Labyrinthitis ossificans

Timothy C. Hain, MD • Page last modified: March 7, 2021

Labyrinthitis Ossificans
CT scan of labyrinthitis ossificans. On the left (right inner ear) is a normal labyrinth. On the right, (left inner ear), is a similar level but the lateral semicircular canal shows no loop.

Labyrinthitis ossificans (LO)

The inner ear contains the labyrinth, which consists of a set of interconnected channels in the bone that contain fluid, membranes, and neural cells that respond to sound and motion. In LO, the labyrinth is replaced by bone, almost always as a result of a bacterial infection. This typically results in profound deafness and loss of vestibular function on the affected side. If there is bilateral LO, patients are completely deaf and have no vestibular sensation.

Little is known as to why some patients develop LO and others don't. Aminpour (2005) suggested that TNF-alpha may play an important role in an animal model of meningitis.

Mineralization in animals is rapid, and begins 3 days after infection (Tinling et al, 2004). Nabili et al (1999) reported that mineralization started at 3 weeks, and continued over a 12 month course.

Frequency of LO:

Labyrinthitis ossificans is rare, occurring in only about 2% of persons who have had mastoidectomy. (Lin et al., 2014).

In our experience, most patients with LO are completely deaf, have no balance function, and developed this as a child as a result of meningitis.

We have encountered only one patient who developed this as a result of otitis media (i.e. middle ear infection). This is likely due to the current propensity for patients with otitis media to get antibiotics.

Causes of LO.

Most of the data comes from case reports.

Diagnosis of LO.

Imaging studies are needed to diagnose LO. The CT scan of the temporal bone is the most straightforward, as it shows bone replacing the labyrinth. MRI scan of the inner ear area can show the loss of fluid in the labyrinth, but cannot distinguish plugging from soft tissue from bone.

Treatment (prevention) of LO.

Hartnick et al (2001) reported that patients treated with steroids had less LO.

There is considerable literature concerning cochlear implant in LO patients. The question is whether or not the electrodes can be threaded into a cochlea that is blcoked by bone.