[1] Univ Utah Hlth, Clin Neurosci Ctr, 175 North Med Dr East, Salt Lake City, UT 84132 USA
[2] Univ Louisville, Norton Childrens Hosp, Norton Leatherman Spine Ctr, Dept Orthoped,Pediat Orthoped, Louisville, KY USA
[3] Thomas Jefferson Univ, Delaware Valley SCI Ctr, Dept Neurol Surg, Div Spine & Peripheral Nerve Surg, Philadelphia, PA USA
[4] Thomas Jefferson Univ, Delaware Valley SCI Ctr, Dept Orthoped Surg, Div Spine & Peripheral Nerve Surg, Philadelphia, PA USA
[5] Univ Florida, Dept Neurosurg, Coll Med, Gainesville, FL USA
[6] Univ Florida, Dept Anesthesiol, Coll Med, Gainesville, FL USA
[7] Univ Calif San Francisco, Dept Neurosurg, San Francisco, CA USA
[8] Med Coll Wisconsin, Dept Neurosurg, Wauwatosa, WI USA