1. Department of Neurology, NYU Multiple Sclerosis Care Center, NYU School of Medicine, 240 East 38th St, 18th floor, New York, NY 10026, USA
2. Department of Neurology, NYU Multiple Sclerosis Care Center, NYU School of Medicine, New York, NY, USA
3. Department of Biostatistics, University of Alabama at Birmingham School of Public Health, Birmingham, AL, USA