Masticatory muscle symptoms in a patient with McArdle's disease.

Myofascial pain dysfunction syndrome is a syndrome characterized by chronic preauricular pain and tenderness involving the muscles of mastication. The cause is often multifaceted and generally poorly defined. A case of McArdle's disease is discussed in which the patient presented with symptoms consistent with myofascial pain dysfunction syndrome. McArdle's disease is a rare autosomal recessive glycogen storage disorder in which there is a metabolic myopathy that results in exercise intolerance, muscle pain, and tenderness, and that in this patient gave rise to chronic symptoms of myofascial pain. Although uncommon, McArdle's disease should be considered in the diagnosis of patients with symptoms of myofascial pain dysfunction syndrome because the condition has important implications with respect to the patients renal function and because it can be readily distinguished by simple investigations.