1. Department of Neurology, Haaglanden Medical Center, The Hague 2501 CK, The Netherlands
2. Department of Radiology, Haaglanden Medical Center, The Hague 2501 CK, The Netherlands
3. Department of Neurology, VU University Medical Center, Amsterdam 1007 MB, The Netherlands
4. Department of Neurology, Leiden University Medical Center, Leiden 2300 RA, The Netherlands