'Congenital' cholesteatomas of the supralabyrinthine region.

Twelve cases of congenital cholesteatomas developing in the region of the geniculate ganglion are presented. The diagnosis was made from a radiological sharp-cut erosion of bone found medial to the superior semicircular canal and superior to the internal auditory meatus in presence of progressive facial palsy. The main problems of the surgical treatment of the presented lesions were: 1 the presence of an unsuspected large fistula of the basal turn of the cochlea; 2 the necessity of resecting the superior semicircular canal in order to drain the supralabyrinthine region; and 3 extensive re-routeing and grafting of the facial nerve. The etiology of the presented cholesteatomas is discussed on the basis of the migratory theory and metaplasia of the first epibranchial placode.