Fibromyalgia and Eosinophilia-Myalgia Syndrome

Abstract

Objectives: Epidemiologic studies have linked eosinophilia-myalgia syndrome [EMS] to use of the amino acid L-tryptophan. However, when interpreting these findings, one complicating factor is that many of the conditions for which L-tryptophan was used-such as insomnia, depression, and fibromyalgia-are themselves frequently associated with myalgia and often pursue a chronic course. We present a case series which illustrates these issues. Methods: We examined the medical records of nine patients who 1. met Center for Disease Control criteria for EMS; 2. had used L-tryptophan prior to the onset of EMS; and 3. had been given a diagnosis of fibromyalgia prior to use of L-tryptophan. All of these patients had sued a manufacturer of L-tryptophan, claiming damages due to EMS. Results: Prior to the L-tryptophan use, the patients had frequently been diagnosed with other disorders often comorbid with fibromyalgia: migraine [n = 31], irritable bowel syndrome [n = 3], mood disorder [n = 6], and anxiety disorders [n = 2...