Introduction:
Developmental disorders of the upper airway are one of the common congenital disorders affecting the population worldwide. Especially developmental defects of the larynx (voice box) account for about 0.3 to 0.5 percent of all laryngeal disorders. Anomalies of the larynx may range from mild soft tissue defects to complete clefts (an opening or split) involving the larynx, trachea (windpipe), and esophagus (food pipe). This condition is mainly referred to as laryngeal clefts. The first case of laryngotracheoesophageal cleft (LC) was described in 1792 by Richter in a newborn. Read below to learn more about laryngotracheoesophageal cleft (LTEC), its epidemiology, causes, clinical manifestations, diagnosis, and management in detail.
What Is Laryngotracheoesophageal Cleft?
Laryngotracheoesophageal cleft is a rare condition that is present from birth and is characterized by developmental disorders of the posterior aspect of the larynx, which could be extending to the trachea, which in turn creates an abnormal split or opening in the airway and the digestive tract. In critical cases, there is a severe downward extension of the separation. The normal biological segregation between the digestive system and the upper way is lost. The clinical presentation of the condition depends on the severity of the cleft. The conditions show varied prognoses depending on the association with other syndromes and the type of LTEC.
What Is the Etiology of LTEC?
During the embryologic development of the respiratory system, the larynx develops from the fourth and sixth branchial arches (an embryonic structure that functions as a building block) and the endoderm that evolves from the foregut (anterior part of the digestive system). The tracheobronchial groove starts to develop in parallel, reaches together in the midline, and fuses to form a tracheoesophageal septum during the fifth week of gestation. Failure or interruption during this process results in developmental defects of the tracheoesophageal septum. This results in laryngotracheoesophageal cleft.
What Are the Associated Conditions of LTEC?
Laryngotracheoesophageal cleft is often associated with other conditions or syndromes in 16 to 68 percent of cases. Cases of LTEC either appear isolated or in combination with other syndromes. The commonly associated conditions include:
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Laryngomalacia (developmental defect of the voicebox).
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Tracheo-bronchial dyskinesia (a developmental anomaly affecting the trachea, main bronchi, and the bronchus).
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Gastroesophageal reflux disease (GERD) (a condition with backward flow of the stomach contents into the esophagus).
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Tracheobronchomalacia (a condition with weak and soft trachea).
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Opitz G/BBB syndrome (a genetic condition affecting the regions along the midline of the body).
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Pallister-Hall syndrome (a rare genetic condition affecting various parts of the body).
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CHARGE syndrome (a rare condition and is an acronym for coloboma, heart defects, atresia of choanae, growth retardation, and genital and ear abnormalities).
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VACTERL syndrome (vertebral disorders, anal atresia, cardiac defects, tracheoesophageal fistula, renal anomalies, and limb defects).
What Is the Epidemiology of LTEC?
Laryngotracheoesophageal cleft is an uncommon congenital condition. It is reported to occur more commonly in males than females, with a ratio of 1:2 to 1:8. The estimated incidence rate of this condition is about one in 10,000 to 20,000 live births. And it accounts for about 0.2 to 1.5 percent of all congenital disorders of the larynx. It is reported to occur infrequently among the population and is believed to be inherited in an autosomal dominant pattern. Some of the risk factors of this condition include drug or alcohol abuse during pregnancy and numerous miscarriages.
What Are the Clinical Manifestations of LTEC?
The clinical manifestations of this condition are based on the type of cleft. There are four types of laryngeal clefts based on the classification of Benjamin-Inglis.
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Type 0: It is called the submucosal cleft. Clinical manifestations of this type are usually mild to asymptomatic. Sometimes patients may have occasional aspiration (accidental breathing of food or liquid into the airway)
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Type 1: Defects of the inter arytenoid (intrinsic muscle of larynx) up to the level of true vocal folds (vocal cords). Symptoms of this type include swallowing disorders, horseness or toneless cries, and high-pitched breathing sounds. Rarely patients may have a cough, aspiration, and breathing difficulties.
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Type 2: Defects of the posterior cricoid cartilage (a ring-shaped structure encircles the trachea).
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Type 3: Defects extending entirely through the posterior cricoid cartilage. Type 2 and type 3 symptoms involve respiratory tract infections and swallowing disorders.
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Type 4: The aperture when extends up to the thoracic trachea. Clinical presentation of this type is severe and may cause difficulty maintaining mechanical ventilation and causes respiratory distress.
How Is LTEC Diagnosed?
Most cases of laryngotracheoesophageal cleft are diagnosed through endoscopic examination (a diagnostic technique that contains a thin, long tube with a camera to view the internal structures). The doctor may use a fiber-optic endoscopy to view the larynx under local anesthesia. They may also perform a complete endoscopic examination of the entire respiratory tract under general anesthesia with spontaneous breathing to diagnose other associated conditions of LTEC. The doctor may conduct physical examinations by palpating the posterior glottis (the posterior third of the vocal cord) under local anesthesia.
Radiographic examination such as CT (computed tomography) scan may be performed to examine the abnormal communication between the trachea and food pipe. However, radiographic examinations are not performed as the primary mode of investigation.
How Is LTEC Treated?
Early diagnosis and prompt treatment of this condition are necessary to avoid irreversible pulmonary damage resulting from recurrent aspiration. The management of type 0 and type 1 are usually conservative management options. The primary goal of management is to maintain satisfactory ventilation, prevent respiratory distress from recurrent aspiration, and maintain the patient's calorie intake. Patients with severe complications may require artificial ventilation. The management of this condition requires surgical intervention, which may involve an external or endoscopic approach to close the cleft. The nutritional status of the patients is continuously monitored to maintain the calorie intake of the patient.
Conclusion:
Laryngotracheoesophageal cleft is a rare developmental anomaly causing an abnormal connection between the trachea and the esophagus. The affected patients may have difficulty swallowing, coughing, breathing, aspiration, and cyanosis. The treatment and prognosis of this condition are based on the severity of the cleft and the type of LC. Recent advancements in endoscopic approaches for surgical management of this condition have greatly improved. However, in severe cases, the preferred method is the open technique.
