1. Department of Neurology; The University of Utah; Salt Lake City UT USA
2. Department of Pediatrics; The Queen Silvia Children's Hospital; Sahlgrenska Academy at the University of Gothenburg; Gothenburg Sweden
3. Department of Neurology; London Health Science Centre; London ON Canada
4. Department of Orthopedics; The University of Utah; Salt Lake City UT USA
5. Division of Epidemiology; The University of Utah; Salt Lake City UT USA
6. Department of Neurology; The University of Rochester; Rochester NY USA