Subglottic Stenosis in Children
Author: John
E McClay, MD, Assistant Professor, Department of
Otolaryngology, Division of Pediatric Otolaryngology, Children's
Medical Center, University of Texas at Southwestern
Editor(s): Russell A Faust, MD, PhD, Carls
Foundation Endowed Chair, Pediatric Otolaryngology, Assistant
Professor, Departments of Otolaryngology and Pediatrics,
Children's Hospital of Michigan; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor,
eMedicine; Gregory
C Allen, MD, Assistant Professor, Department of
Otolaryngology-Head and Neck Surgery, University of Colorado
School of Medicine; Christopher L Slack, MD,
Consulting Staff, Otolaryngology-Facial Plastic Surgery,
Lawnwood Regional Medical Center; and Arlen D Meyers,
MD, MBA, Professor, Department of Otolaryngology-Head
and Neck Surgery, University of Colorado Hospital
INTRODUCTION
Subglottic stenosis (SGS) is a narrowing of the subglottic airway (see
Picture 1), which is housed in the cricoid
cartilage. The subglottic airway is the narrowest area of the airway,
since it is a complete, nonexpandable, and nonpliable ring, unlike the
trachea, which has a posterior membranous section, and the larynx,
which has a posterior muscular section. The term SGS implies a
narrowing that is created or acquired, although the term is applied to
both congenital lesions of the cricoid ring (see Picture
3, Picture 4, Picture 5)
and acquired SGS (see Picture 2, Picture
6, Pictures 7-10, Picture
12-16, Picture 30).
Acquired SGS is the most common acquired anomaly of the larynx in
children and the most common abnormality requiring tracheotomy in
children younger than 1 year. Correction of this abnormality requires
expanding the lumen of the cricoid area to increase airflow and
decrease obstructive breathing. Surgical correction of SGS has been
performed with various techniques over the years.
History of the Procedure: Early in the 20th
century, acquired SGS usually was related to trauma or infection from
syphilis, tuberculosis, typhoid fever, or diphtheria. Also, children
often had tracheotomies placed that caused laryngeal stenosis. In this
era, attempted laryngeal dilation failed as a treatment for SGS.
Acquired SGS occurred increasingly in the late 1960s through the
1970s, after McDonald and Stocks (in 1965) introduced long-term
intubation as a treatment method for neonates in need of prolonged
ventilation for airway support. The increased incidence of SGS focused
new attention on the pediatric larynx, and airway reconstruction and
expansion techniques were developed.
Surgery without cartilage expansion
In 1971, Rethi and Rhan described a procedure for vertical division
of the posterior lamina of the cricoid cartilage with Aboulker stent
placement. A metal tracheotomy tube was attached to the Aboulker stent
with wires, and the anterior cartilaginous incision was closed. In
1974, Evanston and Todd described success with a castellated incision
of the anterior cricoid cartilage and upper trachea, which was sewn
open, and a stent made of a rolled silicone sheet was placed in it for
6 weeks. In 1980, Cotton and Seid described a procedure, in which
tracheotomy is avoided, called the anterior cricoid split (ACS). The
procedure was designed for use in neonates (usually, those born
prematurely) with anterior glottic stenosis or SGS who had airway
distress after extubation. The cricoid ring was divided anteriorly and
a laryngofissure was created in an attempt to expand the airway
without a tracheotomy. Holinger et al also described success with this
procedure in 1987.
Surgery with cartilage-grafting reconstruction
In 1974, Fearon and Cotton described the successful use of
cartilage grafts to enlarge the subglottic lumen in African green
monkeys and in children with severe laryngotracheal stenosis. All
augmentation materials were evaluated, including thyroid cartilage,
septal cartilage, auricular cartilage, costal cartilage, hyoid bone,
and sternocleidomastoid myocutaneous flaps. After significant work, it
appeared that costal cartilage grafts had the highest success rate.
In the 1980s, Cotton reported his experience with laryngeal
expansion with cartilage grafting. His success rates depended on
degree of stenosis: More severe forms of stenosis required multiple
surgical procedures. Cotton used the Aboulker stent.
In 1991, Seid et al described a form of single-stage
laryngotracheal reconstruction in which cartilage was placed
anteriorly to expand the subglottis and upper trachea to avoid a
tracheotomy.
In 1992, Cotton et al described a 4-quadrant cricoid split, along
with anterior and posterior grafting. In 1993, Zalzal reported 90%
decannulation with any degree of SGS with his first surgical
procedure. Zalzal customized the reconstruction on an individual
basis, and most patients received Aboulker stents for stabilization.
Cricotracheal resection
In 1993, Monnier described partial cricotracheal resection with
primary anastomoses for severe SGS, since grade III and grade IV SGS (ie,
severe SGS) often requires multiple (3-4) surgical augmentations for
decannulation. In 1997, Cotton described his experience with the
procedure, reporting a decannulation rate higher than 90% for primary
and rescue cricotracheal resection.
Problem: SGS is narrowing of the subglottic lumen.
SGS can be acquired or congenital. Acquired SGS is caused by either
infection or trauma (see Picture 2, Picture
6, Picture 7-10, Picture
12-16, Picture 30). Congenital SGS has
several abnormal shapes. Holinger evaluated 29 pathological specimens
obtained in children with congenital cricoid anomalies. Half of these
children had an elliptical cricoid cartilage (Picture
5), which Tucker first described in 1979. Elliptical cricoid
cartilage was the most commonly observed congenital abnormality. Other
observed abnormalities included a flattened anterior shape, a
thickened anterior cricoid, and a submucosal posterior laryngeal
cleft.
Frequency: The frequency of congenital SGS is
unknown.
The incidence of acquired SGS has greatly decreased over the past
40 years. In the late 1960s, when endotracheal intubation and
long-term ventilation for premature infants began, the incidence of
acquired SGS was as high as 24% in patients requiring such care. In
the 1970s and 1980s, estimates of the incidence of SGS were 1-8%. In
1998, Choi reported that the incidence of SGS had remained constant at
the Children's National Medical Center in Washington, DC; it was
approximately 1-2% in children who had been treated in the neonatal
ICU. Walner recently reported that, among 504 neonates who were
admitted to the level III ICU at the University of Chicago in 1997,
281 were intubated for an average of 11 days, and in no patient did
SGS develop over a 3-year period. In 1996, a report from France also
described no incidence of SGS in the neonatal population who underwent
intubation with very small endotracheal tubes (ie, 2.5-mm internal
diameter) in attempts to prevent trauma to the airway.
Etiology: The cause of congenital SGS is in utero
malformation of the cricoid cartilage.
The etiology of acquired SGS is related to trauma of the subglottic
mucosa. Injury can be caused by infection or mechanical trauma,
usually from endotracheal intubation but also from blunt, penetrating,
or other trauma. Historically, acquired SGS has been related to
infections such as tuberculosis and diphtheria. Over the past 40
years, the condition typically has been related to mechanical trauma.
Factors implicated in the development of SGS include the size of
the endotracheal tube relative to the child's larynx, the duration of
intubation, the motion of the tube, and repeated intubations.
Additional factors that affect wound healing include systemic illness,
malnutrition, anemia, and hypoxia. Local bacterial infection may play
an important roll in the development of SGS. Gastroesophageal reflux
(GER) may play an adjuvant role in the development of SGS because it
causes the subglottis to be continually bathed in acid, which
irritates and inflames the area and prevents it from healing
correctly. A systemic or gastrointestinal allergy may cause the airway
to be more reactive, creating a greater chance of developing stenosis.
Pathophysiology: Acquired SGS often is caused by
endotracheal intubation. Mechanical trauma from an endotracheal tube,
as it passes through or remains for long periods in the narrowed
neonatal and subglottic airway, can lead to mucosal edema and
hyperemia. These conditions then can progress to pressure necrosis of
the mucosa. These changes have been observed within a few hours of
intubation and may progress to expose the perichondrium of the cricoid
cartilage. Infection of the perichondrium can result in a subglottic
scar. This series of events can be hastened if an oversized
endotracheal tube is used. Always check for an air leak after placing
an endotracheal tube because of the risk of necrosis of the mucosa,
even in short surgical procedures. This practice is common among
anesthesiologists. Usually, the pressure of the air leak should be
less than 20 cm of water, so that no additional pressure necrosis
occurs in the mucosa of the subglottis.
Clinical: History
Children with SGS have an airway obstruction that may manifest in
several ways. In neonates, SGS may manifest as stridor and obstructive
breathing after extubation that requires reintubation. At birth,
intubation in most full-term neonates should be performed with a
3.5-mm pediatric endotracheal tube. If a smaller-than-appropriate
endotracheal tube must be used, narrowing of the airway may be
present, which could suggest SGS.
The stridor in SGS usually is biphasic. Biphasic stridor can be
associated with glottic, subglottic, and upper tracheal lesions.
Inspiratory stridor usually is associated with supraglottic lesions;
expiratory stridor usually is associated with tracheal, bronchial, or
pulmonary lesions.
The level of airway obstruction varies depending on the type or
degree of SGS. In mild SGS, only exercise-induced stridor or
obstruction may be present. In severe SGS, complete airway obstruction
may be present and may require immediate surgical intervention.
Depending on the severity, SGS can cause patients to have decreased
subglottic pressure and a hoarse or a weak voice. Hoarseness or vocal
weakness also can be associated with glottic stenosis and vocal cord
paresis or paralysis.
Always ask about a history of recurrent croup. A child with an
otherwise adequate but marginal airway can become symptomatic with the
development of mucosal edema associated with a routine viral upper
respiratory infection (URI). Children with these conditions may have
subglottic narrowing and an evaluation of the airway is appropriate.
Always assess the history of GER disease (GERD). If present, always
evaluate GERD prior to surgical intervention. A child who eventually
has a diagnosis of SGS often has a history of either laryngotracheal
trauma or intubation and ventilation. Frequently, these patients were
born prematurely, have bronchopulmonary dysplasia, and may require
oxygen administration. The degree of pulmonary disease and the amount
of oxygen the child requires may affect the ability to perform
decannulation. Prior to surgical intervention, the child should not
require a substantial oxygen supplementation.
Physical examination
The physical examination varies depending on the degree of SGS
present. Auscultate the child's lung fields and neck to assess any
symptoms of airway obstruction and to evaluate pulmonary function.
Completely evaluate the head and neck, and identify associated facial
abnormalities such as cleft palate, choanal atresia, retrognathia, and
facial deformities. Evaluate the child's initial overall appearance,
and ask the following questions:
- Is the child comfortable?
- Does the child have difficulty breathing?
- Does the child have difficulty breathing when emotionally upset?
- Does the child have any suprasternal, substernal, or intercostal
retractions?
- Does the child have any nasal flaring?
- Is the voice normal? Is it weak? Is the voice breathy?
- Does the child have stridor? If so, what is the nature of the
stridor (ie, inspiratory, expiratory, or biphasic)?
- What is the child's neurologic status?
- Does the child have a tracheotomy? Can the patient occlude the
tracheotomy and still breathe without laboring?
INDICATIONS
Staging
Surgical reconstruction is performed on the basis of the symptoms,
regardless of SGS grade. Children with grade I and mild grade II SGS
often do not require surgical intervention.
Myers and Cotton devised a classification scheme for grading
circumferential subglottic stenosis from I-IV, which is established
endoscopically and by using noncuffed pediatric endotracheal tubes of
various sizes and sizing the airway. The scale describes stenosis as a
percent of area that is obstructed.
The system contains 4 grades, as follows:
- Grade I - Obstruction of 0-50% of the lumen obstruction
- Grade II - Obstruction of 51-70% of the lumen
- Grade III - Obstruction of 71-99% of the lumen
- Grade IV - Obstruction of 100% of the lumen (ie, no detectable
lumen)
The percentage of stenosis is evaluated by using endotracheal tubes
of different sizes. The largest endotracheal tube that can be placed
with an air leak less than 20 cm of water pressure is recorded and
evaluated against a scale that has previously been constructed by
Myers and Cotton (see Picture 26). This
grading system applies mainly to circumferential stenosis and does not
apply to other types of SGS or combined stenoses, although it can be
used to obtain a rough estimate. Typically, children with grade I (see
Picture 4) or mild grade II stenosis do not
require surgical intervention. Children with these conditions may have
intermittent airway symptoms, especially when infection or
inflammation causes mucosal edema.
Indications
Surgical intervention may be avoided if periods of airway
obstruction are rare and can be treated on an inpatient or outpatient
basis with anti-inflammatory and vasoconstrictive agents, such as
oral, intravenous, or inhaled steroids and inhaled epinephrine (racemic
treatment). If children with these conditions continue to have
intermittent or persistent stridor and airway obstructive symptoms
when they are well, or if they frequently become ill, surgical
intervention may be necessary.
Development of upper respiratory symptoms during routine infections
can indicate whether a child with SGS requires surgical
reconstruction. Viral infections of the upper respiratory tract can
create swelling in any area of the respiratory epithelium from the tip
of the nose to the lungs. If a child with SGS has a cold and/or
bronchitis but no significant symptoms of stridor or upper airway
obstruction, the airway may be large enough to tolerate stress, and
reconstruction may not be needed. A history of recurrent croup
suggests SGS.
Occasionally, older children have exercised-induced airway
obstruction. At evaluation, these children may have grade I or grade
II SGS. Expansion of the airway with cartilage augmentation may allow
them to lead a healthy and active lifestyle.
Children with grade III or grade IV SGS need one or more of the
forms of surgical treatment discussed in Surgical
therapy.
While croup, bacterial infection, GERD, and bronchopulmonary
dysplasia may occur or be involved in the development of SGS, a
history of prolonged endotracheal tube intubation is the most common
factor seen in patients with SGS that requires surgical correction.
RELEVANT
ANATOMY AND CONTRAINDICATIONS
Relevant Anatomy: The subglottis is defined as the
area of the larynx housed by the cricoid cartilage that extends from 5
mm beneath the true vocal cords to the inferior aspect of the cricoid
ring (see Picture 1). Because of the proximity
and close relationship of the subglottis to the glottic larynx,
glottic stenosis often can be present with SGS. When SGS is corrected
surgically, good voice quality can be preserved by not violating the
true vocal cords if they are uninvolved in the disease process. When
creating the entry incision into the airway in an isolated SGS, divide
the cricoid cartilage, upper 2 tracheal rings, and the inferior third
to half of the laryngeal cartilage in the midline; avoid dividing the
anterior commissure. However, if the disease dictates or if exposure
for repair cannot be obtained without dividing the anterior commissure,
carefully perform the procedure. Endoscopic guidance can help in
preventing injury to the glottic larynx.
If a laryngofissure is required for glottic stenosis or to gain
access to the posterior aspect of the stenosis for suturing of the
posterior graft, care must be taken to identify the anterior
commissure and correctly put it back into place. Once the
laryngofissure is created in the midline, immediately suture the
anterior aspect of the true vocal chords near the anterior commissure
to the laryngeal cartilage with a 6-0 monofilament suture such as
polydioxanone (PDS) or Monocryl. This procedure helps prevent anterior
commissure from becoming blunted and helps mark approximately where it
should be once the laryngofissure is closed.
When dividing the posterior cricoid lumen, note that the esophagus
is immediately adjacent and posterior to it. Take care to avoid
injuring the esophagus when completely dividing the posterior cricoid
lamina during cartilage augmentation.
The recurrent laryngeal nerves enter the larynx in the posterior
lateral portion of the cricoid ring. When surgery is performed in the
midline, the recurrent laryngeal nerves should be far enough away from
an anterior division to prevent injury. Any surgical procedure in
which the lateral cricoid is divided could jeopardize the laryngeal
nerve and result in paresis or paralysis of the true vocal cords. In
the cricotracheal resection procedure, no attempt is made to identify
the recurrent laryngeal nerves because of dense scarring. This lack of
identification has resulted in one reported case of paresis of the
true vocal cord.
Contraindications: No specific absolute
contraindications to the laryngotracheal reconstruction procedure
exist. However, if general anesthesia is absolutely contraindicated,
surgical correction of SGS cannot be performed.
A relative contraindication to reconstruction of a narrow
subglottis is present in children who have a tracheotomy and SGS but
need a tracheotomy for other purposes (eg, access for suctioning
secretions caused by chronic aspiration) or in those who have airway
collapse or obstruction in the nasal cavity, nasopharynx, oral cavity,
oropharynx, supraglottic larynx, or trachea that cannot be repaired.
However, if severe or complete laryngeal obstruction exists and if the
child might be able to vocalize if the airway were surgically
corrected, reconstruction may be beneficial, despite the need to
maintain the tracheotomy tube. Severe GER is another relative
contraindication. Once GER is treated successfully (medically or
surgically) or resolves on its own, reconstruction can be considered.
An additional relative contraindication to airway reconstruction is
pulmonary or neurological function that is inadequate to withstand
tracheotomy decannulation.
Regardless of the cause of SGS, it is usually best to delay
reconstructive efforts in children who have reactive or granular
airways (see Picture 6) until the reactive
nature of the patient’s condition subsides.
WORKUP
Lab Studies:
- Specific laboratory studies are not required.
Imaging Studies:
- The criterion standard for evaluation of the airway is direct
laryngoscopy and direct bronchoscopy.
- Certain radiographic examinations can help in obtaining a
diagnosis and determining the severity of the disease. Usually,
the initial radiographic study used to evaluate a child with
airway obstruction is an anteroposterior and lateral plain neck
radiography. Frequently, in a child with SGS, the subglottis
appears narrowed and peaked; this often is described as a steeple
sign. In a patient with a thin web SGS, a lateral plain film x-ray
may show a faint line.
- Fluoroscopy often is performed in children with symptoms of
airway obstruction.
- Fluoroscopy can be used to diagnose lesions of the larynx and
trachea.
- When a barium-enhanced esophagram is added to the procedure,
vascular malformations, along with GERD, may be ruled out.
- CT scans and MRIs are not often used in the primary evaluation
of SGS.
Other Tests:
- Investigate any indication of GERD. Walner showed that children
with SGS have a 3-fold increase in GERD compared with the general
pediatric population.
- Currently, the best test in evaluating for GER is dual-channel
pH probe testing. One probe is placed above the lower esophageal
sphincter, and another is placed at the area of the
cricopharyngeus near the larynx.
- Walner and Cotton recommend treating GER for 1 month before and
12 months after airway reconstructive surgery, even if only mild
disease is present.
- If moderate or severe GERD is diagnosed, start medical therapy
and confirm disease resolution with another pH probe test prior to
surgery.
- Do not perform laryngeal reconstruction until GER has resolved.
- If reconstruction is being considered, pediatric laryngologists
frequently perform tests to rule out GER, even in the absence of
symptoms, because the disease may affect the outcome.
- A recent concern suggests that an "allergic"
esophagitis may exist and affect the outcome of surgery.
- To evaluate for this entity, a esophagogastroduodenoscopy (EGD)
is performed with biopsies of the proximal and distal esophagus,
stomach, and duodenum.
- If more than 15 eosinophils are found in the mucosa per high
power field, the patient may have "allergic"
esophagitis.
- Evaluation and treatment for GERD must have taken place prior
to this evaluation, since reflux may elicit eosinophils as well.
- If "allergic" esophagitis is discovered, then
treatment with weeks to months of oral steroids or orally
applied inhaled steroids is performed to help diminish the
affects of the disease and possibly allow for a better success
rate of laryngeal reconstruction.
Diagnostic Procedures:
- Flexible fiberoptic nasopharyngoscopy and laryngoscopy
- During flexible fiberoptic nasopharyngoscopy and laryngoscopy,
topical anesthesia and decongestion can be accomplished in older
infants and children with topical Afrin and lidocaine. A 3-mm
endoscope can be used, even in an infant. Pass the endoscope
into both nasal cavities to access pyriform aperture stenosis,
midnasal stenosis, choanal atresia or stenosis, lesions of the
nose and nasopharynx, and the adenoid pad.
- Pass the endoscope into the superior oropharynx and
hypopharynx. The hypopharynx and larynx can be assessed.
Identify the structure and position of the supraglottis.
Evaluate the epiglottis and arytenoids for malacia or stenosis.
Evaluate the position and movement of the true vocal cords.
Evaluate edema or erythema of the true vocal cords, epiglottis,
and arytenoids.
- This can be performed with the patient in the supine or
sitting position. The supine position often results in the
obstruction of certain supraglottic processes. If the goal is to
obtain the best visualization of the true vocal cords and
supraglottis, place a child (even an infant) in the sitting
position with his or her neck extended.
- If the child is older, the voice can be evaluated, and
videostroboscopy can be performed to assess the vocal cord
waveform and vocal cord mobility.
- Occasionally, the subglottis can be visualized with flexible
endoscopy; however, rigid laryngoscopy and bronchoscopy are the
safest procedures and offer the best visualization for the
subglottis and tracheobronchial tree.
- Rigid laryngoscopy and bronchoscopy
- Rigid laryngoscopy and bronchoscopy is the best single test
for evaluating airway obstruction in children. The
otolaryngologist must have knowledge of the pediatric airway,
and the OR must have adequate bronchoscopes and telescopes of
various sizes. Prepare all equipment for bronchoscopy, including
laryngoscopes, light sources, video documentation equipment,
telescopes, and bronchoscopes prior to the child’s arrival in
the OR. Throughout the procedure, maintain good communication
between anesthesiologists, surgical nursing staff, and
physicians, so that any potential airway obstruction can be
quickly assessed and addressed.
- Do not further injure the pediatric airway—this point is of
paramount importance. Use the smallest bronchoscope or telescope
alone for evaluation of the subglottis in a child who does not
require ventilation throughout the procedure. This practice
allows good visualization without iatrogenic injury to the area.
If ventilation is required throughout the evaluation, use a
bronchoscope-telescope combination.
- If a child has a tracheotomy or is not in extreme distress,
the child can breathe spontaneously and inhale oxygen and
anesthetics through an endotracheal tube in the pharynx while
the airways are visualized with a laryngoscope and large
telescope. Frequently, the true vocal cords are anesthetized
with lidocaine prior to evaluation to help prevent laryngospasm.
- Determine the size of the child's airway by using endotracheal
tubes. Myers and Cotton have established a scale for SGS
severity that is based on the child’s age and the size of the
endotracheal tube that can be placed in the airway with an air
leak pressure of less than 20 cm of water.
- Evaluate the subglottis and glottis for fixation, scarring,
granulation, edema, paralysis or paresis, and other
abnormalities. Evaluate the distance and caliber of the stenosis.
Apply the Myers and Cotton staging system only to
circumferential SGS. Glottic stenosis and SGS often coexist and
must be considered when reconstruction is planned.
- Evaluate the maturity of the stenosis. If a firm white scar is
present, the stenosis is mature. If the stenosis has a granular
or erythematous appearance, GERD, viral infection, allergic
esophagitis, or another inflammatory process may be present.
- Examine the area below the subglottis into the trachea and
bronchi for secondary lesions. The suprastomal area is important
because pathological stenosis or malacia can influence the
choice of surgical procedure. In severe SGS, viewing the
suprastomal area requires the passage of a tiny telescope
through a narrow subglottis or a telescope or bronchoscope
through a tracheotomy site, if available.
TREATMENT
Medical therapy: No known medical therapy for mature
SGS exists. If a granular or immature SGS is noted (see Picture
6), treatment of the inflammatory process with oral or inhaled
steroids sometimes can decrease the severity of disease. Findings from
animal studies have shown that treatment with antibiotics and steroids
can help improve an immature or granular SGS; however, the optimal
treatment duration is unknown. Evaluate each case on an individual
basis. Once SGS is mature, medical therapy is almost always
unsuccessful. However, suspected GER must receive aggressive medical
treatment for optimal surgical results.
Surgical therapy: Endoscopic procedures
For mild or granular SGS, investigators have reported success with
serial endoscopic dilation with or without steroid injections. Healy
popularized the use of the carbon dioxide laser as an option for soft
circumferential SGS. This procedure involves making incisions in 4
quadrants, followed by dilation. This technique is best used in
conjunction with steroids when an immature or granular SGS is present.
Normally, use of a laser causes recurrence of the scar in a mature
stenosis; however, in unusual types of mature SGS (eg, spiraling SGS),
improvement may be accomplished with a few serial carbon dioxide laser
excisions (see
Picture 7, Picture
8, Picture 9, Picture
10).
Open reconstruction of subglottic stenosis
Base the approach to open reconstruction of SGS on the location and
degree of scarring. Reconstruction often may be unnecessary for SGS
classified as grades I and II on the Myers and Cotton scale (ie, as
much as 70% obstruction of the subglottic airway). When surgery is
necessary on the basis of the severity of symptoms, perform an open
reconstruction in mature circumferential SGS. The surgical technique
depends on adjacent areas of scarring and on the location and
appearance of SGS. For severe SGS, classified as grades III and IV (ie,
>70% luminal obstruction), laryngeal expansion almost always is
necessary.
The goals of open reconstruction are decannulation or resolution of
symptoms, with preservation of the voice by expanding the subglottic
airway and stabilizing the expanded frame.
Various procedures for treating SGS include the following: (1)
anterior cricoid split (ACS); (2) single staged procedure: anterior
cartilaginous grafting with costal, thyroid, or auricular cartilage;
(3) multistaged procedure applying (a) anterior and posterior
cartilage grafting, usually with costal cartilage, (b) anterior
cartilaginous grafting with a posterior cricoid split and stent
placement, (c) posterior grafting with costal cartilage, and (d)
anterior and posterior costal cartilage with lateral cricoid splits;
and (4) cricotracheal resection.
Anterior cricoid split
In 1980, Cotton and Seid described the use of ACS to avoid
tracheotomy in neonates with SGS, good pulmonary and cardiac function,
and airway obstructive symptoms after extubation. ACS allows
decompression of the edematous submucosal glands of the subglottis and
thus, expansion of the airway.
Criteria have been developed to identify the children who are
likely to benefit from ACS. These include the following: (1) patient
weight of more than 1500 g, (2) failure to extubate in identified SGS,
(3) oxygen requirement of less than 30%, (4) no active respiratory
infection, and (5) good pulmonary and cardiac function.
Transport the already intubated child from the ICU, and make
horizontal incisions over the cricoid cartilage. Divide the strap
muscles in the midline, and identify the thyroid cartilage, costal
cartilage, and upper tracheal rings (see Picture
11). Place Prolene stay sutures (4-0) around each side of the
anterior component of the cricoid ring. Use a double-sided beaver
blade to make an incision in the cricoid ring as far as the tracheal
rings and the inferior third to half of the laryngeal cartilage. Then,
reintubate the child with an endotracheal tube appropriately sized for
his or her age. Do not expand the airway more than necessary, since
pressure on the mucosa and persistent SGS can result.
Loosely close the skin over the wound, and place a rubber band
drain. Mark the Prolene sutures in the cricoid as left and right.
Generally, leave the nasal tube in place for 7-10 days. If self-extubation
occurs, reintubate from above. Should the endotracheal tube protrude
through the airway into the neck during reintubation, the stay sutures
can be lifted and crossed to block the cricoid split incision and to
direct the endotracheal tube down the trachea. If this procedure is
unsuccessful, the stay sutures can be pulled up to the neck and opened
so that a tracheal or endotracheal tube can be placed in the airway
until the child can be returned to the OR for intubation through the
mouth.
Administer antibiotics and antireflux medication during the
intubation period. Begin the administration of steroids 24 hours
before extubation and continue for 48 hours afterwards. Usually, the
tube can be removed after 7-10 days. If an air leak around the
endotracheal tube is present with a pressure of less than 20 cm of
water, extubation should be successful. If airway obstruction that is
not amenable to medical therapy (including racemic treatments and
steroids) occurs after extubation, return the patient to the OR for
evaluation, or immediately reintubate in the ICU if necessary.
Complications of ACS are unusual and include pneumothorax,
pneumomediastinum, subcutaneous emphysema, wound infection, and
persistent SGS.
Picture 12 and Picture
13 were obtained in a 4-month-old infant born 3 months
prematurely who required intubation and ventilation for 3 months. She
had a grade III SGS and underwent ACS with intubation and ventilation
for 1 week in the ICU. Picture 14 shows the
subglottis 1 week after extubation. The size of the larynx was
determined with an endotracheal tube, and subsequent dilation of the
soft mild restenosis is depicted in Picture 14
and Picture
15. The child received oral steroids for 5 days and underwent
follow-up bronchoscopy 2 weeks later (see Picture
16).
Single-stage laryngotracheoplasty with cartilage expansion
In 1991, Seid et al reported the use of single-stage
laryngotracheoplasty (LTP). Their approach to the airway resembles ACS;
however, instead of leaving the area anterior to the fibrosis, a piece
of costal cartilage was placed. The procedure was performed in 13
patients with SGS grades I-IV. However, the procedure failed in a
patient who had complete glottic and subglottic stenosis (grade IV).
The researchers indicated that grade IV SGS was a contraindication to
single-stage LTP. Two patients had grade III SGS and a successful
result.
Seid et al stressed the postoperative course in these patients.
Instead of leaving the endotracheal tube in place for 7-10 days, they
checked the air leak surrounding the endotracheal tube on a daily
basis and removed it when the pressure of the leak was less than 20 cm
of water.
The authors also were concerned about the transient weakness of the
extremities caused by neuromuscular blockade and hydrocortisone. They
used vecuronium and benzodiazepines for sedation. Aggressive pulmonary
toilet was stressed, since wandering atelectasis can be present in a
patient who is ventilator dependent for as many as 10 days. The
authors stressed the repeated use of a full range of passive extremity
motions to decrease the likelihood of transient muscle weakness during
the period of induced paralysis for long-term intubation.
Seid et al believed that selection of patients was critical and
that any child with difficulties in addition to SGS (eg, tracheal
problems, true vocal cord paralysis) was not a good candidate for
single-stage LTP. The procedure could fail after extubation for
reasons other than the newly repaired SGS.
In 1995, Rothschild et al reviewed the effectiveness and
complications of single-stage LTP. In 104 patients from the Children's
Hospital of Cincinnatti, repair was successful in 86-92%, depending on
the year of correction. The authors further reported that they did not
use paralysis in their patients during the 5- to 10-day period of
endotracheal tube placement; they used sedation with chlorohydrate and
benzodiazepines instead. In fact, if the patient could tolerate
nasotracheal intubation without much difficulty, they were allowed to
engage in their usual activities, including eating, playing, and
walking. (A modified cap placed on the endotracheal tube prevents
crust formation in the tube and airway during these activities.)
Rothschild et al believed that younger children require heavier
sedation and increased ventilation secondary to decreased respiratory
effort. Neuromuscular paralysis usually was avoided. Among their 104
patients, the researchers found neuromuscular weakness in only one.
They did not comment about the presence or absence of pulmonary
atelectasis.
The average duration of endotracheal tube placement in their
patients was 9 days. They did not explain why endotracheal tubes were
in place longer than 10 days (as long as 26 d) in 37 children.
Twenty-three children, however, had a posterior costal cartilage
graft, which normally requires the use of stents for at least 2 weeks
to stabilize the cartilaginous framework.
Seid and Cotton agreed that ICU staff who are knowledgeable and
attentive are important to the success and safety of the procedure.
In 1991, Lusk and Muntz also described a single-stage LTP in which
auricular cartilage is used for reconstruction when an anterior SGS is
repaired. Patients had endotracheal tubes in place for 7-10 days,
similar to the duration of intubation in patients in whom an ACS was
performed. Lusk and Muntz sutured the cricoid to the strap muscles to
help maintain airway patency; their success rate was similar to that
of other procedures (ie, approximately 80-90%). This author’s
experience with the use of auricular cartilage has been less
successful. If significant anterior SGS exists, use of cartilage that
is rigid enough to maintain the splay of the cricoid cartilage usually
is necessary to ensure continued expansion after extubation.
Zalzal added to the efficiency of the anterior cartilage
single-stage procedure by describing the technique of carving the
harvested rib into the shape of a boat with flanges on each end (see Picture
17, Picture 18). In this technique,
cartilage extends outside the lumen of the trachea, over the cricoid
and tracheal rings, to help prevent the lumen from prolapsing into the
airway (see Picture 19). With this technique
(once any air leak is sealed during the surgery), extubation can be
performed without fear of the cartilage requiring further
stabilization or prolapsing into the airway.
After the procedure has been performed and the child has been
admitted to the ICU, air leaks from the neck are checked on a daily
basis. Usually, the air leak seals within 48-72 hours; extubation can
be accomplished with confidence that the graft is stabilized. In this
way, children can avoid the complications of long-term intubation
mentioned above.
Reports of use of the superior section of the thyroid cartilage, as
well as the septal cartilage, as grafting material exist. These
materials, along with the auricular cartilage, usually do not provide
much support. Instead, they act mainly as a patch over the divided
area of the cricoid region. In these situations, the stent provides
most of the force necessary to keep the lumen open while the
surrounding area heals. Some of the other types of cartilage can be
used in conjunction with ACS to improve that success rate of the
procedure, which traditionally has been 70-80%.
Richardson and Inglis performed a prospective study to compare the
cricoid split procedure with and without costal cartilage grafting for
the treatment of acquired SGS in infants younger than 6 months in whom
extubation in the ICU failed. The researchers found that results were
improved in 90% of patients in whom cartilage was placed between the
cricoid rings to expand the airway, compared with 56% in whom
cartilage was not placed. This study was prospective and included only
20 patients, but its findings indicate that placing the lumen expander
at the time of surgery greatly improves the likelihood that extubation
succeeds and adequate airway is maintained.
Zalzal and Choi pointed out, however, that when the results of
laryngotracheal reconstruction was evaluated in 48 patients aged 4
years or younger, success was decreased in children younger than 25
months compared with that of children aged 2-4 years. (Note that the
patients <2 years had SGS that was less severe than that of the
older patients.) Zalzal and Choi still recommended laryngotracheal
reconstruction in younger patients, because the procedure may aid the
child's speech and language development and help prevent tracheotomy
complications.
Anterior and posterior grafting
For severe SGS (grade III-IV), anterior and posterior cricoid
splitting with costal cartilage grafts placed anteriorly and
posteriorly has been effective in expanding the lumen and allowing
decannulation. Most authors, including Zalzal and Cotton, agree that
when a posterior graft is used, cartilage of sufficient strength must
be placed posteriorly to keep the airway expanded. Both Zalzal and
Cotton have reported success rates higher than 90% with decannulation,
frequently achieved with a single procedure. Occasionally, revision
surgery is needed.
Often, the posterior graft is formed into an ellipse or elongated
hexagon and placed so that the perichondrial side of the graft is
flush with the mucosa of the posterior subglottic and tracheal wall.
Occasionally, flanges can be fashioned on the posterior that can be
placed posteriorly and outside the lumen in a manner similar to that
of the boat graft (described by Zalzal), which is placed anteriorly.
For a posterior graft, sutures to the posterior cartilage split are
all placed individually prior to sliding the graft in position (see Picture
20), at which time the sutures can be tied. Sied described using
fibrin glue in an animal study to keep a posterior graft in place,
avoiding the arduous task of suturing it in.
Place the anterior graft in a similar fashion. Construction of the
flanges on the anterior graft is not as critical as it is with a
single-stage procedure, since children require stents for a minimum of
2 weeks. Usually, stents are used for 4-6 weeks when anterior and
posterior grafts are placed and the tracheotomy is maintained. Once
the stent is removed, follow-up bronchoscopies are performed to
confirm the stenosis has not recurred before the patient is
decannulated. Maintenance of a patent airway can be is evaluated with
further bronchoscopies.
Usually, an Aboulker stent (see Picture 21,
Picture 22) or Montgomery T tube (natively as
in Picture 25, or cut to fit and used like an
Aboulker stent, which are no longer commercially available) is used.
Other types of stents also have been used. Often, if the collapse or
scar extends into the area of the tracheotomy site, longer-term stent
placement is required with an Aboulker stent that is attached to a
metal Holinger tracheotomy tube with wire (see Picture
23, Picture 24) or a Montgomery T tube.
Complications of short-term stent placement (4-6 wk), such as
granulation tissue and scarring from the distal end of the short stent,
can be prevented with longer-term techniques for stent use.
The surgical approach for anterior and posterior grafting is
similar to the approach for ACS and anterior cartilage grafting.
Specific care for the posterior cricoid split with or without grafting
requires visualization of the esophagus after the posterior cricoid
cartilage has been incised. During division, take care to spread the
cartilage to identify the esophageal mucosa so that no inadvertent
injury occurs. Additionally, make the incision in the midline to
prevent injury to the recurrent laryngeal nerve and to ensure that an
appropriate site is created for placement of the graft.
Partial cricotracheal resection
In Switzerland, Monnier first reported the use of partial
cricotracheal resection in 31 pediatric patients with grade III and IV
stenosis in whom decannulation with anterior-posterior grafting
failed. The decannulation rate after cricotracheal resection was 97%.
Cotton and others began to evaluate the use of cricotracheal resection
because of failures with grade III and grade IV stenoses.
Investigators in the “Cincinnati Experience” recently reported
that decannulation occurred in 90% of children with refractory grade
III and IV stenoses.
The best candidates for partial cricotracheal resection are
patients with severe SGS (grade III-IV) without associated glottic
pathologic conditions and with a margin of at least 4 mm in the
healthy airway below the vocal folds and above the stenosis. This
space allows resection away from the glottic larynx, with anastomosis
of healthy mucosa. Expect significant glottic edema to last 4-6 weeks;
use a tracheotomy or T tube during the postoperative period to protect
the airway until the edema resolves.
Perform the procedure with the patient under general anesthesia;
the approach to the larynx and trachea is similar to that of other
laryngotracheal reconstructive procedures. Vertically enter the airway
with the beaver blade in the midline at the level of the cricoid. Make
the incision superior to the inferior margin of the thyroid cartilage
and inferior to the second tracheal ring. The superior extent of the
stenosis can be defined at endoscopy while simultaneously and directly
viewing the open wound, so that a precise view of the scarred
subglottic segment can be achieved. Make a horizontal cut just above
the superior extent of the stenosis, from the anterior aspect to the
posterior aspect, stopping at the level of the cricothyroid joint. By
staying anterior to the cricothyroid joint at this level, injury to
the recurrent laryngeal nerve can be prevented.
Make lateral cuts inferior to the cricothyroid joints, and continue
inferiorly through the lateral aspects of the cricoid cartilage to
expose the posterior cricoid plate. Approach the inferior area of the
stenosis, and place stay sutures in the distal normal tracheal
segment. Incise the trachea just below the inferior aspect of the
stenosis through the anterior lateral portions of the trachea down to
the membranous tracheal wall, then dissected this from the esophageal
wall at the superior aspect. Connect the superior incision and remove
the segment. Next, suture the uninvolved part of the trachea to the
anterior thyroid ala and the exposed posterior cricoid plate.
During the dissection from the inferior aspect to the superior
aspect, take care to dissect in a perichondrial plane over the cricoid
to prevent injury to the recurrent laryngeal nerve. If identification
of the esophagus is difficult during this portion of the procedure, a
palpable dilator can be placed in the esophagus to delineate the
esophageal wall. Before anastomosis, remove the scar tissue from the
inner aspect of the posterior cricoid plate by using a small curet or
drill. Perform a hyoid release procedure to decrease tension at the
suture line. In addition, dissect the trachea until 4-5 rings are
mobilized to aid in decreasing tension on the suture line. In
addition, place 2-3 additional tension-releasing sutures on the
thyroid ala and the upper tracheal rings to help release tension from
the suture line. Place Proline stitches (0-0) from the chin to the
chest of the child to keep the head flexed for a week.
In an older child with minimal glottic involvement, a single-stage
procedure can be performed with nasotracheal intubation of 7-10 days’
duration. In younger children with more severe glottic involvement, a
Montgomery T tube can be placed for 4-6 weeks. Take meticulous care to
prevent plugging of the T tube and resultant airway obstruction. Stern
and Cotton recently reported good results with decreased morbidity
with T tubes in children.
Preoperative details: The most important part of
laryngotracheal reconstruction is the preoperative assessment.
Assessment involves direct bronchoscopy with an evaluation of the
severity and level of stenosis. If the stenosis is defined properly,
the correct procedure can be used for the best surgical outcome.
Additionally, evaluate the child’s pulmonary status and presence
or absence of GERD. The pulmonary status, including the amount of
oxygen required by the patient, may determine whether laryngotracheal
reconstruction should be attempted.
Evaluate the neurologic status as well. Children who have severe
neurologic delays may need a tracheotomy for other reasons than SGS,
such as access for suctioning of thick secretions or to bypass
obstruction from a malacic pharynx or supraglottic larynx.
Intraoperative details: Specific technical tips
exist for each procedure; these have been elucidated earlier in this
section (see Surgical therapy). Often,
laryngoscopy performed before and during the procedure helps in
preventing iatrogenic injury to the larynx and ensures the correct
placement and extent of laryngeal incisions.
Postoperative details: Postoperative care is
critical in children. As stated earlier, any child requiring an ICU
stay may have difficulties while receiving intubation and ventilation.
Meticulous care from health care providers in the ICU may decrease the
number of complications.
Follow-up care: Children who undergo various
laryngotracheal reconstruction procedures may have different follow-up
care and courses, depending on the procedure performed. If a
single-stage laryngotracheal reconstruction or ACS has been performed,
bronchoscopy at extubation is not necessarily required; such decisions
are left to the surgeon. However, 1-3 weeks after the procedure,
bronchoscopy can be used to assess for any complications. Some authors
examine the children after laryngotracheal reconstruction only if they
have difficulty.
The author often performs laryngoscopy and bronchoscopy 1-2 weeks
after extubation to evaluate the airway, since granulation tissue
often forms in this period (see Picture 26)
and can lead to airway obstruction and scarring. A carbon dioxide
laser can be used to remove and control the granulation tissue well
(see Picture 27, Picture
28). Certainly, any time the child has airway obstructive
symptoms, bronchoscopy should be considered.
In a child undergoing 2-stage laryngotracheal reconstruction with
grafting and stent placement, the tracheotomy remains in place. The
length of follow-up is determined by the duration of stent placement
and the quality and quantity of symptoms after stent removal. For
short-term stent placement (4-6 wk), follow up is 2 weeks after stent
removal.
If this appears satisfactory, bronchoscopy should be performed at 4
weeks. In the interval, capping of the tracheotomy can be performed
intermittently to evaluate for obstruction. If the bronchoscopy at 6
weeks is satisfactory, attempted decannulation can be considered.
Prior to decannulation, the tracheotomy tube usually is downsized and
plugged intermittently. If the child tolerates plugging, a sleep study
can be performed, or the child can be decannulated and watched in the
ICU or in a regular hospital room while monitored over night,
depending on the individual case. Various methods to evaluate adequate
airway prior to decannulation are available.
Walner and Cotton recommend repeat endoscopy at 1, 3, 6, 12, and 24
months after reconstructive surgery. This pattern allows long-term
evaluation and detection of a recurring stenosis before it reaches a
critical stage. Walner and Cotton also recommend capping and
downsizing the tracheotomy in the hospital before decannulation.
COMPLICATIONS
Complications include the following:
- Failure to correctly repair the stenosis occurs more often in
severe stenosis than in moderate or mild stenosis. Zalzal and Choi
examined 27 patients in whom laryngotracheal reconstruction failed
and found that failure was related to the following:
- Inappropriate choice of graft
- Inappropriate choice of stent
- Inappropriate length of stent
- Inappropriate duration of stent placement
- Inadequate assessment and endoscopy
- Poor postoperative follow-up
- Anterior suprastomal collapse
- Slipped Aboulker stent
- Interactive progression of GERD
- Keloid formation
- Failure to repair all abnormalities noted at preoperative
evaluation
- Injury to recurrent laryngeal nerve has been reported in a
single case of cricoid tracheal resection. Avoidance techniques
are outlined in Surgical therapy.
- The voice quality of patients with glottic stenosis and SGS is
decreased and never restored to the preoperative state. However,
once the SGS is repaired subglottic pressure can be increased to
increases volume and improve speech quality (see Picture
29, Picture 30, Picture
31, Picture 32, Picture
33). If an anterior laryngeal fissure is required to repair
the SGS, voice quality can worsen, even if the anterior cartilage
is displaced only mildly. Therefore, if possible, avoid dividing
the anterior commissure.
- Complications from laryngotracheal reconstructive surgery itself
include pneumothorax, pneumomediastinum, neck wound infection,
chest wound infection, and emphysema.
- Complications during the postoperative ICU course can include
those of laryngotracheal surgery itself in addition to atelectasis
of lung segments, pneumonia, and neuromuscular weakness with the
use of paralytic agents and steroids.
OUTCOME
AND PROGNOSIS
The outcome of laryngotracheal reconstruction depends on its grade and
the procedure performed. Most authors report success rates of 80-90%
when the patient has undergone successful preoperative evaluation and
when the appropriate surgery has been performed (see Picture
33, Picture 34). The presence of acute or
chronic respiratory illness, GER, or a reactive larynx may decrease
the success rate. Choi and Zalzal showed that age can affect success
rates; scars are more likely to recur in children younger than 2 years
than in others.
Zalzal noted that, in any child with voice abnormalities before
surgery, those abnormalities persisted after surgery. Subglottic
pressure is required to produce a strong voice. If the narrowed
subglottic airway is expanded, subglottic airflow and pressure
increase, and the voice usually is stronger (see Picture
29, Picture 30, Picture
31, Picture 32, Picture
33). Voice therapy may help relieve nonsevere glottic stenosis
over time.
The voice of a patient with SGS, especially those who require
reconstruction, may never return to it preoperative state because the
following are possible: (1) glottic stenosis, (2) imperfect closure of
a laryngofissure through the anterior commissure, and (3) potential
vocal cord weakness or tension caused by other laryngeal pathologic
conditions. Since reconstructive techniques have improved over the
last 20 years, the focus of attention in patients with SGS who require
reconstruction has switched from decannulation to decannulation with
improved voice outcome.
FUTURE
AND CONTROVERSIES
Controversies remain concerning the surgical techniques for
mild-to-moderate SGS. Options including endoscopic laser removal and
dilation for mild SGS versus an open procedure. Most authors believe
that, in children, scar excision with laser and dilation usually is
unsuccessful in mature and severe SGS. Many authors have reported the
use of topical Mitomycin-C applied to the area of laser excision of
subglottic scar to improve the patency rate. Mitomycin is proposed to
help decrease scar formation by decreasing the cell division through
its action on the microtubules in anaphase of mitosis. Despite the
feeling that this antiproliferative agent is helpful, no
placebo-controlled studies have been performed.
The type of cartilage used for augmentation and reconstruction can
be controversial as well. Some authorities believe that thinner
cartilage (eg, auricular cartilage, thyroid ala) is satisfactory
reconstructive material in certain situations. Most authorities
recognize that costal cartilage provides the most support and that, in
severe stenosis, weaker cartilage may be inadequate. The choice of
cartilage often depends on the degree and location of the stenosis and
on the postoperative care. Most airway reconstructive surgeons believe
that posterior SGS requires lumen augmentation with firm cartilage.
The selection of the anterior cartilage is not as critical, especially
when stents are used after the procedure. In this setting, various
authors have reported good success with superior strips of thyroid
cartilage and auricular cartilage.
As with most diseases requiring surgical treatment, evaluations
based on genetic predisposition and medical therapies to prevent the
disease process that requires surgery are being evaluated. Novel ideas
of expanding the airway, including the use of expandable and
bioabsorbable airway stents, are being investigated. The role of
growth factors and techniques to prevent wound healing are being
evaluated as well. Unquestionably, any technique, device, or therapy
that decreases the need for surgical intervention or donor cartilage
decreases morbidity.
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