[Duplication of the auditory canal. A vestige of the 1st branchial cleft].
Anomalies of the first branchial cleft appear as duplicated auditory canals; they are rare clinical entities. Patients will present with a history of recurrent fistulas of the neck or parotid gland close to the angle of the mandible. There are two distinct malformations associated with the first cleft: A simple sinus which is lined with squamous epithelium and runs parallel to the auditory canal (Type I); the Type II anomaly, on the other hand, has a close, though variable relationship to the facial nerve and contains cartilage, a mesodermal derivate, within the wall. Embryologically it appears that the point of time at which the disorder developed dictates whether the malformation is of Type I or II. The authors present six cases of first branchial cleft anomalies, two patients with Type I and four with Type II lesions. The sex distribution was striking: all the patients were female. In case of a Type II defect, three variations of the facial nerve with split main trunks were found. Recurrent operations and infections lead to scar tissue and subsequent surgery is more difficult, with serious hazard to the facial nerve. Where positive identification of the facial nerve is a major problem it is advisable to identify the nerve in the mastoid cavity and trace it to the stylomastoid foramen and parotid gland.