Division of Neurology, Department of Medicine, Chulalongkorn University, Rama IV Road, Bangkok, 10330, Thailand. Electronic address: nijasris@yahoo.com. Chulalongkorn Stroke Center, King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Division of Neurology, Department of Medicine, Bhumibol Adulyadej Hospital, Bangkok, Thailand. Division of Clinical Epidemiology, Department of Medicine, Chulalongkorn University, Bangkok, Thailand. Division of Neurology, Department of Medicine, Thammasat University, Pathumtani, Thailand. Division of Neurology, Department of Medicine, Siriraj Hospital, Thailand. Division of Neurology, Department of Medicine, Chiang mai University, Chiang mai, Thailand. Division of Neurology, Department of Medicine, Khon kaen Univerisity, Khon kaen, Thailand. Department of Neurology and Comprehensive Stroke Center, David Geffen School of Medicine, University of California, Los Angeles, CA, United States.