Myalgia-eosinophilia syndrome associated with tryptophan

Myalgia-eosinophilia syndrome associated with tryptophan, also known as eosinophilia-myalgia syndrome (EMS), is a systemic disorder that was first identified in 1989 in association with the ingestion of contaminated L-tryptophan dietary supplements. The condition is characterized by severe, debilitating myalgia (muscle pain) and marked peripheral eosinophilia (elevated eosinophil counts in the blood, typically greater than 1,000 cells per microliter). The disease affects multiple body systems including the musculoskeletal, dermatological, neurological, and pulmonary systems. Key clinical features include intense muscle pain, skin changes such as scleroderma-like skin thickening and fasciitis, peripheral neuropathy, fatigue, hair loss, skin rashes, and respiratory symptoms including cough and dyspnea. Some patients develop ascending polyneuropathy, cognitive difficulties, and cardiac involvement. The condition can range from mild to life-threatening, and in the original epidemic, several deaths were reported. The syndrome was linked to specific contaminants (including a compound known as 'Peak E' or 1,1'-ethylidenebis[tryptophan]) found in L-tryptophan produced by a single manufacturer. Treatment is primarily supportive and includes discontinuation of L-tryptophan supplementation, corticosteroids to reduce inflammation and eosinophilia, and symptomatic management of pain, neuropathy, and skin manifestations. While many patients improve after withdrawal of the offending supplement and corticosteroid therapy, some develop chronic symptoms including persistent myalgia, neuropathy, and skin changes that may require long-term management. There is no specific curative therapy, and the chronic phase of the disease can be difficult to treat.

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