1. Department of Internal Medicine, Singapore General Hospital , Singapore , Singapore
2. Department of Neurology, National Neuroscience Institute, Singapore General Hospital , Singapore , Singapore
3. Department of Neurosurgery, National Neuroscience Institute, Singapore General Hospital , Singapore , Singapore
4. Department of Diagnostic Radiology, Singapore General Hospital , Singapore , Singapore
5. Department of Infectious Disease, Singapore General Hospital , Singapore , Singapore
6. Department of Respiratory and Critical Care Medicine, Singapore General Hospital , Singapore , Singapore