We report a case of Eosinophilia- Myalgia syndrome with central nervous system (CNS) involvement following ingestion of the essential amino acid, tryptophan. The Eosinophilia- Myalgia syndrome can be diagnosed when there is a severe myalgia and peripheral eosinophilia in the absence of other diseases causing eosinophilia. This condition has been associated with the ingestion of the tryptophan in many cases, but the amount and duration of ingestion have been yet to be elucidated. Although many cases have been reported, few cases involved the CNS.

We present a 28 year- old male who complained of a severe myalgia and disorientation after taking the taken tryptophan for 2 weeks. Thorough examination revealed the peripheral eosinophilia, vasculitis on brain MRI, abnormal VEP, and muscle atrophy on muscle biopsy. Symptoms improved with the steroid pulse after discontinuation of the tryptophan.