Sunday, May 3, 2009

Vomitiously ill*

Back in January, I had to go out on a boat. This happens sometimes in my line of work, so you might think that I'm used to it. And I am, for it is surprisingly easy to get used to any unhealthy relationship.

I love boats! Every time I climb on board I hear Ratty, from The Wind in the Willows, exuberantly claiming that "there is nothing--absolutely nothing--half so much worth doing as simply messing about in boats." Fresh wind in the hair! Rainbows in the salt spray! It's incredible!

Boats, meanwhile, hate me. Boats want me to be as sick as possible. They want to wring as much pleasure as they can out of my whole boating experience. But I will not be daunted! I am determined to continue loving boats, and so every time I am invited on board I say yes! Defiantly I toss back my meclizine, chew the ginger, munch on Triscuits, and dare the boat: do your worst.

Generally speaking, it does.

It's an arms race: me finding new ways to stave off seasickness, and boats finding creative new combinations of yaw, pitch, and roll. Back in January, I thought I might have finally won. I took a tablet of prescription-strength meclizine hours before the boat left, and popped a chewable Bonine every two hours on the boat. I ate lots and lots of crackers, and I felt fine. I felt great! I could have stayed on that boat all day! Come to think of it, I did.

After that, I didn't have occasion to get on a boat again until last Tuesday night. I remembered to bring all my anti-seasickness weapons to work, and I remembered to take the meclizine a couple of hours before we hit the water. But other than that one quick swallow, I wasn't thinking about seasickness at all. Instead, I was caught up in the packing list, the float plan, the science to be done.

(This is my problem, you see. Selective memory. Unchecked optimism. It does not matter how vomitiously ill I have been on a boat trip, that sickness remains but the faintest of clouds on the horizon of an otherwise idyllic boating memory. So by the time another boating opportunity presents itself, all I can think is: Yes please! I love boats! . . . But I digress.)

Hah, just kidding, we've left the parenthetical only to plunge into another digression. Let's meet that meclizine I keep talking about:

It's an antihistamine (blocks allergic reactions, like Benadryl) and an anticholinergic (blocks the neurotransmitter acetylcholine). I got a prescription for it back when I was going on a boat for a month and asked a doctor for something to help me with my nausea. (Incidentally, this turned out to be pretty foolish, because after the first night I got my sea legs and was just dandy fine for the whole month.) According to the copious labels covering the little orange plastic vial, it may cause DROWSINESS and BLURRED VISION (the latter illustrated with a charming pair of noses).

What is awesome though, and I didn't realize until much later, is that apparently Bonine is made out of meclizine, and in fact it has more meclizine per tablet than my prescription. Does that make any sense? No. It is dumb. Even dumber is that I keep taking the prescription stuff, feeling like it should have more of an effect than an OTC drug, although there is less drug in it. Hi, I'm a scientist! I'm clever!

So, why does an antihistamine/anticholinergic think it can do anything about seasickness? And why did it perform so spectacularly well in January and so appallingly badly last Tuesday (as you will read about)?

Before answering those questions, I'm going to take a step back and try to understand seasickness itself. My thoughts (as you may have noticed!) are somewhat chaotic, so I have attempted to impose order by organizing the rest of this post in three parts: I. Seasickness, II. Drugs, and III. How Tuesday Night Was The Worst Thing Ever, The End.

I. SEASICKNESS

As I was educating myself on this subject, I stumbled across a 1926 article from Time Magazine. According to the doctor quoted in this article,

There are five
theories for [seasickness'] causation: 1) the labyrinthine (the ear contains
two tiny sacs, the utricle and the saccule, and three semicircular
canals, all of which aid in special orientation); 2) "muscle sense"
disturbance (the muscle nerves localize in space the position of
the limbs, head, eyes and other parts of the body); 3) eyestrain (the
patient gets dizzy looking at the ever-changing sea); 4) peripheral
vagus-nerve irritation (the insides get shaken up by the complicated
motion of the boat and by the minute, incessant vibration of the
engines); and 5) psychic stimuli (the patient sees others kharouping
and vomiting over the rail and gets sick).

Let's take a moment to lament the fact that "kharoup" might not have seen print since 1926. What a great word.

Okay, let's look at those theories. Dr. Desnoes kindly states theories 3, 4 and, 5 in layman's terms that make some intuitive sense. For theories 1 and 2, however, he takes care to define "inner ear" and "muscle sense" but makes no mention of how motion would affect them negatively. Presumably they are "disturbed" in some way.

In the intervening decades, medical science hasn't come a whole lot closer to a definitive explanation for motion sickness.

The explanation you most commonly hear these days is a combination of Dr. Desnoes' theories 1 and 3. Your brain gets one message from the inner ear and a different message from the eyes, and this makes it confused. This makes sense, whether you're looking at the boat (which is moving along with you, so it looks like you're still) or the water (the waves that you're looking at are not the ones underneath you, so you're not moving in sync with them) or even the horizon--although this latter option is an oft-touted method for staving off sickness.

But why should conflicting messages from the inner ear and the eyes make you nauseous? In the immortal words of Eddie Izzard,

Throwing up is controlled by
three little bones in the inner ear. They're called Shadrach, Meshach and
Abednego. And they control hearing and vomiting.
Don't know why they go together. God went, "Inner ear, you shall
have hearing and vomiting as well. Yes, that'll be fun."
I don't know why they do it! Do you? Does anyone?

In fact, there's a researcher out there who thinks this whole "conflict theory" (inner ear vs. eyes) is total bunk. "Stoffregen has branded the conflict theory with the highest-order insult a scientist can muster: unfalsifiable," reads the article in Scientific American. This guy Stoffregen has a new theory: postural instability. This is sort of like a combination of Dr. Desnoes's theories 2 and 4. Basically, your body is getting shaken around on an unstable platform, you have a hard time keeping your balance, and that makes you sick. An interesting theory, and one that's gaining some support.

But he's got nothing to offer to those of us still hungering for a mechanistic explanation. Even if it is postural instability that causes motion sickness--again, why with the vomiting?

So, we don't really know why you get seasick. But here, have some nasty medicine!

II. DRUGS

An endlesss variety of related drugs are used to treat nausea and vertigo. Here are some of the most common (brand names in parentheses): meclizine (Bonine, Antivert), scopolamine (Transderm-Scop, usually a patch, Maldemar), dimenhydrinate (Dramamine), promethazine (Pentazene, Phenergan), and cyclizine (Bonine for kids).

They are all both antihistamines and anticholinergics, and the reason they work against nausea is, well . . .  "The precise mechanism of action in inhibiting the symptoms of motion sickness is not well understood." Honestly, this shouldn't be surprising. Since we don't know the mechanism behind seasickness, how could we possibly know the mechanism behind the drugs that work against it? It's pure trial and error. Come to think of it, the situation is not unlike psychiatric medication.

However, I'm pleased to report that there are plenty of studies about the practical effectiveness of various treatments. And not just the drugs, either.

Various behavioral modifications can be effective treatments too. Eating constantly works well for me (when I can keep it down), and others swear by it. Where on the boat do you stand? Where in the world do you look? Stoffregen might suggest that if we all just walk around straddling the deck, we'd be fine!

As usual, attitude is often the best drug. If you're afraid you'll get seasick, you probably will. If you're determined you won't, you'll likely stay healthy. But no matter how fervently I believe in mind over matter, it just won't work for me. Case study: Tuesday night.

III. HOW TUESDAY NIGHT WAS THE WORST THING EVER, THE END

(No, it's not quite the end. I know, I know, have I ever been so verbose? If you are still reading, thanks! You're a trooper! I promise to be done soon!)

Tuesday night: I took meclizine. I got on the boat with a fellow grad student, our advisor, and an intrepid captain. I ate about a quarter of a box of Triscuits. We arrived at our first station, did some science. I took careful notes. We embarked on a very bumpy ride to our second station. The boat stopped, in the sense that the motor was turned off, but kept going, in the sense that we were being juggled by some of the more unperiodic, unpredictable waves I've ever felt. I looked up, noted the beginnings of mutiny from within, and announced, "Sorry guys, I'm not going to be much help."

I tried, I really did, to keep taking notes. With intense focus, I wrapped my hand around the pen, and labored to scribe each letter and number. My fingers were tingling as though asleep, so I began to work my hands vigorously, trying to bring them back to life. Instead, the tingling spread. I noticed it in my arms, legs, and torso. Have you ever felt pins-and-needles in your torso? It's novel. Also, freaky.

While Fellow Grad and Advisor engaged in Science, I engaged the captain in a conversation about the tingling phenomenon, and discovered that I was suffering neurological symptoms in my speech as well. That is to say: I was slurring like a drunk. Fabulous.

My fine motor control was pretty much gone, so I gave up the notebook and concentrated on keeping myself alive. It was freezing cold, so I pulled on my gloves and scarf, although sometimes I would get the sweats and have to open my jacket and pull the scarf away from my neck so I could feel like I was getting enough air. It's worth recording that I was practically hyperventilating at this point. The captain suggested that I breath more slowly. I told her that I couldn't.

What an interesting set of symptoms, you are saying, yes, yes, but what about the nausea? I was nauseous, but I didn't come close to throwing up until near the very end of the Science, and it wasn't until we were almost back home that I managed a really good kharoup. After that, recovery proceeded quickly to basic usefulness, but exhaustion and mild nausea clung to me persistently through the next day.

Wow, you are saying now, thanks for sharing! I didn't need to hear that story at all! Okay, true, but here is the interesting medical information: meclizine, like many another antivertigo drug, acts to prevent you from throwing up. (By blocking acetylcholine, apparently. Who knows why that works?) But it has no effect on the other symptoms of seasickness, like exhaustion and dizziness,and it doesn't even alleviate your nausea, it just keeps you from vomiting. Which would probably make you feel better. Thanks for nothing, meclizine!

But it's even better than that--blocking acetylcholine can have some delightful side effects of its own. Blurred vizion and dizziness are, of course, well advertised on the packaging, but I feel pretty comfortable blaming my slurred speech and tingling on the meclizine, too. I'm lucky I didn't get any hallucinations.

We did catch squid that night, didn't we?


* The title of this entry came from a friend of mine who used to be a naval engineer. If I understand correctly, part of her job was to calculate a seasickness index for every area of the ships she worked on--"vomitiously ill" being an unacceptable level of seasickness. Or something.


2 comments:

  1. I presume that since we don't know what causes seasickness, we don't
    know why some people are more prone to it than others. Has anyone
    done lab experiments attempting to simulate it? I guess you'd
    probably have to pay the volunteer subjects a lot....
    Does throwing up actually make you feel better when you are nauseous
    from seasickness? I always figured it made you feel better when you
    were nauseous for a good reason (like having eaten something that
    disagreed with you) because it got rid of whatever was bothering you.
    Is whatever gives you nausea designed to go away after you throw up,
    no matter the actual cause of the nausea?

    ReplyDelete