[1] Franz Tappeiner Hosp, Dept Neurol, I-39012 Merano, BZ, Italy
[2] Paracelsus Med Univ, Dept Neurol, Christian Doppler Clin, Salzburg, Austria
[3] Paracelsus Med Univ, Inst Neurosci, Christian Doppler Clin, Salzburg, Austria
[4] Univ Pittsburgh, Dept Radiol, Med Ctr, Pittsburgh, PA 15260 USA