Pediatric Surgical Diseases of the Larynx, Trachea, and Bronchi Flashcards
How do the larynx, trachea and bronchi develop?
The larynx, trachea/oesophagus, bronchi and lungs have individual embryological developmental patterns.
The laryngotracheal groove, or sulcus, appears in the proximal foregut in the 3rd week of gestation and progresses caudally to form a tracheoesophageal septum which separates primitive airway and digestive tracts, and complete separation of the trachea and oesophagus has usually occurred by the 6th week.
The bronchial primordia develop in parallel as asymmetric tracheal tip buds.
The cartilaginous and muscular components of the trachea and bronchi are detectable from the 10th week and are derived from proliferating coelomic cavity cells.
At birth the tracheal length is approximately 3 cm in length and 5 mm in diameter.
It continues to grow around 5 mm a year, reaching full adult dimensions of around 15 cm in length and 20 mm in diameter by the age of 16 years.
These separate embryological developments account for the diversity in congenital anomalies that can be found in the respiratory tree, as possible malformations exist on a spectrum of severity and can affect any portion of the upper respiratory tract from face to bronchi.
What surgical pathologies are classically seen in the pediatric airway?
The common surgical pathologies of the larynx and trachea are shown in
Table 12.1, and can represent either:
• narrowing of the airway caliber (i.e. subglottic stenosis or congenital tracheal stenosis);
• structural deficiency of the airway (i.e. laryngomalacia, tracheobronchomala- cia or laryngeal cleft); or
• problems with functional mobility (i.e. vocal cord palsy).
The severity and symptoms can vary greatly for each condition, and can all be congenital, secondary or due to a mixture of etiologies.
It should be noted that, with the exception of laryngomalacia, most conditions are uncommon or rare in the general population, and as such there should be a low threshold for management of these children in a tertiary pediatric center.
How are pediatric airway problems assessed?
Clinical evaluation should include a history that is focused on airway symptoms, which will be dependent on the location and severity of disease.
Characteristic symptoms include dysphonia, abnormal cry and dysphagia.
There may be a history of increasing respiratory distress, shortness of breath (related to exertion/ feeding) and accompanying stertor or stridor.
Cyanotic episodes are a notable feature that should expedite clinical investigations.
Recurrent unexplained aspiration episodes or lower respiratory tract infections should raise clinical suspicions of abnormal communications between the airway and esophagus.
Direct evaluation of the airway is typically performed through endoscopy.
Flexible nasendoscopy will allow evaluation of the nasopharynx, pharynx and larynx, and can be performed in the awake child.
Laryngomalacia can typically be diagnosed by this method, and the child’s inevitable cry during examination is of a characteristic quality.
In a severely affected infant, the risk of a second, more distal, airway lesion may be as high as 50% [2], so clinicians should maintain a high index of suspicion and a low threshold for full evaluation of the large airways by microlaryngoscopy and tracheobronchoscopy (MLB) under general anesthesia (Fig. 12.1).
This investigation is performed with a child self-ventilating, provides some dynamic information of the airway and enables evaluation from the larynx to the first bronchial division.
Alternative evaluation can also be performed through flexible bronchoscopy and allows for distal evaluation of the airway.
Radiological assessment includes computed tomography (CT) particularly when evaluating for external (vascular) compression.
Other radiological investigations include bronchography (Fig. 12.1), which provides dynamic evaluation of the airway particularly related to malacia.
Increasingly 4D CT is being used to evaluate the airway in the appropriate child.
What is laryngomalacia and how is it assessed?
Laryngomalacia is a congenital condition whereby the supraglottic component of the larynx partially or completely collapses on inspiration.
It is the most common cause of congenital stridor, but its precise pathophysiology is unclear.
A clinical history will typically be characterized by a high-pitched inspiratory stridor present shortly after birth.
Stridor will often be exacerbated when the infant is active or cry, and symptoms resolve when settled or asleep.
The natural history of the disease is such that symptoms are at their peak at 9 months and then resolve after 12–18 months.
Evaluation would include evaluating a child’s weight and continued growth according to their birth centile, as well as a history of respiratory distress or decompensation in times of illness, and a flexible nasendoscopy can be performed in an outpatient clinic.
Features seen on endoscopy will included a long and curled epiglottis (omega shaped) and aryepiglottic folds that are tall and bulky.
The aryepiglottic folds will tend be short in anteroposterior direction or tether to the epiglottis.
With significant respiration, a soft epiglottis and/or the redundant mucosa of the aryepiglottic folds may be seen to collapse into the airway.
How is laryngomalacia managed?
As with most pediatric airway conditions, the management of laryngomalacia is primarily guided by the degree of symptoms experienced.
Babies with otherwise asymptomatic stridor or mild difficulties with feeding should be managed conservatively as long as the child is gaining weight appropriately.
Adjustments to sleeping and feeding strategies (i.e. front sleeping and bottle-feeding) may be necessary to support this.
If a child is failing to thrive or gain weight, or has evidence of ongoing or recurrent respiratory distress, endoscopic assessment and surgical management is required.
Surgery is performed according to the areas of the supraglottis that are seen to be causing excessive obstruction under spontaneous ventilation, and classically involve partial or complete division of the aryepiglottic folds (aryepiglottoplasty) and/or trimming of excess prolapsing arytenoid mucosa.
Given the inevitable improvement in the condition as the child ages, an extremely conservative approach to removing tissue is always preferable to prevent the likelihood of swallow compromise.
What is respiratory papillomatosis and how is it managed?
Recurrent respiratory papillomatosis (RRP) is a condition caused by infection of the upper airway by the human papilloma virus (HPV) strains 6 and 11, whereby exophytic outgrowths occur in the airway.
HPV11 is the more aggressive viral strain.
They are considered to be the most common benign laryngeal tumor to occur in children.
In children, the virus is thought to be transmitted from mother to child at the time of delivery, although it is still rare even in neonates born to HPV-positive mothers.
RRP can occur at any age, but pediatric cases are associated with a more aggressive course.
Patients generally experience hoarseness and depending on the degree and location of these papillomata, severe cases may also develop subacute airway obstruction.
Lesions are most commonly seen at the level of the glottis and/or supraglottis, but papillomata may extend along the entire length of the trachea (Fig. 12.3).
Treatment to clear established papillomatous disease is primarily surgical, with the utmost care taken to preserve the underlying structures.
The biggest revolution in recent years in this condition has been the introduction of population-level HPV vaccination in North America, UK and Australia, which has already started showing demonstrable reductions in annual incidence levels.
The vaccine may also have a role in treatment, by increasing average time intervals between surgical procedures.
Other new medical treatments for established disease may include monoclonal antibody therapy such as Bevacizumab (Avastin) which targets VEGF receptors.
What are the main causes for subglottic stenosis and how is it assessed?
Subglottic stenosis (SGS) may be a primary, classically oval-shaped, pathology or may be a sequela of prolonged or traumatic intubation.
Given general improvements in the prognosis of neonatal and pediatric intensive care graduates, post-intubation subglottic stenosis is growing in incidence. SGS can also be found in association with syndromes such as Down’s.
Children classically present with subacute respiratory distress (as the child outgrows their fixed subglottic airway diameter) with signs of decompensation during times of higher respiratory demand (i.e. feeding or concurrent illness).
Recurrent croup episodes requiring hospital admission should therefore raise suspicion of an underlying stenosis and this presentation requires endoscopic evaluation.
A classical presentation of secondary SGS would be an evolving difficulty in intubating an infant with an endotracheal (ET) tube of an age-appropriate diameter.
At the time of MLB, the surgeon sizes the subglottis relative to endotracheal tubes of an age-appropriate size (calculated as (age in years+4)/4).
If an ‘age-appropriate’ tube does not pass, smaller tubes are passed with a stepwise increase in size until an ET tube size that just passes with a leak of air around it.
What are the management options for subglottic stenosis?
Management of mild SGS can be conservative with a watch-and-wait policy as the child grows.
Gastroesophageal reflux disease may be a contributing factor to the formation of post-traumatic stenosis and should be managed closely.
Temporary relief can be obtained with endoscopic balloon dilatation of the subglottis.
A cricoid split can be considered in an acute scenario for more immediate management.
In symptomatic cases that have failed repeated endoscopic management, surgical augmentation of the cricoid may be necessary via laryngotracheal reconstruction (LTR).
In the procedure, the cricoid ring is split in the anterior midline and a ‘boat-shaped’ cartilage rib autograft inserted to augment its diameter.
In more severe or oval-shaped cases, a straight posterior graft may also be used.
How are vocal cord palsies assessed and managed in pediatrics?
The intrinsic muscles of the larynx responsible for vocal cord movement are supplied by the recurrent laryngeal nerves (the notable exception being the cricothyroid muscle, responsible for pitch regulation, which is innervated by the external laryngeal nerves).
Sensation is supplied by superior laryngeal nerves.
Vocal cord palsies may be primary (idiopathic) or secondary and may one or both cords.
In adults, the risk of neuropraxia or more permanent damage to the recurrent laryngeal nerves during thyroid surgery is well-documented, but this is a rare surgical pathology in children where the left recurrent laryngeal nerve is more commonly at risk during cardiac surgery, particularly patent ductus arteriosus ligation or aortic arch repairs.
Symptoms generally include an impact on voice/cry and a history of an unsafe swallow with overt or silent aspiration leading to recurrent chest infections. Movement and sensation can be affected independently.
Impaired sensation is often inferred from a history of recurrent chest infections or by video- fluoroscopic examination demonstrating silent aspiration without a reliable cough reflex.
Children can usually compensate extremely well for a unilateral vocal cord palsy both in terms of voice and swallow function, and the mainstay of treatment should be speech and language therapy.
Bilateral vocal cord palsies are far more likely to be symptomatic, and the symptoms experienced are related to the position of the cord.
The non-functional cord(s) may lie in either adducted or abducted positions.
Cords in the midline can lead to respiratory obstruction necessitating tracheostomy with the potential for a relatively preserved voice and swallow, whereas bilateral cord palsies in more abducted positions will lead to aspiration problems and aphonia.
Laryngeal innervation is increasingly considered for permanent vocal cord paralysis, and whilst full function is unlikely to be obtained, regaining muscle tone alone can lead to appreciable functional benefits as a salvage treatment option.
What are the causes and management options for tracheobronchomalacia?
Tracheobronchomalacia (TBM) remains an exceedingly difficult condition to manage successfully in the paediatric population, as evidence for diagnosis, classification and management is limited.
It is arbitrarily defined by the excessive (>50%) collapse in the cross-sectional luminal area of the large airways during the normal physiological pressures of quiet respiration (such that life-threatening cardiopulmonary events can occur.
TBM may occur in isolation (potentially due to failure of the coelomic cavity cells responsible for cartilage formation to populate the trachea), or secondary to other local or general tracheal disease.
Extrinsic compression by aberrant vasculature (such as pulmonary artery slings, aberrant aortic morphology or innominate artery compression) or other mediastinal structures may also lead to localised segments of TBM.
Diagnosis is usually made on MLB and/or flexible bronchoscopy, but other dynamic techniques such as bronchography and CT may also show the condition.
External compression from vascular structures is identified from a suspicious endoscopic appearance of the luminal tracheal shape and confirmed with a CT angiogram.
Management is largely related to the underlying cause.
Respiratory support, if required, is generally given as continuous positive airway pressure via face mask or tracheostomy.
Medical treatments include bronchodilators, mucolytics, antibiotics and chest physiotherapy.
Surgical options are also targeted to the underlying area of structural weakness but can include aortopexy or posterior tracheopexy, resection of affected segments if short, internal stents or consideration of external splinting.
Although disease severity usually decreases after the first year or two of life in most primary non-syndromic cases as the child’s airway cartilage matures, respiratory failure and resultant severe infections often require intensive therapy during infancy.
What are laryngeal clefts and how do they present?
Laryngeal clefts are a congenital posterosuperior defect in the posterior larynx and trachealis, caused by the failure of the tracheoesophageal septum to develop appropriately.
This leads to an aberrant connection of variable size and length between the larynx/trachea and the esophagus.
The spectrum of congenital abnormality is diverse and they are often associated with esophageal atresia (EA—see Chap. 5), tracheoesophageal fistulae, vocal cord palsies and malacia or other abnormalities including cardiac defects (ASD and VSD), gastrointestinal and genitourinary anomalies.
They are also associated with midline malformation syndromes.
Whilst mainly sporadic in inheritance there are reports of autosomal dominant pattern.
The most commonly used classification system is by Benjamin and Inglis which classifies clefts into 4 types:
• Type 1: the cleft involves the supraglottic inter-arytenoid region but no further than the level of true vocal cords;
• Type 2: the cleft extends beyond the true vocal cords into the cricoid (but not completely through it);
• Type 3: the cleft extends through the cricoid and into cervical trachea;
• Type 4: the cleft extends into the posterior wall of the thoracic trachea as far as the carina.
A large laryngeal cleft (long Grade III and Grade IV) will present with acute respiratory distress on delivery.
Intubation may be difficult as the endotracheal tube (ETT) is likely to displace posteriorly into the oesophagus through the cleft.
Most children with Grades II and III will also be identified in the neonatal period with acute or subacute airway obstruction, recurrent chest infections, swallowing and/ or feeding difficulties.
However, smaller Grade I and II clefts can be missed and subsequently found in the older child.
These children will present with a history of poor swallow and/or recurrent chest infections or intractable cough due to aspiration.
A high index of suspicion is required to identify the underlying cause.
Specialist paediatric swallow assessment is helpful in diagnosis, aspiration assessment and monitoring surgical success.
A video fluoroscopic swallow study (VFSS) will show contrast penetrating the posterior aspect of the glottis.
Formal identification of the extent of the cleft is performed on MLB by careful and thorough probing of the interarytenoid region and posterior tracheal wall.
How are laryngeal clefts managed?
The decision to use either endoscopic or open repair techniques is largely dependent on the cleft length.
Small clefts may be initially treated with the use of thickened feeds and anti-reflux medication prior to surgical correction.
Endoscopic repair is usually performed on type I and II clefts and involves excising the edges of the cleft with closure either as a single layer or two-layer technique.
Larger clefts (type III and type IV) will not usually tolerate a trial period of conservative management and will need an early surgical repair.
This is typically performed by an open approach with access to the posterior wall of the trachea via a midline incision through the larynx and trachea (laryngofissure).
Excess mucosa is excised and the cleft edges are sutured in a two-layer technique. In some cases, graft material (either periosteum or cartilage) is used between the layers for additional support.
Intubation is usually required for 1 week to allow for the cleft to heal prior to extubation.
Outcomes from laryngeal cleft repair are similarly related to the length of the cleft.
Type I and II clefts generally have excellent prognosis with almost all leading to symptom improvement for children identified at risk of recurrent aspiration.
Other complications include failure of the cleft to close which can be related to dehiscence at the site of repair.
Longer clefts, particularly those that extend to the thoracic inlet and beyond, have a protracted recovery due to inherent structural malacia associated with the cleft.
There is also often a degree of oesophageal dysmotility and the need for a gastrostomy is not uncommon.
How is congenital tracheal stenosis (CTS) classified and managed?
Congenital tracheal stenosis (CTS) is typically classified as either short segment or long segment (spanning over 1 cm in the newborn and 1.5 cm in the infant, or affecting over 50% of the total tracheal length in older children).
Primary CTS is due to the presence of complete tracheal rings rather than the normal ‘C’-shape cartilage morphology, although it may also occur secondary to extrinsic pressure from nearby structures—60% of children born with CTS have other associated malformations, most commonly mediastinal and cardiovascular anomalies.
It is usually the combination of both airway and cardiovascular disease that leads to life threatening compromise.
The trachea may also demonstrate an abnormal branching pattern, often with downstream regions of associated malacia.
Infants with moderate or mild disease may not be diagnosed until later in childhood when their gas exchange demands start to outstrip the flow of air through the narrowed tracheobronchial section.
At the other end of the spectrum, severely affected infants may need extracorporeal membrane oxygenation until definitive surgery can be performed.
The slide tracheoplasty procedure has revolutionised the surgical treatment of children with CTS [6] (Fig. 12.7).
In our patient series, one of the largest in the world, it has been shown to be both safe and reliable for short segment and acquired CTS with low associated morbidity and mortality.
What is the CHAOS syndrome and how is it managed?
Presentation and diagnosis of obstructing laryngeal and high tracheal birth defects usually occurs following routine prenatal ultrasound scanning with confirmation by in utero MRI, but can present later with immediate respiratory distress at birth.
Obstructive lesions can be intrinsic, i.e. the so-called Congenital high airway obstruction syndrome (CHAOS) infant, but are more commonly caused by extrinsic compression by pharyngeal, cervical or thoracic mass lesions such as teratomas or cystic hygromas.
In cases of intrinsic lesions, it is likely that failure of the laryngeal epithelial lamina to recanalize properly underlies cases of laryngeal webs or cysts, near-total stenosis or complete laryngeal atresia.
Without immediate surgical intervention, the congenital lack of a patent proximal airway is unsurvivable unless a bypassing pathway exists for intubation of the bronchi via associated fistulae with the esophagus distal to the obstruction.
Careful discussion with parents must be conducted as to their wishes for treatment, especially given that primary laryngeal obstruction has a strong association with other congenital abnormalities such as Fraser syndrome.
Prolonged obstruction to the respiratory tree throughout gestation may also lead to unsurvivable lung malformation.
If parents are still in favor of continuing with the pregnancy, a planned delivery is possible via the ex utero intrapartum treatment (EXIT) procedure, where the precarious neonatal airway may be salvaged or established de novo via anesthetic techniques or tracheostomy, prior to cutting off oxygenation via the umbilical cord, followed by definitive airway establishment depending on the nature of the lesion.
Typical features of tracheomalacia is seen with anteroposterior compression of the airway. (A–C proximal trachea, mid trachea and carina).
The most serious complication of closure of a tracheocutaneous fistula is:
A bleeding
B wound infection
C wound breakdown
D scar
E pneumothorax.
E
Tracheocutaneous fistula is a result of epithelialisation of the skin tract from the anterior neck to the trachea that fails to close following decannulation.
While all answers are complications of tracheocutaneous fistula, pneumothorax following fistula closure can result in rapid airway compromise and death.
Traditional primary closure, a multilayered technique, can result in air that extravasates from the trachea becoming trapped under the reapproximated cutaneous and deeper layers.
This air can track into the chest, resulting in a pneumothorax or pneumomediastinum.
Drain placement and observation may decrease this risk, as will the use of a secondary intention closure, in which the skin tract to the level of the trachea is excised and no dermal or epidermal closure is performed.
SPSE 1
A patient with a type IV laryngeal cleft has a defect at the level of the:
A tip of arytenoid
B supraglottis
C vocal cords
D mid-trachea
E carina.
E
A laryngeal cleft is a congenital defect that results from incomplete fusion of the cricoid cartilage or incomplete tracheo-oesophageal septum formation.
The most widely utilised classification system was described by Benjamin and Inglis in 1989.
In this system, clefts are divided into four categories based upon the extension of the defect.
A type I cleft extends between the arytenoids of the posterior glottis to the level of the vocal folds.
Type II clefts involve the posterior cricoid cartilage but lack complete involvement of the cartilage.
Extension through the cricoid cartilage, with or without extension into the cervical trachea defines a type III cleft.
A type IV cleft extends to the thoracic trachea and may include the carina.
In general, the severity of the symptomatology correlates to the severity of the cleft present.
SPSE 1
A 3-month-old previously healthy baby girl presents to your clinic. Mum reports that over the last several weeks her child has had noisy breathing. The respiratory sounds are described as being especially pronounced during crying and feeding.
The most likely diagnosis for this child’s breathing difficulties is:
A subglottic stenosis
B laryngomalacia
C laryngotracheomalacia
D nasal airway obstruction
E subglottic haemangioma.
E
Segmental facial haemangiomas in a beard distribution are commonly associated with airway haemangiomas.
Segmental haemangiomas in the submental area especially are highly associated with airway haemangiomas.
Airway haemangiomas can occur in the oral cavity, nasopharynx, hypopharynx, glottis or subglottis.
In contrast to the other sites, haemangiomas of the subglottis are typically bulky and can significantly narrow the upper respiratory tract leading to respiratory insufficiency.
Children with obstructive airway haemangiomas typically present at 2–3 months of age. Important to remember is that only 50% of children with a subglottic haemangioma have a cutaneous haemangioma.
SPSE 1
A 5-month-old child is referred to you by her paediatrician for evaluation of a possible subglottic haemangioma since the child is noted to have a large segmental facial haemangioma (see Figure 19.2). However, after eliciting a history from the parents, you note that the child has no feeding or airway symptoms. Furthermore, a flexible laryngoscopy, and soft tissue airway films demonstrate no obvious subglottic lesions.
At this point the next reasonable step in management is:
A Assure the parents that given there is no subglottic haemangioma at the moment, there is unlikely to be one later.
B Since the airway is normal, send the patient to a facial plastic surgeon for treatment of the lip deformity.
C Refer the patient to an ophthalmologist, cardiologist and neurologist for evaluation of PHACES.
D Tell the parents that there is no airway haemangioma present on initial exam, and advise that the patient should undergo serial airway evaluations in the operating room for the next 4 months.
E Discharge the patient home with no follow-up.
C
Segmental facial haemangiomas can be associated with PHACES syndrome, especially when the haemangioma occurs in a V1 distribution. However, some children have facial haemangiomas that cross all three dermatomes and thus cannot be classified easily into those that are at high risk for airway haemangiomas and those that are at high risk for PHACES syndrome.
PHACES is an acronym that stands for Posterior cranial fossa malformations, Haemangioma, Arterial anomalies, Cardiac defects, Eye anomalies, and Sternal clefts or Supraumbilical raphe.
SPSE 1
