensive care facilities. Double-stage procedure implies placement of
stent above the tracheostomy tube instead of using an endotracheal tube as the
stent (single-staged procedure). Once
this decision is made, the strap muscles are closed to provide blood supply to
the outer surface of the anterior graft.
The first cricotracheal resection (CTR) with
thyrotracheal anastomosis was performed by Conley in 1953 in a patient
undergoing surgery for chondroma of the cricoid cartilage. It was later popularized by Ogura and powers
(1964) as a technique for treatment of traumatic stenosis. In the 1970s it became the treatment of
choice in adults with acquired subglottic stenosis from long term
intubation. Until recently, surgeons
were reluctant to perform this procedure in the pediatric patients because of the
risk of anastamotic dehiscence and recurrent laryngeal nerve injury, and
disturbing the normal growth of the larynx.
The first successful CTR performed in a child was occurred in 1978
(Savary). It wasn't until 1993, however,
that the first series of 15 pediatric patients treated with CTR for severe LTS
was published. Multiple subsequent
series have reported using CTR for severe LTS with good outcomes (Monnier et
al., 1995, Monnier et al., 1998, Stern and Cotton, 1999).
This technique is indicated if there is severe deformity of the cricoid making grafting very likely to fail. Most say that there must be at least 10 mm of normal airway below the glottis, however Cotton states that the resection can be up to the vocal folds but to expect prolonged edema. This technique is technically difficult due to the close proximity of the vocal cords and recurrent laryngeal nerves. Stenosis less than 4 cm can be resected by laryngeal release and cervical tracheal mobilization. Stenting is not required and the tracheotomy tube can usually be removed at around 4 weeks.
The goal of management of subglottic stenosis is
decannulation. Success rates are
dependent on the cause of the stenosis, the number of previous failed attempts,
the status of the remainder of the airway, especially the glottis and the
severity of the stenosis. Cotton has
reported an overall pediatric LTR success rate of 92%, 97% for Grade II, 91%
for Grade III, and 72% for Grade IV.
Bailey (1988) reported results of 131 pediatric airway
reconstructive procedures. He had a 92%
success rate with patients who underwent laryngotracheoplasty procedures (no
grafting) and 80% success with patients who underwent LTR (with grafting). He did not report on use of any grading
system.
Monnier
et al. (1999) has reviewed the
experience with CTR at the Department of Otolaryngology at the University of
Lausanne, Switzerland. 69 CTRs were
performed (48 infants and children and 21 in adults). 95% and 100% of the pediatric and adult
patients, all of whom had Cotton-Myer grade III or IV stenosis, were
successfully decannulated. Stern and
Cotton (1999) reported on 38 pediatric patients who underwent CTR for severe
LTS (grade III and IV). 33 patients were
successfully decannulated. Complications
preventing decannulation in this study included one patient with persistent
aspiration, three who restenosed, one with arytenoid prolapse, and one with
recurrent laryngeal nerve injury.
Overall, 94% successful decannulation has been reported in the
literature when CTR is used in pediatric patients with severe LTS (Monnier,
1999).
Bibliography
Cotton
RT, Prescott CJ. Congenital anomalies of
the larynx. In: Practical
Pediatric
Otolaryngology.
Cotton RT and Myer CM eds. Philadelphia, PA:
Lippincott-Raven:
1999: 497-514.
Cotton
RT, Reilly JS. Congenital malformations
of the larynx. In: Pediatric
Otolaryngology. Bluestone CD, Stool
SE, and Kenna MA eds. Philadelphia: WB
Saunders: 1996.
De
Jung AL, Coppersmith RB, Sulk M, et al.
Vocal cord paralysis in children.
Otolaryngol Clin N Am 33(1): 131-149.
Hartnick
CJ, Cotton RT. Congenital laryngeal
anomalies. Otolaryngol Clin N Am
33(6): 1293-1308.
Hartnick CJ, Rutter M, Lang F, et al. Congenital high airway obstruction syndrome and
airway reconstruction. Arch
Otolaryngol Head Neck Surg 128: 567-570.
Lee
KJ. Embryology of Clefts and Pouches.
In: Lee KJ, ed. Essential
Otolaryngology,
Appleton
& Lange, 1991: 243.
Sichel J, Dangoor E, Eliashar R, et al. Management of congenital laryngeal
malformations. Am J Otolaryngol
21(1): 22-30.
Sie
KCY, McGill T, Healy GB: Subglottic
hemangioma: Ten years' experience with
the
carbon dioxide laser. Ann Otol Rhinol Laryngol 1994; 103:167.
Tucker
JA, Tucker GF, Vidic B. Clinical correlation of anomalies of the supraglottic
larynx
with staged sequence of normal human laryngeal development. Ann Otol
Rhinol
Laryngol
1978; 87:636.
Walner
DL and Cotton RT. Acquired anomalies of
the larynx and trachea. In: Practical
Pediatric
Otolaryngology.
Cotton RT and Myer CM eds. Philadelphia, PA:
Lippincott-Raven: 1999:515-537.
Wiatrak
BJ. Congenital anomalies of the larynx
and trachea. Otolaryngol Clin N Am
33(1): 91-110.