Implantable medical lead with threaded fixation

Abstract

The disclosure is directed to securing electrodes of a medical lead adjacent to a target tissue site. The medical lead may include one or more threaded fixation structures disposed circumferentially about the outer surface of the lead body, or elongated member, that resembles a “screw” or “auger.” During implantation, a clinician may rotate the entire lead to “screw” the lead into the tissue of the patient until electrodes of the lead reside adjacent to a target tissue. In this manner, the threaded fixation structure secures the lead within the patient to resist lead migration and improper therapy and provide a fine adjustment for depth of placement. The threaded fixation structure may be disposed on a portion of the lead proximal to or distal to the electrodes of the lead or over the portion of the lead that includes the electrodes.

1 . A medical lead comprising:
 an elongated member having a proximal end and a distal end;   at least one stimulation electrode disposed closer to the distal end of the lead than the proximal end of the lead; and   at least one threaded structure extending around a portion of an outer surface of the elongated member and configured to engage tissue within a patient to resist migration of the medical lead.   
   
   
       2 . The medical lead of  claim 1 , wherein the portion of the outer surface is proximal to the at least one stimulation electrode. 
   
   
       3 . The medical lead of  claim 1 , wherein the portion of the outer surface is distal to the at least one stimulation electrode. 
   
   
       4 . The medical lead of  claim 3 , further comprising a tapered tip at the distal end of the elongated member, wherein the tapered tip includes the portion. 
   
   
       5 . The medical lead of  claim 1 , wherein the portion of the outer surface includes the at least one stimulation electrode. 
   
   
       6 . The medical lead of  claim 1 , wherein a plurality of threaded fixation structures are formed around the portion of the outer surface of the elongated member to simulate a continuous threaded fixation structure. 
   
   
       7 . The medical lead of  claim 1 , wherein the threaded fixation structure is foldable in one direction to allow the thread structure to lay substantially flat against the elongated member when restrained by a sheath. 
   
   
       8 . The medical lead of  claim 1 , further comprising a helical reinforcement member disposed within an inner surface of the elongated member to provide torsional rigidity to the elongated member. 
   
   
       9 . The medical lead of  claim 8 , wherein the helical reinforcement member is disposed in a direction different than the direction of the threaded fixation structure. 
   
   
       10 . The medical lead of  claim 1 , wherein the threaded fixation structure comprises a pitch between adjacent threads or approximately 0.5 millimeters (mm) to approximately 3 mm. 
   
   
       11 . The medical lead of  claim 1 , wherein the threaded fixation structure comprises a thread height between approximately 0.1 millimeters (mm) and approximately 3 mm. 
   
   
       12 . The medical lead of  claim 1 , wherein the threaded fixation structure comprises at least one of a biocompatible metal alloy and a biocompatible polymer. 
   
   
       13 . A method comprising:
 inserting a medical lead into a patient, wherein the lead comprises at least one stimulation electrode and at least one threaded fixation structure extending around a portion of an outer surface of the lead; and   rotating the lead to engage the threaded fixation structure with tissue of the patient to resist migration of the lead.   
   
   
       14 . The method of  claim 13 , further comprising removing a sheath from the lead to expose the at least one threaded fixation structure after the lead is inserted into the patient. 
   
   
       15 . The method of  claim 14 , wherein removing the sheath allows the at least one threaded fixation structure to unfold and extend from the lead. 
   
   
       16 . The method of  claim 13 , further comprising generating electrical stimulation with a stimulator and delivering the electrical stimulation to the patient via the at least one stimulation electrode of the lead. 
   
   
       17 . The method of  claim 13 , further comprising rotating the lead to disengage the threaded fixation structure from the tissue in the patient. 
   
   
       18 . The method of  claim 13 , further comprising sliding a sheath over the lead to cover the at least one threaded fixation structure with the sheath. 
   
   
       19 . The method of  claim 18 , further comprising removing the lead and sheath from the patient 
   
   
       20 . The method of  claim 13 , wherein inserting a medical lead into a patient comprises forcing the at least one threaded fixation structure to fold down against the outer surface of the lead in a first direction. 
   
   
       21 . The method of  claim 20 , further comprising pulling the lead in the first direction to extend the at least one threaded fixation structure into the tissue, and wherein rotating the lead causes the at least one threaded fixation structure to advance the lead in a second direction opposite the first direction. 
   
   
       22 . The method of  claim 13 , further comprising positioning the at least one electrode adjacent to at least one of a sacral nerve, a pudendal nerve, a spinal cord, and an occipital nerve. 
   
   
       23 . A system comprising:
 a medical lead comprising:
 an elongated member having a proximal end and a distal end; 
 at least one stimulation electrode disposed closer to the distal end of the lead than the proximal end of the lead; and 
 at least one threaded structure extending around a portion of an outer surface of the elongated member and configured to engage tissue within a patient to resist migration of the medical lead; and 
   a stimulator that delivers electrical stimulation therapy to a patient via the medical lead within the patient.   
   
   
       24 . An apparatus comprising:
 an elongated member having a proximal end and a distal end;   a conduit disposed within the elongated member;   an exit port disposed on an outer surface of the elongated member in fluidic communication with the conduit; and   at least one threaded fixation structure extending around a portion of an outer surface of the elongated member and configured to engage tissue within a patient to resist migration of the medical lead.   
   
   
       25 . The apparatus of  claim 24 , wherein the exit port is disposed on an axial outer surface of the distal end of the elongated member. 
   
   
       26 . The apparatus of  claim 24 , wherein the exit port is disposed on a longitudinal outer surface of the elongated member. 
   
   
       27 . The apparatus of  claim 26 , wherein the at least one threaded fixation structure is disposed at least one of proximal to the exit port and distal to the exit port. 
   
   
       28 . The apparatus of  claim 24 , wherein the at least one threaded fixation structure is foldable in one direction to allow the thread structure to lay substantially flat against the elongated member when restrained by a sheath. 
   
   
       29 . The apparatus of  claim 24 , further comprising a helical reinforcement member disposed within an inner surface of the elongated member to provide torsional rigidity to the elongated member. 
   
   
       30 . The apparatus of  claim 29 , wherein the helical reinforcement member is disposed in a direction different than the direction of the at least one threaded fixation structure. 
   
   
       31 . The apparatus of  claim 24 , wherein the threaded fixation structure comprises a pitch between approximately 0.5 millimeters (mm) and 3 mm. 
   
   
       32 . The apparatus of  claim 24 , wherein the threaded fixation structure comprises a thread height between approximately 0.1 millimeters (mm) and 3 mm. 
   
   
       33 . The apparatus of  claim 24 , wherein the threaded fixation structure comprises at least one of a biocompatible metal alloy and a biocompatible polymer. 
   
   
       34 . The apparatus of  claim 24 , wherein the conduit delivers a therapeutic agent to the patient via the exit port.