The Story Told By Fingers That Don’t Wrinkle

A boy who researchers called F.S. had a severed nerve in his arm. They did not mention his age, and his case is buried deep in a study published in 1936. But that severed nerve exposed an unusual phenomenon that has been a curiosity for many scientists since.

The nerve, called the median, is connected to the thumb, index and middle fingers. So, for F.S., those three fingers were numb. Scientists Thomas Lewis and George Pickering watched F.S. closely, hoping to learn more about the nerve’s function, and they found something bizarre and unexpected. When immersed in water, the fingers with feeling wrinkled, but the three numb fingers remained smooth. In fact, Lewis and Pickering wrote, wrinkling in F.S.’s entire palm was “almost sharply separated by a line” from his wrist to the base of his middle finger. After a few months, the boy healed naturally and full feeling returned to his hand.

Wikimedia Commons. Photo credit: Flagstaffotos

The study, published in 1936 in the journal Clinical Science, brought a new mystery to the surface. Common perception is that wrinkling is a local effect on the skin, unconnected to rest of the body. But if that was the case, why would a nerve that stretches down the length of the arm be involved? Decades of research have since provided some answers, and some scientists believe these answers could help doctors diagnose diseases that disrupt the nervous system.

Einar Wilder-Smith, a neurologist at the National University of Singapore, has done research looking into the wrinkling effect over the past decade. His research suggests that finger wrinkling relies on nerve endings that entangle sweat glands and blood vessels in our fingers. “We always think of nerve fibers as motor function or sensory function,” says Wilder-Smith. “But there are many in the background that go unnoticed, and possibly only get noticed by wrinkling.” Many nerve fibers sit on key crossroads for blood, small arteries called arterioles which lead to tinier blood vessels. These nerves either tell blood vessels to constrict or allow them to relax depending on signals like temperature.

Palms are also riddled with sweat glands, especially in fingers. These sweat glands can act as a two-way street; not only does sweat come out, but water can go in. When water intrudes on a sweat gland, the water comes in contact with nerve fibers. The nerve fibers are collectively jostled from their sleep and begin to fire all at once, telling the arterioles to constrict. The arterioles constrict as a group and for a stretch of time, leaving an empty space between the blood vessels and the skin. The skin on the finger tips then slowly sinks inward, creating a set of folds like a collapsed tent. The end result is the prune-like fingertips that fascinate children and scientists alike.

So, unwrinkled fingers could mean that a major nerve has been entirely disabled, as was the case with F.S. “Cutting nerve is like cutting a power supply to your socket,” said Wilder-Smith. But it could also signify a less direct kind of nerve damage, such as the corrupting effect of a larger disease such as leprosy or diabetes. Because of this, some doctors are already using the wrinkle-effect as a diagnostic tool.

Andre van Rij, a surgeon with the University of Otago in New Zealand, sometimes uses the test took look for nerve damage from diabetes in patients’ legs and feet. Since sweating is also reliant on working nerves, he said, the classical way to look for general nerve damage is to see if feet sweat. The method is called the iodine and starch test; doctors swab iodine on the patient’s skin, let it dry, sprinkle on some white starch powder, then put the foot in a plastic bag. If the foot sweats, the iodine turns the starch dark blue, and doctors know there is nerve damage. But van Rij says it’s easier to look for wrinkling on feet. “It’s easy just putting someone’s foot in warm water, and you see if they don’t wrinkle,” he said.

Another study shows some correlation between finger wrinkling and the central nervous system — the brain and spinal cord. A 2001 study out of Tel Aviv University in Israel compared finger wrinkling in 18 Parkinson’s disease patients with nine healthy patients. The researchers counted the wrinkles on their research subjects’ fingers one at a time, and found that while those suffering from Parkinson’s still wrinkled, they wrinkled less than people without the disease. Wilder-Smith said the Parkinson’s study isn’t necessarily useful as a diagnostic tool.  “The differences are much more subtle,” he said. But the study does demonstrate the connectivity of nerves throughout the body, he said, because when part of the central nervous system breaks down, still-working networks of nerves are more likely to try to compensate for what was lost.

Wilder-Smith has been looking for ways to use wrinkling as a diagnostic tool while avoiding water altogether. Soaking a hand in warm water can be inconvenient, he said, because it takes about half an hour of soaking for skin to wrinkle, which is about as long as a conventional neurological exam. He’s taken to using an anesthetic cream that causes blood vessel constriction called EMLA. Wilder-Smith says the cream produces wrinkles faster than water does and can be applied directly to the fingertips. “We’re not sticking hands in buckets anymore because it’s much more practical to put EMLA on the skin,” he said.

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Catching Puppies

This was it—go time. Standing poised but slightly crouched like a football player about to spring into action, our eyes were on the clock. My hands were beginning to sweat within the latex gloves I was wearing and I nervously adjusted my face mask to bide the time.

“Okay guys, here we go,” I heard the surgeon say as my fellow ‘team mates’ stood in line behind me at the ready, and we counted down the seconds in our heads as he did so aloud in front of us. Hey, this was my first time doing something like this after all—and I couldn’t help but be a little nervous, not to mention I had only just been hired. I would NOT mess this up.

Standing at the door of the surgical suite, I looked at the patient. She had been secured upside-down on her back, and was being remarkably well-behaved—luckily for all of us, as it’s not always the case. Her enlarged abdomen had been shaved and scrubbed with antiseptic, and the orange-yellow sheen of betadine was apparent thanks to the bright overhead lights. The look on her face was curious, and not panicked in the least. The perfect patient.

“5…4…3…2…1… BEGIN!”  The exact time was noted by another technician as the patient was sedated, intubated, and hooked up to an anesthesia machine—the surgical team had moved as if part of a well-choreographed dance, while the familiar beeping of the electrocardiogram machine began to echo eerily in the room like a metronome as it helped monitor her condition. Beep… beep… beep… 

The surgeon’s skill was evident as within just minutes, a newborn baby puppy was tossed gently through the air, and I caught the little blob of flesh in the warm towel I held in my outstretched arms. I dashed with the precious cargo to a station that we had prepared in advance, and started cleaning mine up— followed closely by the other catchers with their own puppies in tow.

We removed each one from their amniotic sac, used a suction bulb to remove fluid from their mouths and noses to clear their upper respiratory tracts, and rubbed each one clean as the mother would, which stimulated them to breathe and cry. Although it’s no glamorous task, hearing that puppy cry is one of the most rewarding experiences in the world. Then, once the puppy was clean, dry, and stable, we each tied off our puppy’s umbilical cord with suture material, cut off the rest of the placenta, and placed the baby in a pre-warmed incubator until mom was recovered enough to take care of them.

Score!

Image
Radiograph image of canine fetuses in utero, courtesy of the Animal Hospital of Pasco (http://www.pascovets.com). Can you count how many puppies there are?

As you may have guessed, before I was a Science Writing student here at Hopkins, I had worked for a few years as a veterinary technician at an animal hospital back home. As a ‘vet tech,’ I was responsible for assisting the veterinarians in a similar manner to the way that nurses assist doctors in human hospitals. Since I always tell crazy animal stories to my classmates, we all thought my first post on this new blog should have something to do with animals, and perhaps one of the lesser-known procedures that are performed at an animal hospital. If you haven’t guessed by now, this is a canine or feline cesarean section.

Now many of you may scoff, thinking a c-section on animals? Well it’s actually more common than you might think. There are a number of reasons as to why it might have to be performed, such as the animal is way past her due date with no sign of parturition (birth), she is somehow too weak to give birth naturally, she is straining too much or having some kind of trouble (dystocia), the baby is stuck or improperly positioned near the birth canal (breeched), and so forth. In addition, some breeds almost always have to have cesarean sections performed because they have been bred to a point where their heads/hips are too oddly-shaped for natural birth to be possible. This is often the case with dogs that are extremely small, as well as pugs and other brachycephalic (flat-faced) dogs. It is almost impossible for bulldogs to be born naturally for this reason, and practically every pregnant female of this breed will have to have this procedure done.

I hope to never see a human doctor toss a newborn human baby to a nurse so she can catch it in a towel, but there actually is some science behind it when done with dogs and cats. After reading my first-person account, you may be slightly horrified and wonder why on earth a veterinarian would toss sweet little newborn puppies or kittens at his assistants rather than just handing them over. I spoke with Dr. Michael Petranto, a veterinarian with a special interest in animal reproduction and who is also the medical director at Twin Rivers Animal Hospital in East Windsor, New Jersey to shed some light on the subject.

He explained that the purpose of the toss/catch procedure, which is done during all veterinary c-sections, is mainly for speed. Plus, the entire surgery itself is carefully timed. “The ultimate goal,” he said, “is to resuscitate the pups or kittens as quickly as possible, get them warm and stable, and then get them nursing once mom is strong enough after surgery.” This is important because they must drink the mother’s “first milk” or colostrum, a substance rich in nutrients, proteins, and vital antibodies, which is only produced within 8 hours after birth.

The entire process can be done even faster when other technicians form an assembly-line, as opposed to the same person catching a baby, resuscitating it, and running back for another—that would take too long and some babies take longer than others to stabilize. This way the surgeon can just take each puppy or kitten and quickly toss one after another to a waiting technician who can give all their attention to the one they have.

If the mother is calm enough and behaves well, she will be prepped for surgery while she is awake. Usually for most other procedures, an animal’s surgical site is shaved and cleaned with antiseptic while they are under anesthesia in order to make it easier for the technicians, and to cause less stress for the animal. With c-sections, there is a concern for both the mother and her unborn litter, who can all be affected by the anesthetic drugs if they’re in the mother’s system for too long. The same holds true with people. Speed is the key.

The surgeon also has to remain sterile throughout the procedure. If the catchers get too close, they could run the risk of contaminating the doctor, as well as the surgical table and equipment if they were to accidentally touch anything. This could lead to the mother developing a dangerous infection. The doctor gently tosses the newborns one by one, which is only the distance of a few feet at most, in order to avoid this.

Dr. Petranto explained that in all his years of practice, he couldn’t remember a technician ever dropping a puppy or kitten during one of these procedures—they really have it down to an art. But, he said that even if one was dropped, natural birth would have been more traumatic. “Think about a Great Dane,” he said. “When a female is whelping [giving birth], those puppies are going to fall about the same distance if she happens to be standing. Plus the mothers pick them up, lick them, move them around and so forth. They get shaken up quite a bit and are pretty resilient.”

Interestingly, he also mentioned that many people ask if there is a different bond that forms between a mother and her litter after a cesarean section versus a natural birth, and the answer is that there may just be. As a matter of fact, there is a pheromone that the mother is stimulated to produce during natural birth that she does not during a c-section. Referred to as Appeasing Pheromone, it was only recently discovered within the last few years, and helps to calm the babies and reassure them. It also helps them become more confident and by so doing, encourages them to start exploring their surroundings as they get older. However, more research is needed at this point to determine if the lack of this pheromone in female animals who have had cesarean sections significantly affects their offspring in a negative way.

From what I have seen with my own eyes though, the mothers and their litters tend to turn out just fine.


Blood Thinners Don’t Make Your Blood Thinner

When I was a teenager, I was tentatively diagnosed with a genetic disorder called Marfan syndrome. The short explanation: My connective tissue is stretchier than normal, making me tall and somewhat gangly. It also has the potential to cause heart problems. But I’m a marginal case. So years of having a modest income and poor health insurance led me to avoid what should have been annual visits to a cardiologist to make sure my heart and aorta were running smoothly.

When I enrolled in the Johns Hopkins University science writing program I got my first decent health insurance in years. So I jumped on the opportunity to get re-evaluated at the age of 31, a good 15 years after the original diagnosis. Our knowledge of Marfan, as with most things, has grown in the last decade, and more than anything else I wanted to know if I actually needed to worry about my ticker so much that I needed yearly heart sonograms. So I went to the hospital and met with a cardiologist there.

To my relief, it turns out I don’t need yearly sonograms after all. But this story isn’t about that.

As we discussed my history, the cardiologist asked me what I was going to school for. I told him about the science writing program, and doing the tricky work of trying to simplify science for a general audience while not sacrificing our accuracy. His eyes widened, he tilted his head, and he leaned back in his chair a little. Something had just leaped into the doctor’s mind. I realized I was about to hear his opinion on what I do.

These platelets don't care how thin your blood is

He told me he wasn’t fond of the simplified term “blood thinners.” It’s often used to describe drugs that chemically control the microscopic bits and pieces — proteins, other molecules, and cell fragments called platelets — in our bloodstreams responsible for clotting. The doctor told me patients regularly assumed that blood thinners made their blood less gooey and more watery. He called it one of the more frustrating simplifications out there. “We have people around here on blood thinners who think they’ve got thin blood!” he said.

His statement got me thinking. My first impulse was to try to come up with ways the term could be defensible. Maybe if the drug reduced the number of clot-causing proteins, you could say the content of those proteins has become thinner? But I really felt like I was grasping.

The man had a point. Blood thinners just plain don’t make your blood thinner. It’s a convenient metaphor, attaching an every-day idea to a more complex biochemical concept, but it isn’t clear that it is a metaphor, which makes it easy to confuse the chemical changes going on in your bloodstream with a change in the blood’s consistency.

This is an old misconception, too, rooted in a very traditional way of thinking on blood thinness and thickness. If you’re interested in reading about what scientists know happens in blood compared to what the general public often thinks, check out this charming study on folk hematology, in which physicians and patients are interviewed on their familiarity with concepts like “thick blood” and “high blood.” This quote sums up the author’s take on “blood thinners”:

These drugs [“blood thinners”] are given to patients to prevent abnormal blood clotting. These drugs do not, as folk theory has it, “thin” the blood to a less viscous and more “watery” consistency. To avoid a befuddling biomedical explanation and accommodate a patient’s need for explanation, some physicians have opted for the term “blood thinner”, a term perhaps originally borrowed from their patients.

I had a sense of the issues with simplification before I joined the program — it is, after all, one of science writing’s central issues. I’m now seeing first hand how this kind of hazard pops up all the time, and we may not even be aware of it. Simplifications can be wonderful and elegant, or they can completely mislead. A metaphor can be brilliantly effective, but it must be clear that it’s a metaphor.

In the case of blood thinners, it’s probably naive to think the term will disappear from our language any time soon. Just type “blood thinner” into Google News, and hundreds of articles from the past month will pop up. The term is deeply embedded in our primal conceptualization of blood and drugs. Though I wonder what term would even make a good alternative. Clot stoppers?