Eosinophilia myalgia syndrome.

The term eosinophilia myalgia syndrome (EMS) was coined in 1989 after a cluster of cases with symptoms of incapacitating myalgias and eosinophilia were reported. This syndrome has been only defined as varying degrees of myalgias and peripheral eosinophilia. Case reports of EMS are protean and do not show a consistent clinical picture, raising the question of whether this reflects a single disorder or is a conflation of various disorders. There have been only two studies evaluating the association of EMS with 1-tryptophan. These two included only 23 patients with EMS. Apart from the obvious statistical fragility inherent in such small studies, each is further weakened by differences in the mechanisms by which patients and controls were selected. Furthermore, the continued reports of EMS after 1-tryptophan was removed from the market raise additional questions about the association. Nonetheless, there has been an inordinate reliance on a history of 1-tryptophan ingestion in making the diagnosis of EMS. When presented case studies, clinicians were much more likely to make the diagnosis of EMS when a history of 1-tryptophan ingestion was included. These observations underscore the need for careful application of well-considered diagnostic criteria to the study of new syndromes and their potential associations.