[Anomalies of the stapes (author's transl)].

Reported are four cases of anomalies of the stapes and the oval window niche. Their diagnostic and operative problems are discussed. The report includes one case of spontaneous cerebrospinal otorrhea. Surgical exploration of the middle ear demonstrated a fluid leak from a fistula in the stapes footplate. Two cases presented combined congenital anomalies of the stapes and facial nerve as a cause of hearing loss. Additionally one case of "columella" shaped stapes was observed. The embryological aspects of the middle ear structures are discussed.