Cochlear cleft

The cochlear cleft is a curvilinear radiolucent area of incomplete endochondral ossification in the otic capsule adjacent to the cochlea. It is a variant most prominent in children that may also be visible in adults .

Gross anatomy

The cochlear cleft is a C-shaped structure in the otic capsule of the temporal bone that is parallel and lateral to the basal turn of the cochlea . It is located anterior to the oval window and underneath the cochleariform process.

The prevalence/prominence of the cochlear cleft decreases with age .

Histology

The cochlear cleft corresponds to fatty marrow spaces, consistent with a process of incomplete endochondral ossification . It is distinct from the fissula ante fenestram, which is slightly more posteriorly located and composed of connective tissue.

Related pathology

The structure is a normal variant without any relationship with hearing loss . It should not be confused for otosclerosis, which commonly affects the area anterior to the oval window or the pericochlear otic capsule.