[1] Charite Univ Med Berlin, Dept Neurosur, Berlin, Germany
[2] Univ Ulm, Dist Hosp Gunzburg, Neurosurg Dept, Ulm, Germany
[3] Klinikum Klagenfurt Worthersee, Dept Neurosurg & Neurorestaurat, Klagenfurt, Austria
[4] Christliches Krankenhaus Quakenbruck GmbH, Peripheral Nerve Unit Nord, Quakenbruck, Germany
[5] Helios Klinikum Erfurt, Dept Neurosurg, Erfurt, Germany
[6] Charite, Campus Benjamin Franklin, Klin Neurochirurg, Hindenburgdamm 30, D-12203 Berlin, Germany