I have been told that it is rude to ask people what they do for a living in Italy. I know that seems like a strange way to start a blog about vestibular disorders, but hang in here with me for a minute. I just got back from a week-long vacation visiting friends at their lake house in Michigan. I had the opportunity to meet many of their very nice neighbors, and was reminded how it is almost expected in the United States to answer the question, “So, what do you do for a living?” in the first few minutes of casual social conversation.
Most people are just making polite conversation and looking for something in common to talk about. I noticed that the most common response to “I specialize in inner ear disorders, you know, vertigo, dizziness and such.” Is “Oh, I get motion sickness (or seasickness, etc. etc.). That puts me in the awkward position of having to respond. I could say, “My, this certainly is some tasty cheese dip,” or I could say, “Oh, motion sickness usually is not caused by an inner ear disorder.” Which do you think would make my new acquaintance feel more at ease?
Motion sickness is believed to be primarily a result of a mismatch between sensory information arriving at the brain from the inner ear, the eyes, and the proprioceptive system (the sense of touch). For example, when riding on a boat, your environment is moving. When you are inside the boat, your inner ear knows you are moving, your tactile feedback (feeling the pitch of the floor) changes, yet visually the walls in the room are going up and down with you. In this situation, the visual feedback is conflicting, creating what is called a “sensory conflict.” The nausea that follows shortly thereafter is basically nature’s way of warning you that your balance system is temporarily unreliable. The nausea makes you want to sit or lie down, not move around where you might get hurt.
Why some people get motion sickness and others don’t is a mystery. We know that motion sickness is much more common in Migraine patients, so it is likely that some people’s brains are just better at dealing with sensory conflicts than others. If you want to review other theories, click here.
We will discuss Sensory Conflicts in more detail next week.