A lead anchor includes a first outer shell and a second outer shell adjacent the first outer shell. The first outer shell defines a first opening and the second outer shell defines a second opening, and the first and second outer shells together define a lead lumen extending from the first opening to the second opening. The lead anchor also includes a flexible sleeve disposed in the lead lumen and attached to both the first outer shell and the second outer shell. The first and second outer shells are configured and arranged to rotate relative to each other and cause the flexible sleeve to twist within the lead lumen to facilitate gripping of a lead within the lead lumen.
