Address correspondence to Adriana ­Valcamonico, MD, Vanderbilt University, De­partment of Radiology, 31^st and Garland, Nashville, TN 37333-3675, Ph: 615-343-0595, Fax: 615-343-4890

Synonyms: Atresia of larynx, types I, II, III; glottic atresia; congenital laryngeal atresia; stenosis at the cornus elasticus¹.

Definition: Congenital atresia of the larynx is defined as complete absence of the laryngeal lumen⁷. The three types of larynx atresia are: Type I which is both supra- and infraglottic, Type II is infraglottic and Type III is glottic.

Prevalence: Undetermined, but rare. There have been about 50 reported cases of larynx atresia in the world literature. The sex ratio is presumably M1:F1¹.

Etiology: Presumably autosomal dominant inheritance for the partial form¹.

Pathogenesis: The various types of atresia are the result of arrest at different stages in embryonic development. A chromosomal basis has also been suggested.

Associated anomalies: About one-half the cases reported in the literature had other potentially fatal malformations. They include: CNS (hydrocephaly, malformations of the aqueductus); alimentary system (esophageal atresia, bronchoesophageal fistula, trache­oesophageal fistula and atresia); urogenital system (hypoplasia of kidney, hydroureter, urethral atresia, vesicovaginal fistula, bicornuate uterus), and skeletal system (varus deformity of feet, partial absence of cervical vertebrae, absence of radius, syndactyly)¹.

Differential diagnosis:  Adenomatoid malformation of lung type III, bronchial atresia, airway obstruction from compression by external mass (tumors), laryngeal stenosis and hypoplasia¹¹, laryngeal membrane, tracheal atresia.

Prognosis: The vast majority of fetuses with complete larynx atresia die because the condition is not recognized and not treated immediately or because of other life threatening anomalies. Survivors have a normal life span, unless the condition is complicated by serious associated malformations¹.

Recurrence risk: Mendelian inheritance for the partial form.

Management: Complete larynx atresia is incompatible with life unless it is recognized immediately at birth and an immediate tracheotomy is performed. Survivors are extremely rare^1,5,6,7. The prenatal diagnosis has only been reported in the complete form, for which the prognosis is poor and the option for pregnancy termination can be offered.

MESH Larynx-abnormalities, -pathology; Laryngostenosis-congenital BDE 0571 MIM150300 ICD9 748.3 CDC 748.305

Introduction

Congenital laryngeal atresia is a rare upper airway obstruction. It leads to death unless a surgical airway is immediately established. In the literature, survivors are extremely rare, thanks to an immediate recognition of the disease and a rapid tracheotomy.

Case report

A 29-year-old G2P1 woman was referred for a routine scan at 18 weeks of gestation. The examination revealed a single fetus with ascites, enlarged and echogenic lungs that compressed and displaced the heart (fig. 1,2).

Figure 1: Bilaterally enlarged echogenic lungs that depress the diaphragm. 

Figure 2: The heart (arrow) is compressed between the lungs.

The trachea was dilated and fluid-filled. Color Doppler differentiated it from the adjacent aorta (fig. 3, 4). The amniotic fluid volume was within the normal limits. The patient underwent an amniocentesis that revealed a normal male karyotype (46 XY).

Figure 3: The fluid-filled trachea (arrow) is enlarged.

Figure 4: Color Doppler distinguishes the fluid-filled trachea from the aorta.

The diagnosis of laryngeal atresia was made and the parents opted to terminate the pregnancy.

The autopsy showed a 440g male fetus (expected weight: 234g) with edema of the head and abdomen. The increased weight was due to ascites and enlarged lungs. The lungs were bulky and pale and had prominent rib markings (fig. 5). The lungs weighted 43g. The heart was normal in size, morphology and weight (2g).

Figure 5: The lungs at autopsy. Note the compressed heart (arrow).

At microscopic examination the lungs were not expanded and did not contain air. Microscopic section of the laryngotracheal tube showed marked cross-sectional narrowing of the lumen compatible with atresia. This narrowing explained the sonographic finding of a fluid-filled trachea.

The umbilical cord contained two vessels, but no other anomalies were found.

Discussion

Embryology

The development of the larynx begins in the fourth week of embryonic life with the formation of a primitive glottis, the laryngeal aditus, in the floor of the foregut (fig. 6). Anterior to the aditus is the primordium of the epiglottis and posteriorly is the narrow pharyngotracheal duct, connecting the pharynx with the tracheal lumen¹. Smith and Bain⁴ described three types of laryngeal atresia (fig. 6):

Type I: supra- and infraglottic. The arytenoid cartilages as well as the paired muscles are fused across the midline. The cricoid is conical and the vestibule is absent

Type II: infraglottic, which is characterized by a dome-shaped cricoid cartilage occluding the lumen; the arytenoids, vestibule and vocal cords are normal.

Type III: glottic. The vestibule and cricoid cartilage are normal. The glottis is occluded by an anterior membrane of fibrous connective tissue and muscle, and a posterior bar of cartilage formed by fusion of the arytenoids at their vocal processes².

Figure 6: Embryology of the larynx in the rat embryo (8-20 mm), and corresponding stages of developmental arrest in the human. Type I is supra- and infraglottic. The arytenoid cartilages as well as the paired muscles are fused across the midline. The cricoid is conical and the vestibule is absent. Type II is infraglottic. It is characterized by a dome-shaped cricoid cartilage occluding the lumen. The arytenoids, vestibule and vocal cords are normal. Type III is a glottic obstruction. The vestibule and cricoid cartilage are normal. The glottis is occluded by an anterior membrane of fibrous connective tissue and muscle, and a posterior bar of cartilage formed by fusion of the arytenoids at their vocal processes1.

Pathogenesis

An arrest of the normal development of the larynx during embryonic life seems to be the cause of the lack of its canalization. The three different types of atresia previously described are not absolute, but rather gradations of a continuous spectrum and indicate that the arrest has happened in different stages of embryonic development. Walander has shown that the laryngotracheal development of 8, 12 and 20 mm rat embryos is similar to the three stages described by Smith and Bain (fig. 6)¹⁵.

Diagnosis

One of the most common findings is pulmonary hyperplasia (Table 1). The lungs are enlarged by volume and weight, yet their general histology is normal³. They have been shown to consist of an increased amount of tissue and not simply an accumulation of lung secretion caused by the laryngeal obstruction³.

The extension of the pulmonary hyperplasia correlates with the degree of laryngeal obstruction. Scurry et al. demonstrated that complete atresia leads to enlarged lungs, with dilatation of trachea and bronchi, while a partial laryngeal obstruction is associated with lungs of normal size at autopsy².

The heart and great vessels are compressed and cardiac failure from obstructed venous return is almost always present, with varying degrees of ascites and hydrops.

Polyhydramnios is commonly associated with laryngeal atresia and is attributable to the decreased fetal swallowing of amniotic fluid, from compression of esophagus by the lung and/or compression of the stomach by ascites³.

Color Doppler helped in distinguishing the fetal aorta from the dilated trachea (fig. 4).

The ultrasonographic diagnosis in utero has only been made in cases of complete atresia. The diagnosis is based on indirect signs— consequences of the total airway obstruction, such as bulky lungs, fetal hydrops and ascites, polyhydramnios, etc.¹³. The failure to recognize incomplete atresia is probably due to a lack of pulmonary distension. Recognition of the characteristic changes may be difficult in the early second trimester¹⁴.

Only half-a-dozen cases of laryngeal atresia have been diagnosed in utero with ultrasound: most cases have only been recognized at birth (Table 1). The diagnosis must be suspected if a newborn infant, normal at the time of birth, develops severe cyanosis and respiratory distress after ligation of the cord and an attempt at endotracheal intubation is unsuccessful. In such instances, only an immediate tracheotomy will save the newborn^3,5-7.

Table 1: Review of the literature.

Differential diagnosis

Cystic adenomatoid malformation of the lung, type III, creates a large solid mass affecting an entire lobe with a bulky appearance of the whole lung¹². Similarly, the less common bronchial atresia presents with an enlarged echogenic lung. Rarely, these two conditions can be bilateral. When bilateral, they can be differentiated from laryngeal atresia by the presence of a fluid-filled trachea in laryngeal atresia. Other differential diagnoses include laryngeal stenosis and hypoplasia, laryngeal membrane and tracheal atresia.

Associated anomalies

Associated anomalies are listed in Table 2. Sometimes, laryngeal atresia can also occurr in the context of a rare congenital syndrome such as Fraser syndrome⁸ (an autosomal recessive disorder, whose most consistent feature is cryptophtalmos, but includes other anomalies of the ears, nose, genitalia, skeleton and mental retardation) or 47 XXX chromosome constitution⁹.

Table 2: Associated animalies.

Prognosis

The prognosis of larynx atresia is poor if an immediate diagnosis is not made, or when other severe anomalies are associated. Only very few cases of surviving newborns are reported in the literature^5,6; one of these⁵ is in good health a

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Management

When not rapidly diagnosed at birth, complete larynx atresia is a fatal malformation. In about half of the cases, other severe anomalies are associated. In these cases, the prognosis is very poor and the option for pregnancy termination can be offered.

References

1. Buyse ML: Birth Defects Encyclopedia. Center for Birth Defects Information Service, Inc. Dover MA. Blackwell Scientific Publications, Cambridge, MA, 1990.

2. Gatti WM, MacDonald E, Orfei E et al.: Congenital laryngeal atresia. Laryngoscope 97: 966-9, 1987.

3. Scurry JP, Adamson TM, Cussen LJ: Fetal lung growth in laryngeal atresia and tracheal agenesis. Aust Paediatr J 25:47-51, 1989.

4. Silver MM, Thurston W, Patrik JE: Perinatal pulmunary hyperplasia due to laringeal atresia. Hum Pathol 19: 110-113, 1988.

5. Smith II, Bain AD: Congenital atresia of the larynx. Ann Otol Rhinol Laryngol 74:338-349, 1964.

6. Hoka S, Sato M, Yoshitake J, Kukita J: Management of a newborn infant with congenital laryngeal atresia. Anesth Analg 69:535-6, 1989.

7. Nakayama DK, Killian A, McBride T et al: Pulmunary function studies in a newborn with congenital laryngeal atresia. Pediatr Surg 26:210-212, 1991.

8. Leiberman A, Bar-Ziv J, Karplus M: Subglottic laryngeal atresia associated with tracheoesophageal fistula. Clin Pediatri 24:523-25, 1985.

9. Ford GS, Irving RM, Jones NS, Bailey CM: ENT manifestations of Fraser syndrome. J Laryngol Otol 106:1-4, 1992.

10. Hood OJ, Hartwell EA, Shattuc KE et al.: Multiple congenital anomalies associated with a 47,XXX chromosome constitution. Am J Med Genet 36:73-75, 1990.

11. Buckley JC, Hinton AE, Penter G et al: Laryngotracheal hypoplasia in a case of G syndrome. J Laryngol Otol 102:1056-1059, 1988.

12. Nyberg, Mahony, Pretorius: Diagnostic ultrasound of fetal anomalies: text and atlas. Year Book Medical Publisher, Chicago, 1990.

13. Fox H, and Coker J: Laryngeal atresia. Arch Dis Child 39:641- 645, 1964.

14. Watson WJ, Thorp JM, Miller RC et al: Prenatal diagnosis of laryngeal atresia. Am J Obstet Gynecol 163: 1456-7, 1990.

15. Walander A: Prenatal development of the epithelial primordium of the larynx in rat. Acta Anat (Basel) 10: supp. 2, 1950.

16. Gemke RJ, Van der Baan S, Ekkelkamp S et al: Congenitale larynstenose; een zeldzame oorzaak van dyspnoe bij de pasgeborene. Ned Tijdschr Genneeskd 134:541-3, 1990.

17. Arizawa M, Imai S, Suehara N: Prenatal diagnosis of laryngeal atresia. Acta Obst Gynecol Jpn 41:907-910, 1989.

18. Furness ME, Donnelley BW, Lipset J: Larynx, atresia. The Fetus 7483-1-3; 1991.