Bilateral Loss of Labyrinthine Function
The labyrinth is a chamber in the inner ear consisting of vestibular (balance) and auditory (hearing) organs. Bilateral (occurring on both sides) loss of labyrinthine function causes jumpy vision with head movements and chronic imbalance.
- The labyrinths help generate reflexes so that people can see clearly when the head is moving.
- Loss of function in both labyrinths leads to characteristic problems with jumpy vision while the head is in motion, known as oscillopsia.
Bilateral Loss of Labyrinthine Function: Symptoms
Oscillopsia is an illusory movement of the stationary environment, usually either caused by abnormal movement of the eyes (such as nystagmus) or bilateral (both sides) vestibular loss when the person’s head is moving.
It occurs when the deficient vestibulo-ocular (inner ear reflexes) and the back part of the eye (the retina) cannot keep the visual environment stable and the world appears to bounce or move.
A person experiencing oscillopsia may notice the following:
When riding in a car on a bumpy road, it is hard to read street signs.
It can be hard to recognize faces during movement or walking.
It may be difficult to focus on objects while quickly turning the head, such as glancing for traffic when crossing the street or looking at side view mirrors while driving.
Balance Problems and Falls
The other major symptom of the bilateral loss of labyrinthine function is lack of balance and a risk of falls. Falls are most likely when walking in the dark or on soft surfaces such as carpeting, sand or grass.
Because people affected with labyrinthine function loss have trouble orienting themselves and the position of their bodies, swimming can be dangerous. They should never swim alone, especially at night or on a cloudy or dark day, because when they are under water, they may not be able to sense up from down due to the lack of visual and other sensory cues.
Sometimes the loss of vestibular function is due to ototoxic effects of an antibiotic given to treat a severe infection. (Gentamicin is most common and tends to spare auditory function.) In this case, the person may not notice balance or vision problems until they recover from their infection and start moving around more normally.
Losing labyrinthine function in both ears at the same time usually does not result in a sense of spinning or falling with nausea and vomiting that is seen in labyrinthine problems affecting just one ear.
What causes bilateral loss of labyrinthine function?
Although the reason for many cases is never determined, bilateral loss of labyrinthine function can be due to:
A toxic side effect of an antibiotic, usually an aminoglycoside medication such as gentamicin.
Certain infections, especially viral illness or meningitis in children.
Bilateral Loss of Labyrinthine Function: Treatment
Recovering from a bilateral loss of labyrinthine function depends on many factors, including:
How fast the loss of function progressed — the slower the loss, the more readily the brain can adapt to compensate for it.
The person’s age — younger people tend to adapt more easily.
The amount of remaining function — more function makes it easier to compensate.
The other ways the brain determines where a person is in space (in addition to the vestibular system) are through the visual and proprioceptive/joint position sensor systems. If one or both of these are also compromised, recovery and compensation will be more difficult.
Treatment for bilateral loss of labyrinthine function is physical rehabilitation with an individualized program designed by a vestibular rehabilitation specialist.
Depending on the degree of the problem, therapy works to improve labyrinthine function or help the person develop alternative sensory cues such as from the neck, feet or eyes that can substitute for the missing sensations from the labyrinth. Tai chi or other balance exercises may also help patients regain balance over time.
Recovering from bilateral loss of labyrinthine function takes time and commitment, as well as the help of a supportive team. Continued exercises and practice can help people compensate for their condition, improve balance and improve quality of life.