What inflammation looks like up close and personal, part I

July 29, 2010  |  General  |  No Comments

Here’s a snippet from the first chapter of my new book, How Your Child Heals. It picks up at the point where you, the reader, have begun a microscopic voyage to see what an infected splinter looks like from the perspective of inside your child’s body.

Now that you have had the full-sized, outside view of what happened to your son’s finger, it is time for you to go inside to places where the ancient physicians could not go. It is time to take a seat in the audience of the microscopic drama. You are about to make the first of several trips you will make throughout this book in a tiny, imaginary, high-tech vessel. Think of it as a cross between a submarine and an all-terrain vehicle; it can swim in the blood stream or leave the circulation to crawl around between the cells of the body. It is well-equipped with spotlights and spacious windows, allowing you to see what is happening all around you. The dramatic setting for your first foray is the time just before you called the doctor’s office to ask what to do about it.

The blood vessels in the body form an immense, self-contained system that is divided into two halves. We need oxygen to live, and one half of the circulation, the arteries, carries oxygen-rich blood out to all the parts of the body, down to the tiniest places. The other half, the veins, brings oxygen-depleted and carbon dioxide-laden blood back to the lungs to get more oxygen, which we breathe in, and dump the carbon dioxide waste, which we breathe out. The two halves of the circulation join in a microscopic meshwork of vessels called the capillaries. This is where the true business of circulation happens, where oxygen and other important nutrients get delivered to the body’s cells.

The capillary bed of your son’s throbbing finger is the key place to visit as you investigate what is causing all the problems, but to get there you must first get inside his circulation. You need a location where the tiniest of blood vessels are accessible, close to the surface. The lining of the eye is such a place.

Imagine you begin by poising your craft at the base of one of his lower eyelashes. You look over the edge into the wet, shiny world below. Your son momentarily pulls down his lower lid, revealing the pink inner lining of his lower lid, called the conjunctiva. You seize your chance, zip over the edge, and find yourself motoring about in the clear liquid of his tears, nature’s way of keeping our eyeballs moist. Here there are blood vessels close at hand, just below the surface. You slide your craft into the nearest one and then drift along with the stream, ever faster, as it takes you toward the heart.

You do not stay in his heart long, though, because nothing does. The blood rockets out of the heart like a fire hose because the heart pumps an enormous amount of blood very quickly. A typical adult heart, for example, sends out about a gallon and a half of blood every minute, proportionately less in a child. The effect on your vessel is the equivalent of taking a trip over Niagara Falls. You get bounced around, but soon find yourself in the aorta, the large vessel exiting from his heart.

The aorta is wide and fast, but it soon divides, then subdivides, into multiple rounds of ever smaller vessels. As this branching happens, the velocity of the stream in each of them slows down dramatically. Within seconds after leaving his heart you are scooting down one of these tributaries, headed for his painful index finger.

Things were moving so fast in the aorta and the first couple of branchings that you could not see any details in the surrounding walls of the blood vessels. Although you are going slower now, your pace is still a brisk one, and the flow still pulses along–now faster, now slower–in rhythm with your son’s heartbeat. Soon the stream slows down enough for you to get some idea of just what kind of pipe you are traveling through. The first thing you see when you shine a light at the walls is that the surface is covered by a bumpy layer of cobblestone-appearing cells. The junctions between these cells make a completely watertight barrier; no blood can leave this sealed pipe, and thus you cannot see what is going on in the tissues outside of it.

You soon find you are slowing down even further as you come closer to the sore on his finger, and you notice a dramatic change in the walls of the blood-filled passage you are passing down. For one thing, the wall of the tube is now translucent; you can shine your light right through and get a hazy view of what lies beyond. There are now some small gaps between the pavement of flat cells that makes up the walls, but the cells still mostly touch one another along their edges.

You have reached the capillaries. In real life there would be millions upon millions of options for you to have chosen on your trip from the aorta as the tubes branched into ever smaller pathways, but for our purposes we assume your miniature craft has the proper instruments to sense the correct path among the myriad of choices to lead you to the sore spot on your son’s finger.

Why we doctors order far too many scans

July 23, 2010  |  General  |  6 Comments

There’s a provocative editorial in a recent New England Journal of Medicine about the explosive rise in high-tech medical imaging. Everyone knows doctors order a lot of CT scans, MRI scans, and ultrasound studies, and that the number of these has been steadily increasing. And the cost is enormous. From the article: ” . . . these costs were the fastest-growing physician-directed expenditures in the Medicare program, far outstripping general medical inflation.”

To be fair, rising use of new medical technology is expected because, well, it’s new. What is unclear is that how much of this increased use has led to improved health to justify the cost. Clearly much of it doesn’t, and unnecessary scans, particularly CT scans, lead to risk with no benefit.

The practice of “defensive medicine,” of doctors ordering tests out of a fear of being sued for missing rare conditions, is often given as a cause for overuse of scans. There is some truth to that: the article cites a Massachusetts study showing that 28% of scans are done for that reason. Lawsuits over failing to diagnose things are common; lawsuits about overuse of tests are vanishingly rare.

Physician conflict-of-interest also plays a part. Through a loophole in Medicare regulations, physicians are allowed to refer patients for scans from which the physician benefits financially. That is wrong and needs to be fixed.

But there are deeper reasons. The root cause may well be “the style and content of clinical education and their impact on medical practice.” In other words, how doctors are trained. We use scans unthinkingly, and, unthinkingly, can cause harm. Again from the editorial: “The greatest risk that patients face with unnecessary imaging is the needless exposure to downstream testing and inappropriate treatment related to misdiagnosis and the overdiagnosis of common but unimportant findings.” I’ve seen that happen more than a few times.

How many calories does your child need to grow?

July 16, 2010  |  General  |  No Comments

In the PICU we focus a lot on nutrition because critically ill children need good nutrition for them to heal from their illness or injury. We often struggle to provide those needed calories. We usually can manage it one way or another, either with high potency oral feedings, special intravenous feedings known as total parenteral nutrition (TPN), or some combination of both of these. We have formulas we use to calculate what a child’s nutritional needs are.

But what about normal children? Many mothers, and it seems most grandmothers, don’t think their children are eating enough to grow. Aside from charting progress in height and weight, how can we calculate if a normal child is getting enough calories?

Here are some good rules of thumb. It’s simplified, but it works. The first thing you must do is determine your child’s weight in kilograms, since that is how we do the calculations: 1 kilogram = 2.2 pounds. Once you know that, you can calculate the average amount of calories needed to grow this way:

  • Age newborn to 3 months:  100 calories per kilogram per day
  • Age 3 months to 3 years : 90-100 calories per kilogram per day
  • Age 3 years to 8 years: 80-90 calories per kilogram per day
  • Age 8 years to 12 years: 60-80 calories per kilogram per day
  • Age 12 years to 16 years: 45-60 calories per kilogram per day

These calculations assume a normally active child. A significantly more active child needs more. A reasonable rule of thumb for this extra need is for an active child (defined as an hour per day of sustained physical activity) to have about 1.25 times their baseline calories and very active children (defined as more than 90 minutes of sustained physical activity per day) to have 1.5 times their baseline calories.

What does this work out to be in actual numbers? A normal 6-year-old in first grade weighs about 20 kilograms (44 pounds). For him, the daily need is 1700 calories. How about a 17-year-old girl who is a serious soccer player? The average weight for a girl of that age is 55 kilograms (120 pounds), and she needs about 3700 calories; her baseline need is 2400 calories or so, multiplied by 1.5 for her intense activity.

You can find lots of growth charts listing normal heights and weights for children here, and how to use them here.

What causes diarrhea in children?

July 10, 2010  |  General  |  1 Comment

Here’s another excerpt from my new book, How Your Child Heals. It’s from the chapter on symptoms, and it’s about what causes diarrhea.

Diarrhea, the frequent passage of watery stools, is something with which most parents of small children are well acquainted. It is a common symptom because its most common causes, intestinal viruses, are all around us. There are many of these for a child’s immune system to meet as it matures. Each new encounter usually causes illness, but subsequent exposures often cause few or no problems. These viruses are highly infectious, so they spread easily wherever toddlers gather to share toys and cookies. The result is what doctors call gastroenteritis, a fancy term for an inflamed stomach and intestines.

Other things besides viruses can cause diarrhea, but most of these cause it in the same way intestinal viruses do — injuring the cells lining the intestines so they cannot do their job of absorbing the nutrients passing by them. A wide variety of food intolerances can also lead to diarrhea, often because the absorbing cells, though present in the intestine, are in some individuals unable to deal with a particular food properly. Common examples of this include a deficiency of the absorbing cells that process lactose, a type of sugar in dairy products, or a sensitivity to the proteins present in cow’s milk. Whatever the cause of the poor functioning of the absorbing cell lining, the result is often diarrhea. If there is significant stretching and squeezing going on in the intestine the child will often have cramping pain, too.

When the intestinal lining is injured, it cannot do its job of absorbing food. If a large amount of unabsorbed food makes it to the lower reaches of the small intestine, it draws water out of the intestinal wall. It also becomes excellent food for all the bacteria living there, and the action of the germs gorging themselves on this sudden feast produces even more substances that draw water into the intestine. When this mixture is dumped into the large intestine, the enormous mass of bacteria normally living there magnifies the effect. The large intestine can absorb quite a bit of water, but it can become overwhelmed by the volume of what it is being asked to take in. Plus, its lining cells may themselves be injured by the infection and be less able to do their job.

These things makes the stools watery. Diarrhea also means more frequent stools. The simple increase in the amount of material the intestines must deal with is one cause of the more frequent stools. Another is that most causes of diarrhea also speed up the transit time, the length of time it takes what a child swallows to pass all the way through.

There is another kind of diarrhea, one less common in children. This disorder is of the large intestine, the colon, and is called colitis because that word means an inflamed colon. It is typically caused by one of several varieties of infectious bacteria. Since the colon can become quite irritated and inflamed, the diarrhea of colitis often has blood in it from oozing off the intestinal wall. It is usually a more serious illness than simple gastroenteritis of the upper reaches of the intestine. This is why seeing blood in your child’s stools is a reason to visit or call the doctor, especially if your child has fever as well.

We have several ways to deal with diarrhea, the first of which is to do nothing other than make sure your child is getting enough fluid to replace that lost in the stools. This is how doctors usually handle the situation, because typical gastroenteritis is quite self-limited and will pass soon. When it does, the damaged absorbing cells very rapidly replace themselves on the villi and all is well. If it persists for many days, that is a reason to suspect something else is causing it.

Simple common sense teaches us we should not challenge the intestines of a child with diarrhea with large meals full of complex, difficult to absorb foods, because the poorer the absorption, the worse the diarrhea potential. Parents have known this for generations. This is the rationale for using smaller, more frequent meals of simple starches like rice and bread, or even of eliminating all solids for a day or so. There are several ways of approaching this issue, but many parents find out by trial and error which dietary manipulations work for their children and which ones do not.

We do have several drugs to treat diarrhea, most of which work by slowing down the transit time through the intestines. Lomotil is the brand-name of a commonly used one. These drugs affect the intestinal nerves that control how fast the intestines squeeze the food along, slowing down the process. They work well in adults, although you can easily see how it is possible to overshoot and end up with constipation. However, doctors rarely recommend these drugs for small children because, as with the nausea and vomiting medicines, the potential side effects outweigh any benefit of using them for a condition that usually quickly passes without treatment.

Cell phones and brain tumors: is there any link?

July 4, 2010  |  General  |  No Comments

People today use their cell phones a lot — so much so that some folks I know seemed to have them glued to their ear all day long. Is there any risk to that? Some have questioned if the radio waves involved might lead to an increased risk of tumors — cancer — in those who do this. A recent article in the International Journal of Epidemiology sheds some light on the question. (Epidemiology is the study not of individual sick people, but of how disease affects populations.)

The study is what is called a case-control study. This matches people with a particular condition with people who don’t have the condition, but who otherwise are similar to those with the disorder. The investigators then look for things — evironmental exposures, for example — that are present in the patients with the disorder but not in the control group, those without the disease.

In this case, the investigators found no link between cell phone use and the occurance of two common brain tumors. These results need to be confirmed, like all medical research, especially since there was some possibility of a link at very high exposures, but overall the results are reassuring.

Why do children cough?

June 24, 2010  |  General  |  No Comments

Here’s another excerpt from my new book, How Your Child Heals. It’s from the chapter on symptoms, and it’s about what causes cough.

The hallmark of most respiratory illness, both in children and in adults, is a cough. Coughing is a reflex, one difficult to suppress. You probably know this from the experience of sitting in a quiet setting, such as in a lecture audience or in church, when you have a cold. The urge to cough is nearly impossible to deny, even with intense effort.

The upper and middle portions of the airway, meaning the space between the back of the throat, through the vocal cords, and down to the first branching of the windpipe, are thickly sown with sensors. They are particularly abundant right around the vocal cords and down at the area of the first branching of the windpipe into smaller breathing tubes. If anything touches these sensors the response is a cough. The reason this reflex is so powerful is that nature is fanatic about protecting our airways. We need to breathe every minute, and objects that might block our airways are potentially very dangerous. Since the last line of defense for the lungs is at the windpipe’s first branching, it makes sense that touching that spot provokes a particularly explosive episode of coughing.

Infections of the upper respiratory tract cause the mucous-secreting cells that line the walls to make more mucous, sometimes large amounts of it, and this extra material trips the cough sensors. The upshot is that we cough and cough until the mucus is cleared out of the airway via a mechanism doctors term a productive cough, meaning it produces sputum.

Often, however, a cough is dry–it does not produce any sputum at all because the cause for it is not excess mucous. We term this a nonproductive cough. It often comes in spasms of multiple coughs in succession, followed by a period of relative quiet. This kind of cough is caused by inflammation of the walls of the airway, something respiratory viruses do, and the inflammation triggers the cough sensors. In children, asthma is another common cause because asthma inflames the airways. A nonproductive cough can also happen if we inhale anything that irritates our airways, such as dust, smoke, or a noxious gas.

If a cough is from asthma, we have several medicines to treat that, such as inhaled albuterol. If it’s not asthma, specific treatment is more difficult. There are dozens of products sold over-the-counter as remedies for cough. None of them do much to help it, although they may soothe the back of the throat. The things many of them contain cause unwanted side effects in small children, so most doctors recommend not using them, as does the American Academy of Pediatrics. The last thing we want in a medication for children is something that does not help the situation and may actually cause harm.

We have medicines that really do suppress cough. They do not work on the airway; rather, they work on the brain itself to suppress the cough reflex. Codeine, a narcotic, is the one most commonly used, but there are others. We rarely use these medicines in children, especially small children, because they have significant side effects, primarily drowsiness and altered mental state. Additionally, if a cough is being caused by excess mucous or other material in the airway, we can make the situation worse by blocking the child’s ability to clear the stuff out.

What causes nausea and vomiting?

June 18, 2010  |  General  |  5 Comments

Here’s another excerpt from my new book, How Your Child Heals. It’s from the chapter on symptoms, and it’s about what causes nausea and vomiting.

Most of us are familiar with nausea, that queasy feeling experience has taught us may soon be followed by vomiting. When that happens, we begin to feel a quiver at the base of our tongue and in the back of our throat. At this point we may be able to suppress the feeling enough to keep from vomiting by swallowing a few times or taking some deep breaths. If none of that works, we soon toss whatever is inside our stomach out through our mouths, after which the nausea is typically improved, at least for a short time. If there is nothing in our stomachs, we may still go through the vomiting reflex–the dry heaves.

Vomiting differs from mere spitting up, what parents of a baby often call a wet burp. Vomiting is a very forceful act involving contraction of powerful muscles in the stomach and abdomen. When a baby spits up it is because the muscular tissue at the junction between her stomach and the lower part of her esophagus is too lax to keep the food inside. We call that regurgitation or reflux of stomach contents. An older child or adult with heartburn is experiencing a version of the same thing, only usually the stomach contents do not make it all the way up into the mouth. Spitting up is simply a local event in the lower esophagus, with the stomach contents running back up the wrong way for a moment. In contrast, vomiting is a complex reflex in which several parts of the brain and the digestive system need to communicate with each other and coordinate what they are doing.

Both nausea and vomiting are controlled by a place in the lower part of the brain in the region we call the brain stem. Regulatory centers for many of our basic reflexes, like the one that keeps us breathing, are located nearby. This fact tells us that vomiting is an ancient and primitive reflex that has been with us for a very long time. Doctors are notorious for devising esoteric and fancy names for anatomic places, but this spot in the brain is called by a very practical term–the vomiting center.

Many things can awaken the vomiting center and cause it to do its job. Signals from the higher centers in the brain where we do our thinking can do it. Anyone who has had a queasy thought after seeing something distasteful can attest to this connection. The links between the vomiting center and the parts of the brain that regulate balance are especially close, which is why a ride in a roller coaster or a bumpy airplane can make you throw up. The vomiting center also is sensitive to mechanical pressure on it, so vomiting is a common symptom when people have increased pressure inside their brain.

The vomiting center also quickly responds to a whole host of things it detects in the bloodstream. Many medications have nausea and vomiting as a side effect. This is a particular problem with some of the drugs we use to treat cancer. We even have drugs we can give to provoke vomiting as their intended effect. Changes in the body’s hormones, such as occurs with pregnancy, can activate the center. The majority of woman will have at least some problems with nausea and vomiting when they are pregnant, especially during the early months.

For a parent with a sick child, the most important things that tickle the vomiting center are those that happen in the digestive tract, since many disorders of the stomach and intestines lead to vomiting. There are nerves located throughout the digestive tract, especially in the upper portions of it, which run back to the vomiting center. These even begin in the mouth, which is why a person who gags when the back of the throat is touched may quickly vomit. For some people, even brushing their teeth can bring this on if they are not careful.

For the stomach and small intestines, any inflammation there sends messages back up the neural network to the vomiting center. If the signals are strong enough, the person will vomit. For children, the most common cause of this is a viral infection, the stomach flu. Intestinal nerves are especially sensitive to stretching. This also applies to the nerves that control nausea and vomiting, so a digestive tract that is stretched full of air and food that is not going anywhere can do more than hurt; it is also primed for the vomiting reflex. We know this is so because, in such a situation, often the simple technique of slipping a tube down into the stagnant lake of stuff in the stomach and upper intestines and sucking it back out will relieve a person’s nausea and vomiting.

The vomiting act itself, though it happens quickly, is an intricate series of events. When the vomiting center sends out the go signal, the stomach muscles first relax, halting any further movement of its contents. The next stage is what is properly called retching, which is several sharp, jerky spasms of the muscles in the chest and of the diaphragm, the powerful muscle sheet that spans the floor of the chest and separates the heart and lungs from the stomach, intestines, and other organs in the abdomen. Part of the retching reflex is to close the vocal cords tightly together. Then comes the actual vomiting. The abdominal muscles squeeze the stomach, the esophagus opens, and whatever is in the stomach comes back out. The vocal cords stay shut, preventing any of the vomited material from getting into the lungs. This is an important protective reflex; when it does not function, stomach contents with all their acid can cause serious injury to the lungs.

We know a lot about what things trigger the vomiting center and how they do it. The particular molecular signals themselves are even known. This information has allowed researchers to fashion drugs that block these signals. These drugs are most effective for the vomiting caused by extremely powerful signals to the vomiting center, such as those that come from cancer treatment drugs. A drug called ondansetron (brand-named Zofran) is an example.

Most parents deal with vomiting children in the context of the stomach flu. For these children, whose vomiting is less severe, doctors generally do not recommend using any of the drugs that suppress the vomiting center. There are several good reasons for this recommendation. The anti-vomiting drugs work on the brain by blocking the action of several molecules that brain cells use to talk to one another, called neurotransmitters. The drugs target neurotransmitters that are particularly abundant in the vomiting center. But these neurotransmitters work elsewhere in the brain, too, and blocking them can cause unwanted side effects, especially in children. There are exceptions to everything in medicine, but since the vomiting from stomach flu is not severe and passes in a day or so, the risk of side effects from these medications generally outweighs the potential benefit of using them.

Is vomiting of any use, and does it help healing when your child is sick? Certainly it is helpful for the body to have a way to get unwanted and toxic material quickly out of the digestive system, and vomiting accomplishes that. Nausea seems a useful thing to have, too, as a way of notifying us to get ready because vomiting is likely to follow.

Until recently doctors deliberately provoked vomiting in children who had eaten something potentially dangerous, and we advised parents to keep ipecac, a drug that does this, handy for such an occasion. We no longer recommend this because the risk of all the retching and throwing up outweighs any benefit of bringing it on. For parents, it is logical to regard vomiting as a natural reflex that may be doing some good in spite of the brief misery it can cause a child. Because the drugs that either block or provoke vomiting can have significant side effects, in nearly all situations it is best to let nature decide when she is going to make use of the reflex.

What causes fever?

June 11, 2010  |  General  |  No Comments

Here is another excerpt from my upcoming book, How Your Child Heals. It’s about fever, from the chapter about symptoms and signs.

Fever means an abnormal elevation of body temperature. But what is abnormal? Most of us have heard or read that “normal” is 98.6 degrees Fahrenheit, which is 37 degrees centigrade. In fact, normal temperature varies throughout the day. It is as much as one degree lower in the morning than in the afternoon, and exertion of any kind raises it. Where you measure it also matters. Internal temperature, such as taken on a child with a rectal thermometer, is usually a degree or so higher than a simultaneous measurement taken in the mouth or under the arm pit.

There is also a range of what is normal for each individual — not all people are the same. So what is a fever in me may not be a fever in you. As a practical matter, most doctors stay clear of this controversy by choosing a number to label as fever that is high enough so this individual variability does not matter. Most choose a value of 100.4 degrees Fahrenheit, or 38 degrees centigrade, as the definition of fever. It is not a perfect answer, but it is a number that has stood the test of time in practice.

We maintain our normal body temperature in several ways. Chief among them is our blood circulation. Heat radiates from our body surface, so by directing blood toward or away from our skin we can unload or conserve heat. We can also control body temperature by sweating — evaporation of sweat cools us down. We know how important a mechanism this is because the rare person who cannot sweat, or who is taking a medicine that interferes with sweating, has trouble keeping his body temperature regulated when he gets sick. If a swing in blood flow inwards to raise temperature happens very fast, we respond by shivering. This is also why we shiver if we go outside without a coat in the winter; our bodies are redirecting blood flow from our skin to our core in order to maintain temperature.

All parents know that a common cause of fever in children is infection. A more precise way to think about it is that a common cause of fever is actually inflammation. Since in children infection is the most common cause of inflammation, we generally assume a child with a fever has an infection somewhere in her body unless we can prove otherwise.

Our brains have a kind of thermostat built into them. Like the thermostat in a house, it senses the temperature of the blood passing by it and uses a series of controlling valves in the blood circulation to fine-tune the temperature. Also like your house thermostat, it continues to sense the temperature, and adjust it as necessary, until it has reached the value for which the thermostat is set. Fever happens when the thermostat is reset, just as happens when you twist the dial on the wall for your furnace — the body reacts to bring itself to the new setting. What twists the knob on the brain’s thermostat to cause fever are substances in the blood.

These fever-inducing substances belong to a family of inflammatory molecules that are released from body cells. Mostly they come from a cell called a macrophage, but germs themselves can also release things that have the same effect. The sudden rises and falls a parent often sees in their child’s temperature when they have an infection reflect the usually brief time these substances are in the blood. Sustained fever for many hours can happen if these materials are steadily present.

Opinions vary among doctors about when fever needs treatment. Fever itself virtually never causes harm on its own. The only times it can do harm is when it gets very, very high — 106 degrees or more — for a sustained period. That only happens in highly unusual situations; ordinary childhood infections never get it that high. It is true fever can make a child uncomfortable, although children generally tolerate it much better than adults. For that reason alone many doctors advise treatment.

There is another reason to treat fever. Toddlers may experience brief convulsions – seizures — when their body temperature rises very fast. These so-called febrile seizures cause no harm to the brain itself, and often run in families, but fever treatment makes good sense for a child who has had them in the past.

We have two effective drugs to treat fever — acetaminophen (Tylenol) and ibuprofen (Motrin). Both work the same way: they reset the brain thermostat back down to a lower lever. Both only last a few of hours or so in their effect, which is why you will see your child’s fever go back up again when they wear off if there are still any of those fever-causing substances from the inflamed site still in the circulation.

How can we treat pain?

June 4, 2010  |  General  |  No Comments

In a previous post I wrote about what causes pain. In this one I’ll write a little about how we can treat it.

We have two main approaches for treating pain: we can do things that reduce the pain signals coming from the spot that hurts, or we can use medications that confuse the brain into thinking the pain is either not there or is not so bad.

There are several simple things we can do to reduce the pain signals coming up the nerve fibers. A simple one has been known to parents for eons — simple rubbing of a painful spot. Stimulating one set of nerve fibers, particularly the fast, insulated ones, affects how our brain processes sensations. Every parent knows how to do this, although you probably did not know why it works. When your child comes running to you after falling down and bonking her head, what do you do? Generally you rub it, and it really does feel better. This is not just from parental love. Stimulating the touch fibers in the same place where the pain is coming from causes them to intervene and dampen back the pain signal coming from the other fibers. The same thing happens when we rub any body part after we hit it on something.

Cooling the area with an ice pack is another way to reduce the pain signals coming up the nerve network. Yet another is to put a medicine that interferes with how the nerves work right on the painful spot. Examples of this approach include ear drops that can numb the ear drum for a child with an infection or numbing sprays and ointments for a child with sunburn. A dentist injecting a painkiller around a sore tooth is using a more powerful version of these same methods.

The other way to treat pain is to use medications that act directly on the nervous system to alter how the brain reacts to the signals coming up from the painful place. They convince the brain to downplay or even ignore the information. This is how both acetaminophen (Tylenol and many other brands) and ibuprofen (Motrin and many other brands) work. Ibuprofen also relieves pain in another way that acetaminophen does not; ibuprofen can work directly at the site, such as the inflamed finger or ear, to block the production of some of those substances that cause the inflammation. We also have an injectable medication related to ibuprofen, only more potent, called ketorolac (brand-named Toradol).

More severe pain, such as from a broken arm, calls for medications more powerful than Tylenol or Motrin. Members of the opiate family, also called narcotics, are the standard. There are many members of this family, which vary in how they are given, their appropriate dose, and some of their side-effects, but they all work in the same way: they go to the brain and the spinal cord and alter a person’s perception of the pain. They also can alter mood and a person’s level of awareness to things around them. A common oral narcotic used for children is codeine; a common injectable one is morphine.

Even though we give narcotic medications for severe pain, a fascinating thing about them is that they are not really foreign to the body at all. We have similar substances that occur naturally in our body, and presumably these natural narcotics, called endorphins, are performing some useful function inside us, most likely involving pain control. So when we give a child with more severe pain, such as a broken leg, a medication of this type we are really just reinforcing a normal pathway. The presence of these natural substances could explain why some persons, an Indian Yogi for example, can walk across a bed of hot coals without pain because he has learned how to alter his brain’s perception of what is painful.

Pain, uncomfortable as it is, does serve some useful purpose, and in that sense helps a child heal. Pain alerts us that something is wrong and tells us we should try to do something about it. If we cannot feel the pain, worse injury often results. A good example of this is what happens when a person lacks sensation in an arm or a leg. Because he cannot feel there, painful things, such as an ill-fitting shoe, can go unnoticed and lead to injury.

But pain can also interfere with healing. Mild or moderate pain does not seem to affect healing much, but more severe pain, if it persists, can interfere with it. This stems from the effects of what we call stress hormones, substances like adrenaline, which the body releases at times of stress. They are called “fight or flight” hormones because they probably helped our ancient ancestors deal with things like a wild animal attack. Although they can help in times of acute danger, prolonged high levels of these hormones, such as occurs with continuing severe pain, do inhibit proper healing. Researchers have studied this phenomenon in children who have had major surgery, and it is clear that using pain-killers does not just make the children feel better — it also makes them heal better.

What is pain, anyway?

May 28, 2010  |  General  |  No Comments

My next book, due out in mid-July, is about healing. Important to understanding healing is understanding the symptom of pain. What follows is an excerpt from my book that talks about this universal symptom – what it is and why it is.

Pain, in all its varieties and subtleties, is among the most complex of human symptoms. It has been described in uncounted ways by writers and portrayed by actors, but we read or view these characterizations through the lens of the pains we ourselves have had. Even though we all have felt pain, and in that sense have shared the experience with all other humans, it is also unique to us. Pain is both universal and profoundly personal. It’s a complicated subject.

Pain is not limited to humans, of course. All mammals certainly feel pain. Some aspects of the pain response reach far down below mammals in the animal kingdom to quite primitive creatures. How these creatures perceive it, if that is even the right word, is mysterious, but this observation tells us pain has been with us for many eons. That fact alone should tell us it must serve some important purpose.

All of us know that pain comes in many forms. There is the sharp pain from stepping on a tack. There is the vague, dull aching of a twisted knee, the cramping pain in the lower abdomen that comes with the flu, the pounding inside the skull of a migraine headache, the gnawing pain of a toothache. There is the restless pain that persists in spite of what positions you take, as well as the pain that only relents when you lie completely still. All of us could think of many more examples.

Pain is reported to the brain via a dense network of nerve fibers. Think of this network as an intricate grid of electrical wires, because that is what nerve signals are made of — electricity. These wires are of several kinds, but there are two principal ones. They differ in how well insulated they are. Instead of the plastic insulation that protects electrical wires, the body uses a substance called myelin to insulate the neural wiring. Some wires are more tightly wrapped with myelin than are others. Some nerve fibers have no myelin at all. The more wrapping, the faster the electrical signal travels, so myelinated fibers transmit signals faster than those without myelin.

The nervous system uses a series of switching stations to pass a signal from, for example, the end of your finger to your brain. The first of these are in the spinal cord. When you prick your finger, an electrical signal goes from a nerve fiber there, up your arm, and on to a relay station in the spinal cord in your neck. From there, it continues on up your spinal cord to your brain. What happens to it when it reaches your there is fascinating — and complicated.

Pain is a subjective feeling, meaning no one besides yourself can know precisely how you are feeling it. This means no two people will experience pain in the same way; the exact same finger prick may be perceived quite differently by two different people. An injured person can even be initially unaware of his injury because he does not feel it at first. Probably you have experienced the situation in which, distracted by something else, you did not feel a stubbed toe or a bug bite to the same extent you would have if your mind were not focused on something else.

This variability in how pain is perceived, of the discomfort it causes us, is because the simple electrical signal running up your finger from that needle prick gets modulated by a maze of other nerve cells in the spinal cord and in the brain. Some of these influences dampen down the signal, others ramp it up. The result is when it finally gets to your upper brain, where your consciousness lies, all sorts of things have affected the signal, things that are unique to you and your brain.

You have several kinds of nerve fibers in your finger. The ones that transmit the fastest signals, the heavily myelinated ones, mostly are concerned with light touch and position sense, which is knowing where your finger is in space. This makes sense, because these bits of information are things the brain needs to learn as rapidly as possible. If you want to demonstrate this for yourself, close your eyes, open your mouth, and rapidly stick your finger in your mouth. You can do this without poking yourself in the eye because your brain knows, every millisecond, just where your finger is in space in relation to your mouth. These nerves are also involved in the pain response, particularly in blocking some of its input in the spinal cord. When they do not work, the perceived pain from a pricked finger is worse.

The nerve fibers in your finger that transmit pain signals, the ones with less or no myelin insulation, can sense three kinds of things: mechanical forces like hard pressure, hot and cold, and chemical substances. If you pay attention when you whack your finger with a hammer, hard as that may be to do, you can distinguish between them in action. You first feel a very sharp, very localized pain. This is a signal from the insulated fibers, which gets to your brain first. An instant later you begin to feel a more diffuse, deeper pain that is less well localized to the precise spot. This is input from the slower fibers with no myelin.

Another way we experience the difference between fast and slow fibers is when we bark our shins on a piece of furniture when walking in the dark. We first feel our leg hit the furniture — those are the insulated touch and position sense fibers at work. After a perceptible lag, we feel like yowling in pain — those are the uninsulated pain fibers catching up with their messages.

I’ll put up another post about what things we can use to treat pain and how they work.