Viral labyrinthitis

What it is

Labyrinthitis is inflammation and swelling of the vestibulocochlear nerve taking both the vestibular and the cochlear portions; put the other way round, it is an infection of the membranous labyrinth that affects the vestibular nerve and the cochlear end organs at once. That is what marks it off from vestibular neuritis, which takes the vestibular portion of CN VIII alone: unaffected hearing means vestibular neuronitis, and affected hearing means labyrinthitis. Usually labyrinthitis is viral.

Causes and risk

The viral form follows a viral upper respiratory tract infection, and the serous, viral organisms named are rubella, CMV, measles, mumps and varicella zoster. Labyrinthitis also comes as a complication of otitis media, bacterial meningitis, cholesteatoma and temporal bone fractures; the purulent, bacterial organisms are S. pneumoniae, H. influenzae, M. catarrhalis, P. aeruginosa and P. mirabilis.

How it presents

The symptoms come on suddenly, and the episode lasts hours to days. Severe disabling vertigo with nausea, vomiting and imbalance is the heart of it, and the vertigo can be made worse by movement but is not triggered by it. The auditory symptoms come with it: tinnitus, whistling when present, and sensorineural hearing loss, given as unilateral in one source and as uni- or bilateral in another. Aural fullness is not a feature of it, and there may be a recent otitis media (AOM). There is no associated fever or pain. Two conditions are separated from it here:

• Benign paroxysmal positional vertigo, where the episodes are very short, only 10-20 seconds, and are triggered by head movement.
• Meniere's disease, where the episodes last minutes to hours instead of being continuous, and aural fullness is felt as well.