Summary
Laryngotracheal cleft (LC) represent a spectrum of anomalous connections of the trachea and esophagus extending from laryngeal inlet. In general, the degree of symptoms varies with length of the LC. Diagnosis requires a high index of suspicion. Shallow clefts maybe treated with conservative or medical management but longer clefts will require surgical repair. Surgery can be done endoscopically or open and depends on the cleft size and the experience of the surgeon. In all cases, management requires a multidisciplinary approach.
52 Laryngotracheal Cleft Repair
52.1 Introduction
LC represents a spectrum of anomalous connections of the trachea and esophagus extending from laryngeal inlet. In general, the degree of symptoms varies with the length of the LC. LCs are typically classified based on their length in relation to surrounding structures (▶ Table 52.1). The most commonly employed classification was described by Benjamin and Inglis 1 and is outlined in detail below (▶ Fig. 52.1). However, each LC must be viewed in the context of the child’s overall health as a shallow LC will impact an otherwise healthy child differently than a child with concomitant cardiac disease. 2 , 3 The most common sequelae include recurrent aspirations, pneumonia, and bronchiectasis. Children often undergo multiple investigations prior to diagnosis and are often hospitalized with infection. Type 1 and even some type 2 LCs may go unnoticed for prolonged periods, and diagnosis is often quite delayed. It is critical for physicians to be cognizant of LCs when considering children with recurrent aspiration or else they are likely to be missed. 2 Deeper LCs are often more symptomatic. Type 3 or type 4 LC will often present within days after birth; however, patients presenting later in life have been described. 2
LCs are rare with estimates ranging from 1:10,000 to 1:20,000 live births. 8 However, considering the subtle presentation of many type 1 and type 2 LCs, the true incidence is not known. Among children undergoing direct laryngoscopy for recurrent respiratory symptoms, the incidence ranges from 0.2% to 7.6%. 2 , 9 It is believed that there is a slight male predominance for LCs, but no genetic inheritance patterns have been confirmed. 2
52.2 Embryology of Laryngotracheal Clefts
The etiology of LC is controversial, as the understanding of how the tracheoesophageal septum forms remains incomplete. 10 , 11 Traditionally, it was felt that the aerodigestive tracts became separated by the outgrowth and fusion of lateral ridges from the sidewalls of the primitive foregut. 10 , 11 It was believed that incomplete fusion of these ridges led to the formation of LC. Subsequent embryological studies have not found evidence of these ridges and this theory has fallen from favour. 6 , 11 More recent studies have suggested that at approximately 28 days gestation a series of folds develop on the ventral wall of the endodermic foregut just distal to the fourth pharyngeal pouches. 12 This results in the formation of the respiratory diverticulum which continues to descend ventrocaudally through the mesenchyme of the surrounding foregut. The intervening mesenchyme between the trachea and esophagus becomes the septum and maintains a constant height via rapid proliferation of the caudal fold. If growth in this area cannot match the descent of the respiratory diverticulum, this can result in a range of tracheoesophageal anomalies including LCs. 10 This process may explain the significant rate (12%) of concomitant LC and tracheoesophageal fistula. 8 For type 1 and 2 LCs, the defects likely represent impairments in the structural components of the larynx itself which are derived from the neural crest cells of the fourth and sixth pharyngeal arches. 12 The mesenchyme here proliferates rapidly and forms arytenoid swellings which grow upwards toward the tongue and for a brief period become completely occluded. Recanalization of the larynx appears to be complete by the tenth week. The epithelial lining of the larynx develops from the endoderm at the cranial end of the laryngeal tube. The cricoid develops from two lateral cartilage centers which fuse ventrally and then dorsally approximately one week later. The development of the interarytenoid muscle depends to some extent on this process and cannot occur in the absence of cartilaginous fusion. Incomplete formation of the interarytenoid muscle without absence of the interarytenoid mucosa would form a deep LC. The incomplete formation of both the interarytenoid muscle and mucosa results in a type 1 LC. The addition of incomplete formation of the posterior cricoid cartilage results in a type 2 LC.
52.3 Presentation
Presenting signs and symptoms of an LC are most often respiratory in nature. Chronic cough is common, especially during feeding. The degree of associated respiratory distress typically depends on the depth of the LC; however, in a child with significant comorbidities, cough can be associated with frank cyanosis.
Roughly 90% of patients with type 1 to 3 LCs have respiratory symptoms including aspiration, recurrent pneumonia, stridor, and cyanosis. 13 Specifically, type 1 and 2 LCs are associated with respiratory symptoms such as wheezing and cough in 50% to 60% of children. 14 Admission to hospital is reported in 15% of children with type 1 LCs and 25% of those with type 2 LCs. 14 Smaller LCs usually do not have significant symptoms until at least several months of age and diagnosis commonly established between 2 and 5 years of age. Significant delay in diagnosis can occur if LC is not included on the differential diagnosis of patients with recurrent respiratory symptoms and may not be picked up until later in life. Type 3 and 4 LCs usually present within the first few days of life are invariably associated with greater respiratory symptoms including recurrent pneumonia and often excessive mucus. 2
Over half (58–68%) of patients with LCs have an associated congenital defect. 9 , 14 , 15 These defects can be conceptually grouped as other anatomic malformations or coincident pathology. Gastrointestinal anomalies are the most commonly associated anatomic malformations and can include esophageal atresia, microgastia, tracheoesophageal fistula, imperforate anus, and intestinal malformation. Genitourinary defects are less common and included: hypospadias and kidney malformations. Cardiac abnormalities such as aortic coarctation, transposition of the great vessels, patent ductus arteriosus, and septal defects have also been described. Particular attention must be made to vocal cord function in children who have undergone repair of these conditions as unilateral vocal focal paralysis may occur in as many as 30% of these patients. 16
One of the most common coincident pathologies seen with LCs is laryngomalacia which was found in up to 90% of patients with type 1 LC in one study. 17 Over half of those patients had tracheobronchomalacia and gastroesophageal reflux disease (GERD). The abnormal configuration of the posterior larynx and possibly tracheal can result in redundant arytenoid, posterior laryngeal, and esophageal mucosa, which results in prolapse during inspiration and associated airway narrowing. Given the greater chance of aspiration of gastric contents in the setting of LC, the coincidence of clinically significant GERD is likely quite high. “Cobble stoning” of the airway mucosa and aspirated saliva is often seen on endoscopy; however, pH probe proven disease is usually not established.
Although genetic causes of LCs have not been identified and most cases are sporadic, a number of syndromic associations that include LCs have been identified (▶ Table 52.2). Opitz G/BBB syndrome (hypertelorism, hypospadias, cleft lip, and palate), Pallister–Hall syndrome (hypothalamic/pituitary abnormalities, poly- and syndactyly, imperforate anus, cardiac, pulmonary, renal abnormalities), VACTERL syndrome (vertebral anomalies, anal atresia, cardiac anomalies, renal anomalies, limb anomalies), and CHARGE syndrome (coloboma, heart anomalies, choanal atresia, growth and mental retardation, genitourinary anomalies, and ear anomalies) have all been described.
52.4 Preoperative Evaluation and Management
It is critical to maintain a broad differential diagnosis for patients with recurrent respiratory issues and may include laryngomalacia, GERD, neuromuscular swallowing disorders, and reactive airway disease, all of which are more common than LCs. However, unless a high index of suspicion is maintained, diagnosis may be delayed. Most diagnostic practices include a comprehensive history and physical examination paying close attention to the characteristics of the breathing around feeding, chest X-ray, swallowing assessment, and flexible fiberoptic laryngoscopy. Although these are important in understanding the global picture of aerodigestive health in these patients, the cornerstone of diagnosis of LC is direct laryngoscopy with palpation of the interarytenoid area.
52.4.1 Investigations
The majority of children who present with the above respiratory symptoms are usually accompanied by a chest X-ray. Recurrent, chronic aspiration will be identified as pneumonia or peribronchial cuffing. It is important to note that 25% of children with type 1 LCs and 13% of type 2 LCs will have a normal chest X-ray.
A feeding assessment via videofluoroscopic swallowing study (VFSS) is a critical part of the evaluation of LC patients. In this study, the speech/swallowing pathologist will administer varying consistencies of food containing radiolabelled tracers that can be identified under fluoroscopy. Anteroposterior and lateral views are obtained to study oral, pharyngeal, esophageal, and gastric phases of swallowing. However, as it represents a single picture in time, it may be normal in children who aspirate intermittently. VFSS can also be used to identify patients who have a discoordinated swallow, which is commonly found in children with other neurodevelopmental delays. This can be helpful when counseling patient who will under surgical intervention, as continued work with the speech/swallowing pathology team may be needed postoperatively. 18 In an otherwise healthy child, a positive swallow study for aspiration has a strong correlation with an anatomic abnormality. Overall, over 75% of patients with a type 1 and type 2 LC will display aspiration on VFSS. 2 Children with LC will often require multiple VFSS studies and the cumulative radiation dose must be kept in mind when ordering these tests. 2 , 19
Flexible fiberoptic laryngoscopy is critical for obtaining a dynamic view of the larynx. In particular, it is essential for determining vocal cord function which can lead to decreased laryngeal sensation and aspiration. It can also be done while a speech/swallow pathologist administers dyed food in the form of a flexible endoscopic evaluation of swallow (FEES). In this way, pooling or penetration/aspiration of swallowed food can be observed directly.
The gold standard of LC diagnosis is operative endoscopy via direct laryngoscopy and palpation of the interarytenoid area. As many of the presenting symptoms overlap across a number of clinical entities, patients undergo “triple endoscopy” by otolaryngology (direct laryngoscopy), pulmonology (flexible bronchoscopy), and gastroenterology (flexible esophagogastroduodenoscopy) under the same general anesthetic. At our institution, direct laryngoscopy is often performed with spontaneous ventilation to achieve a dynamic view of the airway. A Parson’s laryngoscope and 0° degree 4 mm telescope (Karl Storz Co., Tuttlingen, Germany) is used to visualize the larynx. After direct laryngoscopy, telescopic tracheobronchoscopy is usually done to assess for edema, cobble stoning, rigid or malacic stenosis, blunting of tracheal rings, and tracheoesophageal fistula. A blunt-tipped laryngeal probe is then used to palpate the depth of the interarytenoid groove. Palpation must be done gently to avoid excessive pressure that would distort or deepen the interarytenoid mucosa. During this process the presence of and extent of the LC can be determined. The extent of the LC can be classified in a number of ways (▶ Table 52.1), the most common being the Benjamin–Inglis classification (▶ Fig. 52.1a–e). 1 Type 1 LCs involve an interarytenoid defect to the level of the true vocal folds. Differentiation of a type 1 LC from a deep groove can be challenging. It is helpful to keep the patient’s symptoms in mind while making this assessment. Type 2 LCs extend beyond the true vocal cords into the posterior cricoid. Type 3 LCs extend completely through the posterior cricoid into the cervical trachea. Finally, type 4 LCs involve an extension into the thoracic trachea. Monnier has further subclassified type 3 and type 4 LCs based on their extent. 4 Type 3a LCs penetrate completely through the cricoid and type 3b LCs go through the cricoid into the extrathoracic trachea. Type 4a LCs extend into the thoracic trachea up to the carina; however, type 4b LCs extend beyond the carina into the mainstem bronchus. Paradoxically, although long, type 3 and type 4 LCs can be challenging to diagnose because redundant mucosa herniation through the LC obscures the surgeon’s view (▶ Fig. 52.1e).
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