An electrode assembly includes one or more electrode contact surfaces, and a cuff, to which the contact surfaces are fixed, and which comprises an electrically insulating material, is configured to assume open and closed positions, and, when in the closed position, is shaped so as to define a plurality of planar cross sections perpendicular to a longitudinal axis of the cuff, distributed continuously along an entire length of the cuff along the longitudinal axis, such that the perpendicular cross sections define respective inner closed curves that together define an inner surface that defines and completely surrounds a volume that extends along the entire length of the cuff. The inner closed curves of at least two of the perpendicular cross sections would cross, and not merely intersect, one another if superimposed while preserving orientation and position of the perpendicular cross sections with respect to the cuff. Other embodiments are also described.