Sporadic inclusion body myositis (sIBM) is the most common form of acquired myopathy in people over the age of 50 years. It has been estimated that it affects more than 1 in every 20,000 Australians. This disease is more common in men than women and causes weakness of limb muscles as well as swallowing difficulties. sIBM is a slowly progressive disease and in more severe cases affected people may become wheelchair bound.
The cause of this disease is poorly understood. It causes degeneration and inflammation of the muscles, but what sets this off is unknown. It appears to involve both dysfunction of the immune system and also abnormal protein accumulation inside the muscle cells. There is no known effective treatment for sIBM.
Recently developed computerized neurophysiological techniques allow the study nerve and muscle excitability, which is an indirect measure of cell membrane function. Electrical dysfunction of the cell membrane can occur under several circumstances and these studies give clues as to where the problem is occurring. This includes dysfunction of ion channels and pumps in the cell membrane as well as problems with energy supply to the cell, which can result from problems with the blood supply or mitochondria, which are the energy generators within each cell.
This project will use these recently developed techniques to characterize the change in nerve and muscle excitability in patients with sIBM. We hope to shed light on whether electrical dysfunction of nerve and muscle cells in sIBM plays a role in the development of symptoms and this may in turn lead to development of more effective therapies through a better understanding of the mechanisms of disease.