[1] Natl Univ Singapore Hosp, Div Neurol, Dept Med, Singapore, Singapore
[2] Natl Univ Singapore Hosp, Yong Loo Lin Sch Med, Singapore, Singapore
[3] AbbVie, N Chicago, IL USA
[4] Kings Coll London, London, England
[5] Univ Calif Los Angeles, Los Angeles, CA USA