[1] Univ Uppsala Hosp, Dept Neurosci, S-78185 Uppsala, Sweden
[2] Karolinska Inst, Dept Clin Neurosci, Sect Personal Injury Prevent, Stockholm, Sweden
[3] Univ Alberta, Dept Publ Hlth Sci, Alberta Ctr Injury Control & Res, Edmonton, AB, Canada
[4] Univ Alberta, Dept Med, Edmonton, AB, Canada
[5] Univ Iowa, Ctr Hlth, Dept Internal Med, Iowa City, IA USA
[6] Karolinska Inst, Dept Neurosurg, Stockholm, Sweden
[7] Karolinska Inst, Dept Neuroradiol, Stockholm, Sweden