[1] UCSF, Neurol, San Francisco, CA USA
[2] SFVAMC, San Francisco, CA USA
[3] Univ Calif San Francisco, San Francisco, CA 94143 USA
[4] Harvard Med Sch, Brigham & Womens Hosp, Massachusetts Gen Hosp, Phys Med & Rehabil,Spaulding Rehabil Hosp, Charlestown, MA USA
[5] Univ Calif San Francisco, Neurosurg, San Francisco, CA 94143 USA