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.