Lead body and method of lead body construction
In one embodiment, a neurostimulation lead, comprises: a lead body, the lead body comprising an inner insulator, an outer insulator positioned around the inner insulator, wherein the outer insulator and the inner insulator are fused together; at least one conductor that is wound between the inner insulator and the outer insulator; and at least one electrode that is electrically coupled to the at least one conductor.
1. A method for manufacturing a neurostimulation lead, comprising:
providing a mandrel having inner insulating material disposed intermediate a first end and a second end of the mandrel, wherein the mandrel extends beyond the inner insulating material at the first end and the second end of the mandrel;
securing respective first ends of a plurality of conductors to the first end of the mandrel;
positioning the plurality of conductors spirally around the inner insulating material and securing respective second ends of the plurality of conductors to the second end of the mandrel;
providing at least one insulating spacer;
spirally winding the at least one insulating spacer between an adjacent pair of conductors of the plurality of conductors;
disposing an outer insulating material around the wound plurality of conductors coextensive with the inner insulating material;
fusing the inner insulating material, the at least one insulating space, and the outer insulating material to each other to form a lead assembly;
forming a lead body from the lead assembly; and
forming a stimulation lead, from the lead body, adapted for stimulation of neural tissue, the stimulation lead comprising at least one electrode.
2. A method, as in claim 1 , wherein the fusing comprises:
disposing shrink-wrap tubing over the outer insulating material; and
heating the shrink-wrap, the outer insulating material, the at least one insulating spacer, and the inner insulating material to shrink the shrink-wrap tubing and fuse the outer insulating material, at least one insulating spacer, and the inner insulating material.
3. A method, as in claim 1 , wherein the fusing comprises:
disposing tubing over the outer insulating material;
sealing a first end of the tubing;
applying a partial vacuum to a second end of the tubing; and
heating the tubing, wherein the partial vacuum draws the outer insulating material, the at least one insulating spacer, and the inner insulating material into contact and the heating fuses the outer insulating material, the at least one insulating spacer, and the inner insulating material thereby encapsulating the plurality of conductors.
4. A method, as in claim 1 , further comprising:
removing the mandrel from the inner insulator to form a lumen.
5. A method, as in claim 2 , further comprising:
removing the shrink-wrap material.
6. A method, as in claim 1 , wherein the inner insulating material, the at least one insulating spacer, and the outer insulating material comprise material selected from the group consisting of polyurethane and silicone rubber.
7. A method of fabricating a lead for spinal neurological stimulation, comprising:
providing a first insulator layer; spirally wrapping a plurality of conductors about the first insulator layer;
spirally wrapping at least one insulating spacer about the first insulator layer in between at least two adjacent conductors of the plurality of conductors;
providing a second insulator layer over the plurality of conductors and the at least one insulating spacer;
fusing the first insulator layer, the at least one insulating spacer, and the second insulator layer to each other to form a lead body, wherein the plurality of conductors and the at least one insulating spacer extend substantially along the length of the lead body, the at least one spacer maintaining a pitch between the at least two adjacent conductors substantially along the length of the lead body; and
forming a lead, from the lead body, for spinal neurological stimulation, the lead comprising a plurality of electrodes.
8. The method of claim 7 wherein the at least one insulating spacer is wrapped about the first insulator layer simultaneously with the wrapping of the plurality of conductors.
9. The method of claim 7 wherein the first insulator layer, the at least one insulating spacer, and the second insulator layer have similar melting points.
10. The method of claim 7 wherein the fusing comprising:
applying heat to the first insulator layer, the at least one insulating spacer, and the second insulator layer to adhere the first insulator layer, the at least one insulating spacer, and the second insulator layer to each other without substantially disrupting their respective shapes.