[1] Toronto Western Hosp, Dept Anesthesia & Pain Management, Toronto, ON, Canada
[2] Toronto Gen Hosp, Dept Anesthesia & Pain Management, Pain Res Unit, Eaton Wing,Ste 3-460,200 Elizabeth St, Toronto, ON M5G 2C4, Canada
[3] St Michaels Hosp, Li Ka Shing Knowledge Inst, Toronto, ON, Canada