Dzondi was one of the first to recognize and classify congenital fistulas of the neck.
The proper classification is into lateral and median fissures.

In a case studied by Fevrier the exploration of a lateral pharyngeal fistula produced by the introduction of the sound violent reflex phenomena, such as pallor of the face and irregular, violent beating of the heart.
The rarest of the lateral class is the preauricular fissure, which has been observed by Fevrier, Le Dentu, Marchand, Peyrot, and Routier.
The median congenital fissures of the neck are probably caused by defective union of the branchial arches, although Arndt thinks that he sees in these median fistulas a persistence of the hypobranchial furrow which exists normally in the amphioxus.

They are less frequent than the preceding variety.
The most typical form of malformation of the esophagus is imperforation or obliteration.

Van Cuyck of Brussels in 1824 delivered a child which died on the third day from malnutrition.

Postmortem it was found that the inferior extremity of the esophagus to the extent of about two inches was converted into a ligamentous cord.