What is the average package from SIBM

The portal for rare diseases and orphan drugs


A more up-to-date brief description is available in the English version for this disease


The IBM has a very variable prevalence depending on geographical and ethnic origin and age. The prevalence in the general population ranges from 1: 1,000,000 to 1: 14,000, but a three-fold increase is seen when looking only at the population over the age of 50. Underdiagnosis could explain the strong ethno-geographical differences. The male to female ratio is on average 2: 1 (0.5 to 6.5: 1).

Clinical description

IBM becomes manifest at the age of over 50, but occasionally also in the fifth decade of life. The first signs are weakness or even atrophy of the quadriceps or finger flexors, causing problems standing up, climbing stairs, holding on, lifting and using tools, and causing falls. The Flexor digitorum profundus and the Flexor pollicis longus are more involved than the forearm extensor muscles, especially in the early stages of the disease. As the disease progresses, other muscle groups become involved, such as the extensor muscles of the elbow, hip, knee, and neck, and the dorsiflexors of the ankle, resulting in a stepping gait. Patients often show slight weakness in the muscles of the face, with the exception of the extraocular muscles. Dysphagia can occur in approximately 66% of patients in the advanced stages of the disease, and in some cases it can be severe.


The etiology of IBM is still largely unclear. No causative gene has yet been identified, but it has been shown that the genotypes HLA-DR3 and 8-1 MHC correlate with vulnerability to IBM. Aging and environmental factors are also assigned a triggering role. Whether IBM is primarily an immune-related inflammatory disease that leads to muscle degeneration or a degenerative disease that leads to inflammation of muscles is currently still being discussed; likewise the pathogenic role of the anti-IBM-43, an antibody which is directed against the muscle protein cytosolic 5'-nucleotidase 1A and which was discovered in about half of the patients.

Diagnostic procedures

The diagnosis is based on the physical examination (especially detecting the weakness of the finger flexors); In addition, the age of the patient and a duration of symptoms of over 6 months are further diagnostic clues. A muscle biopsy allows the identification of endomysial inflammatory cells that enclose myofibrils and rimmed vacuoles and, occasionally, an abnormally increased number of COX-negative fibers. Laboratory results are not specific as serum creatine kinase is only slightly increased in some cases. Electromyography can only help confirm the myopathic origin of the muscle weakness or atrophy. Magnetic resonance imaging (MRI) helps describe the characteristic patterns of muscle involvement.

Differential diagnosis

Differential diagnoses include polymyositis (see there) and, in the early stages of the disease, arthritis or motor neuron disease.

Genetic counseling

IBM occurs sporadically, but was rarely observed in family cases (then referred to as family IBM) with an unknown inheritance, almost always in siblings.

Management and treatment

There is no curative treatment from IBM. Patients typically do not respond to anti-inflammatory or immunomodulatory therapies. Symptomatic treatments include exercise therapy, occupational therapy, and the use of orthotics.


After 5 years most patients need a walking aid and after 10 years a wheelchair. No change in mean life expectancy was observed.

Reviewer: Dr Steven GREENBERG - Last update: November 2012

Detailed information

Articles for the general public

Further information

More information about this disease

Patient-centered resources for this disease

Relevant research activities

Specialized social service

The documents contained in this website are for general information only. The content of this website is in no way a substitute for professional advice or treatment by qualified specialists. This information should not be used as a basis for diagnosis or treatment.