1. Parkinson and Movement Disorders Unit; Neurology Service; Institut Clínic de Neurociències; Hospital Clínic; Barcelona Spain
2. Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS); University of Barcelona; Barcelona Spain
3. Parkinson and Movement Disorders Unit - Neurology Service; Fundació Clínic per la Recerca Biomèdica; Barcelona Spain
4. Medical Statistics Core Facility; IDIBAPS (Hospital Clinic); Barcelona Spain
5. Biostatistics Unit; Faculty of Medicine; Universitat Autònoma de Barcelona; Barcelona Spain
6. Neurosurgery Service; Institut Clínic de Neurociències; Hospital Clínic; Barcelona Spain
7. Department of Surgery and Surgical Specialties; University of Barcelona; Barcelona Spain