1. Department of Neurology , Satakunta Central Hospital , Pori , Finland
2. Department of Neurology , University of Turku , Turku , Finland
3. Mutual Insurance Company Etera , Helsinki , Finland
4. Department of Neurosurgery , Helsinki University Central Hospital , Helsinki , Finland
5. Department of General Practice , Turku University and Turku University Hospital , Turku , Finland
6. Department of General Practice and Primary Health Care , University of Helsinki , Helsinki , Finland
7. Unit of Primary Health Care , Kuopio University Hospital , Kuopio , Finland
8. Folkhälsan Research Centre , Helsinki, University of Helsinki , Helsinki , Finland
9. Division of Clinical Neurosciences/General Neurology , Turku University Hospital , Turku , Finland