[1] New York Med Coll, Sch Med, Valhalla, NY USA
[2] Univ New Mexico Hosp, Dept Neurosurg, Albuquerque, NM USA
[3] Univ Utah, Sch Med, Salt Lake City, UT USA
[4] Westchester Med Ctr, Dept Neurosurg, Valhalla, NY USA
[5] New York Med Coll, Valhalla, NY USA
[6] Univ New Mexico, Dept Surg, Albuquerque, NM USA
[7] Univ Utah, Dept Neurosurg, Clin Neurosci Ctr, Salt Lake City, UT USA