[1] Mayo Clin, Dept Neurol, 200 First St SW, Rochester, MN 55905 USA
[2] Univ Texas Southwestern, Dept Neurol, Dallas, TX USA
[3] Univ Texas Southwestern, Dept Family Med, Dallas, TX USA
[4] Univ Texas Southwestern, Dept Phys Med & Rehabil, Dallas, TX USA
[5] Mayo Clin, Dept Phys Med & Rehabil, Rochester, MN USA
[6] Mayo Clin, Dept Palliat Med, Rochester, MN USA