an implantable lead is provided with at least one extendable member to position therapy delivery elements , which may be electrodes or drug delivery ports , after the lead has been inserted into the body . the lead may formed as a resilient element which is contained in a retainer tube that may be removed to permit the lead to deploy . alternatively , a non - resilient lead may be provided with a slotted retainer tube . a series of mechanical linkages for expanding and retracting the lead within the human body may be actuated with various mechanisms . a control system may be provided for closed - loop feedback control of the position of the extendable members . the invention also includes a method for expanding an implantable lead in situ .