Thursday, April 29, 2010

Backseat Enemy: My Relationship with Motion Sickness

I'd like to consider myself a member of the "Strong-Stomach Club", but that's simply not the case. Instead, I can claim fame to numerous times I've had to tell someone to "pull over" because I couldn't handle the constant stop-go motion of a car ride. Yep, that's me. The one whose either car sick, air sick, train sick, sea sick, rollercoaster sick, or you-name-it sick. For those fortunate enough to not suffer from motion sickness (kinetosis), feel lucky because the symptoms of constant dizziness, cold sweats, headache, and nausea all typically lead to vomiting and grumpiness (in my case, that is).
I can recall the last major episode was during a five hour flight to Phoenix. I had braved air travel several times before, but this particular event was a disaster. Hitting turbulence immediately after our departure was not friendly on my Cheez-It filled stomach and the bag strategically placed infront of my seat contained all the proof.

But what exactly are the mechanics of this annoying sickness that I'm faced with every adventure I dare take? Actually, the vestibular system (or, the inner ear) plays an important role in deciphering the position of the body. The skeletal and muscular system along with our visual perception (all co-workers for the inner ear) are responsible for sending important informational signals back to the central nervous system to help coordinate our balance. The inner ear uses the mechanical force of gravity to determine our body position.
Motion sickness is triggered by contradictory signals to the CNS which results in the unpleasant symptoms previously mentioned. Basically, the body is being overloaded with perceptual signals when it is determining the proper spatial orientation of the body and is perceived as a miscommunication. This signal confusion may initiate vomiting in an act of self-defense against possible ingested neurotoxin.
The area within the brain responsible for inducing vomiting is called the area postrema located within the medullary structure. This region of the brain is responsible for controlling vomiting when poisons are present and is responsible for vision and balance communication. Obviously you can see how miscommunications between these signals would lead to motion sickness. When feeling motion, but not actually seeing it, the inner ear transmits a signal to the brain that motion is occurring. At the same time, the eyes are sending a signal to the brain that nothing is moving. This miscommunication allows the brain to perceive that one of these signals is hallucinating. The brain then determines that the hallucination may be poison induced and sends the body into instant defense mode. The symptoms set in and you immediately feel sick. Your body thinks it's under attack.

Luckily there are several tricks that (sometimes) work and being the veteran motion sickee that I am, believe me I've tried them all.

The first trick being that you always get to ride shotgun (you don't want to make a mess on your friend's car floor). Or better yet, be the driver because it's a lot harder to make yourself carsick than it is to be tousled around in the back seat smashed between your friends.

Get plenty of cool air whether that be putting the window down, cranking the AC up, or whatever it is you have to do to avoid roasting.

Try to stare at the horizon because focusing on objects off in the distance will help stabilize the dizziness. So looking down, reading, texting, organizing your cluttered purse should be the last thing on your mind if you're like me and are in a moving vehicle.

When traveling by air, do what ever possible to get a seat by the window and concentrate on distant objects instead of the plane jerking the passenger behind you into the back of your seat.

If these suggestions don't work, take some antiemetic meds like Meclizine before your travel. These tend to knock you out (especially after a glass of wine) so maybe take half the dose the first time.

Recent studies have suggested that continual exposure to motion sickness usually results in a decrease of symptom onset (3). This included adaptation training on simulation sickness and frankly these people are crazy. They analyzed the use of simulated rotary stimulation (SRS) on visually induced motion sickness. Also, the susceptibility of motion sickness may be genetically linked in a single nucleotide polymorphism of the alpha-2-adrenergic receptor. It was concluded that exposure to excessive rotation did decrease motion sickness symptoms, but whether it is an adaptation phenomenon is still in question. I have yet to agree with these findings and I hesitate to volunteer myself to physically induce such horrible symptoms (I'd rather take Dramamine as preventative measures than be keeled over the porcelain throne from sheer curiosity).

1. Terrie, Yvette C. "Motion Sickness: Calming the Waves of Upset." Pharmacy Times 74.5 (2008): 63-72

2. "Head maneuvers work best for common vertigo." Harvard Women's Health Watch 15.12 (2008): 4-5.

3. DOI: 10.1080/10508410802346921

1 comment:

  1. I get motion sickness any time I'm in the backseat when traveling. Some of this I've figured out with trial and error, but I'm glad to have learned new things to help and have support for my own remedies. Good job!