Medical devices for nerve modulation through the wall of a blood vessel are disclosed. The medical device may include an elongate member having a proximal end and a distal end. A hollow ablation member may be disposed at the distal end of the elongate member and includes a number of electrodes positioned on its outer surface. The ablation member may be configured to shift between a collapsed position and an expanded position such that that a portion of the ablation member can be brought into contact with the wall of the blood vessel or placed adjacent to the wall of the blood vessel. The ablation member may also be retractable from the blood vessel treatment site.
