1. Clinic and Policlinic of Neurology, University of Rostock, Rostock, Germany
2. Department of Neurology, Medical University of Vienna, Vienna, Austria
3. Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
4. Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, USA
5. Neurology Section, Dallas VA Medical Center, Dallas VA Medical Center, Dallas, TX, USA