[1] CHA Univ, CHA Bundang Med Ctr, Dept Orthoped, Seongnam 13496, South Korea
[2] CHA Univ, Coll Life Sci, Dept Biomed Sci, Seongnam 13488, South Korea
[3] Shim Jeong Hosp, Dept Neurosurg, Seoul 08761, South Korea
[4] Baylor Colleage Med, Dept Neurosurg, Houston, TX 77030 USA
[5] CHA Univ, CHA Bundang Med Ctr, Dept Neurosurg, Seongnam 13496, South Korea