1. Neurological Surgery Unit, Division of Surgery, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand;
2. Division of Anesthesiology, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand;
3. Division of Health and Applied Sciences, Faculty of Sciences, Prince of Songkla University, Hatyai, Songkhla, Thailand; and
4. Division of Internal Medicine, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand