[1] Natl Yang Ming Univ, Sch Med, Taipei 11221, Taiwan
[2] Triserv Gen Hosp, Dept Neurol Surg, Taipei 11490, Taiwan
[3] Natl Def Med Ctr, Taipei 11490, Taiwan
[4] Natl Def Med Ctr, Grad Inst Med Sci, Taipei 114, Taiwan
[5] Cheng Hsin Gen Hosp, Dept Neurosurg, Taipei 112, Taiwan
[6] Taipei Vet Gen Hosp, Dept Med Res & Educ, Taipei 11217, Taiwan
[7] Taipei Vet Gen Hosp, Dept Phys Med & Rehabil, Taipei 11217, Taiwan
[8] Taipei Vet Gen Hosp, Neurol Inst, Dept Neurosurg, Taipei 11217, Taiwan