1. Carver College of Medicine, Department of Neurology, The University of Iowa, Iowa City, IA, USA;
2. Department of Neurology, The University of Florida, Gainesville, FL, USA;
3. Department of Biomedical Engineering, The University of Iowa, Iowa City, IA, USA;
4. Muscular Dystrophy Association, Cedar Rapids, IA, USA;
5. Department of Neurosurgery, The University of Florida, Gainesville, FL, USA