Inclusion-body myositis (IBM) primarily affects men, although women can be affected. It occurs mainly in those older than 50.
IBM usually begins with the gradual onset of slowly progressive weakness in the muscles of the wrists and fingers, and those at the front of the thigh (quadriceps). The muscles that lift the front of the foot also may be affected. The weakness may not be the same on both sides of the body.
Trouble with gripping, such as a shopping bag or briefcase, and frequent stumbles are common experiences. About a third of people with IBM have some weakness of the swallowing muscles.
IBM is generally a slowly progressive disease, and life expectancy isn’t significantly affected. Most people with IBM remain able to walk, although they may require a cane or wheelchair for long distances. Some are more profoundly affected, and require a wheelchair full time within 10 or 15 years of the first symptoms.