[1] Mayo Clin, Dept Neurol, Phoenix, AZ 85054 USA
[2] Maricopa Integrated Hlth Syst, Dept Emergency Med, Phoenix, AZ USA
[3] Univ Calif San Diego, Dept Neurosci, Sch Med, San Diego, CA 92103 USA
[4] Univ Calif San Diego, Dept Family & Prevent Med, Sch Med, San Diego, CA 92103 USA
[5] Mayo Clin, Dept Radiol, Phoenix, AZ USA