Labyrinthitis

 

Labyrinthitis is an ailment of the inner ear and a form of unilateral vestibular dysfunction. It derives its name from the labyrinths that house the vestibular system, which senses changes in head position. Labyrinthitis can cause balance disorders, vertigo, hearing loss and tinnitus.

Labyrinthitis is usually caused by a virus, but it can also arise from bacterial infection, toxins, head injury, extreme stress or emotion, an allergy or as a reaction to medication. Both bacterial and viral labyrinthitis can cause permanent hearing loss.

A prominent and debilitating symptom of labyrinthitis is severe vertigo. The vestibular system is a set of sensory inputs consisting of three semicircular canals, sensing changes in rotational motion, and the otoliths, sensing changes in linear motion.

The brain combines visual cues with sensory input from the vestibular system to determine adjustments required to retain balance. The vestibular system also relays information on head movement to the eye muscle, forming the vestibulo-ocular reflex to retain continuous visual focus during motion.

When the vestibular system is affected by labyrinthitis, rapid and undesired eye motion (nystagmus) often results from the improper indication of rotational motion. Nausea, anxiety, and a general ill feeling are common due to the distorted balance signals that the brain receives from the inner ear.  This can also be brought on by pressure changes such as those experienced while flying or scuba diving.

As nausea is such a defining symptom of the disease, there is more about the causes in the section on Nausea.