Inclusion Body Myositis (IBM).

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1. Introduction:

Inclusion Body Myositis (IBM). This web page focuses on Inclusion Body Myositis (IBM). 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. This disease has traditionally been referred to as sporadic inclusion body myositis or sIBM.

■ 1.1 This page is a good starting point for a person interested in IBM and contains information suitable to take to a family physician.

■ 1.2 The site provides two levels of information:

▣ 1.2.1 basic introductions aimed at the IBM patient, his or her family, and caregivers;

▣ 1.2.2 selected research on IBM intended for physicians.

■ 1.3 General overview of IBM.

▣ 1.3.1 Inclusion body myositis (IBM) is often seen as a mysterious disease, due to uncertainties about its cause, diagnosis, classification and treatment.

▣ 1.3.2 IBM is a slowly progressive skeletal muscle disease. Patients typically experience weakness in the muscles that bend the fingers (finger flexors) and extend the knee (the quadriceps). These clinical findings distinguish IBM from most other muscle diseases.

▣ 1.3.3 Examination of muscle tissues under the microscope reveals that the muscle cells have been invaded by T cells, a type of white blood cell involved in the immune response against viruses and other pathogens.

▣ 1.3.4 Recent research on the involvement of the immune system strongly suggests that IBM is an autoimmune disorder. However, immunosuppressive drugs used to treat other autoimmune disorders are ineffective against IBM.

▣ 1.3.5 In patients with IBM, the onset of symptoms of muscle weakness typically occurs between 45 and 70 years of age. Early symptoms may go unnoticed, and the disease may proceed slowly, in a gradual, subtle way, with harmful, accumulating effects.

▣ 1.3.6 IBM is commonly misdiagnosed, often as arthritis or polymyositis, an autoimmune condition that causes muscle weakness in the hips, thighs, arms, back, and neck. Polymyositis develops quickly—within weeks or months and is quite responsive to treatment. Sometimes patients are misdiagnosed with motor neuron disease (MND)—amyotrophic lateral sclerosis (ALS) is the most common type of MND.

▣ 1.3.7 IBM is often associated with other diseases (called "co-morbidities"), including high blood pressure, diabetes, cardiovascular issues, and autoimmune diseases. Research suggests that IBM co-morbidities are not caused by IBM treatments, such as immunosuppressant therapy, but rather may result from the systemic inflammation observed in patients with autoimmune conditions.

■ 1.4 The problem of heterogeneity in IBM.

▣ 1.4.1 General: IBM shows wide diversity in a number of variables. The reason for this diversity is not clear. There are several possibilities that could explain the different patterns that are seen. One explanation would be that IBM is actually more than one disease and that the differences we see are because the different diseases cause different presentations. Another explanation would be that IBM is essentially one disease, but for some reason, it is expressed differently in different patients. These differences could be due to genetic differences between the patients, they could be due to environmental differences in the lives of the patients or a combination. Clearly, there are more questions raised by heterogeneity in IBM that need to be answered.

▣ 1.4.2 Why is this a problem? One reason is that when doing research on IBM, heterogeneity poses problems for the researcher. It is possible that some treatments work better in some people (with one presentation) compared to other people with a different presentation. In other words, the diversity of IBM has to be taken into account when examining the results of clinical trials and research on IBM.

▣ 1.4.3 Examples: Presentation — The known heterogeneity of IBM involves the age at onset of weakness, the site of onset of weakness, the rate of progression of weakness, and ultimately the course of the disease (Kushlaf 2020). Clinical differences — "The current theory of what causes IBM supports autoimmunity that comes before degenerative changes. The presence of anti-CN1A autoantibody in the blood of IBM patients supports the immune-mediated cause of IBM. In different studies, anti-CN1A autoantibody positivity predicts more severe weakness; lower frequency of proximal upper limb weakness; a higher likelihood of assistive device use and bulbar (swallowing difficulties) and respiratory involvement; a higher adjusted mortality rate; a lower probability of rimmed vacuoles; and a higher prevalence of cytochrome oxidase deficient fibers. The reasons for these differences are unclear. (Based on Kushlaf 2020). Some patients have the anti-CN1A antibody while others do not.


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2. Key points:

■ Inclusion body myositis (IBM) is often seen as a mysterious disease, due to uncertainties about its cause, diagnosis, classification and treatment.

■ Inclusion body myositis is a rare disease affecting muscle cells (it does not affect nerve cells).

■ As more and more muscle cells are involved, the muscle becomes weaker and weaker.

■ Not all muscles are impacted, for example, the heart is not affected.

■ Muscles are not all equally affected at the same time.

■ Different muscles groups are affected at different rates.

■ After symptoms of IBM first become noticeable, exactly how it will affect you, and how fast it will progress are difficult to predict. IBM is quite variable between different people.

■ The illness is chronic: once you get it you have it all your life.

■ The illness is progressive: the disabilities keep accumulating and you get worse and worse as time goes on.

■ In most cases, the muscles of the arms and legs are affected first and weakness in the hands and tripping are common first symptoms.

■ The illness can cause severe disability and often, eventually, necessitates use of a wheelchair.

■ The illness is age related; it usually occurs after age 30 and becomes more common in the population as people age;  it is the most common acquired myopathy in people over the age of 50.

■ Researchers do not understand what causes IBM.

■ The illness can be difficult to diagnose (takes up to 5 years on average) and is often first mistaken as polymyositis.

■ No effective treatment has been developed yet.

■ The most effective coping strategy is watching for, and managing, complications and the prevention of injuries due to falls.

■ A common serious complication is weakness in swallowing (dysphagia) that can cause choking or aspiration (taking food into the lungs) causing pneumonia (sometimes a cause of death). Swallowing involvement is a critical factor that should be investigated as soon as an IBM diagnosis is made.

■ Another serious complication is respiratory impairment caused by weakness of the diaphragm. Respiratory involvement is a critical factor that should be investigated as soon as an IBM diagnosis is made. Respiratory dysfunction can be identified, treated and monitored. The most common causes of death in IBM patients are complications due to respiratory failure and aspiration pneumonia (associated with both weak respiration and dysphagia — weakness in swallowing). Therefore, ongoing monitoring and awareness of these issues is highly recommended to both the patient and his or her physicians.

■ IBM does not appear to be directly genetic (it is not passed on to children) however, genetics may be involved in creating a predisposition to getting it.

■ Traditionally, corticosteroids have been used in an attempt to treat IBM. However, research shows that chronic use of these medications is ineffective and may even worsen the long-term course of the illness.

Figure 2.1

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).

Figure 2.2


A recent illustration is helpful (Greenberg, 2019).


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3. For new patients:

■ An information page for patients, family and caregivers. (PDF, easy to print). (07/2019) DRAFT

■ An information page to take to your family doctor. (PDF, easy to print). (07/2019) DRAFT

■ Questions to ask your doctor. (PDF, easy to print).

■ A brochure from the Myositis Association of America to take to your family doctor. (PDF, easy to print)

■ Potential complications.

■ Practical coping aspects.

■ Highlighted summaries of the research aimed at the average patient.

■ IBM Details (Older but may be of use).

■ Jerry King's youtube IBM channel.

■ Webpage credibility.

■ Seven warning signs of bogus science. (This is not my website)


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4. Treatment:

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

■ "Currently, no evidence is available to support any specific treatment in clinical practice. To date, there are no effective or approved treatment options for inclusion body myositis" From: (Hanna et al., 2019).

■ 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.

■ "Standard of care for most patients with IBM involves strictly nonpharmacological management, including emotional support, physical therapy, education on fall precautions and exercise." From: Greenberg, 2019.

■ 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.

■ 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 IBM. 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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5. Management:

■ 5.1 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.

■ 5.2 Because this illness is dynamic (it keeps changing over time) and progressive, your symptoms will likely change dramatically over time. People are always having to deal with new issues and new weaknesses and it's important to monitor these changes carefully and try to keep adapting as changes keep occurring. In this disease, coping has to be ongoing and keep up with the changes in the symptoms as they are experienced. (See Coping.)

■ 5.3 As muscles in the legs are often affected, this creates a major vulnerability to tripping and falling. Prevention of falls is critical.

■ 5.4 A common complication is weakness in swallowing and one must be vigilant to prevent choking (see Potential Complications: Dysphagia).

■ 5.5 Individuals with IBM whose mobility is restricted need to be aware of complications related to this, including:

▣ 5.5.1 the development of swelling (edema), especially around the ankles, and the possibility of developing pressure sores in the skin from sitting in one place for long periods.

▣ 5.5.2 Weak respiration may cause difficulty coughing and recovering from common colds.

▣ 5.5.3 Limited mobility means limited exercise, often reflected in weight gain.

■ 5.6 Potential impacts on respiration (diaphragm weakness) are less common but serious. Awareness of respiratory shallowness, especially while sleeping, is important, leading to proper assessment and management. (see Potential Complications: Respiration).

■ 5.7 We must prevent iatrogenic complications. This means complications introduced by efforts to treat the illness. In this case, the most common is the harm caused by prednisone. This medication has often been prescribed although it has not demonstrated any positive effect and many people needlessly suffer its complications.

■ 5.8 Diet: Generally speaking I have not seen any suggestion that a particular diet will actually help inclusion body myositis. I believe if you get an overall balanced and healthy dietary intake, you should be okay. One thing I would emphasize is that with IBM, the less you move, the less energy you need and therefore the less food you should eat. If you are in a wheelchair you must eat a reduced amount of food to avoid gaining weight.


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6. Theories of what causes IBM:

Note: there is still significant controversy within the research community concerning the basic causes of inclusion body myositis.

■ 6.1 After nearly 50 years of research, the basic causes of IBM remain unknown. It appears that multiple factors work together to cause IBM (a multifactorial disorder).

■ 6.2 Three basic theories have been proposed over the years. (presented in the order of likelihood based on contemporary research)

▣ 6.2.1 That the immune system is somehow involved in damaging the muscle cells, then causing protein abnormalities.

⧈ IBM appears to be an autoimmune disease. In these diseases, in response to some unknown cause, the immune system begins to produce antibodies that attack the body's own tissues. Normally, the immune system is triggered by some foreign invader (like a virus) and this causes the production of antibodies designed to attack and kill the invader. In autoimmune diseases, immune defences attack normal body tissues. Common examples are rheumatoid arthritis, lupus, Type 1 diabetes, and Sjögren's syndrome. Treatment for autoimmune diseases generally focuses on reducing immune system activity.

⧈ For some reason, the medications that normally reduce the activity of the immune system have not improved the symptoms of IBM.

⧈ IBM is sometimes also associated with cases of Sjögren's syndrome.

⧈ The families of patients with IBM also often have various other autoimmune disorders (for example, Crohn's disease, rheumatoid arthritis, autoimmune hepatitis, lupus, etc.).

▣ 6.2.2 That protein abnormalities damage the muscle cells, then causing immune system abnormalities.

▣ 6.2.3 An older theory was that a virus is the cause, however, no virus has been clearly linked to IBM. But, also see this.

■ 6.3 It could also be possible that both autoimmune factors and protein degeneration are both involved in the causes of IBM.

■ 6.4 Over the years, abnormalities associated with part of the cell called the mitochondrion have been implicated and recent research has emphasized this aspect (see De Paepe, 2019).

■ 6.5 Until the basic causes are discovered, a specific treatment will remain elusive.

Figure 6.1


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

Figure 6.2


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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7. Research:

■ 7.1 What's new?

▣ 7.1.1 2019: Currently, the evidence suggests that IBM is an autoimmune T cell-mediated disease (Greenberg, 2019).

▣ 7.1.2 2019: Greenberg et al., (2019) described the specific cytotoxic CD8 + T cells responsible for muscle cell destruction in IBM and a marker these cells display (KLRG1). This suggests an optimistic direction to take in the development of a medication to treat IBM. IBM may be the only muscle disease characterized by killer cells of the immune system attacking muscle cells.

■ 7.2 There are two main approaches to research; 1) general research into muscles (and muscle diseases) and 2) research specifically focused on IBM.

▣ 7.2.1 General Research:

⧈ Muscles are very complex systems and research into their basic structures and functions continues.

⧈ The causes of some muscle diseases (like IBM) are unknown and in turn, few specific treatments are available. Until more specific treatments are developed, researchers are looking into trying to develop general approaches to enhance muscle function.

⧈ If researchers could boost muscle function it might be possible to offset the effects of the different muscle diseases. Even a small increase in function could be very important to the patient having one of these illness.

 In normal muscle, there is a mechanism to stop muscle growth. Without this inhibitory system, muscle growth could go unchecked. Researchers are trying to take advantage of this inhibitory system. If this system could be short-circuited then more muscle growth would occur. The basic goal is to have the body produce more muscle than normal. The underlying muscle disease will not be treated but with more muscle being produced, the overall impact of the disease may be reduced. As mentioned, even small gains might be very important for the affected patient.

 An example of a general approach to increase muscle growth is a drug called Bimagrumab. This drug has been used to try to produce more muscle in various conditions. A new report says its safe to use but did not appear to work in IBM: See: (Hanna et al., 2019).

▣ 7.2.2 IBM Research:

⧈ Research specifically focused on IBM attempts to understand what causes the disease and how it operates. The basic cause of IBM is not currently understood and this is a major focus of IBM research.

⧈ Most research on the treatment of IBM has looked at using existing medications and examining their impact on IBM. Generally speaking, no medication has shown significant improvements in IBM patients (see above).

⧈ No treatment specifically designed for IBM has been developed.

⧈ 2017: "For the past two decades, the field of IBM research has been split with some researchers suggesting that IBM 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."

⧈ Generally, today, IBM is viewed as both a degenerative and an autoimmune disease.

⧈ Summary: IBM is a very complex and challenging disease to research. Much has been learned about the disease, but frustratingly, more remains unknown. The understanding of IBM and its causes is a very slowly evolving phenomenon.

■ 7.3 Current IBM Research.

■ 7.4 IBM as an autoimmune disease: Simplified.

■ 7.5 Past IBM Research/Other:

▣ 7.5.1 Past research.

▣ 7.5.2 Statins and IBM.

■ 7.6 Blood tests in making the diagnosis of inclusion body myositis.
Anti-cytosolic 5'-nucleotidase.

■ 7.7 Functional assessment of IBM.

8. Coping.    

9. Complications.    


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10. Genetics of IBM:

■ 10.1 Genetic predisposition.

▣ 10.1.1 Due to their genetic make-up, some individuals within the population appear to be more at risk of developing inclusion body myositis than others. The two major forms of myositis, IBM and fIBM, are not directly genetic and are not passed on to subsequent generations. It appears that these forms are related to a region of genes that increase the likelihood or chance of developing various autoimmune disorders. This is called a genetic predisposition.

▣ 10.1.2 It is clear that many factors contribute to the development of inclusion body myositis and genetic predisposition appears to be one risk factor.

■ 10.2 Familial IBM (fIBM)

▣ 10.2.1 Familial IBM refers to rare cases where (typical) 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).

▣ 10.2.2 The symptoms and features of fIBM are very similar to those seen in IBM. The familial occurrence of such a rare disorder likely highlights the importance of genetic predisposition in the causation of IBM.

■ 10.3 Hereditary inclusion body myopathy (hIBM)

▣ 10.3.1 Hereditary inclusion body myopathy refers to a group of ultra-rare inherited disorders; passed on from parents to children. Note that these diseases are called myopathy (myopathies) and their characteristics are different from inclusion body myositis, but at this point, these various myopathies are still lumped together with inclusion body myositis.

▣ 10.3.2 "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).

▣ 10.3.3 Greenberg (2019) points out that it is a mistake to think IBM and hIBM reflect the same pathophysiological process that can either occur sporadically or be inherited: "IBM", is an entirely different disease than the group of diseases known as hereditary inclusion body myopathies, often abbreviated as "hIBM."

▣ 10.3.4 The different forms of hereditary inclusion body myopathy are caused by mutations in different genes that can be passed from generation to generation.


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11. Classification of IBM:

■ 11.1 The classification of muscle diseases has been evolving over time as more and more research discoveries are made. Different diseases are being recognized and categories adjusted. At one time, muscle diseases were classified mainly based on their clinical presentation. Today, the recognition of antibodies associated with different muscle diseases has impacted classification.

Figure 11.1



 Figure 11.1 is based upon:
Simon, J. P., Marie, I., Jouen, F., Boyer, O., & Martinet, J. (2016).
Autoimmune Myopathies: Where Do We Stand?
Frontiers in Immunology, 7(JUN), 1-7.


Figure 11.2



Figure 11.2 is based on: Mariampillai, K., Granger, B., Amelin, D., Guiguet, M., Hachulla, E., Maurier, F., … Benveniste, O. (2018).
Development of a new classification system for idiopathic inflammatory myopathies based on clinical manifestations and myositis-specific autoantibodies.
JAMA Neurology, 75(12), 1528.
JAMA Neurol. 2018;75(12):1528-1537. doi:10.1001/jamaneurol.2018.2598

■ 11.2 Notes on Figure 11.2.


▣ 11.2.1 ^ trigger: statin use

▣ 11.2.2 * trigger: malignancy

▣ 11.2.3 ** anti-cN1A — anti-NT5c1A:

⧈ According to Greenberg (2019), Anti-cN1A antibodies are highly specific to IBM and are seen in 90-95% of patients with IBM compared with 5-10% of patients with polymyositis, dermatomyositis or non- immune neuromuscular diseases. However, these antibodies have only moderate diagnostic sensitivity, ranging from 37% to 76%. Varying sensitivities may be related to the different methods of testing that have been used.

⧈ "Anti-NT5C1A autoantibodies were detected in 71 (61%) of 117 patients with IBM, 2 (5%) of 42 patients with PM, 2 (5%) of 42 healthy volunteers, 24 (15%) of 159 patients with DM, 10 (23%) of 44 patients with Sjögren's syndrome, and 13 (14%) of 96 patients with systemic lupus erythematosus" (Lloyd et al., 2016).

⧈ "Anti-cN-1A autoantibodies are demonstrated in one third of the patients with sIBM and in less than 5% with other IIMs or neuromuscular diseases. A recent study demonstrated that positive anti-cN-1A sIBM patients are included in a more severe sIBM subtype and represent a homogeneous group as exhibiting higher mortality risk, less proximal upper limb weakness (not typical of sIBMs) and a cytochrome oxidase deficiency in muscular fibers, when compared to negative patients" (Palterer et al., 2018).

▣ 11.2.4 # Based on my reading of the literature, it seems that there is considerable controversy over polymyositis. Articles on the characteristics and diagnosis of polymyositis continued to appear. On the other hand, several authors have suggested that polymyositis will eventually become a meaningless diagnosis. For example, (Santos & Isenberg, 2019) state that polymyositis now accounts for only 5% of AIM patients. Montagnese (2019) stated: "many patients previously diagnosed as polymyositis may develop new clinical features suggestive of other diagnoses. For this reason, some authors even doubt the existence of PM as a distinct disease entity." Allenbach (2017) stated "The diagnosis of polymyositis (PM) is probably obsolete, since it may encompass many different diseases."


▣ 11.2.5 Summary: Antibodies are protective proteins produced by the immune system in response to the presence of a foreign substance, called an antigen. Antibodies recognize and latch onto antigens in order to remove them from the body. In the case of an autoimmune disease autoantibodies mistakenly recognize a person’s own tissues and attack them as if they were invaders. Researchers have discovered various autoantibodies directed against various tissues in the body, including skeletal muscle. These discoveries have led to the classification of myositis as an autoimmune disease. Some autoantibodies are only found in specific muscle disorders—myositis-specific [auto] antibodies (MSAs). Other [auto] antibodies may be linked to more than one disorder. When one of these disorders includes a muscle disorder it is called a myositis-associated antibody (MAA). It is a major challenge for researchers to decide if newly discovered autoantibodies belong to either the MSAs or MAAs group. In some cases, the detection of an autoantibody may help with making the diagnosis of a particular condition, in some cases, they are correlated to the way a disease progresses.

⧈ References:
Allenbach, Y., Benveniste, O., Goebel, H.H., & Stenzel, W. (2017). Integrated classification of inflammatory myopathies. Neuropathology and Applied Neurobiology, 43(1), 62-81.
Greenberg, S. A. (2019). Inclusion body myositis: Clinical features and pathogenesis. Nature Reviews Rheumatology 2019, 1.
Lloyd, T. E., Christopher-Stine, L., Pinal-Fernandez, I., Tiniakou, E., Petri, M., Baer, A., … Mammen, A. L. (2016). Cytosolic 5'-Nucleotidase 1A as a target of circulating autoantibodies in autoimmune diseases. Arthritis Care & Research, 68(1), 66-71.
Montagnese, F., Babacic, H., Eichhorn, P., & Schoser, B. (2019). Evaluating the diagnostic utility of new line immunoassays for myositis antibodies in clinical practice: A retrospective study. Journal of Neurology, 266(6), 1358-1366.
Palterer, B., Vitiello, G., Carraresi, A., Giudizi, M. G., Cammelli, D., & Parronchi, P. (2018). Bench to bedside review of myositis autoantibodies. Clinical and Molecular Allergy, 16(1), 5.
Santos, L. R., & Isenberg, D. (2019). Myositis. In Neuroimmune Diseases (pp. 787-808). Cham: Springer.

■ 11.3 Hallmark features:

▣ 11.3.1 AIM: The presence of a muscle inflammatory infiltrate is a hallmark of autoimmune myositis.

▣ 11.3.2 “Necrotizing autoimmune myopathy manifests with subacute proximal limb muscle weakness and persistently elevated CK levels. In contrast to immune-mediated inflammatory myopathies, NAM muscle biopsies often reveal no or minimal inflammation but prominent muscle fiber necrosis and regeneration” (Milone, 2017). Necrotizing autoimmune myopathies are strongly associated with specific autoantibodies in two-third of cases: anti-SRP or anti-HMGCR.

▣ 11.3.3 IBM: Inclusion body myositis has three prominent features: finger flexor and/or quadriceps weakness, inflammatory infiltrates of muscle fibres, or the presence of rimmed vacuoles.

▣ 11.3.4 DM: Inflammation and perifascicular atrophy of muscle fibers are the hallmark features of dermatomyositis. In addition to muscle weakness, dermatomyositis patients often present with a characteristic skin rash. Dermatomyositis includes several clinically distinct sub-types, and specific autoantibodies are associated with each unique sub-type. Patients with dermatomyositis who have little or no muscle involvement are referred to as hypomyopathic or as having amyopathic dermatomyositis.

▣ 11.3.5 ASS: Anti-tRNA synthetase syndromes are associated with specific autoantibodies directed against one of the aminoacyl-tRNA-synthetase enzymes. These enzymes enable tRNA to bind to specific amino acids.

■ 11.4 For information on myositis-associated autoantibodies see:

Figure 11.3



■ 11.5. Inclusion body myositis is a type of muscle disease, usually listed under the umbrella of muscular dystrophy diseases.

▣ 11.5.1 Subcategory: Idiopathic inflammatory myopathy. Idiopathic inflammatory myopathies (IIMs) are a group of rare acquired muscle disorders that includes, dermatomyositis, inclusion body myositis, immune-mediated necrotizing myopathy, and antisynthetase syndrome. Idiopathic traditionally means that the cause is unknown.

▣ 11.5.2 inclusion body myositis was recently classified as a type of autoimmune inflammatory rheumatic disease (AIIRD).

■ 11.6 IBM has traditionally been classified along with PM and DM, but the features of IBM are clearly distinct from these other types.

■ 11.7 The hereditary, myopathy type is also clearly distinct from the myositis forms.

■ 11.8 Myositis versus myopathy.

▣ 11.8.1 IBM is an abbreviation for 'inclusion body myositis' not 'inclusion body myopathy' (Greenberg, 2019, Milone, 2017). The abbreviation IBM refers clearly and only to the single disease IBM, not to the hereditary inclusion body myopathies ("hIBMs"). On this page, IBM will only refer to inclusion body myositis and I will not specify sporadic.

▣ 11.8.2 It would be less confusing if, in the future, researchers and doctors used IBM to specify inclusion body myositis, dropped the terms "sporadic" and "hIBM" and used the the names of each specific form of hereditary myopathy discovered, e.g. GNE mutation myopathy, DES mutation myopathy, VCP mutation myopathy, MYHC2A mutation myopathy, and others yet to be discovered (?).


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12. Brief History

■ Background: A few highlights.

▣ Early descriptions of inclusion body myositis are fairly disjointed and some did not reflect the disease we know today as inclusion body myositis.

▣ 1965: First case report made by Adams, who described inclusions in the muscles of a 20-year-old male (Kagen, 2009).

▣ 1967: Chou described inclusions in the muscle cells of a 60-year-old man with "chronic polymyositis."

▣ 1971: Yunis & Samaha first used the term inclusion body myositis.

▣ These early reports led to the recognition that inclusion body myositis might be a distinct disease (Kagen, 2009).

▣ 1984: Arahata, & A. G. Enge/A. G. Engel & Arahata described the inflammation in IBM and identified cytotoxic CD8 + T cells invading muscle cells.

▣ 1989: Lotz reviewed 40 cases and concluded that IBM should be considered a distinct disease. Data were consistent with previous observations that corticosteroid therapy (usually prednisone) does not work in IBM.

▣ 1991: Mendell described the presence of amyloid in the inclusions found in IBM muscle cells.

▣ 1992: Askanas & W. K. Engel outline the beta-amyloid theory.

▣ 1993: Oldfors describes mitochondrial abnormalities in IBM.

▣ 1995: Griggs describes diagnostic criteria for IBM.

▣ 2006: Askanas & W. K. Engel, describe beta amyloid protein in IBM.

▣ 2006: Dalakas found in addition to the vacuoles and inclusions, muscle tissue in inclusion body myositis shows an inflammatory invasion of intact muscle cells by macrophages and cytotoxic CD8 + T cells.

▣ 2007: Askanas & W. K. Engel point out that muscle cell degeneration is characterized by progressive cell death, of the development of vacuoles, and the accumulation of clumps made up of different proteins—amyloid inclusion bodies. The amyloid inclusions are of two types, one of which contains beta amyloid protein, and the other, tau protein.

▣ 2008: Chahin stated that rimmed vacuoles are absent in 20% of patients with typical clinical features of IBM.

▣ 2010: Pandya identified CD28 + (CD244 - ) a highly differentiated cytotoxic CD8 + T cell in IBM.

▣ 2011: Salajegheh (of the Greenberg group) discovered that a circulating autoantibody against a 43-kDa muscle autoantigen is present in IBM.

▣ 2013: Rose presents The European Neuromuscular Centre (ENMC) diagnostic criteria for IBM.

▣ 2013: The target autoantigen of the IBM [auto]antibody discovered in 2011 was identified simultaneously by two research groups and the findings published in tandem: Larman (of the Greenberg group), Pluk (of the Badrising group) Cytosolic 5' -nucleotidase 1A (cN1A; NT5C1A).

▣ 2016: Greenberg recognizes highly differentiated effector and effector memory CD8 + T cells in IBM muscle and blood overlapping with T cell large granular lymphocytic leukaemia.

▣ 2017: Lilleker described differences in clinical and histopathological features between anticytosolic 5'-nucleotidase 1A antibody positive and negative IBM patients.

▣ 2017: Rothwell reported alleles in the HLA-DRB1 (an autoimmune haplotype) were found to be independently associated with IBM.

▣ 2018: Britson found variants within the HLA locus are genetic risk factors for developing IBM.

▣ 2018: Britton noted 65% to 80% of IBM patients have dysphagia and associated issues with excessive thick mucus.

▣ 2018: Felice reported the anti-cN1A antibody test has a low predictive value for IBM parameters. In our cohort, 20 of 40 (50%) of patients tested positive for anti-cN1A, and, of these, antibodies were strong positive in 12 (60%), moderate positive in 5 (25%), and weak positive in 3 (15%). … Based on all clinical studies published to date including the present, the anti-cN1A antibody test shows low predictive value in regards to disease severity and associated clinicopathological findings.

▣ 2019: Greenberg (2019) pointed out that, despite the finding that less than one percent of muscle cells contain abnormal proteins, for some reason, the degenerative aspects of IBM have dominated past research. Although immune system involvement was seen early on, it has not received as much research attention. Today, mounting evidence that IBM is an autoimmune T cell-mediated disease provides hope for the development of new, immune based therapies.

▣ 2019: Greenberg et al., (2019) described the specific cytotoxic CD8 + T cells responsible for muscle cell destruction in IBM and a marker of these cells (KLRG1).

▣ 2019: Ramdharry presents the latest version of the clinician rated inclusion body myositis functional rating scale.

⧈ References.


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13. How common is IBM?

■ 13.1 Terminology:

First, it is important to understand some terminology. This Information is from the New York State Department of health.

▣ 13.1.1 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)

▣ 13.1.2 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)

▣ 13.1.3 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.

▣ 13.1.4 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.

■ 13.2 Prevalence of IBM:

▣ 13.2.1 The prevalence of IBM 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 is 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.

▣ 13.2.2 Men get IBM slightly more often than females, about on average 1.6 times (so for every 16 men there would be 10 women with IBM).

▣ 13.2.3 Numbers reflecting the prevalence of IBM are probably underestimates because of the high rate of misdiagnosis. In a good study published in 2017, the overall prevalence of IBM was 46 patients per million.

⧈ From: Greenberg, S. A. (2019). Inclusion body myositis: Clinical features and pathogenesis. Nature Reviews Rheumatology 2019, 1.

▣ 13.2.4 IBM should be considered in patients with appropriate symptoms who are older than 30 years.

▣ 13.2.5 Symptom onset before age 60 occurs in 18 % to 20 % of patients.

▣ 13.2.6 In an Olmsted County population study the estimated incidence of IBM, 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.

▣ 13.2.7 IBM 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.

▣ 13.2.8 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.

▣ 13.2.9 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.

Table 13.1



■ 13.3 Age:

▣ 13.3.1 As seen below, IBM is an age-related disease. It's onset is usually well into adulthood.

Table 13.2



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


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14. Relevant Webpages:

■ 14.1 A key resource: Myositis Support and Understanding (MSU)

■ 14.2 Other Relevant Webpages:


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15. Other topics:

■ 15.1 IBM Facebook pages:

▣ 15.1.1 IBM Facebook Page #1 (open):

▣ 15.1.2 IBM Facebook Page #2 (membership):

■ 15.2 Clinical Trials for IBM:

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

▣ 15.2.2

■ 15.3 Yale IBM Registry:

▣ 15.3.1 Yale IBM Registry.

■ 15.4 Miscellaneous:

▣ 15.4.1 IBM in Images.

▣ 15.4.2 Selections from Outlook (TMA).

■ 15.5 Donate to Fund IBM Research:

▣ 15.5.1 The Inclusion Body Myositis Foundation (IBMF).

▣ 15.5.2 Donation Suggestions of Cure IBM.

■ 15.6 How to Use PDF files:

▣ 15.6.1 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:

■ 15.7 Mission Statement:

▣ 15.7.1 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.

■ 15.8 Disclaimer:

▣ 15.8.1 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.

■ 15.9 Contact:

▣ 15.9.1 For comments or improvements, please contact Bill at e-mail:

■ Search by JRank

■ Page Created: April 06, 2001.

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