1. Department of Neurology , , Hamburg 20246 , Germany
2. University Medical Center Hamburg-Eppendorf , , Hamburg 20246 , Germany
3. Institute of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf , Hamburg 20246 , Germany
4. Department of Neurology , , Leipzig 04103 , Germany
5. University Medical Center , , Leipzig 04103 , Germany