Describe What Is Actually Seen

The recommendation to describe what is actually seen should be followed by the clinician both before and after birth. In principle, antenatal ultrasound abnormalities should be described using such terms as increased echogenicity with large, small, or multiple cysts rather than as “CPAM,” which is, and remains, a histological diagnosis. The presence or absence of abnormal feeding vessels should be defined using imaging appropriate to developmental stage (i.e., antenatal or postnatal). Other features, such as mediastinal shift, should also be described. In the postnatal period, a radiographic abnormality should be described as solid or cystic. If cystic, the cysts are either single or multiple, and the uniformity and thickness of the walls should be described. They may be filled with air, or partially or completely with fluid; moreover, their size should be recorded. Postnatally, an air–fluid level suggests that the abnormality is ventilated, albeit with a long time constant. If the lesion has been excised, the pathologist should describe the tissues found (epithelial, mesenchymal) and the contents of any cysts that may be present, thus giving a simple description of what is seen under the microscope. Only then is it relevant to make a pathologic diagnosis, such as one of the various histologic types of CPAM (see subsequent sections). Any classification system that is to be robust cannot be based on embryologic speculation.

Use Clear Terms

Many terms are ambiguous and are best avoided. For example, hypoplastic lung could be taken as meaning a lung that is small but otherwise normal, or small because the underlying structure is abnormal; the term congenital small lung (CSL, which is what is actually seen) avoids such ambiguity. The use of the term emphysema as in congenital lobar emphysema is another source of confusion, since it implies lung destruction, whereas in at least some variants (e.g., polyalveolar lobe) there may be too many, not too few, alveoli. What is actually seen is a congenital large hyperlucent lobe (CLHL), which is the term that should be used in clinical practice. Throughout this chapter, unwarranted established terms will be given in parentheses after our proposed nomenclature; for the convenience of the reader, the new terms will be spelled out in full, with the abbreviated form being given in parentheses. A summary comparison of old and our current nomenclature is provided in Table 18.1 .

Use a Systematic Approach

The lung can be considered to be formed from six “trees”: bronchial, arterial (systemic and pulmonary), venous (systemic and pulmonary), and lymphatic. There are no known congenital abnormalities of bronchial venous drainage, so in practice, only five trees have to be considered. There are three other areas wherein malformations may affect the respiratory system and that should also be assessed. These are (1) the heart and great vessels; (2) the chest wall, including the respiratory neuromuscular apparatus; and (3) the abdomen. Finally, the possibility of multisystem disease (e.g., tuberous sclerosis) should be considered. Each patient suspected of having a congenital lung malformation should be systematically evaluated along these lines, if important coexistent abnormalities are not to be missed. The importance of a systematic approach to treatment, with an appropriate evaluation of all trees and associated systems before embarking on treatment, cannot be overstated.

Keep Clinical and Pathologic Descriptions Separate

This is an extension of the principle of describing what is seen. Black-and-white images on a scan are unlikely to be pathognomonic of a single histologic entity. It is more logical to describe the clinical appearances and construct a pathologic differential diagnosis. Only after excision of the lesion can the pathologist make an appropriate diagnosis from examination of the excised specimen.

Antenatal Presentation

Antenatal presentation is usually associated with an abnormality detected at the time of a routine fetal anomaly scan as described in detail later. However, abnormalities of amniotic fluid volume may also be associated with underlying pulmonary pathology. This may be secondary, as in bilateral CSL (pulmonary hypoplasia) associated with both early-onset oligohydramnios for whatever reason (bilateral renal dysplasia/agenesis, first- or early second-trimester rupture of the membranes, etc.), or polyhydramnios associated with conditions, such as the Pena-Shokeir phenotype or antenatal onset of severe spinal muscular atrophy, wherein severe neuromuscular disease prevents normal respiratory movements and lung development; another possibility is compression of the fetal esophagus by a mass, preventing normal swallowing of amniotic fluid. In other situations there is a primary pulmonary anomaly (e.g., tracheoesophageal fistula or laryngeal/tracheal agenesis) that causes the polyhydramnios. Other presentations include short limbs in those skeletal dysplasias associated with bilateral CSL secondary to small chests and short ribs (e.g., Jeune’s asphyxiating thoracic dystrophy), or talipes and polyhydramnios in congenital myotonic dystrophy.

What Can We Diagnose and When?

Fetal lung abnormalities are increasingly detected prenatally as a result of advances in ultrasound imaging, which improves the diagnosis, and because fetal anomaly scanning is now routinely offered to many women in the developed world. A fetal lung lesion is suspected either when a mass (cystic or solid) is identified in the thorax or because of mediastinal shift ( Tables 18.3 and 18.4 ). The opportunity to identify an intrathoracic anomaly in the antenatal period permits further investigation and occasionally offers the potential for intrauterine therapy. It also identifies fetuses that may benefit from delivery in a center offering tertiary-level neonatal support and the option of early postnatal surgical intervention. Many of these lesions can be detected around 20 weeks’ gestation, but for some, in particular diaphragmatic hernias and pleural effusions, late presentation is well recognized. Such lesions may not be detected until an incidental scan in the third trimester is undertaken, or, indeed, until after birth when the neonate or infant presents clinically. It must also be recognized that a sonographic diagnosis can only describe the macroscopic nature of the lesion, and a definitive diagnosis for many anomalies must await definitive radiologic or histologic diagnosis after birth. Many reported studies are seriously limited, because they base conclusions solely on prenatal ultrasound or postnatal imaging, which is often limited to plain radiology. While advances in technology have improved antenatal diagnosis of lesions that may benefit from early postnatal intervention, many of the abnormalities detected appear to resolve spontaneously or are clinically silent. The pediatrician is frequently faced with a new dilemma: how to manage a healthy infant with a lesion that would not have been brought to medical attention were it not for antenatal imaging. What is the natural history of some of these lesions; do they require intervention, or are they benign variants? This section will present an overview of the antenatal diagnosis and management of the more common types of congenital intrathoracic abnormalities. Postnatal management of the abnormalities is discussed in subsequent sections. A summary approach to counseling mothers whose fetus has a cystic or solid CTM is given in Box 18.1 , and discussed in more detail below. The enormous anxiety that is caused by uncertainty, even when the malformation probably has a good prognosis, should be acknowledged.

In addition to fetal ultrasound, in recent years there has been an increasing use of fetal MRI to define pathology, detected with ultrasound. There are reports of its use for the delineation and evolution of fetal cystic masses, but how much MRI adds to the ultrasound diagnosis remains to be demonstrated. It may be more sensitive to small lesions than ultrasound, but it is arguable whether detection of tiny abnormalities really matters. It has been shown to be superior to screening ultrasound for the diagnosis of congenital high airway obstruction syndrome (CHAOS) when it changed the diagnosis in 70%, but in 9 of these 10 cases, the MRI diagnosis was concordant with the referral center ultrasound findings. However, it may be useful to accurately determine the level of airway obstruction in this condition. MRI may also be of use to determine the location of feeding vessels in fetuses with pulmonary sequestration, but further comparison with ultrasound-based methods is required before we can say whether it adds significantly to Doppler-based methods. The role of MRI to determine lung volumes in fetuses with congenital diaphragmatic hernia (CDH) or lung masses has been evaluated and may ultimately prove superior to other ultrasound-based methods (see later). Finally, virtual bronchoscopy can be undertaken with fetal MRI.

CTM Subsequently Diagnosed Postnatally as CPAM

Antenatal Diagnosis and Prognosis

CPAM is traditionally classified according to histological and clinical findings; however, sonographic classification is best achieved by considering them as either macrocystic ( Fig. 18.3 ) or microcystic ( Fig. 18.4 ). The main differential diagnosis to consider with a macrocystic CPAM is diaphragmatic hernia. Differentiating features are described above. However, in a series of 87 fetuses seen in the Fetal Medicine Unit at University College London Hospitals (UCLH) with a prenatal diagnosis of CPAM, two in fact had a diaphragmatic hernia and one an eventration of the diaphragm (see Table 18.4 ). In those with a diaphragmatic hernia, the correct diagnosis was made prenatally after serial scanning. In the patient with an eventration, the correct diagnosis was made only on postnatal imaging. Most CPAMs occur in isolation, although other abnormalities, including bronchopulmonary sequestration and CDH, have been reported to occur in association with CPAM as they have a broad range of extrapulmonary malformations, including renal and cardiac anomalies. Indeed, differentiation of these lesions histologically can be challenging as many have a mixed etiology. Aneuploidy is not a recognized association.

Axial (A) and longitudinal (B) view through the fetus thorax in a fetus referred at 21 weeks’ gestation with skin edema and increased liquor. The heart (H) can be seen displaced to the left, and the whole chest appears to be full of abnormal lung tissue. In the longitudinal view the diaphragm is displaced downwards by the abnormally expanded lung tissue. The large cysts were aspirated and pleuro-amniotic shunts inserted, following which the skin edema resolved. The pregnancy continued to term; respiratory support was required at birth with surgery in the neonatal period. The child is now alive and well at school age.

(A) Parasagittal view through the chest at 21 weeks’ gestation showing the echogenic wedge-shaped left lower lung behind the chest in a fetus with a microcystic lesion. In the axial view of the fetal chest (B), the abnormal lung can be seen causing marked mediastinal shift with the heart (H) lying in the right chest. The mediastinal shift resolved as pregnancy progressed, and the baby was well at birth. Postnatal imaging confirmed the presence of the lesion, and a conservative management policy was followed.

In general, the prognosis for a fetus with a CPAM is good with only a small number going on to develop hydrops, which is a poor prognostic sign, particularly if it is evident at the initial presentation in the second trimester. Traditionally, both polyhydramnios and mediastinal shift were considered poor prognostic indicators, but data that are more recent suggest that these may be less reliable. Accurate prediction of outcome for prenatally diagnosed lesions can be difficult following a single scan because they can change in size significantly during pregnancy with the majority reducing in size and many appearing to disappear spontaneously. Some may increase in size until around 26 weeks’ gestation before reducing in size, while others appear to resolve on sonography. Spontaneous resolution of features, such as hydrops or mediastinal shift, which are usually associated with poor prognosis, has been observed. Various attempts have been made to predict outcome using models that include cyst volumes, but the varied course of these lesions means that serial scans are required to detect those lesions that progress in size or display adverse prognostic features that may warrant consideration of intervention. The Kings College London group has reported on 67 fetuses with an antenatally diagnosed congenital lung malformation. A total of 64 were born alive, and 42 underwent postnatal surgery (see later). Surgery was performed in 45% of lesions showing late gestation “resolution.” Although there was some correlation between the antenatal appearances and the need for surgery, this was not usefully predictive for an individual, and the need for operation was judged on the postnatal features of clinical need. In a case series of 119 neonates with an antenatal diagnosis, and who were followed up to the age of 5–16 years, and were cared for at Great Ormond Street Hospital (GOSH), only 8 (6.7%) were symptomatic and required emergency surgery during the neonatal period. This is in keeping with another large case series from the University of Southampton of 72 neonates with a prenatal diagnosis of congenital lung malformation, where only one required emergency surgery. The use of elective surgery remains controversial as indicated by the lower rate of surgery overall (43%) in the GOSH cohort where surgery was usually only performed on clinical grounds compared with the Kings series, and these data demonstrate the varying approach to management. Table 18.4 shows the type of cystic lung lesion, other sonographic findings, diagnosis, and outcome for the UCLH cohort. In all cases, early consultation with neonatal and pediatric surgical staff is helpful for parents.

Congenital Thoracic Malformation Subsequently Diagnosed Pathologically as Bronchopulmonary Sequestration

In the fetus a sequestrated lobe of lung is most often identified as a mass of uncertain origin in the chest or subdiaphragmatic area. Prenatally it is not possible to make a definitive diagnosis unless an independent blood supply is demonstrated using Doppler ultrasound, although it should be noted that a CPAM might also have an aortic blood supply. The sequestrated lobe usually appears as an echogenic mass in the chest ( Fig. 18.5 ) or abdomen ( Fig. 18.6 ). It can be associated with hydrops, mediastinal shift, and polyhydramnios (see Fig. 18.5 ). The outcome for fetuses with bronchopulmonary sequestration is generally good when presentation is uncomplicated by pleural effusions or hydrops. As such, the prenatal management of fetuses with lesions suspected to be a sequestration is similar for those with a suspected CPAM; therefore, serial scanning should be undertaken and the fetus should be delivered in a tertiary unit if there is significant mediastinal shift in the third trimester. Spontaneous improvement in utero is frequently reported. In a review of the literature describing neonatal outcomes after in-utero interventions, laser coagulation of the feeding vessel to a sequestrated lobe in hydropic fetuses has been reported to result in the resolution of the hydrops and a good neonatal outcome in several cases.

Axial (A) and longitudinal (B) view through the thorax of a fetus that presented at 34 weeks’ gestation with hydrops and polyhydramnios. The large echogenic mass can be seen occupying most of the chest. There is a significant rim of ascitic fluid seen in the abdomen as well as pleural effusions in the chest. Preterm labor ensued after amniodrainage. Resuscitation failed and a postmortem demonstrated a sequestrated lobe with associated pulmonary hypoplasia.

Axial (A) and longitudinal (B) view through the abdomen of a fetus at 22 weeks’ gestation. Note the echogenic mass (M) related to the diaphragm lying behind the stomach (S). An ultrasound-guided needle biopsy after birth confirmed this to be a pulmonary sequestration. This subsequently resolved spontaneously in early childhood.

Presentation of Congenital Thoracic Malformations in the Immediate Postnatal Period

Postnatal presentations of many abnormalities of course overlap; in summary, presentation is with immediate neonatal respiratory distress; the delayed development of symptoms or a complication of a known or previously undiagnosed abnormality; or the child may have an asymptomatic lesion for which active management may or may not be indicated.

The differential diagnosis of acute unexpected respiratory distress in a term newborn extends well beyond congenital lung disease to include conditions such as congenital infections, interstitial lung disease, pneumothorax, cardiac disease, and primary ciliary dyskinesia. If a congenital lung abnormality has been identified antenatally, the diagnosis of the cause of the respiratory distress is likely obvious. Not all lesions are detected prenatally, although with increasing use and improvements in technology and sonographic skills, postnatal presentation is becoming less common. Late detection may particularly be an issue in diaphragmatic hernias, some of which do not present with sonographic findings until after the time of the routine anomaly scan, or, indeed, well after birth. Respiratory distress in the absence of major airway disease may be due to disorders of the lung parenchyma. These include a large cystic or solid CTM, the presence of unilateral or bilateral small lungs, and congenital pleural effusion or lymphatic disorder. The differential diagnosis of a cystic abnormality detected postnatally, but not antenatally, includes cysts secondary to infection or pulmonary interstitial emphysema, which may present in localized form even in a term baby who has not been ventilated.

The management of CTMs after the immediate postnatal period, both asymptomatic and those that have become symptomatic after a latent period of as long as many years, is discussed below. The King’s College Hospital group (see earlier) actually performed surgery in 45% of lesions showing late-gestation “resolution.” Although there was some correlation between the antenatal appearances and the need for surgery, this was not usefully predictive for an individual, and the need for an operation was judged on postnatal features rather than clinical need. In general, the approach to the postnatal management of neonates with prenatally diagnosed cystic lung lesions is very variable. There are those who feel that all lesions should be surgically removed, and others who favor a more conservative approach ( Table 18.6 ). At UCLH, we have seen 110 fetuses with cystic lung lesions in the last 15 years, of whom 100 are alive, 20 having had surgery. This is a much lower proportion than in the King’s series and demonstrates the varying approach to management. In all cases, early consultation with neonatal and pediatric surgical staff is helpful for parents. The issues of postnatal management are discussed in more detail below. Where a lesion has persisted or increased in size and mediastinal shift persists in the third trimester, delivery in a center with neonatal intensive care and surgical facilities should be considered. In all cases, careful postnatal follow-up should be undertaken, with CT being offered to all, even if the lesion has apparently disappeared completely antenatally; chest x-ray (CXR) is only 61% sensitive to the presence of lesions on high-resolution computed tomography (HRCT). Lesions that have apparently involuted completely in utero are well documented to still be present when examined by CT after birth.

Vascular abnormalities may present at this time. One such group are aortopulmonary collaterals supplying either a CSL or a CTM. These act hemodynamically as systemic arteriovenous malformations and cause high-output heart failure. Abnormalities of venous drainage, such as “scimitar” syndrome (hemianomalous pulmonary venous drainage to the inferior caval vein), may also present as heart failure or enter the differential diagnosis of pulmonary hypertension in the newborn period. Other vascular problems that may present at this time include alveolar-capillary dysplasia (discussed in Chapter 54 ) and pulmonary arteriovenous malformation (PAVM), which may present as cyanosis in a well infant (not with heart failure, unless there is an associated systemic, usually cerebral, arteriovenous malformation). The presentations of congenital lung disease after the postnatal period, and the issues around prophylactic surgery, are discussed in more detail below.

Stridor

Quite often the most important feature in the history is the time of onset and character of stridor. Stridor present since birth most indicates a congenital pathology, such as laryngeal webs or bilateral vocal cord paralysis, whereas a more gradual onset of symptoms over days/weeks to months points to diagnoses such as laryngomalacia, subglottic hemangiomas, or cysts. An acute onset of symptoms, accompanied by corroborating factors in the history, can lead towards diagnosing foreign body aspiration and inflammatory or infectious conditions as the etiological factor (see Chapter 23 ). The characteristics of the stridor itself can also be a diagnostic aid: inspiratory suggests glottic pathology (and that in the immediate supraglottis); biphasic subglottic or extra thoracic trachea pathology; and expiratory intrathoracic, trachea, and bronchial pathology. Another diagnostic indicator of stridor is its character. Stridor of a constant nature indicates a fixed lesion pathology as opposed to the intermittent symptoms of conditions such as laryngomalacia.

Voice/Cry

In addition to stridor there are other laryngeal symptoms that should be taken into consideration such as the voice/cry and cough. These symptoms particularly implicate glottis level pathology, either structural (webs, papilloma) or functional (vocal cord paralysis).

Cough

Cough itself can be associated with other factors in the history, such as its relation to upper respiratory tract infections (URTIs) and croup. If there is a history of recurrent or prolonged croup, consideration should be given to the need to diagnose an underlying airway stenosis or inhaled and retained foreign body, or subglottic hemangioma. Cough can also be related to aspiration events related to feeds where, with the aid of swallowing, assessment of the presence of vocal cord palsy, laryngeal cleft, or TEF may need to be investigated.

Cyanosis

Episodes of cyanosis certainly indicate severe respiratory difficulty and can be due to several causes, but they are often associated with tracheal disease, including external compression due to the presence of a vascular ring.

Neonatal Intubation

Perhaps one of the most important factors in the history should be that pertaining to the birth history and, more specifically, neonatal intubation. Respiratory difficulty at birth and the need and duration of intubation and ventilation should lower the threshold for proceeding to diagnostic microlaryngobronchoscopy (MLB) in those children with an otherwise less concerning symptomatic history. Subglottic cysts and acquired stenosis are often an endoscopic finding in these cases. The premature infant is therefore often in this high-risk group for airway pathology. Additionally, this patient subgroup is also more likely to have undergone cardiac surgery, which can be associated with upper airway pathology, such as recurrent laryngeal nerve palsy.

Other Comorbidities

These should also be sought in the history as these can be associated with particular pathologies. Many of the craniofacial syndromes are associated with airway difficulties that are often multilevel problems. Down syndrome children are known to have difficulties due to macroglossia and congenital SGS. There are also several conditions that can be associated with hypotonia, such as cerebral palsy, leading to airway difficulties.

Definition

The Emergent Airway is that transition point at which a patient’s oxygen saturation becomes difficult or impossible to maintain above 90% during an intubation or procedure.

Assessment of a neonate presenting in an emergency with airway difficulty is often an unnerving situation for all concerned. It is important to have a clear and methodical plan to implement in these circumstances to aid prompt diagnosis and appropriate intervention. The history is again important and should aim to cover those points discussed in the previous section. Immediate examination in the delivery room may provide an obvious diagnosis by the pediatric staff, such as a major craniofacial abnormality, but severe airway problems, such as congenital tracheal stenosis, may have no external physical signs.

Accordingly, it is not unusual for children to be stabilized by the attending pediatric team before a definitive diagnosis is made. This might include intubation of the child; the use of oral airways in the case of nasal obstruction (e.g., choanal atresia); nursing the child prone in cases of oral/oropharyngeal obstruction (e.g., in Pierre-Robin sequence); and the use of a nasopharyngeal airway (NPA) if the obstruction is not easily relieved. If intubation is extremely difficult, it may be appropriate to consider immediate tracheostomy to avoid the risk of the ET tube becoming dislodged and failure to reintubate. This might be considered with a large cystic hygroma ( Fig. 18.10 ). If the anatomy of the neck is very abnormal, it may be useful to pass a rigid bronchoscope to allow ventilation and act as a marker for the trachea within the distorted anatomy of the neck.

Severe neonatal upper airway obstruction due to cystic hygroma.

(Picture reproduced courtesy of Mr. C.M. Bailey.)

As outlined above, a child who has chronic or episodic stridor may be examined with a flexible endoscope to assess the upper airway and diagnose supraglottic pathology. The requirements for this procedure to be performed safely are given in Box 18.3 .

Examination of the child in this situation is often performed concurrently, as rapid assessment is required. The principle of assessment in this “emergency” should principally address the need to establish an immediate safe airway. The degree of respiratory effort made by the child should be carefully observed, and signs such as an opisthotonic posture with severe recession prompt urgency. Pulse oximetry can be very useful in this situation but not relied upon, as decompensation can be rapid with reduced oxygen saturations being a late sign; in particular, if the child is breathing oxygen-enriched mixtures, severe hypercapnia can be masked. Often a child that is quietening in terms of their respiratory effort could be tiring and deteriorating rather than improving.

General assessment of signs of toxicity should also be made and these include measures of temperature, heart rate, and capillary refill. These signs can be determined by inspection of the patient alone with minimal contact. In an emergent airway, a more probing examination can lead to a rapid deterioration in symptoms and this should be avoided in an uncontrolled environment.

Attempts should be made to further evaluate such a child in a relatively more controlled theatre environment with a senior anesthetist and ear-nose-throat (ENT) surgeon present to assess and secure the airway as deemed appropriate. Several measures can be employed to manage an emergent airway that can lead to adequate control of the symptoms or at least to provide a holding measure whilst deploying the appropriate teams to manage the situation definitively. These include oxygen, nebulized adrenaline, Heliox, and steroids. If an infective etiology is suspected, a diagnostic MLB may not be necessary and, in fact, is often contraindicated in severe cases, such as acute epiglottitis.

The aim should be to stabilize the airway with either medical treatment that can include oxygenation, steroids, and antibiotics, or to secure the airway with intubation, often by the anesthetists with an ENT surgeon merely on standby in case of difficulty. Techniques for a difficult intubation include the use of the ventilating bronchoscope or intubation with an ET tube placed over a 2.7 mm Hopkins rod. These techniques are perhaps used less often by ENT surgeons due to the advances in airway adjuncts for our anesthetic colleagues. Equipment, such as video glidascopes, can improve the grade of view at laryngoscopy facilitating intubation. Fiberoptic intubation is also more commonplace but very difficult in the neonate.

Again, if intubation is not possible, the option of a surgical airway must be considered. The situation is still controlled if ventilation can still be achieved by either the bag and mask technique or a laryngeal mask airway (LMA). An NPA should be considered if the level of obstruction is at the nasal or oropharyngeal level. Similarly, distal disease may require positive airway pressure support.

Laryngomalacia

Laryngomalacia is a dynamic condition and is the most common cause of stridor in infants ( Fig. 18.13 ). It occurs due to collapse of the relatively immature cartilaginous supraglottic structures, which has been postulated due to an incoordination of the laryngeal muscles due to neuromuscular immaturity. This leads to a mistiming of laryngeal movements and tends to cause indrawing and lengthening of the supraglottic structures. However, laryngomalacia may just be a structural variation.

Appearances of laryngomalacia at microlaryngobronchoscopy. (A) Typical omega-shaped epiglottis. (B) Posterior view of collapsing laryngeal inlet. (C) Shortened aryepiglottic folds. (D) prominent arytenoid cartilages.

This functional collapse can be related to specific structural features:

• 1.
  

  The aryepiglottic folds are short and vertical, curling the epiglottis into an omega shape.

  
  
• 2.
  

  Prominent cuneiform and corniculate cartilages lie over the arytenoid cartilages, which prolapse into the airway.

  
  
• 3.
  

  A loose, redundant mucosal covering of the aryepiglottic fold prolapses into the airway.

There is a high concomitant incidence of gastroesophageal reflux in infants with laryngomalacia, presumably because of the more negative intrathoracic pressures necessary to overcome inspiratory obstruction. Conversely, children with significant reflux may also exhibit pathological changes similar to laryngomalacia, especially enlargement and swelling of the arytenoid cartilages.

Laryngeal Atresia and Webs

The larynx develops from the endodermal lining of the cranial end of the laryngotracheal tube and from the surrounding mesenchyme derived from the fourth and sixth pairs of branchial arches. The epithelium proliferates rapidly, and this leads to an occlusion of the laryngeal lumen, which recannalizes by the tenth week of gestation. Failure to reestablish a complete lumen leads either to a laryngeal web or, in extreme cases, to complete atresia.

Laryngeal Webs

Laryngeal webs are a rare congenital anomaly ( Fig. 18.14 ). They result from a failure of recanalization of the laryngotracheal tube during the third month of gestation and similarly can result in varying degrees of laryngeal webs. The most common site at which these develop is the anterior commissure, although webbing can be present in the posterior interarytenoid area, subglottic, or supraglottic regions. Key diagnostic points are to delineate any subglottic disease as well as any underlying congenital diagnosis, such as velocardiofacial syndrome (chromosome 22q11.2 deletion ).

Laryngeal web seen at microlaryngobronchoscopy before (A) and after (B) treatment.

Cohen’s classification system subdivides laryngeal webs into four types:

• 
  

  Type I: An anterior web involving 35% of the glottis or less. The vocal cords are visible through these thin webs.

  
  
• 
  

  Type II: An anterior web involving 35%–50% of the glottis, which may be thin or thick, with extension into the subglottis. The vocal cords are usually visible within the web.

  
  
• 
  

  Type III: An anterior web involving 50%–70% of the glottis, typically with a thick anterior portion and extension into the subglottis.

  
  
• 
  

  Type IV: 75%–90% of the glottis is involved by a uniformly thick web, which extends into the subglottic larynx. The individual vocal cords are not identifiable and may be fused together. There may be an associated abnormality of the anterior cricoid cartilage.

As anterior laryngeal involvement is the most common site, hoarseness is the most common presentation. This is certainly most likely with a thin anterior laryngeal web although a thicker lesion can result in aphonia. If the web is extensive and involves the subglottis, respiratory compromise may be evident ( Fig. 18.15 ). The rarer posterior inter arytenoid webs can present with stridor secondary to the inability to abduct the vocal cords. Flexible nasoendoscopy can diagnose a laryngeal web but on its own is insufficient to evaluate the extent of the lesion or plan any treatment. Formal endoscopic evaluation by way of an MLB allows for the character and true extent of the lesion to be determined.

Microlaryngobronchoscopy picture of an anterior glottic web and associated grade 3 subglottic stenosis.

The management of a laryngeal web may simply be conservative with voice therapy support. Much of the concern regarding surgery relates to the possibility of web reformation and resultant scarring. The rare, thin anterior laryngeal webs may be endoscopically divided and dilated to good effect. More complex, thicker, or larger webs may require an endoscopic or an open approach. Endoscopic approaches involve wedge resection, suturing of the cut edges, placement of stents, mitomycin C topical application, or local flap reconstructions. Open approaches require laryngofissure and anterior cartilage graft placement. In most cases of complex webbing, revision procedures are commonplace and a tracheostomy is inevitable.

Type 1 Clefts

Conservative management of interarytenoid clefts should be the initial choice, with swallowing therapy particularly aimed at thickening feeds to prevent aspiration. If this fails, endoscopic repair is advocated. Through a laryngoscope, the mucosa is cut from the inner margins of the cleft, which are then sutured together ( Fig. 18.16 ).

Endoscopic repair of laryngeal cleft type 1.

Saccular Cysts and Laryngoceles

The saccule is a blind ending structure that opens into the laryngeal ventricle, the lateral space between the true and false vocal cord. It runs in an anterior-superior direction and is usually of modest size in the normal larynx. It is lined by pseudostratified columnar epithelium and contains serous and mucous glands. A laryngocele is an abnormally enlarged laryngeal saccule and is air-filled. The condition is a rare congenital abnormality but may produce significant airway obstruction. It may be entirely within the confines of the larynx or extend into the neck via the thyrohyoid membrane. If the lesion is small, it may be excised using an endoscopic approach. Alternatively, an open operation may be necessary for larger lesions, with the possible need for a prior tracheostomy to ensure an adequate airway postoperatively.

Saccular cysts are mucous filled and are found in the false vocal cord or aryepiglottic fold ( Fig. 18.17 ). They are presumed to arise from a part of the saccule that has become sealed off from its outlet into the ventricle. They may be massive and cause immediate and severe airway obstruction. Standard endoscopic therapy is aspiration and marsupialization with scissors or laser. There is a high rate of recurrence, and open resection may eventually become necessary.

Congenital saccular cyst of aryepiglottic fold.

Hemangiomas—Subglottic and Tracheal

Infantile hemangiomas are benign vascular tumors and account for 1%–2% of all congenital anomalies of the larynx. Similar to cutaneous hemangiomas, they have a natural history, which includes a phase of rapid growth and proliferation followed by phases of involution. They can occur at all sites in the airway but are rare; the subglottis is the most common subsite. They usually present with symptomatic airway obstruction in the first 3 months of life, and this condition manifests itself more commonly in females than males, at a ratio of 2 : 1.

Infants with subglottic hemangiomas present with stridor that is not characteristically present at birth. As the lesion grows, symptoms ensue and typically the child presents with biphasic stridor around the age of 6 weeks. Symptoms can deteriorate as the lesion grows in size and this can occur up until the age of 2 years when the lesion then reduces in size, as seen in many cases of cutaneous hemangiomas. Presentation may mimic croup, and, since the lesion transiently regresses with dexamethasone treatment, the diagnosis may be missed until there have been recurrent bouts of airway obstruction. Infants with subglottic hemangiomas are likely to have a cutaneous lesion in 50% of cases. The need for treatment arises due to the growth of the subglottic lesion in a confined space, which inevitably gives rise to airway compromise.

Again, the gold standard for diagnosis is MLB. This allows for exclusion of other pathologies as well as direct visualization of the lesion. Photo-documentation of the lesion allows subsequent MLBs to determine the response to treatment. The lesion is most often seen as a solitary entity posteriorly in the subglottis, although multiple lesions can occur and rarely, these can be located at the mid-tracheal level. The lesion itself appears as a soft, compressible, red mass. The neurocutaneous disorder, PHACES syndrome (posterior fossa brain malformations, hemangiomas, cardiac anomalies and coarctation of the aorta, and eye anomalies with or without sternal clefts) should be considered and ruled out in cases of subglottic hemangioma.

In 2008, the treatment of hemangiomas was revolutionized by the serendipitous discovery of propranolol therapy. Previous treatments had included systemic and topical steroids and surgical excision; these options are now secondary with propranolol therapy being the first-line treatment option. However, treatment with propranolol is protracted and needs careful monitoring for side effects, and dosages need to be adjusted over the treatment period, which can typically vary from 12 to 18 months, although it can be longer in some cases. Responses, as determined by MLB findings and symptoms, can be seen within a few days of commencing treatment ( Fig. 18.18 ). A minority of patients does not show any improvement with propranolol therapy and may require traditional interventions, such as open or endoscopic debulking or resection of the lesion.

(A and B) Case of tracheal hemangioma prepropranolol and postpropranolol therapy (pictures 2 weeks apart).