1. From the Department of Neurology, National Neuroscience Institute (Tan Tock Seng Hospital Campus), 11 Jalan Tan Tock Seng, Singapore 308433 Singapore
2. Division of Neurology, Department of Medicine, National University Health System, 1E Kent Ridge Road, Singapore 119228
3. Division of Neurology, Department of Medicine, Ng Teng Fong General Hospital: 1 Jurong East Street 21, Singapore 609606
4. Department of Diagnostic Imaging, National University Health System, 1E Kent Ridge Road, Singapore 119228
5. Department of Radiology, Ng Teng Fong General Hospital: 1 Jurong East Street 21, Singapore 609606