Dizziness, vertigo, and motion sickness all relate to the sense of balance and equilibrium. Researchers in space and aeronautical medicine call this sense spatial orientation, because it tells the brain where the body is "in space:" what direction it is pointing, what direction it is moving, and if it is turning or standing still.

Your sense of balance is maintained by a complex interaction of the following parts of the nervous system:

• The inner ears (also called the labyrinth), which monitor the directions of motion, such as turning, or forward-backward, side-to-side, and up-and-down motions.
• The eyes, which monitor where the body is in space (i.e. upside down, rightside up, etc.) and also directions of motion.
• The skin pressure receptors such as in the joints and spine, which tell what part of the body is down and touching the ground.
• The muscle and joint sensory receptors, which tell what parts of the body are moving.
• The central nervous system (the brain and spinal cord), which processes all the bits of information from the four other systems to make some coordinated sense out of it all.

The symptoms of motion sickness and dizziness appear when the central nervous system receives conflicting messages from the other four systems.

For example, suppose you are riding through a storm, and your airplane is being tossed about by air turbulence. But your eyes do not detect all this motion because all you see is the inside of the airplane. Then your brain receives messages that do not match with each other. You might become "air sick."

Or suppose you are sitting in the back seat of a moving car reading a book. Your inner ears and skin receptors will detect the motion of your travel, but your eyes see only the pages of your book. You could become "car sick."

Or, to use a true medical condition as an example, suppose you suffer inner ear damage on only one side from a head injury or an infection. The damaged inner ear does not send the same signals as the healthy ear. This gives conflicting signals to the brain about the sensation of rotation, and you could suffer a sense of spinning, vertigo, and nausea.

The doctor will ask you to describe your dizziness, whether it is light headedness or a sensation of motion, how long and how often the dizziness has troubled you, how long a dizzy episode lasts, and whether it is associated with hearing loss or nausea and vomiting. You might be asked for circumstances that might bring on a dizzy spell. You will need to answer questions about your general health, any medicines, you are taking, head injuries, recent infections, and other questions about your ear and neurological system.

Your physician will examine your ears, nose, and throat and do tests of nerve and balance function. Because the inner ear controls both balance and hearing, disorders of balance often affect hearing and vice versa. Therefore, your physician will probably recommend hearing tests (audiograms). The physician might order skull X-rays, a CT or MRI scan of your head, or special tests of eye motion after warm or cold water is used to stimulate the inner ear (ENG - electronystagmography). In some cases, blood tests or a cardiology (heart) evaluation might be recommended.

Not every patient will require every test. The physician's judgement will be based on each particular patient. Similarly, the treatments recommended by your physician will depend on the diagnosis.

What Can I Do to Reduce Dizziness?

• Avoid rapid changes in position, especially from lying down to standing up or turning around from one side to the other.
• Avoid extremes of head motion (especially looking up) or rapid head motion (especially turning or twisting).
• Eliminate or decrease use of products that impair circulation, e.g. nicotine, caffeine, and salt.
• Minimize your exposure to circumstances that precipitate your dizziness, such as stress and anxiety or substances to which you are allergic.
• Avoid hazardous activities when you are dizzy, such as driving an automobile or operating dangerous equipment, or climbing a step ladder, etc.

What Can I Do for Motion Sickness?

Always ride where your eyes will see the same motion that your body and inner ears feel, e.g. sit in the front seat of the car and look at the distant scenery; go up on the deck of the ship and watch the horizon; sit by the window of the airplane and look outside. In an airplane choose a seat over the wings where the motion is the least.

• Do not read while traveling if you are subject to motion sickness, and do not sit in a seat facing backward.
• Do not watch or talk to another traveler who is having motion sickness.
• Avoid strong odors and spicy or greasy foods immediately before and during your travel. Medical research has not yet investigated the effectiveness of popular folk remedies such as soda crackers and Seven Up® or cola syrup over ice.
• Take one of the varieties of motion sickness medicines before your travel begins, as recommended by your physician.

Some of these medications can be purchased without a prescription (i.e., Dramamine®, Bonine®, Marezine®, etc.) Stronger medicines such as tranquilizers and nervous system depressants will require a prescription from your physician. Some are used in pill or suppository form.

Remember: Most cases of dizziness and motion sickness are mild and self-treatable disorders. But, 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.