 Balance test: The BalanSensTM kinematic sensor will be attached to the legs and lower back and will be used to measure the variation of subjects center of mass measured by the Romberg protocol including double stance, semi-tandem, and full-tandem tests. Patients will be asked to stand straight, feet together, hands crossed for 30 seconds, 20 seconds, and 15 seconds respectively for double stance test, semi-tendem, and full tandem tests with eyes open and closed. 