作者单位:UCSF, San Francisco, CA USA[1]Univ Pittsburgh, Pittsburgh, PA USA[2]Baylor Coll Med, Neurosurg, Houston, TX 77030 USA[3]Michael E De Bakey Vet Affairs Med Ctr, Houston, TX USA[4]Univ Washington, Neurol Surg, Seattle, WA 98195 USA[5]Spaulding Rehabil Hosp, Boston, MA USA[6]Univ Texas Sch Publ Hlth, Houston, TX USA[7]