[1] Univ Western Ontario, Epilepsy Programme, London, ON N6A 5A5, Canada
[2] Univ Calgary, Dept Clin Neurosci, Calgary, AB, Canada
[3] NIH, Epilepsy Sect, Bethesda, MD 20892 USA
[4] Univ Texas Hlth Sci Ctr, Sch Publ Hlth, Houston, TX USA
[5] Univ Calif San Francisco, US Publ Hlth Serv, San Francisco, CA 94143 USA
[6] Ctr Dis Control & Prevent, Atlanta, GA USA