Your Epidermis is showing!

We probably all fell for that joke as kids, but all joking aside, some of the terms used in medicine can be tricky to understand. Medicine is a foreign language that must be learned as if you were learning Spanish or French. Dermatology seems to be a branch of medicine that has unfamiliar or confusing terminology. I would like to address different skin conditions that can manifest in the feet and how they vary. But before we discuss them, I think it would be beneficial to review the components of skin.

The outermost layer of the skin is called the epidermis (0.04 mm thick). There is no blood supply to it and there are no nerves within it. This layer protects your muscles and internal organs from the external environment, and can be considered part of the immune system. The epidermis can be broken down into 5 different layers. One of these layers is responsible for cell division, which replaces the dead skin that falls off.

A different layer contains melanocytes which are responsible for skin color. Another layer contains cells that are “sown” tightly together to prevent passage of foreign elements. Yet another layer secretes a fatty substance that acts a barrier to water and other harmful substances. This is a very robust barrier that is tough to cross, which is why you don’t do not swell up with water when you go swimming!

Maybe you have heard that anything you put on your skin (lotions, make-up, etc.) gets into your blood. But when we remember that there are no arteries in the epidermis, that a layer of cells are tightly packed together, and that a substance must pass the fatty barrier to reach our blood, you can be assured that almost nothing gets across. Only harsh chemicals in highly concentrated amounts should cause you to worry.

The middle layer of the skin is called the dermis (0.5 mm thick). This layer contains blood vessels, nerves, glands, and hair follicles. Collagen and elastin give structural strength to the dermis. Depending on the area of the body, the skin will have different glands that secrete either a smelly substance (armpits, groin), a watery substance (palms of hands, soles of feet), or an oily substance (causes acne).

The last layer of the skin is called the hypodermis or subcutaneous tissue. This layer is made up of fat cells and allows the skin to slide without friction over the underlying muscle and bone.
Each of these layers (or structures within a layer) can be struck with disease. We will discuss common foot dermatologic conditions in our next series of posts.

Give Me the Antibiotics and No One Gets Hurt

Historically, the first antibiotic discovered was penicillin. Although it was discovered several years before World War II, it was not widely manufactured and distributed until the war. This antibiotic has advanced into an entire family of antibiotic drugs to treat different types of bacteria. Previously untreatable staph and strep bacterial infections have become manageable conditions. The discovery and use of antibiotics has without a doubt saved millions of lives. Amoxicillin and Erythromycin are examples of antibiotics currently in use.

So, if antibiotics are so great, why is it that doctors often send people away without them? What purpose would it serve to keep them from their patients?

Just as the name infers, antibiotics are anti-bacterial. However, a sore throat or stomach sickness is often caused by a virus. A runny nose or sinus congestion can be caused by an allergic reaction. Foot infections are commonly caused by fungus. In these situations, what purpose would it serve to give an antibiotic? I hope it is clear that giving an antibiotic to kill a virus, fungus, or solve allergies is similar to using weed killer to kill cockroaches.

To make matters worse, misusing antibiotics can actually cause them to lose effectiveness when they are really needed. Bacteria are very smart little organisms. They are constantly changing so that they can better survive. We all have “normal flora,” otherwise known as bacteria that live in our intestines, on our skin, and in our mouth. However, these bacteria are kept in check by our immune system and by our protective layers of mucous and skin. By taking antibiotics when not indicated, we expose these bacteria to antibiotics. Instead of fighting the source of infection, some bacteria die but others are allowed the opportunity to develop protection against the antibiotics. So when you get a deep cut on your foot and those same bacteria are allowed to penetrate your body, the antibiotics may not be effective. For this reason, it is important to save the antibiotics we currently have for when they are truly needed. Your doctor is your best resource for knowing when they are to be used.

Nerves do pain, and more…

Ok, I know I said last week that we’re going to talk about a devastating foot condition caused by peripheral neuropathy this week, but I wanted to touch on another aspect of nerve dysfunction before we delve into it. So stay tuned….

We talked last week about high blood sugar in association with diabetes and how it damages the function of nerves. Specifically, we focused on how nerves lose the ability to sense pain. But nerves do a lot more than just sense pain.

Nerves are so smart that many of them function without us even knowing. Do you have to remember to keep your heart beating, or to keep your lungs breathing when you are asleep? Of course not! That is because nerves have an “autonomic” function (think of it as a nerve working automatically, without you needing to tell it to work). That is why you do not need to think about your heart beating or your lungs inflating. For this same reason, we do not have to think about digesting the food we eat, or moving the food through our digestive tract. It just happens.
Another important autonomic function of a nerve is its ability to control where the majority of our blood flows. During a marathon, blood is most needed in the muscles, heart and lungs. After a meal, blood is needed in the digestive tract to absorb essential nutrients. During an academic exam, the brain needs blood more than anywhere else. When you’re about to have sex… well… you get the picture. Depending on current needs, our body can shift blood flow so that it is used more efficiently. Just like losing pain sensation, high blood sugar can damage nerves so that they can’t perform their “autonomic” tasks.

Instead of food slowly but surely travelling through the intestines, it sits motionless in the stomach. Instead of bones getting the correct amount of blood flow, they are flooded with blood, making them soft and unable to handle the normal stresses of our weight. As nerve function continues to decrease, symptoms become worse and worse.
With that introduction, next week’s blog will focus on Charcot foot, a condition being seen more and more as diabetes spreads.

Charcot Foot (pronounced shar-co foot)

Our discussion regarding nerve dysfunction has culminated into this week’s topic. We’ve learned that loss of pain sensation and loss of autonomic (or automatic) function of nerves can be caused by diabetes. What happens if you lose both?

When nerves lose their autonomic ability to control blood flow to the bones in the foot, the excess blood makes the bones soft and unable to support weight. The minerals that keep bone strong are washed out and therefore, the bones become very weak. They cannot withstand the pressure that comes with walking around the house to do daily tasks. These patients tend to be overweight which only adds to the stress on the bone. The bones become deformed and the foot becomes unfunctional. This deformity is termed Charcot Foot.

As if that wasn’t bad enough, the people susceptible to Charcot foot are the same people who have lost their protective pain sensation. Even though their bones are being crushed and deformed with walking, they don’t feel a thing. For this reason, it may be weeks before the individual notices the bony bumps on their foot, and goes to see their podiatrist.

Charcot foot develops in stages. Initially, the foot will look swollen, red, and hot, but yet painless. This can be confusing because these symptoms are seen in other conditions like gout, osteomyelitis, and cellulitis, so it is important to seek attention immediately to make the correct diagnosis. If Charcot foot is diagnosed, it is imperative that you follow your podiatrist’s order to be non-weight bearing in a cast for a couple months. This spares the soft bones from being deformed. After the redness and swelling diminish, your bones begin to recover, and eventually they heal. If the patient has been dedicated to keeping weight off the foot, the deformity will be minimized, the patient can be fitted for a boot or shoes that will accommodate any bony protuberances, and reconstructive surgery can be avoided. If the patient has not been as compliant, the foot may no longer be functional and it will be at greater risk for friction ulcers forming where bone protrudes. Surgery will be needed to reverse the deformity, and foot functionality afterward is difficult to predict.

So what is the moral of the story? Nerve function is essential to healthy feet. You can minimize nerve damage by tightly controlling blood sugar. Keep an eye on those precious feet you have. Rub them and talk to them daily. If they look bad, but it doesn’t hurt, you know what to do. Your podiatrist will be waiting.