Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Motion sickness is caused by a disturbance of the inner ear that affects the
organ of balance and equilibrium.
The symptoms of motion sickness usually, but not
always, stop when the motion that causes it ceases.
Medications are available for the prevention and treatment of
motion sickness.
What is motion sickness?
Motion sickness is a very common disturbance of the inner ear that is
caused by repeated motion such as from the swell of the sea, the
movement of a car, the motion of a plane in turbulent air, etc. In
the inner ear (which is also called the labyrinth), motion sickness
affects the organs of balance and equilibrium and, hence, the sense of
spatial orientation.
What causes motion sickness?
Motion is sensed by the brain through three different pathways of the nervous system that send signals coming from the inner ear (sensing motion, acceleration, and gravity), the eyes (vision), and the deeper tissues of the body surface (proprioceptors). When the body is moved intentionally, for example, when we walk, the input from all three pathways is coordinated by our brain. When there is unintentional movement of the body, as occurs during motion when driving in a car, the brain is not coordinating the input, and there is thought to be discoordination or conflict among the inputs from the three pathways. It is hypothesized that the conflict among the inputs is responsible for motion sickness.
For example, when we are sitting and watching a picture that depicts a moving scene, our vision pathway is telling our brain that there is movement, but our inner ear is telling our brains that there is no movement. Thus, there is conflict in the brain, and some people will develop motion sickness in such a situation (even though there is no motion).
The cause of motion sickness is complex, however, and the role of conflicting input is only a hypothesis, or a proposed explanation, for its development. Without the motion-sensing organs of the inner ear, motion sickness does not occur, suggesting that the inner ear is critical for the development of motion sickness. Visual input seems to be of lesser importance, since blind people can develop motion sickness. Motion sickness is more likely to occur with complex types of movement, especially movement that is slow or involves two different directions (for example, vertical and horizontal) at the same time.
The conflicting input within the brain appears to involve levels of the neurotransmitters (substances
that nerves within the brain use to communicate with one another) histamine, acetylcholine, and norepinephrine. Many of the drugs that are used to treat motion sickness act by influencing or
affecting the levels of these compounds within the brain.
Reviewed by Melissa Conrad Stöppler, MD on 3/22/2012
Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: Jay W. Marks, MD
Motion
sickness , sometimes referred to as sea sickness or car sickness, is a
very common disturbance of the inner ear that is
caused by repeated motion. Motion sickness can
develop from the movement of a car, movement of a boat, or from turbulence in an airplane. The
symptoms of motion sickness are nausea, vomiting,
dizziness, sweating, and a sense
of feeling unwell. These symptoms arise from the inner ear (labyrinth) due to changes in one's sense of balance
and equilibrium.
While it may be impossible to prevent all cases of motion sickness, the
following tips can help you prevent or lessen the severity of motion sickness:
Watch your consumption of foods, drinks, and alcohol before and during
your trip. Avoid excessive alcohol and foods or liquids that "do not agree with
you" or make you feel unusually full. Heavy, spicy, or fat-rich foods may
worsen motion sickness in some people.
Avoiding strong food odors may also help prevent nausea.
Try to choose a seat where you will experience the least motion. The
middle of an airplane over the wing is the calmest area of an airplane. On a
ship, those in lower level cabins near the center of a ship generally
experience less motion than passengers in higher or outer cabins.
Dizziness is a symptom that is often applies to a variety of sensations including lightheadedness and vertigo. Causes of dizziness include low blood pressure,
Vertigo is a feeling of spinning movement, and at times accompanied by nausea and vomiting occur. Vertigo is most often associated with an inner ear problem.
Nausea is an uneasiness of the stomach that often precedes vomiting. Nausea and vomiting are not diseases, but they are symptoms of many conditions. The
Balance is a state of body equilibrium or stability. We often take for granted how dependent we are on a healthy balance system. When the system breaks
Nausea and vomiting are symptoms that may be caused by many conditions. Antiemetics are drugs that treat nausea and vomiting. Though some antiemetics for
Travelers should prepare for their trip by visiting their physician to get the proper vaccinations and obtain the necessary medication if they have a medical
