From Arthritis to Zoster

Like love, arthritis is a many-splendored thing. There are dozens of different kinds of arthritis, all with one common property: inflammation in one or more joints (see my previous post). Over time, that inflammation leads to joint damage, and a damaged joint cannot function well.

It might be worthwhile to quickly review the structure of a typical joint. There are different kinds of joints in the human body, but the one most of us are familiar with is the diarthrodial joint. Simply put, this is a joint where the opposing bones are capable of moving in one or more planes. Where the bone ends meet, they are covered with a cushion of cartilage. The joint is lined with a synovial membrane that produces fluid and nutrition, and, in most cases, a tough, fibrous capsule surrounds all of the abovementioned parts. Examples of diarthrodial joints include the knee, elbow, shoulder, hip, wrist, ankle… just about any place in your body where bones meet and you can make them move.

This superficial overview is important, because it helps us to understand what happens when a joint becomes inflamed. Whether the inflammation arises from an infection, an injury, the presence of irritating substances within the joint space, or an immune system gone haywire, all of the structures within and around the joint are affected to some degree. Different kinds of arthritis affect different joints, and the appearance of those joints is often fairly typical for a specific type of arthritis. Hence, someone experienced in evaluating arthritis sufferers can– just by looking at the person’s joints– make a pretty good guess as to which type of arthritis that individual might have. Alas, it is also true that one person can be afflicted with more than one type of arthritis.

Rheumatoid arthritis (RA) offers a classic example of what happens when joints become inflamed. This condition arises when our immune system does something it’s not supposed to do: it recognizes our joint tissues as foreign invaders, and it launches a vigorous campaign to get rid of those tissues. In essence, it’s a case of our immune system trying to reject our own body parts. Confused white cells release substances into the joints that attract other kinds of immune cells that release their own irritating chemicals. These chemicals—and the ongoing activities of the cells that make them—eventually erode the cartilage, cause the synovial membrane to thicken and malfunction, and lead to a loss of stability in the affected joints. No one really knows why this process gets started—some experts believe it is a response to an unidentified infection—but the end result is lots of pain, swelling, and joint deformity. We have all seen people with RA: their hands and feet are bent and gnarled, and involvement of other joints can cause problems with walking, bending and reaching. 

In Western medicine, aside from chasing inflammation with aspirin-like medications, we attempt to dampen the overactive immune response that leads to RA with drugs that suppress the immune system or interfere with the cells (or their chemicals) that cause joint damage. Prednisone is one of the first drugs a person may take when he or she is diagnosed with RA. Methotrexate is another medicine that is sometimes added later. Newer medications, such as Enbrel, can be used early in the course of the disease or later on, depending on how severe the arthritis is. 

One can imagine that drugs designed to suppress the immune response could have adverse effects due to their interference with appropriate immune function. Not surprisingly, all of the abovementioned pharmaceutical agents carry a burden of potentially serious side effects. I often think of a patient I admitted one night when she became extremely short of breath while visiting relatives in the town where I practiced. She had long-standing rheumatoid arthritis, and she had been prescribed methotrexate fairly early in the course of her disease. Unfortunately, she had gone on to develop “methotrexate lung,” a condition characterized by a progressive fibrosis, or scarring, of the lung tissues, accompanied by ever-worsening difficulties with breathing. Between gasps, she told me she had never been informed of the possibility of lung damage when she started the medication, and when she did develop side effects, her physician had said, “Sometimes you just have to choose between your joints and your lungs.”  She swore she would never have taken methotrexate if she had known of its possible side effects.

All I could do was make her as comfortable as possible, and I vividly remember sitting at her bedside, helplessly watching her take her last breaths.          

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