[1] Univ Texas Hlth Sci Ctr Houston, McGovern Med Sch, Dept Anesthesiol, Div Reg Anesthesiol & Acute Pain Med, Houston, TX 77030 USA
[2] Univ Florida, Dept Neurol, Div Trauma Concuss & Sports Neuromed, Coll Med, Gainesville, FL 32610 USA
[3] McGovern Med Sch, Dept Anesthesiol, Div Chron Pain Management, Houston, TX 77030 USA
[4] Harvard Med Sch, Dept Anesthesiol, Beth Israel Deaconness Med Ctr, Boston, MA 02115 USA