Apparatus for implanting an electrical stimulation lead

Abstract

In one embodiment, an introducer is provided for implanting an electrical stimulation lead to enable electrical stimulation of nerve tissue. The introducer includes an outer sheath and an inner penetrator. The outer sheath may accommodate insertion of the electrical stimulation lead and may be inserted into a human body near the nerve tissue. The inner penetrator is removably housed within the outer sheath and includes an inner channel configured to accommodate a guide wire, a tip end having a shape and size substantially conforming to that of the guide wire, a body region having a shape and size substantially conforming to that of the outer sheath, and one or more transition regions substantially connecting the tip end with the body region. At least a portion of the transition regions of the inner penetrator may flex to substantially follow flexures in the guide wire during advancement of the inner penetrator.

1 . A method of implanting an electrical stimulation lead in a minimally invasive percutaneous manner to enable electrical stimulation of a human's spinal nerve tissue, comprising:
 inserting a needle into the epidural space;   inserting a guide wire through the needle until an end of the guide wire is positioned in the epidural space at a desired location relative to the spinal nerve tissue to be stimulated;   removing the needle and leaving the guide wire substantially in position;   advancing an introducer, the introducer comprising an sheath and a penetrator removably housed within the sheath, the penetrator of the introducer comprising a channel configured to accommodate the guide wire and further comprising a body portion and a flexible tip portion with the tip portion configured to extend beyond the sheath, the tip portion having at least three transition regions for providing a transition between the body portion and the tip portion, along the guide wire until an end of the penetrator of the introducer is positioned in the epidural space at a desired location with respect to the spinal nerve tissue to be stimulated, the sheath of the introducer forming a tract as the penetrator of the introducer advances along the guide wire;   removing the guide wire and the penetrator of the introducer and leaving the sheath of the introducer substantially in position; and   inserting the electrical stimulation lead through the sheath of the introducer until the electrical stimulation lead is positioned in the epidural space proximate the spinal nerve tissue to be stimulated.   
     
     
         2 . The method of  claim 1 , wherein the three transition regions of the tip portion include a flexible tip region at the end of the tip portion, a middle region next to the tip region and the body region intermediate the middle region and the body portion. 
     
     
         3 . The method of  claim 2 , wherein the tip region has a substantially circular cross-section extending along the length of the tip region. 
     
     
         4 . The method of  claim 3 , wherein the tip region tapers from the middle region towards the end of the tip region. 
     
     
         5 . The method of  claim 4 , wherein the middle region has a substantially circular and constant cross-section extending the length of the middle region. 
     
     
         6 . The method of  claim 5 , wherein the body region tapers from the body toward the middle region at angle greater that the taper of the tip region. 
     
     
         7 . The method of  claim 6 , wherein the cross section of the body region and the sheath have cross-sections of the same shape. 
     
     
         8 . The method of  claim 6 , wherein the body region transitions from a substantially oval-cross-section adjacent the body to a substantially circular cross-section adjacent the middle region. 
     
     
         9 . A method of implanting a system to enable electrical stimulation of a human's nerve tissue, comprising:
 inserting a needle into tissue proximate nerve tissue to be stimulated;   inserting a guide wire through the needle until an end of the guide wire is positioned at a desired location relative to nerve tissue to be stimulated;   removing the needle and leaving the guide wire substantially in position;   advancing along a guide wire an introducer, the introducer comprising an sheath and a penetrator removably housed within the sheath, the penetrator of the introducer comprising a channel configured to accommodate the guide wire and further comprising a body portion and a flexible tip portion with the tip portion configured to extend beyond the sheath, the tip portion having at least three transition regions for providing a transition between the body portion and the tip portion, along the guide wire until an end of the penetrator of the introducer is positioned in the epidural space at a desired location with respect to the spinal nerve tissue to be stimulated, the sheath of the introducer forming a tract as the penetrator of the introducer advances along the guide wire;   removing the guide wire and the penetrator of the introducer and leaving the sheath of the introducer substantially in position;   inserting an electrical stimulation lead through the sheath of the introducer until the electrical stimulation lead is positioned proximate the nerve tissue to be stimulated;   removing the outer sheath;   connecting the electrical stimulation lead to a generator; creating a subcutaneous pocket for a generator; and   inserting the generator into the subcutaneous pocket.   
     
     
         10 . The method of  claim 9 , wherein the three transition regions of the tip portion include a flexible tip region at the end of the tip portion, a middle region next to the tip region and the body region intermediate the middle region and the body portion. 
     
     
         11 . The method of  claim 10 , wherein the tip region has a substantially circular cross-section extending along the length of the tip region. 
     
     
         12 . The method of  claim 11 , wherein the tip region tapers from the middle region towards the end of the tip region. 
     
     
         13 . The method of  claim 12 , wherein the middle region has a substantially circular and constant cross-section extending the length of the middle region. 
     
     
         14 . The method of  claim 13 , wherein the body region tapers from the body toward the middle region at angle greater that the taper of the tip region. 
     
     
         15 . The method of  claim 14 , wherein the cross section of the body region and the sheath have cross-sections of the same shape. 
     
     
         16 . The method of  claim 14 , wherein the body region transitions from a substantially oval-cross-section adjacent the body to a substantially circular cross-section adjacent the middle region.