Myoclonic involuntary movement associated with chronic manganese poisoning

We report a 17-year-old man showing myoclonic involuntary movement (IVM) associated with chronic manganese (Mn) poisoning. The patient, a welder, showed myoclonic IVM mainly in the right upper and lower extremities, elevated levels of Mn in the blood and hair and high-intensity signals in the globus pallidus on T1-weighted MR images. Chelation therapy resulted in improvement of the myoclonic IVM and MRI abnormalities. This is the first report of Mn poisoning characterized by myoclonic IVM without parkinsonism. (C) 2002 Elsevier Science B.V. All rights reserved.