Wai Hoe Ng1, Taufik Valiante. 1. Division of Neurosurgery, Department of Surgery, Toronto, Western Hospital, Toronto, Ontario, M5T 2S8, Canada. Departmento of Neurosurgery, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433, Singapore. wai_hoe_ng@nni.com.sg