Head and Neck Imaging

Cochlea, pathology

Congenital malformation
According to Jackler, inner ear malformations can be divided into a group with and a group without cochlear malformations. Those with cochlear malformations can be categorized as follows:
- congenital labyrinthine aplasia ( Michel aplasia );
- common cavity (cochlea and vestibule);
- cochlear aplasia (with normal vestibule and semicircular canals) (Fig. 1);
- cochlear hypoplasia; and
- incomplete partition ('true' Mondini's malformation , absence of interscalar septum)
Additionally, anomalies of the modiolus (see cochlea ) have been recognized (see modiolus anomalies ).
Inflammation
Several types of inflammation can affect the cochlea: viral or bacterial infection and autoimmune disease, see labyrinthitis .
Otodystrophies
The otodystrophies that may affect the cochlea are: otosclerosis , Paget's disease , fibrous dysplasia, head and neck , osteopetrosis and osteogenesis imperfecta .
Tumour
Cochlear tumours may arise from within the membranous labyrinth (vestibular or cochlear schwannoma). Intracanalicular acoustic schwannoma may extend into the cochlea along the cochlear nerve (see also hook shape sign, in acoustic schwannoma ). Tumours originating in the region of the cochlea may invade its bony capsule (e.g. glomus tumour ).
Trauma
The cochlea may be involved in a transverse fracture, temporal bone . Hearing loss may be due to cochlear concussion, without a fracture visible on CT. Post-traumatic serous labyrinthitis or cochlear haematoma (Fig. 2) may be revealed on MRI.

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Fig. 02a

Plain axial T1-weighted spin-echo images of temporal bones, a 3 mm more caudal than b. Patient experienced right-sided sudden hearing loss during straining. Compared to the left side, the intensity of the right cochlea (arrowhead) is higher; also the vestibule and semicircular canals (arrows) show a higher intensity on the right side. Intralabyrinthine haemorrhage.
Cochlea, pathology, Fig. 01a
Cochlea, pathology, Fig. 02a (a)
Cochlea, pathology, Fig. 02b (b)