[1] Univ Calif San Francisco, Dept Anesthesiol, San Francisco, CA 94143 USA
[2] Pacific Pain Treatment Ctr, San Francisco, CA 94109 USA
[3] Napa Pain Inst, Napa, CA USA
[4] Vanderbilt Univ, Sch Med, Nashville, TN 37212 USA
[5] W Virginia Univ, Sch Med, Charleston, WV 25304 USA
[6] Univ Florida, Coll Med Jacksonville, Dept Neurosurg, Jacksonville, FL USA
[7] Univ Florida, Coll Med Jacksonville, Shands Jacksonville Neurosci Inst, Jacksonville, FL USA
[8] Touro Med Sch, Vallejo, CA USA