Inclusion Body Myositis (IBM)
An acquired progressive muscular disorder and inflammatory myopathy
Medically reviewed by Rochelle Collins, DO
Inclusion Body Myositis (IBM) is an acquired progressive muscular disorder and one of several types of inflammatory myopathies (skeletal muscle disorders). It causes inflammation that damages muscles, especially in the limbs. IBM develops over time and is most commonly diagnosed in men over the age of 50.
In patients with IBM, inflammatory cells infiltrate the muscles of the body, especially in the hands, arms, legs, and feet. Once they accumulate, protein "bodies" discarded by the cells build up and cause the muscle to degrade, leading to progressive symptoms of weakness and wasting (atrophy). The presence of these damaging "inclusion bodies" in the muscles gives the condition its name.
This article discusses the symptoms, causes, diagnosis, and treatment of inclusion body myositis.
Symptoms of Inclusion Body Myositis
The symptoms of IBM usually take time to develop, rather than coming on suddenly. It may be that patients who later find out they have IBM look back at the preceding months, or even years, and realize that some symptoms they had been experiencing were related to the condition.
The first signs people with IBM may notice are having trouble gripping or holding objects or having difficulty getting out of a chair.
Other common symptoms of IBM include:
Stumbling, tripping, or falling if leg muscles are affected
Weakness on one side of the body
Weakness of the esophageal muscles, leading to dysphagia in about half of patients
Weakness of the wrist and finger muscles causing difficulty with gripping, pinching, and buttoning
Atrophy of the muscles of the forearms
Weakness and visible wasting of the quadriceps muscles
Weakness of other muscle groups as the disease progresses.
While the muscles of the heart and the lungs are affected in other types of myopathy, they are not affected in patients with IBM.
The symptoms of IBM develop slowly—usually over the course of several months or even years. It is believed that the older a patient is when they begin experiencing symptoms, the more aggressively the condition will progress. Additionally, many people who have IBM will eventually need some help with day-to-day living, most often within 15 years of receiving a diagnosis. This could include mobility aids such as canes, walkers, or wheelchairs.
While IBM can lead to disability, life expectancy does not appear to be shorter.
What Causes Inclusion Body Myositis?
The cause of IBM is not known. Almost a decade ago, researchers concluded a combination of factors related to a person's lifestyle, environment, and the immune system play a role in the condition.
Some research suggests that exposure to certain viruses, including HIV, may trigger the immune system to attack normal, healthy muscle tissue. In other studies, certain medications, including Arimoclomol, Bimagrumab, Follistatin, and Rapamycin (Sirolimus), were suspected of contributing to a lifetime risk of developing IBM.
While researchers don't think IBM is an inherited condition, one study suggested a possible "genetic" overlap with IBM and other autoimmune disorders. Some people may have genes that, while they don't cause IBM, could make them more likely to develop the condition in their lifetime (genetic predisposition).
How Is IBM Diagnosed?
IBM is considered a disease of adult-onset and is rarely diagnosed before age 50. IBM is more commonly diagnosed in men, though it also affects women.
IBM is diagnosed through a combination of:
Physical examination
Review of personal and family medical history
Testing the electrical activity in muscle
Muscle biopsy
Creatine kinase (CK) lab tests are also used to diagnose the condition. CK is an enzyme released from muscles that have been damaged. While CK levels can be elevated in people with myopathies, people with IBM often have only mildly elevated or even normal levels of CK.
Since IBM is a condition where the body attacks its own tissues, a healthcare provider may also order tests to look for antibodies commonly found in patients with autoimmune diseases. However, because treatments typically used for autoimmune conditions don't consistently work for people with IBM, researchers are still not sure if IBM is truly an inflammatory disease.
Related: What Are Autoimmune Diseases?
Treatment for Inclusion Body Myositis
There is currently no cure for inclusion body myositis. Even with treatment, the disease will progress over time.
Some people, especially those with other autoimmune disorders, respond to immunotherapy.
Many people with IBM can benefit from physical, occupational, and speech therapy. These therapies help:
Maintain strength and mobility as long as possible
Make daily activities easier
Prevent falling injuries
Manage swallowing problems
Developing strategies to avoid falls, including the use of mobility aids (such as canes, walkers, and wheelchairs), is important to help people stay safe.
Takeaway
There is no standard treatment that works to manage symptoms in every person, so each individual with IBM will need to work with their healthcare provider to decide which, if any, treatments they would like to try.
Medications that suppress the immune system (such as steroids like prednisone) are sometimes used but don't work for everyone and tend to have side effects.
Summary
Inclusion body myositis is a progressive muscular disorder and one of several types of inflammatory myopathies. It is generally diagnosed in men over the age of 50, but women can also be affected. It causes damage to the muscles that leads to weakness which develops slowly, usually over months to years.
Researchers aren't sure what causes IBM, but it's believed that environment and genetics likely play a role. While there's currently no cure for IBM and it can lead to disability, the condition is not life-threatening and doesn't appear to shorten a person's lifespan.
Read the original article on Verywell Health.
