The cochlear cleft.

BACKGROUND AND PURPOSE Recent advances in the display of medical images permit the routine study of temporal bone CT images at high magnification. We noted an unfamiliar structure, which we now call the "cochlear cleft," in the otic capsule. To our knowledge, this report represents the first description of this structure in the medical imaging literature. METHODS Temporal bone CT performed in 100 pediatric patients without sensorineural hearing loss were examined for the presence of cochlear clefts. Incidence of cochlear clefts as well as the relationship between age and incidence was examined. RESULTS Cochlear clefts were present in 41% of the subjects. Incidence decreased with age. CONCLUSION We describe a cleft in the otic capsule that is frequently seen on magnified images of temporal bone CT studies in children. The cleft may be the fissula ante fenestram.