1. Department of Clinical Medicine (M.C., S.H.J., L.-H.J., E.B.M.), UiT The Arctic University of Norway, Tromsø.
2. Department of Neurology, Nordland Hospital Trust, Bodø, Norway (M.C.).
3. Department of Community Medicine (T.W., M.-L.L., I.N.), UiT The Arctic University of Norway, Tromsø.
4. Department of Neurology (S.H.J., E.B.M.), University Hospital of North Norway, Tromsø.
5. Department of Radiology (L.-H.J.), University Hospital of North Norway, Tromsø.