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[Dr. Shapiro] This is Dr. Samantha Shapiro, executive editor of Harrison's Principles of Internal Medicine. Harrison's Podclass is brought to you by McGraw Hill's AccessMedicine, the online medical resource that delivers the latest trusted content from the best minds in medicine. And now, onto the episode.
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[Dr. Handy] Hi, everyone. Welcome back to Harrison's Podclass. We're your co-hosts. I'm Dr. Cathy Handy.
[Dr. Wiener] And I'm Dr. Charlie Wiener, and we're joining you from the Johns Hopkins School of Medicine.
[Dr. Handy] Welcome to episode 102, a 54-year-old with muscle soreness, and we are thrilled to welcome back Dr. Langford to discuss our case today.
[Dr. Wiener] Great because today's case is common and a vexing problem for many outpatient physicians.
[Dr. Handy] Alright, let's hear about it, Charlie.
[Dr. Wiener] So, you are seeing your long-term patient in the clinic, he's 54 years old and he has a history of coronary artery disease and he's had an anterolateral myocardial infarction about a year ago. At that time, he was started on simvastatin, aspirin, metoprolol, and lisinopril. About two months ago, he started noting thigh and shoulder soreness. One month ago, he saw you because his muscle pain increased and he was noticing some possible weakness. You found that his CK level was elevated to eight times the upper limit of normal and you discontinued the simvastatin. Today, he reports that his pain has continued and if anything, it is worse than a month ago. His CK is now 12 times the upper limit of normal. So the question is going to ask, which of the following is the next best test to establish a diagnosis? And the options are, A. an antibody against 3-hydroxy-3-methylglutaryl coenzyme A reductase, or HMGCR; option B. is the antinuclear antibody; C. is the anti-Jo-1 antibody; D. is the antibody against signal recognition particle or SRP; or option E. is aldolase levels.
[Dr. Handy] Well, it sounds like you were initially thinking that this was a mild statin-induced myopathy, but that would be expected to resolve with discontinuation of the statin, but in this case, it sounds like it did not.
[Dr. Wiener] So does that exclude statins as the culprit?
[Dr. Handy] Well, not necessarily. In rare patients, muscle weakness continues to progress even after the statin is withdrawn. In these cases, a diagnostic muscle biopsy is indicated and a search for antibodies against HMGCR is suggested. If histologic evidence of polymyositis or necrotizing myositis is present, then immunotherapy would be initiated.
[Dr. Wiener] So the answer is A., antibody against HMGCR. What about the other choices?
[Dr. Handy] So ANA antibodies may be present, but they're non-specific in these cases. Anti-Jo-1 antibodies are associated with the antisynthetase syndromes where myositis is usually accompanied by interstitial lung disease and stereotypical skin changes, and anti-SRP antibodies are not associated with statin-induced myopathy.
[Dr. Wiener] Great. Well, let's explore this issue more deeply with Dr. Langford. Dr. Langford, what is your approach to patients with muscle aches that are receiving statins?
[Dr. Langford] When we think about muscle problems related with statins, we need to recognize that there can be many different aspects to this, which really include myalgias, myopathy, myositis, myonecrosis, all the way up to full rhabdomyolysis, and how we think about these will vary in terms of what are we seeing clinically in terms of pain and weakness and what are the levels that we're seeing as far as muscle injury?
[Dr. Handy] So what's your approach to patients with myositis?
[Dr. Langford] So when we encounter a patient with myositis, one of the things we see is that there are a variety of different diagnoses that are within this category, some of which have really been very recently described, you know, included in this would be entities such as dermatomyositis, polymyositis, the antisynthetase syndrome, inclusion body myositis, and then the immune-mediated necrotizing myopathy, which is where this particular case comes under concern. How we think about this is that we always want to approach the patient in trying to understand, is there something that is immediately threatening to organ function or life. And we would assess this in terms of thinking about not only the muscles that can be affected peripherally, but also other muscle groups, such as the diaphragm, muscles of swallowing, and the heart, and then we also look at end-organ damage, such can occur with the kidney in terms of myoglobin-related injury. When this is present, we may need to consider as far as hospitalization for urgent assessment to be able to determine what's going on and to be able to initiate management. Included in that would be different types of testing in terms of the laboratory parameters, evaluation as far as swallowing and breathing function, and then we would be looking at more detailed testing to try and understand the extent of the injury in terms of studies such as EMG, potentially MRI of the thighs, and muscle biopsy to determine the type of myositis that may be present.
[Dr. Wiener] Dr. Langford, in a patient in who you've established has myositis, how are they generally treated?
[Dr. Langford] So glucocorticoids initially would be used for most forms of myositis. Beyond that, there have been a range of other treatments. Most recently, the FDA has approved the use of intravenous immunoglobulin for the treatment of dermatomyositis, and there are also a range of other immunosuppressive therapies that would be used. These would be based upon the type of myositis that's present, the degree of severity, and again, really working in a multidisciplinary manner to determine that can be very helpful and important.
[Dr. Wiener] Great. Well, thanks again, and we really appreciate you joining us. So the teaching points in this case are that statin myopathy is a real phenomenon that exists on the spectrum from just aches and pains to full-blown rhabdomyolysis. The diagnosis of myositis requires a multi-D approach and treatments are evolving quickly, and oftentimes, consultation with your experts, is again, the best advice for these kinds of patients.
[Dr. Handy] And you can read more about this in the chapter on muscular dystrophies and other muscle diseases.
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[Dr. Shapiro] Thanks for listening to Harrison's Podclass. You can listen to this episode and more on AccessMedicine.com, which includes the complete Harrison's Principles of Internal Medicine text, Harrison's review questions, which complement and expand upon the questions in this episode, and much more. AccessMedicine.com may already be available to you via your academic institution. Check it out.
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