March 8, 2013
How do we assess dizziness?
How is it that audiology/hearing based practices would find themselves assessing and often treating disorders of dizziness and imbalance?
Few people are aware that the ear is primarily an organ of balance. Its main function, even before hearing our world, is to keep our heads safe atop our bodies and our eyes focused on the environment while we move about. There are organs of balance in the inner ears, some which are sensitive to “linear velocity” or movement forwards, backwards, upward or downward. Others are sensitive to changes in “angular velocity” or movement at an angle, such as head tilts. At any given moment the inner ear balance organs are sending nerve impulses to the brain about the position and movement of the head.
It stands to reason, therefore, that disorders of dizziness and imbalance are highly likely to originate in the ears. Unfortunately, the inner ear is housed within the temporal bone of the skull. It is impossible to observe these organs directly. What physiology has revealed for us, however, is that the nerve running from the inner ear to the muscles that move the eyes and to the spine can provide us with insight as to the state of the inner ear. It is said that the eyes are the window to the soul. The eyes, we find, are absolutely a window to the inner ear.
A major part of our diagnostic test battery includes videonystagmography (VNG) testing. This exploits the connection between the inner ear balance centers and the eyes. Patients perform various tasks involving eye movements, gazing at targets, and changing head positions as camera-mounted goggles track eye movements. In this manner patterns in eye movements can be observed and measured, enabling us to determine the likelihood of an inner ear disorder, central nervous system involvement, or a combination of factors. The results guide treatment. Occasionally a patient will produce normal results on all tests. This necessitates the involvement of other professionals who can evaluate other systems which may produce these symptoms.
The balance centers of our inner ears are intended to work as partners. Each ear sends constant streams of information to the brain about the position or movement of the head. Often one side will sustain damage, due to infection, injury, interruption in blood supply, nerve damage, etc. The ears are no longer equal partners. One side will send stronger information then the other. This induces dizziness episodes and imbalance. Once identified, however, this condition can often be treated with activities designed to promote a “recalibration” to the uneven nerve output. Symptoms decrease over time through repetition. This is known as “central compensation” via accommodation or adaptation.
Another disorder commonly diagnosed is Benign Paroxysmal Positional Vertigo (BPPV). This is very easily treatable and will be the topic of a future blog article. Watch this space!
Balance and dizziness disorders are often highly treatable with timely accurate diagnosis and follow-through. Do not suffer needlessly! Help is available. Let us keep you on a clear path to good hearing and ear health.