Inclusion Body Myositis (IBM)

What is inclusion body myositis?

Inclusion body myositis (IBM) is a progressive muscle disorder. IBM is characterized by muscle inflammation, feebleness, and wasting or atrophy. IBM typically develops in adulthood, somewhere around the age of 50. While the lifespan of those affected by IBM is typically normal, they will often progress to disability and require assistance with daily functions. IBM may also be referred to as inflammatory myopathy, or sporadic inclusion body myositis.

What are the symptoms of inclusion body myositis?

Affected areas, severity, and progression, are all variable in patients with IBM. Typically progression is slow, but the older a person is when onset occurs, the more rapidly IBM progresses. Thigh, wrist, and finger muscles are usually the most affected. For many people the first sign of IBM is a tendency to trip or fall due to a weakening of the quadriceps muscle in the thigh. Other symptoms may include:

• Autoimmunity
• Elevated serum creatine phosphokinase
• EMG abnormality
• Ragged-red muscle fibers
• Rimmed vacuoles
• Skeletal muscle atrophy
• Feeding difficulties in infancy
• Myalgia

What causes inclusion body myositis?

Causes of IBM are currently not well understood. A complex set of genetic, immune-related, and environmental factors likely contribute. There may be a genetic predisposition to developing IBM, but it is currently believed not to be an inherited disorder.

How is inclusion body myositis diagnosed?

Diagnosis of IBM is typically carried out through a clinical evaluation, study of patient history, and several specialized tests. These tests may include muscle biopsy, electromyography, and blood test to measure muscle enzymes such as creatine kinase.

What are the treatments for inclusion body myositis?

No cure for IBM currently exists. IBM does not typically respond to the forms of treatment used for autoimmune disorders. Treatment is often personalized to the patient, but frequently includes physical or occupational therapy and the assistance of braces, wheelchairs, and other devices to aid movement.

Where can I find out more about inclusion body myositis?

• National Organization for Rare Disorders (NORD)
• NIH