 It is the most common of all involuntary movements and can affect the hands, arms, head, face, vocal cords, trunk, and legs.Ataxia is an unsteady and clumsy motion of the limbs or torso due to a failure of the gross coordination of muscle movements.People with ataxia experience a failure of muscle control in their arms and legs, resulting in a lack of balance and coordination or a disturbance of gait.