[1] Heinrich Heine Univ Dusseldorf, Med Fac, Dept Neurosurg, Moorenstr 5, Dusseldorf, Germany
[2] Heinrich Heine Univ Dusseldorf, Univ Hosp Dusseldorf, Moorenstr 5, Dusseldorf, Germany
[3] Int Neurosci Inst, Dept Neurosurg, Hannover, Germany
[4] King Edward Med Univ, Dept Neurosurg, Lahore, Pakistan
[5] Univ Helsinki, Dept Neurosurg, Helsinki, Finland
[6] Helsinki Univ Hosp, Helsinki, Finland