What are the other Names for this Condition? (Also known as/Synonyms)

• IBM (Inclusion Body Myositis)
• Sporadic Inclusion Body Myositis

What is Inclusion Body Myositis? (Definition/Background Information)

• Inclusion Body Myositis (IBM) is a progressive muscle disorder characterized by muscle inflammation, weakness, and atrophy (wasting). It is a type of inflammatory myopathy
• Inclusion Body Myositis develops in adulthood, usually after age 50
• The most common symptoms include progressive weakness of the legs, arms, fingers, and wrists
• Most people with Inclusion Body Myositis progress to disability over a period of years. In general, the older a person is when IBM begins, the more rapid the progression of the condition
• The underlying cause of Inclusion Body Myositis is poorly understood and likely involves the interaction of genetic, immune-related, and environmental factors. Some people may have a genetic predisposition to developing IBM, but the condition itself typically is not inherited
• There is currently no cure for Inclusion Body Myositis. The primary goal of management is to optimize muscle strength and function. Management may include exercise, fall prevention, physical therapy, occupational therapy, and speech therapy (for dysphagia)

(Source: Inclusion Body Myositis; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Inclusion Body Myositis? (Age and Sex Distribution)

• Inclusion Body Myositis is a rare acquired disorder. The presentation of symptoms typically occurs after the age of 50, although in some cases, symptoms may present sooner
• Inclusion Body Myositis is the most common acquired muscle disorder over the age of 50. It is estimated to occur at the rate of 10-71 individuals per million
• Both males and females may be affected; however, the condition is more common in men than women, by a factor of approximately 2:1
• Worldwide, individuals of all racial and ethnic groups may be affected. It has been reported that individuals of African origin are less susceptible to the disorder

What are the Risk Factors for Inclusion Body Myositis? (Predisposing Factors)

• Currently, no risk factors have been clearly identified for Inclusion Body Myositis
• However, it has been suggested that a genetic predisposition and viral infection(s) may contribute to the disorder

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Inclusion Body Myositis? (Etiology)

The exact cause of Inclusion Body Myositis is not known.

• It has been suggested that a genetic predisposition, a viral infection, an autoimmune response and certain environmental factors may combine to cause the disorder
• The prevalence of auto-antigen NT5C1A in individuals with IBM, lends credence to the autoimmune theory

What are the Signs and Symptoms of Inclusion Body Myositis?

The signs and symptoms of Inclusion Body Myositis may include:

• Distal muscle weakness
• Hyporeflexia
• Proximal muscle weakness
• Sporadic

Very frequently present symptoms in 80-99% of the cases:

• Autoimmunity
• Elevated serum creatine phosphokinase
• EMG abnormality
• Inflammatory myopathy
• Quadriceps muscle weakness
• Ragged-red muscle fibers
• Rimmed vacuoles
• Skeletal muscle atrophy

Frequently present symptoms in 30-79% of the cases:

• Feeding difficulties in infancy
• Reduced tendon reflexes

(Source: Inclusion Body Myositis; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Inclusion Body Myositis Diagnosed?

Inclusion Body Myositis is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests, including specific blood tests to check for IBM
• Imaging studies
• Electromyography, to check electrical activity of the muscle being tested
• Muscle biopsy studies

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Inclusion Body Myositis?

The complications of Inclusion Body Myositis may include:

• Progressive muscle weakness
• Poor grip strength
• Inability to perform simple tasks, such as opening a door
• Reduced quality of life
• Loss of balance and frequent falls, which may cause injuries
• Progressive difficulty in standing up from a sitting position
• Foot drop, making it difficult to walk
• Neck drop, if neck muscles weaken
• Progressive weakening of muscles, necessitating a cane, walker, or wheelchair for mobility
• Swallowing difficulties, leading to choking episodes
• Breathing difficulties if muscles in the respiratory tract are affected
• Depression

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Inclusion Body Myositis Treated?

There is no cure for Inclusion Body Myositis. The treatment is usually given to manage the signs and symptoms and any complication that develops. Treatment methods may include:

• Corticosteroids or other drugs for immune-suppression
• Physiotherapy
• Occupational therapy
• Devices to facilitate walking (braces, canes, walkers, wheelchairs)

How can Inclusion Body Myositis be Prevented?

• Currently, Inclusion Body Myositis may not be preventable
• Active research is currently being performed to explore the possibilities for treatment and prevention of disorders such as IBM
• Regular medical screening at periodic intervals with tests and physical examinations are recommended

What is the Prognosis of Inclusion Body Myositis? (Outcomes/Resolutions)

• The prognosis of Inclusion Body Myositis is dependent upon the severity of the signs and symptoms and associated complications, if any
• In general, most affected individuals need assistance with mobility after 5-10 years. They may eventually become wheelchair bound, as the condition is progressive
• Typically, life expectancy is not affected in those with IBM

Additional and Relevant Useful Information for Inclusion Body Myositis:

In individuals affected by Inclusion Body Myositis, cellular components known as “vacuoles” exhibit abnormal clumping or aggregates of various proteins. These clumps are collectively known as “inclusion bodies”, from which the disorder gets its name.

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/