Treatment and Outcomes in Juvenile Myositis

With age many patients with JDM get better and go into remission. We have much less information about JPM since it is much rarer. My suspicion, based on my patients, is that JPM is the same as polymyositis that develops in a younger age – and therefore behaves just like polymyositis with aging.

It depends. If your daughter is in remission and no longer on any medications, then the chance of recurrence is low, and gets lower the longer she has been on remission. We found in our studies a very small proportion of patients who were able to be off medications later had a recurrence.

I recommend that all my patients with JM get influenza vaccination every year. This has been better studied in children with arthritis, and the vaccine in those children is safe and effective. For those children with JM that are still on medications, it is best to avoid influenza if at all possible, and the vaccine is a good way to do that.

There are many reasons for stomach pains to develop if you have JM, especially if you are on medications. JDM can have direct effects on the stomach and intestines when it is active – in this case the bowels are sometimes affected with constipation, diarrhea, or blood in the stools. Many of the medications that we use to treat JM also can cause stomach pains (in some patients, fortunately not in most). This is best checked out by your doctor to see why stomach pains are occurring and to see how best to treat them.

If the calcinosis is painful or troubling it can often be successfully removed surgically without recurrence. In the ‘old days’, when JDM was treated less completely, removing calcinosis while the disease was still active sometimes led to reappearance. Now, with more complete treatment of active JDM, my patients have had much more luck with surgical removal.

The key, in your situation, is for there to be a good working relationship between your paediatrician and your paediatric rheumatologist. If they are communicating well, and frequently, then much of your child’s care can be done locally. Most paediatricians see very few children with myositis (or none at all) and feel inadequate when treating these children, unless they have the help of a dedicated specialist.

The situation regarding IVIG varies in different parts of the world. In Canada, where I’m from, I am able to get IVIG for my patients without restriction. However, there have been no clinical trials in children establishing the benefit of IVIG (we just published an interesting study this year that I think proves IVIG’s benefit, but it is not the type of clinical trial usually required by regulators, or by insurance companies, to grant coverage). Some insurance companies may not provide coverage because of the lack of formal clinical trials.

We don’t have strong information about vitamin D levels and susceptibility to myositis. Many of my patients, though, become vitamin D deficient while on treatment – partly because they are wearing sunscreen all the time. We supplement routinely here to protect our patients’ bones.

Prednisone is one of the best medications for JM, but almost always is associated with troubling side effects. For that reason, all of my patients are also started on methotrexate (and sometimes also IVIG) so that we don’t need to use prednisone for a long period of time. In order to protect the bones from some of the prednisone side effects, I prescribe vitamin D and supplemental calcium. All of my patients are coached to follow a low sodium, low calorie “prednisone diet”.

If your paediatric rheumatologist has determined that there is no longer any active myositis, and that there is no other medical reason for exhaustion and weakness, then a graded program of physical exercise (ideally prescribed by a physiotherapist experienced in myositis care) can work wonders to improve sleep, decrease fatigue, and improve strength. Some children who no longer need medications, still have muscle atrophy (thin muscles) with fat replacement when we check them with MRI. Those children, especially, need a good exercise program.

Some rheumatologists use intravenous forms of prednisone – especially early on in the course of myositis – because some myositis patients don’t absorb oral prednisone all that well from their stomach and intestines. With time that improves in my experience. For most patients, over time, it probably doesn’t make much difference (we studied the differences after 3 years, and couldn’t find any) – but in our study the most severe patients were all treated with intravenous forms of prednisone, so we didn’t have any matches to compare them with. For that reason, for mildly, or moderately ill patients I start with oral prednisone, and only use intravenous forms if I suspect that there is a problem with medicine absorption from the stomach and intestines. For very severe patients, many rheumatologists will start with intravenous forms of prednisone.

There weren’t enough children in the rituximab study to be definitive (in my opinion). Almost all of the children in the study improved by the end of it, but the response was not as quick as anticipated. We are finding out with other diseases (like rheumatoid arthritis) that rituximab may take several months before it is effective. It may be that rituximab is effective in JM, but that it takes a long time to show an effect.

I am not aware of studies of pregnancies in women who are in remission from JM. In my opinion the JM will not have an effect on her children, and it is very unlikely – at this point – that having children will cause your daughter to have a flare of her JM.

In my experience, exercise does not cause JM to flare, rather it is beneficial. There has been a limited amount of scientific study in children, and more in adults, that supports the safety of exercise, even while the myositis is active. I would say – go for it.

Dr. Pachman’s group in Chicago found that many children develop the symptoms of JM around the time of an infection. In Toronto, we confirmed those findings in another study. It is really hard to know – for sure – the role of infection in causing JM. Children get the flu and other infections all the time, so our findings may be the result of coincidences. However, I feel that susceptible children (that is, those with ‘twitchy’ immune systems) may react to infections, and perhaps other stimuli, by developing JM.

It is hard to know why some children gain more weight with prednisone than others, and it has not been thoroughly studied. In our clinic, though, children who are strict with their diet are able to control their weight gain to a greater degree. I would suggest checking with a dietician to make sure that your daughter’s diet plan is healthy. It is also important not to over-do it. Some children have developed anorexia nervosa at the same time as going on prednisone; while it is impossible to know for sure, it is possible that obsessing over weight gain from prednisone led to the anorexia.

This is a tricky question, asked often by parents. Since MMR booster (and other vaccines) are almost universally given, it will happen – purely by bad luck and coincidence – that some children will start their JM very close in time to a vaccine. Dr. Lisa Rider has been studying this relationship between vaccines and myositis in Washington at the NIH. So far as I know, there have not been definitive conclusions from this study yet.

None of my JM patients have had as bad itch as you are describing. Topical corticosteroid creams may reduce inflammation and itch. I think that it would be a good idea to see a paediatric dermatologist to see if there is a good treatment for your daughter, and to make sure that the itch is from JM and not something else. (That is what we would do here.)

We studied arthritis in JM. Almost 2/3 of our patients have arthritis (inflammation of the joints) at some point in their disease. If it is arthritis that is causing your daughter’s joint pains, then the treatments she is getting should settle it down. Another cause of joint pain that we worry about is the result of a side effect of prednisone. Some children react to prednisone by cutting off the blood supply to some of the bones around some of their joints. This can be diagnosed by a bone scan, MRI, or sometimes even by a regular Xray. This type of joint pain does not respond to usual medications and it is often necessary to see an orthopaedic specialist for advice. Of course, there are many other causes of joint pain, and children with JM can get them the same as any other children. Your daughter’s joint pain should be discussed with you paediatric rheumatologist at your next visit so that she can be checked for all these different causes.

In the field of rheumatology the last 15 years have been an exciting time of new medication discovery. Biologic and other molecules targeting specific problems in the immune system have led to much more effective and safer treatments. This has not really paid off yet for myositis. I suspect that over the next few years, myositis patients will get new medications, similar to the ones that are now available for arthritis, that will be safe and highly effective – but I don’t think we know which ones they will be yet.