[1] Lund Univ, Inst Clin Sci, Dept Neurosurg, Lund, Sweden
[2] Karolinska Univ Hosp, Dept Neurosurg, Stockholm, Sweden
[3] Rigshosp, Dept Neurosurg, Copenhagen, Denmark
[4] Karolinska Inst, Dept Clin Neurosci & Med, Stockholm, Sweden
[5] St Olavs Hosp, Dept Neurosurg, Trondheim, Norway
[6] Sahlgrens Univ Hosp, Dept Neurosurg, Gothenburg, Sweden
[7] Univ Gothenburg, Sahlgrenska Acad, Inst Neurosci & Physiol, Dept Clin Neurosci, Gothenburg, Sweden