Imaging description

A six-year-old male with a prior history of meningitis presented with recent onset of bilateral sensorineural hearing loss (SNHL). CT imaging showed developing calcification within the vestibule (Fig. 4.1a, c) as well as within the cochlea (Fig. 4.1b). The history and imaging findings were consistent with labyrinthitis ossificans (LO).

Importance

LO is characterized by new bone formation in the cochlea, classically involving the scala tympani of the basal turn of the cochlea, and vestibule during the end-stage of bacterial/purulent labyrinthitis. In bacterial/purulent labyrinthitis, infection reaches the inner ear from the subarachnoid space via the cochlear aqueduct or the internal auditory meatus. Labyrinthine infection can also occur as a result of bacterial middle ear infections, from direct spread through the oval or round windows or by hematogenous seeding of the labyrinth. Haemophilus influenzae, Streptococcus pneumoniae, and Neisseria meningitidis are the most common organisms causing bacterial meningitis and SNHL in children. Other etiologies of LO include vascular obstruction of the labyrinthine artery, temporal bone trauma, autoimmune ear disease, otosclerosis, leukemia, or tumors of the temporal bone. Treatment by cochlear implantation may mitigate speech and language deterioration in children with LO and SNHL.