[1] Univ Calif San Francisco, Neurol, San Francisco, CA 94143 USA
[2] San Francisco VA Med Ctr, San Francisco, CA USA
[3] Med Coll Wisconsin, Milwaukee, WI 53226 USA
[4] Univ Calif San Francisco, Neurosurg, San Francisco, CA 94143 USA
[5] Virginia Commonwealth Univ, Neurosurg, Richmond, VA USA
[6] Spaulding Rehabil Hosp, Boston, MA USA