Embodiments of the present disclosure include medical devices and methods including a medical device including: an elongate core element, and a generally tubular torsion element surrounding the core element and capable of transmitting torque along its length. The torsion element has a spiral incision that has a proximal end and a distal end. The spiral incision forms a helically coiled strip between the proximal and distal ends of the spiral incision. The helically coiled strip varies in width from the proximal end of the spiral incision to the distal end of the spiral incision and has a narrowest portion. The helically coiled strip bows radially outward at the narrowest portion when the helically coiled strip in the torsion element is unwound.
