Pendred's syndrome. Acoustic, vestibular and radiological findings in 17 unrelated patients.

Seventeen unrelated Danish patients with Pendred's syndrome, whose case stories have not been published previously, are presented. Acoustic and vestibular functions were examined and endocrinological screening was performed. There was a great variation in hearing ability as well as in thyroid function. Furthermore, in contrast to previous investigations, normal caloric function was demonstrated in the majority. In all patients a Mondini malformation was demonstrated. On the basis of this investigation it is concluded that: (1) the Mondini defect is part of Pendred's syndrome; (2) the inherited Mondini malformation is the underlying cause of the sensorineural hearing impairment; and (3) the hearing sensitivity varies greatly in these patients.