Dr. Richard A. Walsh, MB, MD, MRCPI, is a consultant neurologist at Tallaght Hospital and Senior Clinical Lecturer in Neurology at Trinity College Dublin, Ireland. Susan H. Fox, MB ChB, MRCP(UK), PhD, is Associate Professor of Neurology at University of Toronto, Movement Disorders Clinic at Toronto Western Hospital. Robertus MA de Bie, MD, is a neurologist, Department of Neurology, Academic Medical Center, Amsterdam, Netherlands.