After a unilateral peripheral injury, such as would occur with vestibular neuritis, there is a predictable set of clinical signs and symptoms that occur. In addition to an initial period of acute vertigo, there is often a period of motion intolerance that follows.
The acute vertigo usually lasts for several hours, but gradually decreases over a period of three to five days (faster with vestibular-suppressant medications). Once the acute symptoms have passed, you may be fairly comfortable while lying or sitting still. When you feel good enough to get up and walk around, you may notice that you are unsteady on your feet, have blurred vision if you move your head quickly, and can become nauseous if you push yourself too much.
From a functional standpoint, when the inner ear function on one side is disrupted, you develop a sense of rotation because the brain is not receiving equal signals from the two inner ears. Because the inner ears are sending a signal to the brain that you are moving and the rest of your body knows that you are not moving, this creates a conflict within your balance system. This conflict causes vegetative symptoms of nausea (possibly vomiting) and pallor (paleness).
The brain tries to correct this conflict by shutting down its sensitivity to both inner ears, a process called “cerebellar clamp.” This process typically takes a few days. Once this process is completed, there is less conflict between the inner ears and the rest of the body, until you start moving. Now, the rest of the body senses movement (because you are moving), but the inner ears are not registering the same amount of movement because the brain has “shut down” its connection to them. So now your body knows it is moving, but the inner ears are not keeping up. This creates a similar conflict causing the symptoms of motion intolerance.
With time, activity, therapy exercises and withdrawal of vestibular suppressant medication, the brain will figure out that it needs more information from the vestibular system. Over a period of several weeks, the brain will start using the information from the healthy ear and the residual function from the injured ear to increase the VOR response.
About the author
Alan Desmond, AuD, is the director of the Balance Disorders Program at Wake Forest Baptist Health Center, and holds an adjunct assistant professor faculty position at the Wake Forest School of Medicine. He has written several books and book chapters on balance disorders and vestibular function. He is the co-author of the Clinical Practice Guideline for Benign Paroxysmal Positional Vertigo (BPPV). In 2015, he was the recipient of the President’s Award from the American Academy of Audiology.
**this piece has been updated for clarity. It originally published on August 6, 2013