[1] Albert Einstein Coll Med, Dept Neurol, Bronx, NY 10467 USA
[2] Natl Multiple Sclerosis Soc, New York, NY USA
[3] St Agnes Hosp, Med Rehabil Res & Training Ctr Multiple Sclerosis, White Plains, NY USA
[4] Univ Arizona, Hlth Sci Ctr, Dept Neurol, Tucson, AZ USA
[5] Burke Rehabil Hosp, White Plains, NY USA