Polymyalgia rheumatica

Polymyalgia rheumatica is a rheumatic autoimmune inflammatory disease that affects the lining of the joints or around the joints (periarthritis) and, in rare cases, the arteries. The hallmark of the disease is pain and stiffness of muscles around the shoulder and pelvic girdles, particularly in the morning or after prolonged inactivity. The symptoms are treatable and the disease is usually self-limiting and typically resolves itself within a few years, although relapses are possible.

Polymyalgia rheumatica was first described in 1888 as "senile rheumatic gout".

The cause of polymyalgia rheumatica is unknown, although both genetic and environmental factors contribute to disease susceptibility and severity.

Some of the characteristics of PMR suggest that infectious disease expose could be an environmental factor. The disease often has a very sudden onset and new cases occur in cycles, which could indicate an infection as the source. Attention has been focused on PV B19 (parainfluenza virus), Mycoplasma pneumoniae and Chlamydia pneumoniae. There is also observational suggestion of vaccine and statin initiation of the illness.

Inheritance of the disorder has been suggested from some genetic studies and the pattern seen in family histories. The gene(s) that could be responsible for PMR have not been definitively identified. Certain alleles in the "HLA-DR" group have been found to have a possible link to polymyalgia rheumatica (and related giant cell arteritis). Epigenetic changes and differential expression of genes that regulate the expression of inflammatory cytokines may account for the variable presentations and severity of the disease.

Glucocorticosteroids rapidly improve disease symptoms in most patients but may have serious side effects.

Polymyalgia rheumatica is the most common inflammatory disease to affect the elderly and is rarely seen in those who are under age 50. On average, the disease tends to develop around the age of 70 and is the most common inflammatory rheumatic disease in elderly white people; 75% of patients are women. The incidence of the disease in patients over 50 is about 100 per 100 000. Giant cell arteritis is co-present in about 30% of patients.

Polymyalgia rheumatica is seen mainly in people of north European ancestry, although it can occur in any ethnic group. The highest incidence is seen in Scandinavian countries and in people of the northern European descent. The lowest incidence rates occur at the more southern European countries like Italy, and Spain. In the United States the lifetime risk of developing PMR is estimated at 2.43% for women and 1.66% for men.