Semicircular Canal Dehiscence Explained

Nov 21, 2018

We’ve all heard of and probably know someone who gets motion sickness easily if it’s not ourselves who deal with this problem already. Motion sickness is that familiar feeling of dizziness or nausea when our brains receive confusing signals about the world around us when we are in the car, on a boat, or enjoying (or not) an amusement park ride. But did you know that some people also deal with dizziness caused by certain frequencies of sound, such as a piano, another musical instrument, or a simple conversation?
These people are more likely to be living with a genetically caused thinness or hole in the bone encasing the inner ear. This deficiency in the bone causes fluid within the inner ear to move incorrectly when certain sounds are heard. This condition is called semicircular canal dehiscence.  In fact, researchers believe this condition affects one in every 100 people across the world. The feeling perceived when these anomalies occur described as being similar to the feeling you have when drunk.
The Cause
So what exactly causes the feeling of dizziness or vertigo? A study conducted by researchers at the University of Utah discovered eye-movements that are triggered to counteract the normal movement of the head perceived by inner ear fluid movement, are incorrectly triggered by the movement of inner ear fluid caused by the changed perception of sound in people with the hole in the bone casing of the inner ear.
In other words, our eyes move to counteract the movement of the head. Everytime our heads move, our eyes move to stabilize the picture and keep us from feeling dizzy or nauseous. When do our eyes know to move? They depend on messages from the brain that has been received from the inner ear.
The fluid of the inner ear moves when the head moves. This movement results in a signal sent to the processing centers of the brain, telling the brain the head is moving. Consequently, the eyes are told to countermove to avoid feelings of dizziness. If the brain is getting false reads from the inner ear fluid, it will send false movement commands to the eyes, causing a countermovement to a head movement that never happened and thus a perception of spinning. This unnecessary movement of the eyes results in dizziness, vertigo, or nausea.
The Difficulty of Semicircular Canal Dehiscence
For people who have semicircular canal dehiscence, the feeling of dizziness can occur within seconds after hearing a trigger sound. Now that researchers understand the connection between the pathological holes in the bone housing and the nature of the condition that results from it, care providers can be better equipped to address and treat the condition.
Surgery to repair the dehiscence is one viable option that remedies the condition with a high degree of confidence. Other treatment options and coping techniques are also available. For more information about semicircular canal dehiscence, please call our office today to speak with a hearing health professional.