Inclusion Body Myositis (IBM).

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This web page focuses on Sporadic inclusion body myositis (sIBM). This type of IBM occurs spontaneously — it just strikes "out of the blue" and is non-­inherited: it is acquired during one's life. There is usually no one in the family who has the disease other than the patient and it is not passed on to subsequent generations.

Familial IBM (fIBM) refers to rare cases where typical (Sporadic) IBM is seen in two or more patients within a single generation of siblings in a family (it is not passed on to subsequent generations). The symptoms and features of fIBM are very similar to those seen in the sporadic form of IBM. The familial occurrence of such a rare disorder likely highlights the importance of genetic predisposition in the causation of sIBM .

Hereditary inclusion body myopathy (hIBM) refers to a group of very rare inherited disorders; passed on from parents to children. Note that this is called myopathy and its characteristics are different from the myositis forms, but at this point, the myopathy forms are still lumped together with the myositis forms. "The hIBM diseases lack the two main characteristic features of IBM: its distinctive pattern of muscle weakness and the presence of muscle histological immune cell infiltration" (Greenberg, 2019). Greenberg (2019) points out that it is a mistake to think sIBM and hIBM reflect the same pathophysiological process that can either occur sporadically or be inherited: they are separate diseases.

This page is a good starting point for a person interested in sIBM and contains information suitable to take to a family physician. The site provides two levels of information, basic introductions and critical overview articles and also a more complex body of research / medical information, including summaries / reviews of some of the major scientific literature on sIBM.


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Key points:


The common early presentation of weakness is shown in red (below, left).

pattern late

Weakness may develop in the diaphragm and the esophagus (illustrated in orange, above, right).


A recent illustration is helpful (Greenberg, 2019).


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For new patients:


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Summary: Based upon research, no treatment is recognized as effective for sIBM (as of 2019). Based upon their experience and opinions, doctors may try medications with sIBM patients however, this is a clinical judgment where any possible benefits must be weighed against potential side effects.

"Conventional immunotherapies, albeit effective in other forms of myositis, seem to have only a transient or no beneficial effect on disease progression of sIBM. So far, no established evidence-based treatment exists and therapy recommendations are based on expert opinion." From: Update on Treatment of Inclusion Body Myositis

Also see: Schmidt, K., & Schmidt, J. (2017). Inclusion body myositis: Advancements in diagnosis, pathomechanisms, and treatment. Current Opinion in Rheumatology,

Also see: Needham, M., & Mastaglia, F. L. (2016). Sporadic inclusion body myositis: A review of recent clinical advances and current approaches to diagnosis and treatment. Clinical Neurophysiology, 127(3), 1764-1773.

Unfortunately, it would appear that the side effects of all of the current medications far outweigh any benefits seen in sIBM. The best approach is to manage the complications that may arise from the disease. Evaluation of swallowing and respiration are critical, ongoing issues. Prevention of falls is an important consideration.

A cautionary note: There is a strong tendency for both doctors and patients to "want to do something" — anything — to try to slow down or reverse the symptoms of a major debilitating and chronic illness like sIBM. For patients, it can be very frightening and frustrating to simply "do nothing." Caution must be used when no significant benefits of treatment can be demonstrated and when treatments all have significant potential side effects.


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When faced with a progressive disabling disease that has no effective and reliable treatment options, day to day management becomes critically important to avoid complications. Management involves two critical components; awareness and prevention. We need to be aware of the possible consequences of inclusion body myositis and be able to proactively prevent complications. Simple and consistent practices can prevent many of the complications that can threaten one's life.


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Theories of sIBM:


From: Greenberg, S. A. (2016). Inclusion Body Myositis. CONTINUUM: Lifelong Learning in Neurology, 22(21), 1871-1888.


From: Britson, K. A., Yang, S. Y., & Lloyd, T. E. (2018). New Developments in the Genetics of Inclusion Body Myositis. Current Rheumatology Reports, 20(5), 26.


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sIBM Research:

Summary: sIBM is a very complex and challenging disease to research. In approximately the last 40 years of research, much has been learned about the disease, but frustratingly, more remains unknown. The understanding of sIBM and its causes is a very slowly evolving phenomenon.

2017: "For the past two decades, the field of sIBM research has been split with some researchers suggesting that sIBM pathogenesis begins with inflammation leading to myodegeneration and others favouring a primary degenerative myopathy stimulating autoimmunity. Now with emerging therapies aimed at targeting muscle degeneration and other therapies focused on immune modulation, it is essential to understand the connection between these two pathologies. A siloed approach that ignores one or the other will not advance future therapeutics. Instead, additive therapies or dual acting therapies that focus on both aspects of disease pathogenesis will likely need to be employed." From:

2019: "Currently, the evidence suggests that causality flows from autoimmunity to degeneration, not the reverse" (Greenberg, 2019).

Highlighted sIBM Research:

Current sIBM Research:

Past sIBM Research/Other:

Genetics of sIBM:

Classification of sIBM:


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How common is sIBM?


First, it is important to understand some terminology. This Information is from the New York State Department of health.
What is incidence?
Incidence is a measure of disease that allows us to determine a person's probability of being diagnosed with a disease during a given period of time. Therefore, incidence is the number of newly diagnosed cases of a disease. An incidence rate is the number of new cases of a disease divided by the number of persons at risk for the disease. If, over the course of one year, five women are diagnosed with breast cancer, out of a total female study population of 200 (who do not have breast cancer at the beginning of the study period), then we would say the incidence of breast cancer in this population was 0.025. (or 2,500 per 100,000 women-years of study)
What is prevalence?
Prevalence is a measure of disease that allows us to determine a person's likelihood of having a disease. Therefore, the number of prevalent cases is the total number of cases of disease existing in a population. A prevalence rate is the total number of cases of a disease existing in a population divided by the total population. So, if a measurement of cancer is taken in a population of 40,000 people and 1,200 were recently diagnosed with cancer and 3,500 are living with cancer, then the prevalence of cancer is 0.118. (or 11,750 per 100,000 persons)
What is morbidity?
Morbidity is another term for illness. A person can have several co-morbidities simultaneously. So, morbidities can range from Alzheimer's disease to cancer to traumatic brain injury. Morbidities are NOT deaths. Prevalence is a measure often used to determine the level of morbidity in a population.
What is mortality?
Mortality is another term for death. A mortality rate is the number of deaths due to a disease divided by the total population. If there are 25 lung cancer deaths in one year in a population of 30,000, then the mortality rate for that population is 83 per 100,000.


The prevalence of sIBM is very difficult to establish for several reasons:
  —  There is no system of collection of statistics for rare diseases. When your doctor diagnoses you, this information generally is not shared in any database.
  —  This is a very difficult disease to diagnose and it seems clear that many cases are misdiagnosed.
  —  Because the illness is related to aging, many patients assume that mild symptoms are simply signs of getting older and do not seek medical diagnosis.

Prevalence of sIBM:

— sIBM has a male-to-female ratio of 2:1 to 3:1.
— The age-adjusted prevalence of sIBM in people over the age of 50 is 3.5/100,000, making it the most common idiopathic inflammatory myopathy (IIM) in this age group [1].
— sIBM should be considered in patients with appropriate symptoms who are older than 30 years.
— Symptom onset before age 60 occurs in 18 % to 20 % of patients [2, 3].
— In an Olmsted County population study the estimated incidence of sIBM, adjusted for sex and age to the 2000 US Census population, was 7.9 cases per million inhabitants with a prevalence of 70 cases per million inhabitants [4].
— sIBM is rare in African Americans and in non-Caucasians.
• From: Dimachkie, M. M., & Barohn, R. J. (2013). Inclusion body myositis. Current Neurology and Neuroscience Reports, 13(1), 321.

— Using the highest published prevalence rate, it is estimated that 23,000 people are affected in the United States and 72,000 people are affected in the United States, European Union, Canada, Australia, and Japan combined.
— Evidence for a truly increasing prevalence of the disease in Japan has been suggested by muscle pathology-based diagnosis of archived materials, with an estimated prevalence of 1.3 per million in 1991 and 9.8 per million in 2003.(2) The last US-based published estimate of 71 per million was based on 2008 data; it is likely that current true US prevalence is higher.
• From: Greenberg, S. A. (2016). Inclusion Body Myositis. CONTINUUM: Lifelong Learning in Neurology, 22(21), 1871-1888.



As seen above, sIBM is an age-related disease. It's onset is usually well into adulthood.


• From: Greenberg, S. A. (2016). Inclusion Body Myositis. CONTINUUM: Lifelong Learning in Neurology, 22(21), 1871-1888.


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Relevant Webpages:

Relevant Webpages:


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Other topics:

sIBM Facebook pages:

Clinical Trials for sIBM:

You can find information on the latest clinical trials on sIBM by going to this website and entering inclusion body myositis on the search line: NIH Clinical Trials:

Yale IBM Registry:

How to Use PDF files:

Note: some of the PDF files on this site are large and take considerable time to open. PDF files are like a photocopy of an article. To use them you need to install a PDF reader (many computers already have one installed). If you click on a PDF file and you have a reader, it will open automatically. If you need to install a reader, it is easy. You can get a free reader download at:


Donate to Fund sIBM Research:

The Inclusion Body Myositis Foundation (IBMF).

Donation Suggestions of Cure sIBM.

Mission Statement:

There are many excellent web sites that present information on various neuromuscular disorders. When I looked at the web, I was struck by how scattered the information was, and the fact that much of the information is very technical. Therefore, the primary intention of this site is to help integrate different sources and to provide background to help the reader cope with complex medical jargon and methods. I am not trying to be comprehensive and I do not want to be redundant and present information that is already covered elsewhere.


I am not a medical Doctor and this information is not intended to be read as medical advice nor is it a substitute for medical advice. Please consult your Physician if you have medical concerns. I have done my best to offer a layman's interpretation of this material. Any opinions offered are personal and do not reflect those of my employer. Thanks.


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Page Created: April 06, 2001.

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