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Motion Sickness
By peace | October 18, 2006
Motion sickness or kinetosis is a poison response provoked by motion. Nausea is the most common symptom of motion sickness; in fact, nausea in Greek means seasickness (naus means ship). If the motion causing nausea is not resolved, the sufferer will frequently vomit. Unlike ordinary sickness, vomiting in motion sickness tends not to relieve the nausea. Another part of motion sickness is an accompanying stress response. The sufferer feels stressed, and stress hormones are secreted into the blood.
Motion sickness on the sea can result from being in the berth of a rolling boat without being able to see the horizon. Sudden jerky movements tend to be worse for provoking motion sickness than slower smooth ones, because they disrupt the fluid balance more. A “corkscrewing” boat will upset more people than one that is gliding smoothly across the oncoming waves. Cars driving rapidly around winding roads or up and down a series of hills will upset more people than cars that are moving over smooth, straight roads. Looking down into one’s lap to consult a map or attempting to read a book while a passenger in a car may also cause motion sickness.
Humans have developed motion sickness as a defence mechanism. The area postrema in the brain is responsible for inducing vomiting when poisons are detected, and for resolving conflicts between vision and balance. When feeling motion but not seeing it (for example, in a ship with no windows), the inner ear transmits to the brain that it senses motion, but the eyes tell the brain that everything is still. The brain seems to conlude that it has been poisoned and the response is nausea, vomiting, and stress.
Symptoms generally consist of dizziness, fatigue, and nausea which may progress to vomiting. From one third to one half of airline passengers will experience some degree of motion sickness when encountering heavy turbulance, and it has been found that fear or anxiety can promote symptoms. Some individuals seem to be naturally prone to motion sickness since childhood.
Prevention is best accomplished by seeking areas of lesser movement in an interior location of a large ship or by facing forward and looking outside a ship or plane. Several medications are now available both by prescription and over the counter that may prevent or limit the symptoms of motion sickness. If medications are necessary, they are best taken at least one hour before embarking.
The over-the-counter medications Dramamine or Bonine can be very effective for short trips or when symptoms occurr intermittently. For longer trips, a prescription medication called Transderm-Scop comes in the form of a patch can be worn behind the ear for up to three days at a time. Side effects of these medications usually consist of sedation and dry mouth and they should not be taken by people who have glaucoma or urinary obstruction. Recent studies have shown that ginger root may be as effective as the other drug treatments but is associated with fewer side effects.
Causes Of Motion Sickness
In order for the body to determine where it is at all times, the brain combines visual information, touch information, inner ear information, and internal expectations. Under most circumstances, the senses and expectations agree. When they disagree, there is conflict, and motion sickness can occur.
For example, consider the situation when one is reading in the back seat of a car. Your eyes, fixed on the book, say that you are still. However, as the car goes over bumps and accelerates/decelerates, your ears disagree. This is why motion sickness in this situation is common.
Acquired susceptibility to motion sickness occurs occasionally. Persons with an inner ear disturbances, especially a recent one, may be intolerant to activity in general. People with migraine are apt to get motion sick. Persons with rare, central nervous system disorders of the part of the brain that processes signals from the inner ear may also be unusually susceptible to motion sickness. Certain individuals who are constitutionally susceptible to motion sickness and can develop sea sickness on ships, and a prolonged land sickness, when they get off the ship. This rare disorder is called “mal de debarquement“, which is French for “bad getting off the ship”. Persons with unusually good vestibular function may be more susceptible to motion sickness than others (Gordon et al, 1996).
Migraine is a definite risk factor for motion sickness, with roughly a 5 fold greater incidence than non-migraineurs. Female gender and youth is also a risk factor. In women, days 9-15 appear to have a higher incidence of nausea (Ramsay, 1994).
Experimentally, motion-sickness can be eliminated in dogs by surgically removing part of the brain (the nodulus, according to Bard). Motion sickness is sometimes associated with prolonged vestibular responses (Hoffer et al. 2003).
Treatment Of Motion Sickness
There are four strategies to treat motion sickness:
- Behavioral (avoidance, mental activities)
- Medication (conventional, alternative)
- Stimulation (alternative)
- Exercise (habituation)
1. Behavioral Strategies for Motion Sickness
- In the car: sit in the front seat or drive.
- Aboard a ship: stay toward the middle and look at the horizon. Avoid ship travel if possible. Stay out of small tight places where you can’t see the horizon.
- On the airplane: ask for a window seat. The front of the plane may be preferable, as it is usually less noisy.
- For cars: It may be helpful to mentally rehearse a trip route as familiarity and anticipation is sometimes helpful.
- Face leeward (so if you vomit, it gets blown away from the ship, not into it).
- Eat bland foods — crackers and bread, or bananas, rice, applesauce and toast.
2. Medication For Motion Sickness
Most medications for motion sickness need to be taken at least 30 minutes before exposure to the activity that can cause the problem. Persons with glaucoma or prostate problems should not take most of these medications unless so advised by their doctor.
There are numerous “alternative” remedies for motion sickness. The most popular are Ginger derivatives, such as ginger tea, powdered ginger capsules, and even raw ginger between the teeth. We have not seen much success in our patients.
3. Stimulators for Motion Sickness
There are several devices that are advertised to reduce motion sickness through stimulation of various places on the body (usually the wrist). These include “Sea Bands” and “Relief Band”, among others. These devices are probably placebos. Nevertheless we have encountered some people who have had success.
4. Exercises for motion sickness.
The recently has been an exercise method proposed — the “Puma” method. This appears to us to be a habituation protocol — repeated exposure to the things that make one ill. This may well work — if you can tolerate the process. We are cautiously hopeful about this method — although it seems to us to be likely to cause a lot of nausea itself.
Motion Sickness Vs Sea Sickness
Some people experience nausea and even vomiting when riding in an airplane, automobile, or amusement park ride, and this is called motion sickness. Many people experience motion sickness when riding on a boat or ship, and this is called seasickness even though it is the same disorder.
Motion sickness or seasickness is usually just a minor annoyance and does not signify any serious medical illness, but some travelers are incapacitated by it, and a few even suffer symptoms for a few days after the trip.
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