What is Motion Sickness
Motion sickness is dizziness, nausea and possibly vomiting that occurs when traveling in a moving vehicle such as a car, boat, or airplane. Each form of transportation seems to have its own specific term (car sickness, sea sickness, altitude sickness) but all refer to the same problem. The term “motion sickness” will be used throughout this material to refer to all of these forms of sickness. The specific terms will be used only when the material is unique to that form of sickness.
Motion sickness is usually just a minor annoyance and does not signify any serious medical illness. Symptoms are often treatable and, even when not treated, the symptoms go away shortly after the motion stops. However, severe cases and those that become progressively worse deserve the attention of a physician with specialized skills in diseases of the ear, nose, throat, equilibrium, and neurological systems.
What Causes Motion Sickness?
Motion sickness is a conflict between your senses. The brain relies on messages from your inner ear, muscles, and eyes to tell it how your body is moving. When any of these systems send different messages, you can get queasy.
Some examples include:
· If you're reading in the car, your inner ear knows you're moving, but your muscles think that you are sitting still and your eyes don't see anything moving because they're looking at the page.
· On an airplane or in the cabin of a boat or ship, your inner ear senses the motion, but your eyes only see the cabin, which looks stationary. Your body may sense rolling motions that you cannot see from inside a cabin.
· Conversely, during a "virtual reality" simulation, your eyes perceive movement that your body (inner ear and muscles) does not experience.
These conflicting signals end up at the nausea center of the brain and motion sickness is the result.
Motion sickness can be understood in more technical terms. Our brains and body rely on the vestibular apparatus, the three semicircular canals of the inner ear, to maintain our balance. Each canal detects our position within a certain plane of space, also known as our spatial orientation. This allows us to move around in a three-dimensional world while remaining balanced.
Each of the three canals is responsible for detecting a particular plane of space (up/down, left/right, front/back). Within each of these canals are small calcium deposits that are called otoliths (ear stones). Anytime we move out of a particular plane of space these little stones move and nerve transmissions send signals to our brain. In most situations of movement, this is not a problem for the brain to handle. However, in some situations in which movement is chaotic (like in a boat, car or airplane) the brain may misinterpret the nerve transmissions. For some this may eventually cause queasiness, nausea and possibly vomiting.
As noted earlier, our sense of sight can contribute to our brain’s confusion about our position and movement. Some smells can also contribute to the onset of nausea and vomiting, so it’s best to avoid nauseating odors.
Symptoms of Motion Sickness
Motion sickness produces a whole range of symptoms, of which nausea and vomiting are the most severe. Symptoms generally follow a path of increasing severity. Abrupt vomiting without early warning or the presence of other symptoms is rare, usually only occurring in space flight and other zero-G situations.
Early indications of motion sickness onset may include:
|Pallor (paleness, especially in the face)|
|Increased salivation and swallowing|
|Eructation (the medical term for belching and burping)|
|Flatulence (the medical term for passing gas)|
|Feeling cold and clammy|
|Breaking out in sweat, especially on the upper lip or forehead|
|Yawning and drowsiness OR feeling giddy or restless|
As symptoms build, the following may occur:
|Nausea (the sensation associated with anticipation of vomiting)|
|Emesis (the medical term for vomiting)|
|Retching (unproductive vomiting movements or dry heaves).|