[1] McMaster Univ, Dept Anesthesia, Chron Pain Clin, Hamilton, ON, Canada
[2] Hosp Pablo Tobon Uribe, Clin Las Amer, Pain Clin, Dept Surg Anesthesia & Intervent Radiol, Medellin, Colombia
[3] Univ Toronto, Sunnybrook Hlth Sci Ctr, Dept Anesthesia, Toronto, ON M5S 1A1, Canada