IBM is one of a group of muscle diseases known as the inflammatory myopathies, which are characterized by chronic muscle inflammation accompanied by muscle weakness. The onset of muscle weakness in IBM is generally gradual (over months or years) and affects both proximal (close to the trunk of the body) and distal (further away from the trunk) muscles. Apart from weakness, other signs and symptoms commonly associated with IBM include dysphagia (difficulty in swallowing) and frequent falls and tripping.